File:  [LON-CAPA] / loncom / lond
Revision 1.409: download - view: text, annotated - select for diffs
Tue Oct 7 10:08:06 2008 UTC (14 years ago) by foxr
Branches: MAIN
CVS tags: version_2_7_99_0, HEAD
Documented log messages that can be emitted as POD entries.

#!/usr/bin/perl
# The LearningOnline Network
# lond "LON Daemon" Server (port "LOND" 5663)
#
# $Id: lond,v 1.409 2008/10/07 10:08:06 foxr Exp $
#
# Copyright Michigan State University Board of Trustees
#
# This file is part of the LearningOnline Network with CAPA (LON-CAPA).
#
# LON-CAPA is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or 
# (at your option) any later version.
#
# LON-CAPA is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with LON-CAPA; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
#
# /home/httpd/html/adm/gpl.txt
#


# http://www.lon-capa.org/
#

use strict;
use lib '/home/httpd/lib/perl/';
use LONCAPA;
use LONCAPA::Configuration;

use IO::Socket;
use IO::File;
#use Apache::File;
use POSIX;
use Crypt::IDEA;
use LWP::UserAgent();
use Digest::MD5 qw(md5_hex);
use GDBM_File;
use Authen::Krb4;
use Authen::Krb5;
use localauth;
use localenroll;
use localstudentphoto;
use File::Copy;
use File::Find;
use LONCAPA::lonlocal;
use LONCAPA::lonssl;
use Fcntl qw(:flock);
use Apache::lonnet;

my $DEBUG = 0;		       # Non zero to enable debug log entries.

my $status='';
my $lastlog='';

my $VERSION='$Revision: 1.409 $'; #' stupid emacs
my $remoteVERSION;
my $currenthostid="default";
my $currentdomainid;

my $client;
my $clientip;			# IP address of client.
my $clientname;			# LonCAPA name of client.

my $server;

my $keymode;

my $cipher;			# Cipher key negotiated with client
my $tmpsnum = 0;		# Id of tmpputs.

# 
#   Connection type is:
#      client                   - All client actions are allowed
#      manager                  - only management functions allowed.
#      both                     - Both management and client actions are allowed
#

my $ConnectionType;

my %managers;			# Ip -> manager names

my %perlvar;			# Will have the apache conf defined perl vars.

#
#   The hash below is used for command dispatching, and is therefore keyed on the request keyword.
#    Each element of the hash contains a reference to an array that contains:
#          A reference to a sub that executes the request corresponding to the keyword.
#          A flag that is true if the request must be encoded to be acceptable.
#          A mask with bits as follows:
#                      CLIENT_OK    - Set when the function is allowed by ordinary clients
#                      MANAGER_OK   - Set when the function is allowed to manager clients.
#
my $CLIENT_OK  = 1;
my $MANAGER_OK = 2;
my %Dispatcher;


#
#  The array below are password error strings."
#
my $lastpwderror    = 13;		# Largest error number from lcpasswd.
my @passwderrors = ("ok",
		   "pwchange_failure - lcpasswd must be run as user 'www'",
		   "pwchange_failure - lcpasswd got incorrect number of arguments",
		   "pwchange_failure - lcpasswd did not get the right nubmer of input text lines",
		   "pwchange_failure - lcpasswd too many simultaneous pwd changes in progress",
		   "pwchange_failure - lcpasswd User does not exist.",
		   "pwchange_failure - lcpasswd Incorrect current passwd",
		   "pwchange_failure - lcpasswd Unable to su to root.",
		   "pwchange_failure - lcpasswd Cannot set new passwd.",
		   "pwchange_failure - lcpasswd Username has invalid characters",
		   "pwchange_failure - lcpasswd Invalid characters in password",
		   "pwchange_failure - lcpasswd User already exists", 
                   "pwchange_failure - lcpasswd Something went wrong with user addition.",
		   "pwchange_failure - lcpasswd Password mismatch",
		   "pwchange_failure - lcpasswd Error filename is invalid");


#  The array below are lcuseradd error strings.:

my $lastadderror = 13;
my @adderrors    = ("ok",
		    "User ID mismatch, lcuseradd must run as user www",
		    "lcuseradd Incorrect number of command line parameters must be 3",
		    "lcuseradd Incorrect number of stdinput lines, must be 3",
		    "lcuseradd Too many other simultaneous pwd changes in progress",
		    "lcuseradd User does not exist",
		    "lcuseradd Unable to make www member of users's group",
		    "lcuseradd Unable to su to root",
		    "lcuseradd Unable to set password",
		    "lcuseradd Username has invalid characters",
		    "lcuseradd Password has an invalid character",
		    "lcuseradd User already exists",
		    "lcuseradd Could not add user.",
		    "lcuseradd Password mismatch");



#
#   Statistics that are maintained and dislayed in the status line.
#
my $Transactions = 0;		# Number of attempted transactions.
my $Failures     = 0;		# Number of transcations failed.

#   ResetStatistics: 
#      Resets the statistics counters:
#
sub ResetStatistics {
    $Transactions = 0;
    $Failures     = 0;
}

#------------------------------------------------------------------------
#
#   LocalConnection
#     Completes the formation of a locally authenticated connection.
#     This function will ensure that the 'remote' client is really the
#     local host.  If not, the connection is closed, and the function fails.
#     If so, initcmd is parsed for the name of a file containing the
#     IDEA session key.  The fie is opened, read, deleted and the session
#     key returned to the caller.
#
# Parameters:
#   $Socket      - Socket open on client.
#   $initcmd     - The full text of the init command.
#
# Returns:
#     IDEA session key on success.
#     undef on failure.
#
sub LocalConnection {
    my ($Socket, $initcmd) = @_;
    Debug("Attempting local connection: $initcmd client: $clientip");
    if($clientip ne "127.0.0.1") {
	&logthis('<font color="red"> LocalConnection rejecting non local: '
		 ."$clientip ne 127.0.0.1 </font>");
	close $Socket;
	return undef;
    }  else {
	chomp($initcmd);	# Get rid of \n in filename.
	my ($init, $type, $name) = split(/:/, $initcmd);
	Debug(" Init command: $init $type $name ");

	# Require that $init = init, and $type = local:  Otherwise
	# the caller is insane:

	if(($init ne "init") && ($type ne "local")) {
	    &logthis('<font color = "red"> LocalConnection: caller is insane! '
		     ."init = $init, and type = $type </font>");
	    close($Socket);;
	    return undef;
		
	}
	#  Now get the key filename:

	my $IDEAKey = lonlocal::ReadKeyFile($name);
	return $IDEAKey;
    }
}
#------------------------------------------------------------------------------
#
#  SSLConnection
#   Completes the formation of an ssh authenticated connection. The
#   socket is promoted to an ssl socket.  If this promotion and the associated
#   certificate exchange are successful, the IDEA key is generated and sent
#   to the remote peer via the SSL tunnel. The IDEA key is also returned to
#   the caller after the SSL tunnel is torn down.
#
# Parameters:
#   Name              Type             Purpose
#   $Socket          IO::Socket::INET  Plaintext socket.
#
# Returns:
#    IDEA key on success.
#    undef on failure.
#
sub SSLConnection {
    my $Socket   = shift;

    Debug("SSLConnection: ");
    my $KeyFile         = lonssl::KeyFile();
    if(!$KeyFile) {
	my $err = lonssl::LastError();
	&logthis("<font color=\"red\"> CRITICAL"
		 ."Can't get key file $err </font>");
	return undef;
    }
    my ($CACertificate,
	$Certificate) = lonssl::CertificateFile();


    # If any of the key, certificate or certificate authority 
    # certificate filenames are not defined, this can't work.

    if((!$Certificate) || (!$CACertificate)) {
	my $err = lonssl::LastError();
	&logthis("<font color=\"red\"> CRITICAL"
		 ."Can't get certificates: $err </font>");

	return undef;
    }
    Debug("Key: $KeyFile CA: $CACertificate Cert: $Certificate");

    # Indicate to our peer that we can procede with
    # a transition to ssl authentication:

    print $Socket "ok:ssl\n";

    Debug("Approving promotion -> ssl");
    #  And do so:

    my $SSLSocket = lonssl::PromoteServerSocket($Socket,
						$CACertificate,
						$Certificate,
						$KeyFile);
    if(! ($SSLSocket) ) {	# SSL socket promotion failed.
	my $err = lonssl::LastError();
	&logthis("<font color=\"red\"> CRITICAL "
		 ."SSL Socket promotion failed: $err </font>");
	return undef;
    }
    Debug("SSL Promotion successful");

    # 
    #  The only thing we'll use the socket for is to send the IDEA key
    #  to the peer:

    my $Key = lonlocal::CreateCipherKey();
    print $SSLSocket "$Key\n";

    lonssl::Close($SSLSocket); 

    Debug("Key exchange complete: $Key");

    return $Key;
}
#
#     InsecureConnection: 
#        If insecure connections are allowd,
#        exchange a challenge with the client to 'validate' the
#        client (not really, but that's the protocol):
#        We produce a challenge string that's sent to the client.
#        The client must then echo the challenge verbatim to us.
#
#  Parameter:
#      Socket      - Socket open on the client.
#  Returns:
#      1           - success.
#      0           - failure (e.g.mismatch or insecure not allowed).
#
sub InsecureConnection {
    my $Socket  =  shift;

    #   Don't even start if insecure connections are not allowed.

    if(! $perlvar{londAllowInsecure}) {	# Insecure connections not allowed.
	return 0;
    }

    #   Fabricate a challenge string and send it..

    my $challenge = "$$".time;	# pid + time.
    print $Socket "$challenge\n";
    &status("Waiting for challenge reply");

    my $answer = <$Socket>;
    $answer    =~s/\W//g;
    if($challenge eq $answer) {
	return 1;
    } else {
	logthis("<font color='blue'>WARNING client did not respond to challenge</font>");
	&status("No challenge reqply");
	return 0;
    }
    

}
#
#   Safely execute a command (as long as it's not a shel command and doesn
#   not require/rely on shell escapes.   The function operates by doing a
#   a pipe based fork and capturing stdout and stderr  from the pipe.
#
# Formal Parameters:
#     $line                    - A line of text to be executed as a command.
# Returns:
#     The output from that command.  If the output is multiline the caller
#     must know how to split up the output.
#
#
sub execute_command {
    my ($line)    = @_;
    my @words     = split(/\s/, $line);	# Bust the command up into words.
    my $output    = "";

    my $pid = open(CHILD, "-|");
    
    if($pid) {			# Parent process
	Debug("In parent process for execute_command");
	my @data = <CHILD>;	# Read the child's outupt...
	close CHILD;
	foreach my $output_line (@data) {
	    Debug("Adding $output_line");
	    $output .= $output_line; # Presumably has a \n on it.
	}

    } else {			# Child process
	close (STDERR);
	open  (STDERR, ">&STDOUT");# Combine stderr, and stdout...
	exec(@words);		# won't return.
    }
    return $output;
}


#   GetCertificate: Given a transaction that requires a certificate,
#   this function will extract the certificate from the transaction
#   request.  Note that at this point, the only concept of a certificate
#   is the hostname to which we are connected.
#
#   Parameter:
#      request   - The request sent by our client (this parameterization may
#                  need to change when we really use a certificate granting
#                  authority.
#
sub GetCertificate {
    my $request = shift;

    return $clientip;
}

#
#   Return true if client is a manager.
#
sub isManager {
    return (($ConnectionType eq "manager") || ($ConnectionType eq "both"));
}
#
#   Return tru if client can do client functions
#
sub isClient {
    return (($ConnectionType eq "client") || ($ConnectionType eq "both"));
}


#
#   ReadManagerTable: Reads in the current manager table. For now this is
#                     done on each manager authentication because:
#                     - These authentications are not frequent
#                     - This allows dynamic changes to the manager table
#                       without the need to signal to the lond.
#
sub ReadManagerTable {

    #   Clean out the old table first..

   foreach my $key (keys %managers) {
      delete $managers{$key};
   }

   my $tablename = $perlvar{'lonTabDir'}."/managers.tab";
   if (!open (MANAGERS, $tablename)) {
      logthis('<font color="red">No manager table.  Nobody can manage!!</font>');
      return;
   }
   while(my $host = <MANAGERS>) {
      chomp($host);
      if ($host =~ "^#") {                  # Comment line.
         next;
      }
      if (!defined &Apache::lonnet::get_host_ip($host)) { # This is a non cluster member
	    #  The entry is of the form:
	    #    cluname:hostname
	    #  cluname - A 'cluster hostname' is needed in order to negotiate
	    #            the host key.
	    #  hostname- The dns name of the host.
	    #
          my($cluname, $dnsname) = split(/:/, $host);
          
          my $ip = gethostbyname($dnsname);
          if(defined($ip)) {                 # bad names don't deserve entry.
            my $hostip = inet_ntoa($ip);
            $managers{$hostip} = $cluname;
            logthis('<font color="green"> registering manager '.
                    "$dnsname as $cluname with $hostip </font>\n");
         }
      } else {
         logthis('<font color="green"> existing host'." $host</font>\n");
         $managers{&Apache::lonnet::get_host_ip($host)} = $host;  # Use info from cluster tab if clumemeber
      }
   }
}

#
#  ValidManager: Determines if a given certificate represents a valid manager.
#                in this primitive implementation, the 'certificate' is
#                just the connecting loncapa client name.  This is checked
#                against a valid client list in the configuration.
#
#                  
sub ValidManager {
    my $certificate = shift; 

    return isManager;
}
#
#  CopyFile:  Called as part of the process of installing a 
#             new configuration file.  This function copies an existing
#             file to a backup file.
# Parameters:
#     oldfile  - Name of the file to backup.
#     newfile  - Name of the backup file.
# Return:
#     0   - Failure (errno has failure reason).
#     1   - Success.
#
sub CopyFile {

    my ($oldfile, $newfile) = @_;

    if (! copy($oldfile,$newfile)) {
        return 0;
    }
    chmod(0660, $newfile);
    return 1;
}
#
#  Host files are passed out with externally visible host IPs.
#  If, for example, we are behind a fire-wall or NAT host, our 
#  internally visible IP may be different than the externally
#  visible IP.  Therefore, we always adjust the contents of the
#  host file so that the entry for ME is the IP that we believe
#  we have.  At present, this is defined as the entry that
#  DNS has for us.  If by some chance we are not able to get a
#  DNS translation for us, then we assume that the host.tab file
#  is correct.  
#    BUGBUGBUG - in the future, we really should see if we can
#       easily query the interface(s) instead.
# Parameter(s):
#     contents    - The contents of the host.tab to check.
# Returns:
#     newcontents - The adjusted contents.
#
#
sub AdjustHostContents {
    my $contents  = shift;
    my $adjusted;
    my $me        = $perlvar{'lonHostID'};

    foreach my $line (split(/\n/,$contents)) {
	if(!(($line eq "") || ($line =~ /^ *\#/) || ($line =~ /^ *$/))) {
	    chomp($line);
	    my ($id,$domain,$role,$name,$ip,$maxcon,$idleto,$mincon)=split(/:/,$line);
	    if ($id eq $me) {
		my $ip = gethostbyname($name);
		my $ipnew = inet_ntoa($ip);
		$ip = $ipnew;
		#  Reconstruct the host line and append to adjusted:
		
		my $newline = "$id:$domain:$role:$name:$ip";
		if($maxcon ne "") { # Not all hosts have loncnew tuning params
		    $newline .= ":$maxcon:$idleto:$mincon";
		}
		$adjusted .= $newline."\n";
		
	    } else {		# Not me, pass unmodified.
		$adjusted .= $line."\n";
	    }
	} else {                  # Blank or comment never re-written.
	    $adjusted .= $line."\n";	# Pass blanks and comments as is.
	}
    }
    return $adjusted;
}
#
#   InstallFile: Called to install an administrative file:
#       - The file is created with <name>.tmp
#       - The <name>.tmp file is then mv'd to <name>
#   This lugubrious procedure is done to ensure that we are never without
#   a valid, even if dated, version of the file regardless of who crashes
#   and when the crash occurs.
#
#  Parameters:
#       Name of the file
#       File Contents.
#  Return:
#      nonzero - success.
#      0       - failure and $! has an errno.
#
sub InstallFile {

    my ($Filename, $Contents) = @_;
    my $TempFile = $Filename.".tmp";

    #  Open the file for write:

    my $fh = IO::File->new("> $TempFile"); # Write to temp.
    if(!(defined $fh)) {
	&logthis('<font color="red"> Unable to create '.$TempFile."</font>");
	return 0;
    }
    #  write the contents of the file:

    print $fh ($Contents); 
    $fh->close;			# In case we ever have a filesystem w. locking

    chmod(0660, $TempFile);

    # Now we can move install the file in position.
    
    move($TempFile, $Filename);

    return 1;
}


#
#   ConfigFileFromSelector: converts a configuration file selector
#                 (one of host or domain at this point) into a 
#                 configuration file pathname.
#
#  Parameters:
#      selector  - Configuration file selector.
#  Returns:
#      Full path to the file or undef if the selector is invalid.
#
sub ConfigFileFromSelector {
    my $selector   = shift;
    my $tablefile;

    my $tabledir = $perlvar{'lonTabDir'}.'/';
    if ($selector eq "hosts") {
	$tablefile = $tabledir."hosts.tab";
    } elsif ($selector eq "domain") {
	$tablefile = $tabledir."domain.tab";
    } else {
	return undef;
    }
    return $tablefile;

}
#
#   PushFile:  Called to do an administrative push of a file.
#              - Ensure the file being pushed is one we support.
#              - Backup the old file to <filename.saved>
#              - Separate the contents of the new file out from the
#                rest of the request.
#              - Write the new file.
#  Parameter:
#     Request - The entire user request.  This consists of a : separated
#               string pushfile:tablename:contents.
#     NOTE:  The contents may have :'s in it as well making things a bit
#            more interesting... but not much.
#  Returns:
#     String to send to client ("ok" or "refused" if bad file).
#
sub PushFile {
    my $request = shift;    
    my ($command, $filename, $contents) = split(":", $request, 3);
    
    #  At this point in time, pushes for only the following tables are
    #  supported:
    #   hosts.tab  ($filename eq host).
    #   domain.tab ($filename eq domain).
    # Construct the destination filename or reject the request.
    #
    # lonManage is supposed to ensure this, however this session could be
    # part of some elaborate spoof that managed somehow to authenticate.
    #


    my $tablefile = ConfigFileFromSelector($filename);
    if(! (defined $tablefile)) {
	return "refused";
    }
    #
    # >copy< the old table to the backup table
    #        don't rename in case system crashes/reboots etc. in the time
    #        window between a rename and write.
    #
    my $backupfile = $tablefile;
    $backupfile    =~ s/\.tab$/.old/;
    if(!CopyFile($tablefile, $backupfile)) {
	&logthis('<font color="green"> CopyFile from '.$tablefile." to ".$backupfile." failed </font>");
	return "error:$!";
    }
    &logthis('<font color="green"> Pushfile: backed up '
	    .$tablefile." to $backupfile</font>");
    
    #  If the file being pushed is the host file, we adjust the entry for ourself so that the
    #  IP will be our current IP as looked up in dns.  Note this is only 99% good as it's possible
    #  to conceive of conditions where we don't have a DNS entry locally.  This is possible in a 
    #  network sense but it doesn't make much sense in a LonCAPA sense so we ignore (for now)
    #  that possibilty.

    if($filename eq "host") {
	$contents = AdjustHostContents($contents);
    }

    #  Install the new file:

    if(!InstallFile($tablefile, $contents)) {
	&logthis('<font color="red"> Pushfile: unable to install '
	 .$tablefile." $! </font>");
	return "error:$!";
    } else {
	&logthis('<font color="green"> Installed new '.$tablefile
		 ."</font>");

    }


    #  Indicate success:
 
    return "ok";

}

#
#  Called to re-init either lonc or lond.
#
#  Parameters:
#    request   - The full request by the client.  This is of the form
#                reinit:<process>  
#                where <process> is allowed to be either of 
#                lonc or lond
#
#  Returns:
#     The string to be sent back to the client either:
#   ok         - Everything worked just fine.
#   error:why  - There was a failure and why describes the reason.
#
#
sub ReinitProcess {
    my $request = shift;


    # separate the request (reinit) from the process identifier and
    # validate it producing the name of the .pid file for the process.
    #
    #
    my ($junk, $process) = split(":", $request);
    my $processpidfile = $perlvar{'lonDaemons'}.'/logs/';
    if($process eq 'lonc') {
	$processpidfile = $processpidfile."lonc.pid";
	if (!open(PIDFILE, "< $processpidfile")) {
	    return "error:Open failed for $processpidfile";
	}
	my $loncpid = <PIDFILE>;
	close(PIDFILE);
	logthis('<font color="red"> Reinitializing lonc pid='.$loncpid
		."</font>");
	kill("USR2", $loncpid);
    } elsif ($process eq 'lond') {
	logthis('<font color="red"> Reinitializing self (lond) </font>');
	&UpdateHosts;			# Lond is us!!
    } else {
	&logthis('<font color="yellow" Invalid reinit request for '.$process
		 ."</font>");
	return "error:Invalid process identifier $process";
    }
    return 'ok';
}
#   Validate a line in a configuration file edit script:
#   Validation includes:
#     - Ensuring the command is valid.
#     - Ensuring the command has sufficient parameters
#   Parameters:
#     scriptline - A line to validate (\n has been stripped for what it's worth).
#
#   Return:
#      0     - Invalid scriptline.
#      1     - Valid scriptline
#  NOTE:
#     Only the command syntax is checked, not the executability of the
#     command.
#
sub isValidEditCommand {
    my $scriptline = shift;

    #   Line elements are pipe separated:

    my ($command, $key, $newline)  = split(/\|/, $scriptline);
    &logthis('<font color="green"> isValideditCommand checking: '.
	     "Command = '$command', Key = '$key', Newline = '$newline' </font>\n");
    
    if ($command eq "delete") {
	#
	#   key with no newline.
	#
	if( ($key eq "") || ($newline ne "")) {
	    return 0;		# Must have key but no newline.
	} else {
	    return 1;		# Valid syntax.
	}
    } elsif ($command eq "replace") {
	#
	#   key and newline:
	#
	if (($key eq "") || ($newline eq "")) {
	    return 0;
	} else {
	    return 1;
	}
    } elsif ($command eq "append") {
	if (($key ne "") && ($newline eq "")) {
	    return 1;
	} else {
	    return 0;
	}
    } else {
	return 0;		# Invalid command.
    }
    return 0;			# Should not get here!!!
}
#
#   ApplyEdit - Applies an edit command to a line in a configuration 
#               file.  It is the caller's responsiblity to validate the
#               edit line.
#   Parameters:
#      $directive - A single edit directive to apply.  
#                   Edit directives are of the form:
#                  append|newline      - Appends a new line to the file.
#                  replace|key|newline - Replaces the line with key value 'key'
#                  delete|key          - Deletes the line with key value 'key'.
#      $editor   - A config file editor object that contains the
#                  file being edited.
#
sub ApplyEdit {

    my ($directive, $editor) = @_;

    # Break the directive down into its command and its parameters
    # (at most two at this point.  The meaning of the parameters, if in fact
    #  they exist depends on the command).

    my ($command, $p1, $p2) = split(/\|/, $directive);

    if($command eq "append") {
	$editor->Append($p1);	          # p1 - key p2 null.
    } elsif ($command eq "replace") {
	$editor->ReplaceLine($p1, $p2);   # p1 - key p2 = newline.
    } elsif ($command eq "delete") {
	$editor->DeleteLine($p1);         # p1 - key p2 null.
    } else {			          # Should not get here!!!
	die "Invalid command given to ApplyEdit $command"
    }
}
#
# AdjustOurHost:
#           Adjusts a host file stored in a configuration file editor object
#           for the true IP address of this host. This is necessary for hosts
#           that live behind a firewall.
#           Those hosts have a publicly distributed IP of the firewall, but
#           internally must use their actual IP.  We assume that a given
#           host only has a single IP interface for now.
# Formal Parameters:
#     editor   - The configuration file editor to adjust.  This
#                editor is assumed to contain a hosts.tab file.
# Strategy:
#    - Figure out our hostname.
#    - Lookup the entry for this host.
#    - Modify the line to contain our IP
#    - Do a replace for this host.
sub AdjustOurHost {
    my $editor        = shift;

    # figure out who I am.

    my $myHostName    = $perlvar{'lonHostID'}; # LonCAPA hostname.

    #  Get my host file entry.

    my $ConfigLine    = $editor->Find($myHostName);
    if(! (defined $ConfigLine)) {
	die "AdjustOurHost - no entry for me in hosts file $myHostName";
    }
    # figure out my IP:
    #   Use the config line to get my hostname.
    #   Use gethostbyname to translate that into an IP address.
    #
    my ($id,$domain,$role,$name,$maxcon,$idleto,$mincon) = split(/:/,$ConfigLine);
    #
    #  Reassemble the config line from the elements in the list.
    #  Note that if the loncnew items were not present before, they will
    #  be now even if they would be empty
    #
    my $newConfigLine = $id;
    foreach my $item ($domain, $role, $name, $maxcon, $idleto, $mincon) {
	$newConfigLine .= ":".$item;
    }
    #  Replace the line:

    $editor->ReplaceLine($id, $newConfigLine);
    
}
#
#   ReplaceConfigFile:
#              Replaces a configuration file with the contents of a
#              configuration file editor object.
#              This is done by:
#              - Copying the target file to <filename>.old
#              - Writing the new file to <filename>.tmp
#              - Moving <filename.tmp>  -> <filename>
#              This laborious process ensures that the system is never without
#              a configuration file that's at least valid (even if the contents
#              may be dated).
#   Parameters:
#        filename   - Name of the file to modify... this is a full path.
#        editor     - Editor containing the file.
#
sub ReplaceConfigFile {
    
    my ($filename, $editor) = @_;

    CopyFile ($filename, $filename.".old");

    my $contents  = $editor->Get(); # Get the contents of the file.

    InstallFile($filename, $contents);
}
#   
#
#   Called to edit a configuration table  file
#   Parameters:
#      request           - The entire command/request sent by lonc or lonManage
#   Return:
#      The reply to send to the client.
#
sub EditFile {
    my $request = shift;

    #  Split the command into it's pieces:  edit:filetype:script

    my ($cmd, $filetype, $script) = split(/:/, $request,3);	# : in script

    #  Check the pre-coditions for success:

    if($cmd != "edit") {	# Something is amiss afoot alack.
	return "error:edit request detected, but request != 'edit'\n";
    }
    if( ($filetype ne "hosts")  &&
	($filetype ne "domain")) {
	return "error:edit requested with invalid file specifier: $filetype \n";
    }

    #   Split the edit script and check it's validity.

    my @scriptlines = split(/\n/, $script);  # one line per element.
    my $linecount   = scalar(@scriptlines);
    for(my $i = 0; $i < $linecount; $i++) {
	chomp($scriptlines[$i]);
	if(!isValidEditCommand($scriptlines[$i])) {
	    return "error:edit with bad script line: '$scriptlines[$i]' \n";
	}
    }

    #   Execute the edit operation.
    #   - Create a config file editor for the appropriate file and 
    #   - execute each command in the script:
    #
    my $configfile = ConfigFileFromSelector($filetype);
    if (!(defined $configfile)) {
	return "refused\n";
    }
    my $editor = ConfigFileEdit->new($configfile);

    for (my $i = 0; $i < $linecount; $i++) {
	ApplyEdit($scriptlines[$i], $editor);
    }
    # If the file is the host file, ensure that our host is
    # adjusted to have our ip:
    #
    if($filetype eq "host") {
	AdjustOurHost($editor);
    }
    #  Finally replace the current file with our file.
    #
    ReplaceConfigFile($configfile, $editor);

    return "ok\n";
}

#   read_profile
#
#   Returns a set of specific entries from a user's profile file.
#   this is a utility function that is used by both get_profile_entry and
#   get_profile_entry_encrypted.
#
# Parameters:
#    udom       - Domain in which the user exists.
#    uname      - User's account name (loncapa account)
#    namespace  - The profile namespace to open.
#    what       - A set of & separated queries.
# Returns:
#    If all ok: - The string that needs to be shipped back to the user.
#    If failure - A string that starts with error: followed by the failure
#                 reason.. note that this probabyl gets shipped back to the
#                 user as well.
#
sub read_profile {
    my ($udom, $uname, $namespace, $what) = @_;
    
    my $hashref = &tie_user_hash($udom, $uname, $namespace,
				 &GDBM_READER());
    if ($hashref) {
        my @queries=split(/\&/,$what);
        my $qresult='';
	
	for (my $i=0;$i<=$#queries;$i++) {
	    $qresult.="$hashref->{$queries[$i]}&";    # Presumably failure gives empty string.
	}
	$qresult=~s/\&$//;              # Remove trailing & from last lookup.
	if (&untie_user_hash($hashref)) {
	    return $qresult;
	} else {
	    return "error: ".($!+0)." untie (GDBM) Failed";
	}
    } else {
	if ($!+0 == 2) {
	    return "error:No such file or GDBM reported bad block error";
	} else {
	    return "error: ".($!+0)." tie (GDBM) Failed";
	}
    }

}
#--------------------- Request Handlers --------------------------------------------
#
#   By convention each request handler registers itself prior to the sub 
#   declaration:
#

#++
#
#  Handles ping requests.
#  Parameters:
#      $cmd    - the actual keyword that invoked us.
#      $tail   - the tail of the request that invoked us.
#      $replyfd- File descriptor connected to the client
#  Implicit Inputs:
#      $currenthostid - Global variable that carries the name of the host we are
#                       known as.
#  Returns:
#      1       - Ok to continue processing.
#      0       - Program should exit.
#  Side effects:
#      Reply information is sent to the client.
sub ping_handler {
    my ($cmd, $tail, $client) = @_;
    Debug("$cmd $tail $client .. $currenthostid:");
   
    Reply( $client,\$currenthostid,"$cmd:$tail");
   
    return 1;
}
&register_handler("ping", \&ping_handler, 0, 1, 1);       # Ping unencoded, client or manager.

#++
#
# Handles pong requests.  Pong replies with our current host id, and
#                         the results of a ping sent to us via our lonc.
#
# Parameters:
#      $cmd    - the actual keyword that invoked us.
#      $tail   - the tail of the request that invoked us.
#      $replyfd- File descriptor connected to the client
#  Implicit Inputs:
#      $currenthostid - Global variable that carries the name of the host we are
#                       connected to.
#  Returns:
#      1       - Ok to continue processing.
#      0       - Program should exit.
#  Side effects:
#      Reply information is sent to the client.
sub pong_handler {
    my ($cmd, $tail, $replyfd) = @_;

    my $reply=&Apache::lonnet::reply("ping",$clientname);
    &Reply( $replyfd, "$currenthostid:$reply\n", "$cmd:$tail"); 
    return 1;
}
&register_handler("pong", \&pong_handler, 0, 1, 1);       # Pong unencoded, client or manager

#++
#      Called to establish an encrypted session key with the remote client.
#      Note that with secure lond, in most cases this function is never
#      invoked.  Instead, the secure session key is established either
#      via a local file that's locked down tight and only lives for a short
#      time, or via an ssl tunnel...and is generated from a bunch-o-random
#      bits from /dev/urandom, rather than the predictable pattern used by
#      by this sub.  This sub is only used in the old-style insecure
#      key negotiation.
# Parameters:
#      $cmd    - the actual keyword that invoked us.
#      $tail   - the tail of the request that invoked us.
#      $replyfd- File descriptor connected to the client
#  Implicit Inputs:
#      $currenthostid - Global variable that carries the name of the host
#                       known as.
#      $clientname    - Global variable that carries the name of the hsot we're connected to.
#  Returns:
#      1       - Ok to continue processing.
#      0       - Program should exit.
#  Implicit Outputs:
#      Reply information is sent to the client.
#      $cipher is set with a reference to a new IDEA encryption object.
#
sub establish_key_handler {
    my ($cmd, $tail, $replyfd) = @_;

    my $buildkey=time.$$.int(rand 100000);
    $buildkey=~tr/1-6/A-F/;
    $buildkey=int(rand 100000).$buildkey.int(rand 100000);
    my $key=$currenthostid.$clientname;
    $key=~tr/a-z/A-Z/;
    $key=~tr/G-P/0-9/;
    $key=~tr/Q-Z/0-9/;
    $key=$key.$buildkey.$key.$buildkey.$key.$buildkey;
    $key=substr($key,0,32);
    my $cipherkey=pack("H32",$key);
    $cipher=new IDEA $cipherkey;
    &Reply($replyfd, \$buildkey, "$cmd:$tail"); 
   
    return 1;

}
&register_handler("ekey", \&establish_key_handler, 0, 1,1);

#     Handler for the load command.  Returns the current system load average
#     to the requestor.
#
# Parameters:
#      $cmd    - the actual keyword that invoked us.
#      $tail   - the tail of the request that invoked us.
#      $replyfd- File descriptor connected to the client
#  Implicit Inputs:
#      $currenthostid - Global variable that carries the name of the host
#                       known as.
#      $clientname    - Global variable that carries the name of the hsot we're connected to.
#  Returns:
#      1       - Ok to continue processing.
#      0       - Program should exit.
#  Side effects:
#      Reply information is sent to the client.
sub load_handler {
    my ($cmd, $tail, $replyfd) = @_;

   # Get the load average from /proc/loadavg and calculate it as a percentage of
   # the allowed load limit as set by the perl global variable lonLoadLim

    my $loadavg;
    my $loadfile=IO::File->new('/proc/loadavg');
   
    $loadavg=<$loadfile>;
    $loadavg =~ s/\s.*//g;                      # Extract the first field only.
   
    my $loadpercent=100*$loadavg/$perlvar{'lonLoadLim'};

    &Reply( $replyfd, \$loadpercent, "$cmd:$tail");
   
    return 1;
}
&register_handler("load", \&load_handler, 0, 1, 0);

#
#   Process the userload request.  This sub returns to the client the current
#  user load average.  It can be invoked either by clients or managers.
#
# Parameters:
#      $cmd    - the actual keyword that invoked us.
#      $tail   - the tail of the request that invoked us.
#      $replyfd- File descriptor connected to the client
#  Implicit Inputs:
#      $currenthostid - Global variable that carries the name of the host
#                       known as.
#      $clientname    - Global variable that carries the name of the hsot we're connected to.
#  Returns:
#      1       - Ok to continue processing.
#      0       - Program should exit
# Implicit inputs:
#     whatever the userload() function requires.
#  Implicit outputs:
#     the reply is written to the client.
#
sub user_load_handler {
    my ($cmd, $tail, $replyfd) = @_;

    my $userloadpercent=&Apache::lonnet::userload();
    &Reply($replyfd, \$userloadpercent, "$cmd:$tail");
    
    return 1;
}
&register_handler("userload", \&user_load_handler, 0, 1, 0);

#   Process a request for the authorization type of a user:
#   (userauth).
#
# Parameters:
#      $cmd    - the actual keyword that invoked us.
#      $tail   - the tail of the request that invoked us.
#      $replyfd- File descriptor connected to the client
#  Returns:
#      1       - Ok to continue processing.
#      0       - Program should exit
# Implicit outputs:
#    The user authorization type is written to the client.
#
sub user_authorization_type {
    my ($cmd, $tail, $replyfd) = @_;
   
    my $userinput = "$cmd:$tail";
   
    #  Pull the domain and username out of the command tail.
    # and call get_auth_type to determine the authentication type.
   
    my ($udom,$uname)=split(/:/,$tail);
    my $result = &get_auth_type($udom, $uname);
    if($result eq "nouser") {
	&Failure( $replyfd, "unknown_user\n", $userinput);
    } else {
	#
	# We only want to pass the second field from get_auth_type
	# for ^krb.. otherwise we'll be handing out the encrypted
	# password for internals e.g.
	#
	my ($type,$otherinfo) = split(/:/,$result);
	if($type =~ /^krb/) {
	    $type = $result;
	} else {
            $type .= ':';
        }
	&Reply( $replyfd, \$type, $userinput);
    }
  
    return 1;
}
&register_handler("currentauth", \&user_authorization_type, 1, 1, 0);

#   Process a request by a manager to push a hosts or domain table 
#   to us.  We pick apart the command and pass it on to the subs
#   that already exist to do this.
#
# Parameters:
#      $cmd    - the actual keyword that invoked us.
#      $tail   - the tail of the request that invoked us.
#      $client - File descriptor connected to the client
#  Returns:
#      1       - Ok to continue processing.
#      0       - Program should exit
# Implicit Output:
#    a reply is written to the client.
sub push_file_handler {
    my ($cmd, $tail, $client) = @_;

    my $userinput = "$cmd:$tail";

    # At this time we only know that the IP of our partner is a valid manager
    # the code below is a hook to do further authentication (e.g. to resolve
    # spoofing).

    my $cert = &GetCertificate($userinput);
    if(&ValidManager($cert)) { 

	# Now presumably we have the bona fides of both the peer host and the
	# process making the request.
      
	my $reply = &PushFile($userinput);
	&Reply($client, \$reply, $userinput);

    } else {
	&Failure( $client, "refused\n", $userinput);
    } 
    return 1;
}
&register_handler("pushfile", \&push_file_handler, 1, 0, 1);

# The du_handler routine should be considered obsolete and is retained
# for communication with legacy servers.  Please see the du2_handler.
#
#   du  - list the disk usage of a directory recursively. 
#    
#   note: stolen code from the ls file handler
#   under construction by Rick Banghart 
#    .
# Parameters:
#    $cmd        - The command that dispatched us (du).
#    $ududir     - The directory path to list... I'm not sure what this
#                  is relative as things like ls:. return e.g.
#                  no_such_dir.
#    $client     - Socket open on the client.
# Returns:
#     1 - indicating that the daemon should not disconnect.
# Side Effects:
#   The reply is written to  $client.
#
sub du_handler {
    my ($cmd, $ududir, $client) = @_;
    ($ududir) = split(/:/,$ududir); # Make 'telnet' testing easier.
    my $userinput = "$cmd:$ududir";

    if ($ududir=~/\.\./ || $ududir!~m|^/home/httpd/|) {
	&Failure($client,"refused\n","$cmd:$ududir");
	return 1;
    }
    #  Since $ududir could have some nasties in it,
    #  we will require that ududir is a valid
    #  directory.  Just in case someone tries to
    #  slip us a  line like .;(cd /home/httpd rm -rf*)
    #  etc.
    #
    if (-d $ududir) {
	my $total_size=0;
	my $code=sub { 
	    if ($_=~/\.\d+\./) { return;} 
	    if ($_=~/\.meta$/) { return;}
	    if (-d $_)         { return;}
	    $total_size+=(stat($_))[7];
	};
	chdir($ududir);
	find($code,$ududir);
	$total_size=int($total_size/1024);
	&Reply($client,\$total_size,"$cmd:$ududir");
    } else {
	&Failure($client, "bad_directory:$ududir\n","$cmd:$ududir"); 
    }
    return 1;
}
&register_handler("du", \&du_handler, 0, 1, 0);

# Please also see the du_handler, which is obsoleted by du2. 
# du2_handler differs from du_handler in that required path to directory
# provided by &propath() is prepended in the handler instead of on the 
# client side.
#
#   du2  - list the disk usage of a directory recursively.
#
# Parameters:
#    $cmd        - The command that dispatched us (du).
#    $tail       - The tail of the request that invoked us.
#                  $tail is a : separated list of the following:
#                   - $ududir - directory path to list (before prepending)
#                   - $getpropath = 1 if &propath() should prepend
#                   - $uname - username to use for &propath or user dir
#                   - $udom - domain to use for &propath or user dir
#                   All are escaped.
#    $client     - Socket open on the client.
# Returns:
#     1 - indicating that the daemon should not disconnect.
# Side Effects:
#   The reply is written to $client.
#

sub du2_handler {
    my ($cmd, $tail, $client) = @_;
    my ($ududir,$getpropath,$uname,$udom) = map { &unescape($_) } (split(/:/, $tail));
    my $userinput = "$cmd:$tail";
    if (($ududir=~/\.\./) || (($ududir!~m|^/home/httpd/|) && (!$getpropath))) {
        &Failure($client,"refused\n","$cmd:$tail");
        return 1;
    }
    if ($getpropath) {
        if (($uname =~ /^$LONCAPA::match_name$/) && ($udom =~ /^$LONCAPA::match_domain$/)) {
            $ududir = &propath($udom,$uname).'/'.$ududir;
        } else {
            &Failure($client,"refused\n","$cmd:$tail");
            return 1;
        }
    }
    #  Since $ududir could have some nasties in it,
    #  we will require that ududir is a valid
    #  directory.  Just in case someone tries to
    #  slip us a  line like .;(cd /home/httpd rm -rf*)
    #  etc.
    #
    if (-d $ududir) {
        my $total_size=0;
        my $code=sub {
            if ($_=~/\.\d+\./) { return;}
            if ($_=~/\.meta$/) { return;}
            if (-d $_)         { return;}
            $total_size+=(stat($_))[7];
        };
        chdir($ududir);
        find($code,$ududir);
        $total_size=int($total_size/1024);
        &Reply($client,\$total_size,"$cmd:$ududir");
    } else {
        &Failure($client, "bad_directory:$ududir\n","$cmd:$tail");
    }
    return 1;
}
&register_handler("du2", \&du2_handler, 0, 1, 0);

#
# The ls_handler routine should be considered obsolete and is retained
# for communication with legacy servers.  Please see the ls3_handler.
#
#   ls  - list the contents of a directory.  For each file in the
#    selected directory the filename followed by the full output of
#    the stat function is returned.  The returned info for each
#    file are separated by ':'.  The stat fields are separated by &'s.
# Parameters:
#    $cmd        - The command that dispatched us (ls).
#    $ulsdir     - The directory path to list... I'm not sure what this
#                  is relative as things like ls:. return e.g.
#                  no_such_dir.
#    $client     - Socket open on the client.
# Returns:
#     1 - indicating that the daemon should not disconnect.
# Side Effects:
#   The reply is written to  $client.
#
sub ls_handler {
    # obsoleted by ls2_handler
    my ($cmd, $ulsdir, $client) = @_;

    my $userinput = "$cmd:$ulsdir";

    my $obs;
    my $rights;
    my $ulsout='';
    my $ulsfn;
    if (-e $ulsdir) {
	if(-d $ulsdir) {
	    if (opendir(LSDIR,$ulsdir)) {
		while ($ulsfn=readdir(LSDIR)) {
		    undef($obs);
		    undef($rights); 
		    my @ulsstats=stat($ulsdir.'/'.$ulsfn);
		    #We do some obsolete checking here
		    if(-e $ulsdir.'/'.$ulsfn.".meta") { 
			open(FILE, $ulsdir.'/'.$ulsfn.".meta");
			my @obsolete=<FILE>;
			foreach my $obsolete (@obsolete) {
			    if($obsolete =~ m/(<obsolete>)(on|1)/) { $obs = 1; } 
			    if($obsolete =~ m|(<copyright>)(default)|) { $rights = 1; }
			}
		    }
		    $ulsout.=$ulsfn.'&'.join('&',@ulsstats);
		    if($obs eq '1') { $ulsout.="&1"; }
		    else { $ulsout.="&0"; }
		    if($rights eq '1') { $ulsout.="&1:"; }
		    else { $ulsout.="&0:"; }
		}
		closedir(LSDIR);
	    }
	} else {
	    my @ulsstats=stat($ulsdir);
	    $ulsout.=$ulsfn.'&'.join('&',@ulsstats).':';
	}
    } else {
	$ulsout='no_such_dir';
    }
    if ($ulsout eq '') { $ulsout='empty'; }
    &Reply($client, \$ulsout, $userinput); # This supports debug logging.
    
    return 1;

}
&register_handler("ls", \&ls_handler, 0, 1, 0);

# The ls2_handler routine should be considered obsolete and is retained
# for communication with legacy servers.  Please see the ls3_handler.
# Please also see the ls_handler, which was itself obsoleted by ls2.
# ls2_handler differs from ls_handler in that it escapes its return 
# values before concatenating them together with ':'s.
#
#   ls2  - list the contents of a directory.  For each file in the
#    selected directory the filename followed by the full output of
#    the stat function is returned.  The returned info for each
#    file are separated by ':'.  The stat fields are separated by &'s.
# Parameters:
#    $cmd        - The command that dispatched us (ls).
#    $ulsdir     - The directory path to list... I'm not sure what this
#                  is relative as things like ls:. return e.g.
#                  no_such_dir.
#    $client     - Socket open on the client.
# Returns:
#     1 - indicating that the daemon should not disconnect.
# Side Effects:
#   The reply is written to  $client.
#
sub ls2_handler {
    my ($cmd, $ulsdir, $client) = @_;

    my $userinput = "$cmd:$ulsdir";

    my $obs;
    my $rights;
    my $ulsout='';
    my $ulsfn;
    if (-e $ulsdir) {
        if(-d $ulsdir) {
            if (opendir(LSDIR,$ulsdir)) {
                while ($ulsfn=readdir(LSDIR)) {
                    undef($obs);
		    undef($rights); 
                    my @ulsstats=stat($ulsdir.'/'.$ulsfn);
                    #We do some obsolete checking here
                    if(-e $ulsdir.'/'.$ulsfn.".meta") { 
                        open(FILE, $ulsdir.'/'.$ulsfn.".meta");
                        my @obsolete=<FILE>;
                        foreach my $obsolete (@obsolete) {
                            if($obsolete =~ m/(<obsolete>)(on|1)/) { $obs = 1; } 
                            if($obsolete =~ m|(<copyright>)(default)|) {
                                $rights = 1;
                            }
                        }
                    }
                    my $tmp = $ulsfn.'&'.join('&',@ulsstats);
                    if ($obs    eq '1') { $tmp.="&1"; } else { $tmp.="&0"; }
                    if ($rights eq '1') { $tmp.="&1"; } else { $tmp.="&0"; }
                    $ulsout.= &escape($tmp).':';
                }
                closedir(LSDIR);
            }
        } else {
            my @ulsstats=stat($ulsdir);
            $ulsout.=$ulsfn.'&'.join('&',@ulsstats).':';
        }
    } else {
        $ulsout='no_such_dir';
   }
   if ($ulsout eq '') { $ulsout='empty'; }
   &Reply($client, \$ulsout, $userinput); # This supports debug logging.
   return 1;
}
&register_handler("ls2", \&ls2_handler, 0, 1, 0);
#
#   ls3  - list the contents of a directory.  For each file in the
#    selected directory the filename followed by the full output of
#    the stat function is returned.  The returned info for each
#    file are separated by ':'.  The stat fields are separated by &'s.
# Parameters:
#    $cmd        - The command that dispatched us (ls).
#    $tail       - The tail of the request that invoked us.
#                  $tail is a : separated list of the following:
#                   - $ulsdir - directory path to list (before prepending)
#                   - $getpropath = 1 if &propath() should prepend
#                   - $getuserdir = 1 if path to user dir in lonUsers should
#                                     prepend
#                   - $alternate_root - path to prepend
#                   - $uname - username to use for &propath or user dir
#                   - $udom - domain to use for &propath or user dir
#            All of these except $getpropath and &getuserdir are escaped.    
#                  no_such_dir.
#    $client     - Socket open on the client.
# Returns:
#     1 - indicating that the daemon should not disconnect.
# Side Effects:
#   The reply is written to $client.
#

sub ls3_handler {
    my ($cmd, $tail, $client) = @_;
    my $userinput = "$cmd:$tail";
    my ($ulsdir,$getpropath,$getuserdir,$alternate_root,$uname,$udom) =
        split(/:/,$tail);
    if (defined($ulsdir)) {
        $ulsdir = &unescape($ulsdir);
    }
    if (defined($alternate_root)) {
        $alternate_root = &unescape($alternate_root);
    }
    if (defined($uname)) {
        $uname = &unescape($uname);
    }
    if (defined($udom)) {
        $udom = &unescape($udom);
    }

    my $dir_root = $perlvar{'lonDocRoot'};
    if ($getpropath) {
        if (($uname =~ /^$LONCAPA::match_name$/) && ($udom =~ /^$LONCAPA::match_domain$/)) {
            $dir_root = &propath($udom,$uname);
            $dir_root =~ s/\/$//;
        } else {
            &Failure($client,"refused\n","$cmd:$tail");
            return 1;
        }
    } elsif ($getuserdir) {
        if (($uname =~ /^$LONCAPA::match_name$/) && ($udom =~ /^$LONCAPA::match_domain$/)) {
            my $subdir=$uname.'__';
            $subdir =~ s/(.)(.)(.).*/$1\/$2\/$3/;
            $dir_root = $Apache::lonnet::perlvar{'lonUsersDir'}
                       ."/$udom/$subdir/$uname";
        } else {
            &Failure($client,"refused\n","$cmd:$tail");
            return 1;
        }
    } elsif ($alternate_root ne '') {
        $dir_root = $alternate_root;
    }
    if (($dir_root ne '') && ($dir_root ne '/')) {
        if ($ulsdir =~ /^\//) {
            $ulsdir = $dir_root.$ulsdir;
        } else {
            $ulsdir = $dir_root.'/'.$ulsdir;
        }
    }
    my $obs;
    my $rights;
    my $ulsout='';
    my $ulsfn;
    if (-e $ulsdir) {
        if(-d $ulsdir) {
            if (opendir(LSDIR,$ulsdir)) {
                while ($ulsfn=readdir(LSDIR)) {
                    undef($obs);
                    undef($rights);
                    my @ulsstats=stat($ulsdir.'/'.$ulsfn);
                    #We do some obsolete checking here
                    if(-e $ulsdir.'/'.$ulsfn.".meta") {
                        open(FILE, $ulsdir.'/'.$ulsfn.".meta");
                        my @obsolete=<FILE>;
                        foreach my $obsolete (@obsolete) {
                            if($obsolete =~ m/(<obsolete>)(on|1)/) { $obs = 1; }
                            if($obsolete =~ m|(<copyright>)(default)|) {
                                $rights = 1;
                            }
                        }
                    }
                    my $tmp = $ulsfn.'&'.join('&',@ulsstats);
                    if ($obs    eq '1') { $tmp.="&1"; } else { $tmp.="&0"; }
                    if ($rights eq '1') { $tmp.="&1"; } else { $tmp.="&0"; }
                    $ulsout.= &escape($tmp).':';
                }
                closedir(LSDIR);
            }
        } else {
            my @ulsstats=stat($ulsdir);
            $ulsout.=$ulsfn.'&'.join('&',@ulsstats).':';
        }
    } else {
        $ulsout='no_such_dir';
    }
    if ($ulsout eq '') { $ulsout='empty'; }
    &Reply($client, \$ulsout, $userinput); # This supports debug logging.
    return 1;
}
&register_handler("ls3", \&ls3_handler, 0, 1, 0);

#   Process a reinit request.  Reinit requests that either
#   lonc or lond be reinitialized so that an updated 
#   host.tab or domain.tab can be processed.
#
# Parameters:
#      $cmd    - the actual keyword that invoked us.
#      $tail   - the tail of the request that invoked us.
#      $client - File descriptor connected to the client
#  Returns:
#      1       - Ok to continue processing.
#      0       - Program should exit
#  Implicit output:
#     a reply is sent to the client.
#
sub reinit_process_handler {
    my ($cmd, $tail, $client) = @_;
   
    my $userinput = "$cmd:$tail";
   
    my $cert = &GetCertificate($userinput);
    if(&ValidManager($cert)) {
	chomp($userinput);
	my $reply = &ReinitProcess($userinput);
	&Reply( $client,  \$reply, $userinput);
    } else {
	&Failure( $client, "refused\n", $userinput);
    }
    return 1;
}
&register_handler("reinit", \&reinit_process_handler, 1, 0, 1);

#  Process the editing script for a table edit operation.
#  the editing operation must be encrypted and requested by
#  a manager host.
#
# Parameters:
#      $cmd    - the actual keyword that invoked us.
#      $tail   - the tail of the request that invoked us.
#      $client - File descriptor connected to the client
#  Returns:
#      1       - Ok to continue processing.
#      0       - Program should exit
#  Implicit output:
#     a reply is sent to the client.
#
sub edit_table_handler {
    my ($command, $tail, $client) = @_;
   
    my $userinput = "$command:$tail";

    my $cert = &GetCertificate($userinput);
    if(&ValidManager($cert)) {
	my($filetype, $script) = split(/:/, $tail);
	if (($filetype eq "hosts") || 
	    ($filetype eq "domain")) {
	    if($script ne "") {
		&Reply($client,              # BUGBUG - EditFile
		      &EditFile($userinput), #   could fail.
		      $userinput);
	    } else {
		&Failure($client,"refused\n",$userinput);
	    }
	} else {
	    &Failure($client,"refused\n",$userinput);
	}
    } else {
	&Failure($client,"refused\n",$userinput);
    }
    return 1;
}
&register_handler("edit", \&edit_table_handler, 1, 0, 1);

#
#   Authenticate a user against the LonCAPA authentication
#   database.  Note that there are several authentication
#   possibilities:
#   - unix     - The user can be authenticated against the unix
#                password file.
#   - internal - The user can be authenticated against a purely 
#                internal per user password file.
#   - kerberos - The user can be authenticated against either a kerb4 or kerb5
#                ticket granting authority.
#   - user     - The person tailoring LonCAPA can supply a user authentication
#                mechanism that is per system.
#
# Parameters:
#    $cmd      - The command that got us here.
#    $tail     - Tail of the command (remaining parameters).
#    $client   - File descriptor connected to client.
# Returns
#     0        - Requested to exit, caller should shut down.
#     1        - Continue processing.
# Implicit inputs:
#    The authentication systems describe above have their own forms of implicit
#    input into the authentication process that are described above.
#
sub authenticate_handler {
    my ($cmd, $tail, $client) = @_;

    
    #  Regenerate the full input line 
    
    my $userinput  = $cmd.":".$tail;
    
    #  udom    - User's domain.
    #  uname   - Username.
    #  upass   - User's password.
    #  checkdefauth - Pass to validate_user() to try authentication
    #                 with default auth type(s) if no user account.
    
    my ($udom, $uname, $upass, $checkdefauth)=split(/:/,$tail);
    &Debug(" Authenticate domain = $udom, user = $uname, password = $upass,  checkdefauth = $checkdefauth");
    chomp($upass);
    $upass=&unescape($upass);

    my $pwdcorrect = &validate_user($udom,$uname,$upass,$checkdefauth);
    if($pwdcorrect) {
	&Reply( $client, "authorized\n", $userinput);
	#
	#  Bad credentials: Failed to authorize
	#
    } else {
	&Failure( $client, "non_authorized\n", $userinput);
    }

    return 1;
}
&register_handler("auth", \&authenticate_handler, 1, 1, 0);

#
#   Change a user's password.  Note that this function is complicated by
#   the fact that a user may be authenticated in more than one way:
#   At present, we are not able to change the password for all types of
#   authentication methods.  Only for:
#      unix    - unix password or shadow passoword style authentication.
#      local   - Locally written authentication mechanism.
#   For now, kerb4 and kerb5 password changes are not supported and result
#   in an error.
# FUTURE WORK:
#    Support kerberos passwd changes?
# Parameters:
#    $cmd      - The command that got us here.
#    $tail     - Tail of the command (remaining parameters).
#    $client   - File descriptor connected to client.
# Returns
#     0        - Requested to exit, caller should shut down.
#     1        - Continue processing.
# Implicit inputs:
#    The authentication systems describe above have their own forms of implicit
#    input into the authentication process that are described above.
sub change_password_handler {
    my ($cmd, $tail, $client) = @_;

    my $userinput = $cmd.":".$tail;           # Reconstruct client's string.

    #
    #  udom  - user's domain.
    #  uname - Username.
    #  upass - Current password.
    #  npass - New password.
    #  context - Context in which this was called 
    #            (preferences or reset_by_email).
   
    my ($udom,$uname,$upass,$npass,$context)=split(/:/,$tail);

    $upass=&unescape($upass);
    $npass=&unescape($npass);
    &Debug("Trying to change password for $uname");

    # First require that the user can be authenticated with their
    # old password unless context was 'reset_by_email':
    
    my $validated;
    if ($context eq 'reset_by_email') {
        $validated = 1;
    } else {
        $validated = &validate_user($udom, $uname, $upass);
    }
    if($validated) {
	my $realpasswd  = &get_auth_type($udom, $uname); # Defined since authd.
	
	my ($howpwd,$contentpwd)=split(/:/,$realpasswd);
	if ($howpwd eq 'internal') {
	    &Debug("internal auth");
	    my $salt=time;
	    $salt=substr($salt,6,2);
	    my $ncpass=crypt($npass,$salt);
	    if(&rewrite_password_file($udom, $uname, "internal:$ncpass")) {
		&logthis("Result of password change for "
			 ."$uname: pwchange_success");
		&Reply($client, "ok\n", $userinput);
	    } else {
		&logthis("Unable to open $uname passwd "               
			 ."to change password");
		&Failure( $client, "non_authorized\n",$userinput);
	    }
	} elsif ($howpwd eq 'unix' && $context ne 'reset_by_email') {
	    my $result = &change_unix_password($uname, $npass);
	    &logthis("Result of password change for $uname: ".
		     $result);
	    &Reply($client, \$result, $userinput);
	} else {
	    # this just means that the current password mode is not
	    # one we know how to change (e.g the kerberos auth modes or
	    # locally written auth handler).
	    #
	    &Failure( $client, "auth_mode_error\n", $userinput);
	}  
	
    } else {
	&Failure( $client, "non_authorized\n", $userinput);
    }

    return 1;
}
&register_handler("passwd", \&change_password_handler, 1, 1, 0);

#
#   Create a new user.  User in this case means a lon-capa user.
#   The user must either already exist in some authentication realm
#   like kerberos or the /etc/passwd.  If not, a user completely local to
#   this loncapa system is created.
#
# Parameters:
#    $cmd      - The command that got us here.
#    $tail     - Tail of the command (remaining parameters).
#    $client   - File descriptor connected to client.
# Returns
#     0        - Requested to exit, caller should shut down.
#     1        - Continue processing.
# Implicit inputs:
#    The authentication systems describe above have their own forms of implicit
#    input into the authentication process that are described above.
sub add_user_handler {

    my ($cmd, $tail, $client) = @_;


    my ($udom,$uname,$umode,$npass)=split(/:/,$tail);
    my $userinput = $cmd.":".$tail; # Reconstruct the full request line.

    &Debug("cmd =".$cmd." $udom =".$udom." uname=".$uname);


    if($udom eq $currentdomainid) { # Reject new users for other domains...
	
	my $oldumask=umask(0077);
	chomp($npass);
	$npass=&unescape($npass);
	my $passfilename  = &password_path($udom, $uname);
	&Debug("Password file created will be:".$passfilename);
	if (-e $passfilename) {
	    &Failure( $client, "already_exists\n", $userinput);
	} else {
	    my $fperror='';
	    if (!&mkpath($passfilename)) {
		$fperror="error: ".($!+0)." mkdir failed while attempting "
		    ."makeuser";
	    }
	    unless ($fperror) {
		my $result=&make_passwd_file($uname, $umode,$npass, $passfilename);
		&Reply($client,\$result, $userinput);     #BUGBUG - could be fail
	    } else {
		&Failure($client, \$fperror, $userinput);
	    }
	}
	umask($oldumask);
    }  else {
	&Failure($client, "not_right_domain\n",
		$userinput);	# Even if we are multihomed.
    
    }
    return 1;

}
&register_handler("makeuser", \&add_user_handler, 1, 1, 0);

#
#   Change the authentication method of a user.  Note that this may
#   also implicitly change the user's password if, for example, the user is
#   joining an existing authentication realm.  Known authentication realms at
#   this time are:
#    internal   - Purely internal password file (only loncapa knows this user)
#    local      - Institutionally written authentication module.
#    unix       - Unix user (/etc/passwd with or without /etc/shadow).
#    kerb4      - kerberos version 4
#    kerb5      - kerberos version 5
#
# Parameters:
#    $cmd      - The command that got us here.
#    $tail     - Tail of the command (remaining parameters).
#    $client   - File descriptor connected to client.
# Returns
#     0        - Requested to exit, caller should shut down.
#     1        - Continue processing.
# Implicit inputs:
#    The authentication systems describe above have their own forms of implicit
#    input into the authentication process that are described above.
# NOTE:
#   This is also used to change the authentication credential values (e.g. passwd).
#   
#
sub change_authentication_handler {

    my ($cmd, $tail, $client) = @_;
   
    my $userinput  = "$cmd:$tail";              # Reconstruct user input.

    my ($udom,$uname,$umode,$npass)=split(/:/,$tail);
    &Debug("cmd = ".$cmd." domain= ".$udom."uname =".$uname." umode= ".$umode);
    if ($udom ne $currentdomainid) {
	&Failure( $client, "not_right_domain\n", $client);
    } else {
	
	chomp($npass);
	
	$npass=&unescape($npass);
	my $oldauth = &get_auth_type($udom, $uname); # Get old auth info.
	my $passfilename = &password_path($udom, $uname);
	if ($passfilename) {	# Not allowed to create a new user!!
	    # If just changing the unix passwd. need to arrange to run
	    # passwd since otherwise make_passwd_file will run
	    # lcuseradd which fails if an account already exists
	    # (to prevent an unscrupulous LONCAPA admin from stealing
	    # an existing account by overwriting it as a LonCAPA account).

	    if(($oldauth =~/^unix/) && ($umode eq "unix")) {
		my $result = &change_unix_password($uname, $npass);
		&logthis("Result of password change for $uname: ".$result);
		if ($result eq "ok") {
		    &Reply($client, \$result);
		} else {
		    &Failure($client, \$result);
		}
	    } else {
		my $result=&make_passwd_file($uname, $umode,$npass,$passfilename);
		#
		#  If the current auth mode is internal, and the old auth mode was
		#  unix, or krb*,  and the user is an author for this domain,
		#  re-run manage_permissions for that role in order to be able
		#  to take ownership of the construction space back to www:www
		#
		
		
		if( (($oldauth =~ /^unix/) && ($umode eq "internal")) ||
		    (($oldauth =~ /^internal/) && ($umode eq "unix")) ) { 
		    if(&is_author($udom, $uname)) {
			&Debug(" Need to manage author permissions...");
			&manage_permissions("/$udom/_au", $udom, $uname, "$umode:");
		    }
		}
		&Reply($client, \$result, $userinput);
	    }
	       

	} else {	       
	    &Failure($client, "non_authorized\n", $userinput); # Fail the user now.
	}
    }
    return 1;
}
&register_handler("changeuserauth", \&change_authentication_handler, 1,1, 0);

#
#   Determines if this is the home server for a user.  The home server
#   for a user will have his/her lon-capa passwd file.  Therefore all we need
#   to do is determine if this file exists.
#
# Parameters:
#    $cmd      - The command that got us here.
#    $tail     - Tail of the command (remaining parameters).
#    $client   - File descriptor connected to client.
# Returns
#     0        - Requested to exit, caller should shut down.
#     1        - Continue processing.
# Implicit inputs:
#    The authentication systems describe above have their own forms of implicit
#    input into the authentication process that are described above.
#
sub is_home_handler {
    my ($cmd, $tail, $client) = @_;
   
    my $userinput  = "$cmd:$tail";
   
    my ($udom,$uname)=split(/:/,$tail);
    chomp($uname);
    my $passfile = &password_filename($udom, $uname);
    if($passfile) {
	&Reply( $client, "found\n", $userinput);
    } else {
	&Failure($client, "not_found\n", $userinput);
    }
    return 1;
}
&register_handler("home", \&is_home_handler, 0,1,0);

#
#   Process an update request for a resource?? I think what's going on here is
#   that a resource has been modified that we hold a subscription to.
#   If the resource is not local, then we must update, or at least invalidate our
#   cached copy of the resource. 
#   FUTURE WORK:
#      I need to look at this logic carefully.  My druthers would be to follow
#      typical caching logic, and simple invalidate the cache, drop any subscription
#      an let the next fetch start the ball rolling again... however that may
#      actually be more difficult than it looks given the complex web of
#      proxy servers.
# Parameters:
#    $cmd      - The command that got us here.
#    $tail     - Tail of the command (remaining parameters).
#    $client   - File descriptor connected to client.
# Returns
#     0        - Requested to exit, caller should shut down.
#     1        - Continue processing.
# Implicit inputs:
#    The authentication systems describe above have their own forms of implicit
#    input into the authentication process that are described above.
#
sub update_resource_handler {

    my ($cmd, $tail, $client) = @_;
   
    my $userinput = "$cmd:$tail";
   
    my $fname= $tail;		# This allows interactive testing


    my $ownership=ishome($fname);
    if ($ownership eq 'not_owner') {
	if (-e $fname) {
	    my ($dev,$ino,$mode,$nlink,$uid,$gid,$rdev,$size,
		$atime,$mtime,$ctime,$blksize,$blocks)=stat($fname);
	    my $now=time;
	    my $since=$now-$atime;
	    if ($since>$perlvar{'lonExpire'}) {
		my $reply=&Apache::lonnet::reply("unsub:$fname","$clientname");
		&devalidate_meta_cache($fname);
		unlink("$fname");
		unlink("$fname.meta");
	    } else {
		my $transname="$fname.in.transfer";
		my $remoteurl=&Apache::lonnet::reply("sub:$fname","$clientname");
		my $response;
		alarm(120);
		{
		    my $ua=new LWP::UserAgent;
		    my $request=new HTTP::Request('GET',"$remoteurl");
		    $response=$ua->request($request,$transname);
		}
		alarm(0);
		if ($response->is_error()) {
		    unlink($transname);
		    my $message=$response->status_line;
		    &logthis("LWP GET: $message for $fname ($remoteurl)");
		} else {
		    if ($remoteurl!~/\.meta$/) {
			alarm(120);
			{
			    my $ua=new LWP::UserAgent;
			    my $mrequest=new HTTP::Request('GET',$remoteurl.'.meta');
			    my $mresponse=$ua->request($mrequest,$fname.'.meta');
			    if ($mresponse->is_error()) {
				unlink($fname.'.meta');
			    }
			}
			alarm(0);
		    }
		    rename($transname,$fname);
		    &devalidate_meta_cache($fname);
		}
	    }
	    &Reply( $client, "ok\n", $userinput);
	} else {
	    &Failure($client, "not_found\n", $userinput);
	}
    } else {
	&Failure($client, "rejected\n", $userinput);
    }
    return 1;
}
&register_handler("update", \&update_resource_handler, 0 ,1, 0);

sub devalidate_meta_cache {
    my ($url) = @_;
    use Cache::Memcached;
    my $memcache = new Cache::Memcached({'servers'=>['127.0.0.1:11211']});
    $url = &Apache::lonnet::declutter($url);
    $url =~ s-\.meta$--;
    my $id = &escape('meta:'.$url);
    $memcache->delete($id);
}

#
#   Fetch a user file from a remote server to the user's home directory
#   userfiles subdir.
# Parameters:
#    $cmd      - The command that got us here.
#    $tail     - Tail of the command (remaining parameters).
#    $client   - File descriptor connected to client.
# Returns
#     0        - Requested to exit, caller should shut down.
#     1        - Continue processing.
#
sub fetch_user_file_handler {

    my ($cmd, $tail, $client) = @_;

    my $userinput = "$cmd:$tail";
    my $fname           = $tail;
    my ($udom,$uname,$ufile) = ($fname =~ m|^([^/]+)/([^/]+)/(.+)$|);
    my $udir=&propath($udom,$uname).'/userfiles';
    unless (-e $udir) {
	mkdir($udir,0770); 
    }
    Debug("fetch user file for $fname");
    if (-e $udir) {
	$ufile=~s/^[\.\~]+//;

	# IF necessary, create the path right down to the file.
	# Note that any regular files in the way of this path are
	# wiped out to deal with some earlier folly of mine.

	if (!&mkpath($udir.'/'.$ufile)) {
	    &Failure($client, "unable_to_create\n", $userinput);	    
	}

	my $destname=$udir.'/'.$ufile;
	my $transname=$udir.'/'.$ufile.'.in.transit';
	my $remoteurl='http://'.$clientip.'/userfiles/'.$fname;
	my $response;
	Debug("Remote URL : $remoteurl Transfername $transname Destname: $destname");
	alarm(120);
	{
	    my $ua=new LWP::UserAgent;
	    my $request=new HTTP::Request('GET',"$remoteurl");
	    $response=$ua->request($request,$transname);
	}
	alarm(0);
	if ($response->is_error()) {
	    unlink($transname);
	    my $message=$response->status_line;
	    &logthis("LWP GET: $message for $fname ($remoteurl)");
	    &Failure($client, "failed\n", $userinput);
	} else {
	    Debug("Renaming $transname to $destname");
	    if (!rename($transname,$destname)) {
		&logthis("Unable to move $transname to $destname");
		unlink($transname);
		&Failure($client, "failed\n", $userinput);
	    } else {
		&Reply($client, "ok\n", $userinput);
	    }
	}   
    } else {
	&Failure($client, "not_home\n", $userinput);
    }
    return 1;
}
&register_handler("fetchuserfile", \&fetch_user_file_handler, 0, 1, 0);

#
#   Remove a file from a user's home directory userfiles subdirectory.
# Parameters:
#    cmd   - the Lond request keyword that got us here.
#    tail  - the part of the command past the keyword.
#    client- File descriptor connected with the client.
#
# Returns:
#    1    - Continue processing.
sub remove_user_file_handler {
    my ($cmd, $tail, $client) = @_;

    my ($fname) = split(/:/, $tail); # Get rid of any tailing :'s lonc may have sent.

    my ($udom,$uname,$ufile) = ($fname =~ m|^([^/]+)/([^/]+)/(.+)$|);
    if ($ufile =~m|/\.\./|) {
	# any files paths with /../ in them refuse 
	# to deal with
	&Failure($client, "refused\n", "$cmd:$tail");
    } else {
	my $udir = &propath($udom,$uname);
	if (-e $udir) {
	    my $file=$udir.'/userfiles/'.$ufile;
	    if (-e $file) {
		#
		#   If the file is a regular file unlink is fine...
		#   However it's possible the client wants a dir.
		#   removed, in which case rmdir is more approprate:
		#
	        if (-f $file){
		    unlink($file);
		} elsif(-d $file) {
		    rmdir($file);
		}
		if (-e $file) {
		    #  File is still there after we deleted it ?!?

		    &Failure($client, "failed\n", "$cmd:$tail");
		} else {
		    &Reply($client, "ok\n", "$cmd:$tail");
		}
	    } else {
		&Failure($client, "not_found\n", "$cmd:$tail");
	    }
	} else {
	    &Failure($client, "not_home\n", "$cmd:$tail");
	}
    }
    return 1;
}
&register_handler("removeuserfile", \&remove_user_file_handler, 0,1,0);

#
#   make a directory in a user's home directory userfiles subdirectory.
# Parameters:
#    cmd   - the Lond request keyword that got us here.
#    tail  - the part of the command past the keyword.
#    client- File descriptor connected with the client.
#
# Returns:
#    1    - Continue processing.
sub mkdir_user_file_handler {
    my ($cmd, $tail, $client) = @_;

    my ($dir) = split(/:/, $tail); # Get rid of any tailing :'s lonc may have sent.
    $dir=&unescape($dir);
    my ($udom,$uname,$ufile) = ($dir =~ m|^([^/]+)/([^/]+)/(.+)$|);
    if ($ufile =~m|/\.\./|) {
	# any files paths with /../ in them refuse 
	# to deal with
	&Failure($client, "refused\n", "$cmd:$tail");
    } else {
	my $udir = &propath($udom,$uname);
	if (-e $udir) {
	    my $newdir=$udir.'/userfiles/'.$ufile.'/';
	    if (!&mkpath($newdir)) {
		&Failure($client, "failed\n", "$cmd:$tail");
	    }
	    &Reply($client, "ok\n", "$cmd:$tail");
	} else {
	    &Failure($client, "not_home\n", "$cmd:$tail");
	}
    }
    return 1;
}
&register_handler("mkdiruserfile", \&mkdir_user_file_handler, 0,1,0);

#
#   rename a file in a user's home directory userfiles subdirectory.
# Parameters:
#    cmd   - the Lond request keyword that got us here.
#    tail  - the part of the command past the keyword.
#    client- File descriptor connected with the client.
#
# Returns:
#    1    - Continue processing.
sub rename_user_file_handler {
    my ($cmd, $tail, $client) = @_;

    my ($udom,$uname,$old,$new) = split(/:/, $tail);
    $old=&unescape($old);
    $new=&unescape($new);
    if ($new =~m|/\.\./| || $old =~m|/\.\./|) {
	# any files paths with /../ in them refuse to deal with
	&Failure($client, "refused\n", "$cmd:$tail");
    } else {
	my $udir = &propath($udom,$uname);
	if (-e $udir) {
	    my $oldfile=$udir.'/userfiles/'.$old;
	    my $newfile=$udir.'/userfiles/'.$new;
	    if (-e $newfile) {
		&Failure($client, "exists\n", "$cmd:$tail");
	    } elsif (! -e $oldfile) {
		&Failure($client, "not_found\n", "$cmd:$tail");
	    } else {
		if (!rename($oldfile,$newfile)) {
		    &Failure($client, "failed\n", "$cmd:$tail");
		} else {
		    &Reply($client, "ok\n", "$cmd:$tail");
		}
	    }
	} else {
	    &Failure($client, "not_home\n", "$cmd:$tail");
	}
    }
    return 1;
}
&register_handler("renameuserfile", \&rename_user_file_handler, 0,1,0);

#
#  Checks if the specified user has an active session on the server
#  return ok if so, not_found if not
#
# Parameters:
#   cmd      - The request keyword that dispatched to tus.
#   tail     - The tail of the request (colon separated parameters).
#   client   - Filehandle open on the client.
# Return:
#    1.
sub user_has_session_handler {
    my ($cmd, $tail, $client) = @_;

    my ($udom, $uname) = map { &unescape($_) } (split(/:/, $tail));
    
    &logthis("Looking for $udom $uname");
    opendir(DIR,$perlvar{'lonIDsDir'});
    my $filename;
    while ($filename=readdir(DIR)) {
	last if ($filename=~/^\Q$uname\E_\d+_\Q$udom\E_/);
    }
    if ($filename) {
	&Reply($client, "ok\n", "$cmd:$tail");
    } else {
	&Failure($client, "not_found\n", "$cmd:$tail");
    }
    return 1;

}
&register_handler("userhassession", \&user_has_session_handler, 0,1,0);

#
#  Authenticate access to a user file by checking that the token the user's 
#  passed also exists in their session file
#
# Parameters:
#   cmd      - The request keyword that dispatched to tus.
#   tail     - The tail of the request (colon separated parameters).
#   client   - Filehandle open on the client.
# Return:
#    1.
sub token_auth_user_file_handler {
    my ($cmd, $tail, $client) = @_;

    my ($fname, $session) = split(/:/, $tail);
    
    chomp($session);
    my $reply="non_auth";
    my $file = $perlvar{'lonIDsDir'}.'/'.$session.'.id';
    if (open(ENVIN,"$file")) {
	flock(ENVIN,LOCK_SH);
	tie(my %disk_env,'GDBM_File',"$file",&GDBM_READER(),0640);
	if (exists($disk_env{"userfile.$fname"})) {
	    $reply="ok";
	} else {
	    foreach my $envname (keys(%disk_env)) {
		if ($envname=~ m|^userfile\.\Q$fname\E|) {
		    $reply="ok";
		    last;
		}
	    }
	}
	untie(%disk_env);
	close(ENVIN);
	&Reply($client, \$reply, "$cmd:$tail");
    } else {
	&Failure($client, "invalid_token\n", "$cmd:$tail");
    }
    return 1;

}
&register_handler("tokenauthuserfile", \&token_auth_user_file_handler, 0,1,0);

#
#   Unsubscribe from a resource.
#
# Parameters:
#    $cmd      - The command that got us here.
#    $tail     - Tail of the command (remaining parameters).
#    $client   - File descriptor connected to client.
# Returns
#     0        - Requested to exit, caller should shut down.
#     1        - Continue processing.
#
sub unsubscribe_handler {
    my ($cmd, $tail, $client) = @_;

    my $userinput= "$cmd:$tail";
    
    my ($fname) = split(/:/,$tail); # Split in case there's extrs.

    &Debug("Unsubscribing $fname");
    if (-e $fname) {
	&Debug("Exists");
	&Reply($client, &unsub($fname,$clientip), $userinput);
    } else {
	&Failure($client, "not_found\n", $userinput);
    }
    return 1;
}
&register_handler("unsub", \&unsubscribe_handler, 0, 1, 0);

#   Subscribe to a resource
#
# Parameters:
#    $cmd      - The command that got us here.
#    $tail     - Tail of the command (remaining parameters).
#    $client   - File descriptor connected to client.
# Returns
#     0        - Requested to exit, caller should shut down.
#     1        - Continue processing.
#
sub subscribe_handler {
    my ($cmd, $tail, $client)= @_;

    my $userinput  = "$cmd:$tail";

    &Reply( $client, &subscribe($userinput,$clientip), $userinput);

    return 1;
}
&register_handler("sub", \&subscribe_handler, 0, 1, 0);

#
#   Determine the latest version of a resource (it looks for the highest
#   past version and then returns that +1)
#
# Parameters:
#    $cmd      - The command that got us here.
#    $tail     - Tail of the command (remaining parameters).
#                 (Should consist of an absolute path to a file)
#    $client   - File descriptor connected to client.
# Returns
#     0        - Requested to exit, caller should shut down.
#     1        - Continue processing.
#
sub current_version_handler {
    my ($cmd, $tail, $client) = @_;

    my $userinput= "$cmd:$tail";
   
    my $fname   = $tail;
    &Reply( $client, &currentversion($fname)."\n", $userinput);
    return 1;

}
&register_handler("currentversion", \&current_version_handler, 0, 1, 0);

#  Make an entry in a user's activity log.
#
# Parameters:
#    $cmd      - The command that got us here.
#    $tail     - Tail of the command (remaining parameters).
#    $client   - File descriptor connected to client.
# Returns
#     0        - Requested to exit, caller should shut down.
#     1        - Continue processing.
#
sub activity_log_handler {
    my ($cmd, $tail, $client) = @_;


    my $userinput= "$cmd:$tail";

    my ($udom,$uname,$what)=split(/:/,$tail);
    chomp($what);
    my $proname=&propath($udom,$uname);
    my $now=time;
    my $hfh;
    if ($hfh=IO::File->new(">>$proname/activity.log")) { 
	print $hfh "$now:$clientname:$what\n";
	&Reply( $client, "ok\n", $userinput); 
    } else {
	&Failure($client, "error: ".($!+0)." IO::File->new Failed "
		 ."while attempting log\n", 
		 $userinput);
    }

    return 1;
}
&register_handler("log", \&activity_log_handler, 0, 1, 0);

#
#   Put a namespace entry in a user profile hash.
#   My druthers would be for this to be an encrypted interaction too.
#   anything that might be an inadvertent covert channel about either
#   user authentication or user personal information....
#
# Parameters:
#    $cmd      - The command that got us here.
#    $tail     - Tail of the command (remaining parameters).
#    $client   - File descriptor connected to client.
# Returns
#     0        - Requested to exit, caller should shut down.
#     1        - Continue processing.
#
sub put_user_profile_entry {
    my ($cmd, $tail, $client)  = @_;

    my $userinput = "$cmd:$tail";
    
    my ($udom,$uname,$namespace,$what) =split(/:/,$tail,4);
    if ($namespace ne 'roles') {
	chomp($what);
	my $hashref = &tie_user_hash($udom, $uname, $namespace,
				  &GDBM_WRCREAT(),"P",$what);
	if($hashref) {
	    my @pairs=split(/\&/,$what);
	    foreach my $pair (@pairs) {
		my ($key,$value)=split(/=/,$pair);
		$hashref->{$key}=$value;
	    }
	    if (&untie_user_hash($hashref)) {
		&Reply( $client, "ok\n", $userinput);
	    } else {
		&Failure($client, "error: ".($!+0)." untie(GDBM) failed ".
			"while attempting put\n", 
			$userinput);
	    }
	} else {
	    &Failure( $client, "error: ".($!+0)." tie(GDBM) Failed ".
		     "while attempting put\n", $userinput);
	}
    } else {
        &Failure( $client, "refused\n", $userinput);
    }
    
    return 1;
}
&register_handler("put", \&put_user_profile_entry, 0, 1, 0);

#   Put a piece of new data in hash, returns error if entry already exists
# Parameters:
#    $cmd      - The command that got us here.
#    $tail     - Tail of the command (remaining parameters).
#    $client   - File descriptor connected to client.
# Returns
#     0        - Requested to exit, caller should shut down.
#     1        - Continue processing.
#
sub newput_user_profile_entry {
    my ($cmd, $tail, $client)  = @_;

    my $userinput = "$cmd:$tail";

    my ($udom,$uname,$namespace,$what) =split(/:/,$tail,4);
    if ($namespace eq 'roles') {
        &Failure( $client, "refused\n", $userinput);
	return 1;
    }

    chomp($what);

    my $hashref = &tie_user_hash($udom, $uname, $namespace,
				 &GDBM_WRCREAT(),"N",$what);
    if(!$hashref) {
	&Failure( $client, "error: ".($!+0)." tie(GDBM) Failed ".
		  "while attempting put\n", $userinput);
	return 1;
    }

    my @pairs=split(/\&/,$what);
    foreach my $pair (@pairs) {
	my ($key,$value)=split(/=/,$pair);
	if (exists($hashref->{$key})) {
	    &Failure($client, "key_exists: ".$key."\n",$userinput);
	    return 1;
	}
    }

    foreach my $pair (@pairs) {
	my ($key,$value)=split(/=/,$pair);
	$hashref->{$key}=$value;
    }

    if (&untie_user_hash($hashref)) {
	&Reply( $client, "ok\n", $userinput);
    } else {
	&Failure($client, "error: ".($!+0)." untie(GDBM) failed ".
		 "while attempting put\n", 
		 $userinput);
    }
    return 1;
}
&register_handler("newput", \&newput_user_profile_entry, 0, 1, 0);

# 
#   Increment a profile entry in the user history file.
#   The history contains keyword value pairs.  In this case,
#   The value itself is a pair of numbers.  The first, the current value
#   the second an increment that this function applies to the current
#   value.
#
# Parameters:
#    $cmd      - The command that got us here.
#    $tail     - Tail of the command (remaining parameters).
#    $client   - File descriptor connected to client.
# Returns
#     0        - Requested to exit, caller should shut down.
#     1        - Continue processing.
#
sub increment_user_value_handler {
    my ($cmd, $tail, $client) = @_;
    
    my $userinput   = "$cmd:$tail";
    
    my ($udom,$uname,$namespace,$what) =split(/:/,$tail);
    if ($namespace ne 'roles') {
        chomp($what);
	my $hashref = &tie_user_hash($udom, $uname,
				     $namespace, &GDBM_WRCREAT(),
				     "P",$what);
	if ($hashref) {
	    my @pairs=split(/\&/,$what);
	    foreach my $pair (@pairs) {
		my ($key,$value)=split(/=/,$pair);
                $value = &unescape($value);
		# We could check that we have a number...
		if (! defined($value) || $value eq '') {
		    $value = 1;
		}
		$hashref->{$key}+=$value;
                if ($namespace eq 'nohist_resourcetracker') {
                    if ($hashref->{$key} < 0) {
                        $hashref->{$key} = 0;
                    }
                }
	    }
	    if (&untie_user_hash($hashref)) {
		&Reply( $client, "ok\n", $userinput);
	    } else {
		&Failure($client, "error: ".($!+0)." untie(GDBM) failed ".
			 "while attempting inc\n", $userinput);
	    }
	} else {
	    &Failure($client, "error: ".($!+0)." tie(GDBM) Failed ".
		     "while attempting inc\n", $userinput);
	}
    } else {
	&Failure($client, "refused\n", $userinput);
    }
    
    return 1;
}
&register_handler("inc", \&increment_user_value_handler, 0, 1, 0);

#
#   Put a new role for a user.  Roles are LonCAPA's packaging of permissions.
#   Each 'role' a user has implies a set of permissions.  Adding a new role
#   for a person grants the permissions packaged with that role
#   to that user when the role is selected.
#
# Parameters:
#    $cmd       - The command string (rolesput).
#    $tail      - The remainder of the request line.  For rolesput this
#                 consists of a colon separated list that contains:
#                 The domain and user that is granting the role (logged).
#                 The domain and user that is getting the role.
#                 The roles being granted as a set of & separated pairs.
#                 each pair a key value pair.
#    $client    - File descriptor connected to the client.
# Returns:
#     0         - If the daemon should exit
#     1         - To continue processing.
#
#
sub roles_put_handler {
    my ($cmd, $tail, $client) = @_;

    my $userinput  = "$cmd:$tail";

    my ( $exedom, $exeuser, $udom, $uname,  $what) = split(/:/,$tail);
    

    my $namespace='roles';
    chomp($what);
    my $hashref = &tie_user_hash($udom, $uname, $namespace,
				 &GDBM_WRCREAT(), "P",
				 "$exedom:$exeuser:$what");
    #
    #  Log the attempt to set a role.  The {}'s here ensure that the file 
    #  handle is open for the minimal amount of time.  Since the flush
    #  is done on close this improves the chances the log will be an un-
    #  corrupted ordered thing.
    if ($hashref) {
	my $pass_entry = &get_auth_type($udom, $uname);
	my ($auth_type,$pwd)  = split(/:/, $pass_entry);
	$auth_type = $auth_type.":";
	my @pairs=split(/\&/,$what);
	foreach my $pair (@pairs) {
	    my ($key,$value)=split(/=/,$pair);
	    &manage_permissions($key, $udom, $uname,
			       $auth_type);
	    $hashref->{$key}=$value;
	}
	if (&untie_user_hash($hashref)) {
	    &Reply($client, "ok\n", $userinput);
	} else {
	    &Failure( $client, "error: ".($!+0)." untie(GDBM) Failed ".
		     "while attempting rolesput\n", $userinput);
	}
    } else {
	&Failure( $client, "error: ".($!+0)." tie(GDBM) Failed ".
		 "while attempting rolesput\n", $userinput);
    }
    return 1;
}
&register_handler("rolesput", \&roles_put_handler, 1,1,0);  # Encoded client only.

#
#   Deletes (removes) a role for a user.   This is equivalent to removing
#  a permissions package associated with the role from the user's profile.
#
# Parameters:
#     $cmd                 - The command (rolesdel)
#     $tail                - The remainder of the request line. This consists
#                             of:
#                             The domain and user requesting the change (logged)
#                             The domain and user being changed.
#                             The roles being revoked.  These are shipped to us
#                             as a bunch of & separated role name keywords.
#     $client              - The file handle open on the client.
# Returns:
#     1                    - Continue processing
#     0                    - Exit.
#
sub roles_delete_handler {
    my ($cmd, $tail, $client)  = @_;

    my $userinput    = "$cmd:$tail";
   
    my ($exedom,$exeuser,$udom,$uname,$what)=split(/:/,$tail);
    &Debug("cmd = ".$cmd." exedom= ".$exedom."user = ".$exeuser." udom=".$udom.
	   "what = ".$what);
    my $namespace='roles';
    chomp($what);
    my $hashref = &tie_user_hash($udom, $uname, $namespace,
				 &GDBM_WRCREAT(), "D",
				 "$exedom:$exeuser:$what");
    
    if ($hashref) {
	my @rolekeys=split(/\&/,$what);
	
	foreach my $key (@rolekeys) {
	    delete $hashref->{$key};
	}
	if (&untie_user_hash($hashref)) {
	    &Reply($client, "ok\n", $userinput);
	} else {
	    &Failure( $client, "error: ".($!+0)." untie(GDBM) Failed ".
		     "while attempting rolesdel\n", $userinput);
	}
    } else {
        &Failure( $client, "error: ".($!+0)." tie(GDBM) Failed ".
		 "while attempting rolesdel\n", $userinput);
    }
    
    return 1;
}
&register_handler("rolesdel", \&roles_delete_handler, 1,1, 0); # Encoded client only

# Unencrypted get from a user's profile database.  See 
# GetProfileEntryEncrypted for a version that does end-to-end encryption.
# This function retrieves a keyed item from a specific named database in the
# user's directory.
#
# Parameters:
#   $cmd             - Command request keyword (get).
#   $tail            - Tail of the command.  This is a colon separated list
#                      consisting of the domain and username that uniquely
#                      identifies the profile,
#                      The 'namespace' which selects the gdbm file to 
#                      do the lookup in, 
#                      & separated list of keys to lookup.  Note that
#                      the values are returned as an & separated list too.
#   $client          - File descriptor open on the client.
# Returns:
#   1       - Continue processing.
#   0       - Exit.
#
sub get_profile_entry {
    my ($cmd, $tail, $client) = @_;

    my $userinput= "$cmd:$tail";
   
    my ($udom,$uname,$namespace,$what) = split(/:/,$tail);
    chomp($what);


    my $replystring = read_profile($udom, $uname, $namespace, $what);
    my ($first) = split(/:/,$replystring);
    if($first ne "error") {
	&Reply($client, \$replystring, $userinput);
    } else {
	&Failure($client, $replystring." while attempting get\n", $userinput);
    }
    return 1;


}
&register_handler("get", \&get_profile_entry, 0,1,0);

#
#  Process the encrypted get request.  Note that the request is sent
#  in clear, but the reply is encrypted.  This is a small covert channel:
#  information about the sensitive keys is given to the snooper.  Just not
#  information about the values of the sensitive key.  Hmm if I wanted to
#  know these I'd snoop for the egets. Get the profile item names from them
#  and then issue a get for them since there's no enforcement of the
#  requirement of an encrypted get for particular profile items.  If I
#  were re-doing this, I'd force the request to be encrypted as well as the
#  reply.  I'd also just enforce encrypted transactions for all gets since
#  that would prevent any covert channel snooping.
#
#  Parameters:
#     $cmd               - Command keyword of request (eget).
#     $tail              - Tail of the command.  See GetProfileEntry
#                          for more information about this.
#     $client            - File open on the client.
#  Returns:
#     1      - Continue processing
#     0      - server should exit.
sub get_profile_entry_encrypted {
    my ($cmd, $tail, $client) = @_;

    my $userinput = "$cmd:$tail";
   
    my ($udom,$uname,$namespace,$what) = split(/:/,$tail);
    chomp($what);
    my $qresult = read_profile($udom, $uname, $namespace, $what);
    my ($first) = split(/:/, $qresult);
    if($first ne "error") {
	
	if ($cipher) {
	    my $cmdlength=length($qresult);
	    $qresult.="         ";
	    my $encqresult='';
	    for(my $encidx=0;$encidx<=$cmdlength;$encidx+=8) {
		$encqresult.= unpack("H16", 
				     $cipher->encrypt(substr($qresult,
							     $encidx,
							     8)));
	    }
	    &Reply( $client, "enc:$cmdlength:$encqresult\n", $userinput);
	} else {
		&Failure( $client, "error:no_key\n", $userinput);
	    }
    } else {
	&Failure($client, "$qresult while attempting eget\n", $userinput);

    }
    
    return 1;
}
&register_handler("eget", \&get_profile_entry_encrypted, 0, 1, 0);

#
#   Deletes a key in a user profile database.
#   
#   Parameters:
#       $cmd                  - Command keyword (del).
#       $tail                 - Command tail.  IN this case a colon
#                               separated list containing:
#                               The domain and user that identifies uniquely
#                               the identity of the user.
#                               The profile namespace (name of the profile
#                               database file).
#                               & separated list of keywords to delete.
#       $client              - File open on client socket.
# Returns:
#     1   - Continue processing
#     0   - Exit server.
#
#
sub delete_profile_entry {
    my ($cmd, $tail, $client) = @_;

    my $userinput = "cmd:$tail";

    my ($udom,$uname,$namespace,$what) = split(/:/,$tail);
    chomp($what);
    my $hashref = &tie_user_hash($udom, $uname, $namespace,
				 &GDBM_WRCREAT(),
				 "D",$what);
    if ($hashref) {
        my @keys=split(/\&/,$what);
	foreach my $key (@keys) {
	    delete($hashref->{$key});
	}
	if (&untie_user_hash($hashref)) {
	    &Reply($client, "ok\n", $userinput);
	} else {
	    &Failure($client, "error: ".($!+0)." untie(GDBM) Failed ".
		    "while attempting del\n", $userinput);
	}
    } else {
	&Failure( $client, "error: ".($!+0)." tie(GDBM) Failed ".
		 "while attempting del\n", $userinput);
    }
    return 1;
}
&register_handler("del", \&delete_profile_entry, 0, 1, 0);

#
#  List the set of keys that are defined in a profile database file.
#  A successful reply from this will contain an & separated list of
#  the keys. 
# Parameters:
#     $cmd              - Command request (keys).
#     $tail             - Remainder of the request, a colon separated
#                         list containing domain/user that identifies the
#                         user being queried, and the database namespace
#                         (database filename essentially).
#     $client           - File open on the client.
#  Returns:
#    1    - Continue processing.
#    0    - Exit the server.
#
sub get_profile_keys {
    my ($cmd, $tail, $client) = @_;

    my $userinput = "$cmd:$tail";

    my ($udom,$uname,$namespace)=split(/:/,$tail);
    my $qresult='';
    my $hashref = &tie_user_hash($udom, $uname, $namespace,
				  &GDBM_READER());
    if ($hashref) {
	foreach my $key (keys %$hashref) {
	    $qresult.="$key&";
	}
	if (&untie_user_hash($hashref)) {
	    $qresult=~s/\&$//;
	    &Reply($client, \$qresult, $userinput);
	} else {
	    &Failure($client, "error: ".($!+0)." untie(GDBM) Failed ".
		    "while attempting keys\n", $userinput);
	}
    } else {
	&Failure( $client, "error: ".($!+0)." tie(GDBM) Failed ".
		 "while attempting keys\n", $userinput);
    }
   
    return 1;
}
&register_handler("keys", \&get_profile_keys, 0, 1, 0);

#
#   Dump the contents of a user profile database.
#   Note that this constitutes a very large covert channel too since
#   the dump will return sensitive information that is not encrypted.
#   The naive security assumption is that the session negotiation ensures
#   our client is trusted and I don't believe that's assured at present.
#   Sure want badly to go to ssl or tls.  Of course if my peer isn't really
#   a LonCAPA node they could have negotiated an encryption key too so >sigh<.
# 
#  Parameters:
#     $cmd           - The command request keyword (currentdump).
#     $tail          - Remainder of the request, consisting of a colon
#                      separated list that has the domain/username and
#                      the namespace to dump (database file).
#     $client        - file open on the remote client.
# Returns:
#     1    - Continue processing.
#     0    - Exit the server.
#
sub dump_profile_database {
    my ($cmd, $tail, $client) = @_;

    my $userinput = "$cmd:$tail";
   
    my ($udom,$uname,$namespace) = split(/:/,$tail);
    my $hashref = &tie_user_hash($udom, $uname, $namespace,
				 &GDBM_READER());
    if ($hashref) {
	# Structure of %data:
	# $data{$symb}->{$parameter}=$value;
	# $data{$symb}->{'v.'.$parameter}=$version;
	# since $parameter will be unescaped, we do not
 	# have to worry about silly parameter names...
	
        my $qresult='';
	my %data = ();                     # A hash of anonymous hashes..
	while (my ($key,$value) = each(%$hashref)) {
	    my ($v,$symb,$param) = split(/:/,$key);
	    next if ($v eq 'version' || $symb eq 'keys');
	    next if (exists($data{$symb}) && 
		     exists($data{$symb}->{$param}) &&
		     $data{$symb}->{'v.'.$param} > $v);
	    $data{$symb}->{$param}=$value;
	    $data{$symb}->{'v.'.$param}=$v;
	}
	if (&untie_user_hash($hashref)) {
	    while (my ($symb,$param_hash) = each(%data)) {
		while(my ($param,$value) = each (%$param_hash)){
		    next if ($param =~ /^v\./);       # Ignore versions...
		    #
		    #   Just dump the symb=value pairs separated by &
		    #
		    $qresult.=$symb.':'.$param.'='.$value.'&';
		}
	    }
	    chop($qresult);
	    &Reply($client , \$qresult, $userinput);
	} else {
	    &Failure( $client, "error: ".($!+0)." untie(GDBM) Failed ".
		     "while attempting currentdump\n", $userinput);
	}
    } else {
	&Failure($client, "error: ".($!+0)." tie(GDBM) Failed ".
		"while attempting currentdump\n", $userinput);
    }

    return 1;
}
&register_handler("currentdump", \&dump_profile_database, 0, 1, 0);

#
#   Dump a profile database with an optional regular expression
#   to match against the keys.  In this dump, no effort is made
#   to separate symb from version information. Presumably the
#   databases that are dumped by this command are of a different
#   structure.  Need to look at this and improve the documentation of
#   both this and the currentdump handler.
# Parameters:
#    $cmd                     - The command keyword.
#    $tail                    - All of the characters after the $cmd:
#                               These are expected to be a colon
#                               separated list containing:
#                               domain/user - identifying the user.
#                               namespace   - identifying the database.
#                               regexp      - optional regular expression
#                                             that is matched against
#                                             database keywords to do
#                                             selective dumps.
#   $client                   - Channel open on the client.
# Returns:
#    1    - Continue processing.
# Side effects:
#    response is written to $client.
#
sub dump_with_regexp {
    my ($cmd, $tail, $client) = @_;


    my $userinput = "$cmd:$tail";

    my ($udom,$uname,$namespace,$regexp,$range)=split(/:/,$tail);
    if (defined($regexp)) {
	$regexp=&unescape($regexp);
    } else {
	$regexp='.';
    }
    my ($start,$end);
    if (defined($range)) {
	if ($range =~/^(\d+)\-(\d+)$/) {
	    ($start,$end) = ($1,$2);
	} elsif ($range =~/^(\d+)$/) {
	    ($start,$end) = (0,$1);
	} else {
	    undef($range);
	}
    }
    my $hashref = &tie_user_hash($udom, $uname, $namespace,
				 &GDBM_READER());
    if ($hashref) {
        my $qresult='';
	my $count=0;
	while (my ($key,$value) = each(%$hashref)) {
	    if ($regexp eq '.') {
		$count++;
		if (defined($range) && $count >= $end)   { last; }
		if (defined($range) && $count <  $start) { next; }
		$qresult.=$key.'='.$value.'&';
	    } else {
		my $unescapeKey = &unescape($key);
		if (eval('$unescapeKey=~/$regexp/')) {
		    $count++;
		    if (defined($range) && $count >= $end)   { last; }
		    if (defined($range) && $count <  $start) { next; }
		    $qresult.="$key=$value&";
		}
	    }
	}
	if (&untie_user_hash($hashref)) {
	    chop($qresult);
	    &Reply($client, \$qresult, $userinput);
	} else {
	    &Failure( $client, "error: ".($!+0)." untie(GDBM) Failed ".
		     "while attempting dump\n", $userinput);
	}
    } else {
	&Failure($client, "error: ".($!+0)." tie(GDBM) Failed ".
		"while attempting dump\n", $userinput);
    }

    return 1;
}
&register_handler("dump", \&dump_with_regexp, 0, 1, 0);

#  Store a set of key=value pairs associated with a versioned name.
#
#  Parameters:
#    $cmd                - Request command keyword.
#    $tail               - Tail of the request.  This is a colon
#                          separated list containing:
#                          domain/user - User and authentication domain.
#                          namespace   - Name of the database being modified
#                          rid         - Resource keyword to modify.
#                          what        - new value associated with rid.
#
#    $client             - Socket open on the client.
#
#
#  Returns:
#      1 (keep on processing).
#  Side-Effects:
#    Writes to the client
sub store_handler {
    my ($cmd, $tail, $client) = @_;
 
    my $userinput = "$cmd:$tail";

    my ($udom,$uname,$namespace,$rid,$what) =split(/:/,$tail);
    if ($namespace ne 'roles') {

	chomp($what);
	my @pairs=split(/\&/,$what);
	my $hashref  = &tie_user_hash($udom, $uname, $namespace,
				       &GDBM_WRCREAT(), "S",
				       "$rid:$what");
	if ($hashref) {
	    my $now = time;
	    my @previouskeys=split(/&/,$hashref->{"keys:$rid"});
	    my $key;
	    $hashref->{"version:$rid"}++;
	    my $version=$hashref->{"version:$rid"};
	    my $allkeys=''; 
	    foreach my $pair (@pairs) {
		my ($key,$value)=split(/=/,$pair);
		$allkeys.=$key.':';
		$hashref->{"$version:$rid:$key"}=$value;
	    }
	    $hashref->{"$version:$rid:timestamp"}=$now;
	    $allkeys.='timestamp';
	    $hashref->{"$version:keys:$rid"}=$allkeys;
	    if (&untie_user_hash($hashref)) {
		&Reply($client, "ok\n", $userinput);
	    } else {
		&Failure($client, "error: ".($!+0)." untie(GDBM) Failed ".
			"while attempting store\n", $userinput);
	    }
	} else {
	    &Failure( $client, "error: ".($!+0)." tie(GDBM) Failed ".
		     "while attempting store\n", $userinput);
	}
    } else {
	&Failure($client, "refused\n", $userinput);
    }

    return 1;
}
&register_handler("store", \&store_handler, 0, 1, 0);

#  Modify a set of key=value pairs associated with a versioned name.
#
#  Parameters:
#    $cmd                - Request command keyword.
#    $tail               - Tail of the request.  This is a colon
#                          separated list containing:
#                          domain/user - User and authentication domain.
#                          namespace   - Name of the database being modified
#                          rid         - Resource keyword to modify.
#                          v           - Version item to modify
#                          what        - new value associated with rid.
#
#    $client             - Socket open on the client.
#
#
#  Returns:
#      1 (keep on processing).
#  Side-Effects:
#    Writes to the client
sub putstore_handler {
    my ($cmd, $tail, $client) = @_;
 
    my $userinput = "$cmd:$tail";

    my ($udom,$uname,$namespace,$rid,$v,$what) =split(/:/,$tail);
    if ($namespace ne 'roles') {

	chomp($what);
	my $hashref  = &tie_user_hash($udom, $uname, $namespace,
				       &GDBM_WRCREAT(), "M",
				       "$rid:$v:$what");
	if ($hashref) {
	    my $now = time;
	    my %data = &hash_extract($what);
	    my @allkeys;
	    while (my($key,$value) = each(%data)) {
		push(@allkeys,$key);
		$hashref->{"$v:$rid:$key"} = $value;
	    }
	    my $allkeys = join(':',@allkeys);
	    $hashref->{"$v:keys:$rid"}=$allkeys;

	    if (&untie_user_hash($hashref)) {
		&Reply($client, "ok\n", $userinput);
	    } else {
		&Failure($client, "error: ".($!+0)." untie(GDBM) Failed ".
			"while attempting store\n", $userinput);
	    }
	} else {
	    &Failure( $client, "error: ".($!+0)." tie(GDBM) Failed ".
		     "while attempting store\n", $userinput);
	}
    } else {
	&Failure($client, "refused\n", $userinput);
    }

    return 1;
}
&register_handler("putstore", \&putstore_handler, 0, 1, 0);

sub hash_extract {
    my ($str)=@_;
    my %hash;
    foreach my $pair (split(/\&/,$str)) {
	my ($key,$value)=split(/=/,$pair);
	$hash{$key}=$value;
    }
    return (%hash);
}
sub hash_to_str {
    my ($hash_ref)=@_;
    my $str;
    foreach my $key (keys(%$hash_ref)) {
	$str.=$key.'='.$hash_ref->{$key}.'&';
    }
    $str=~s/\&$//;
    return $str;
}

#
#  Dump out all versions of a resource that has key=value pairs associated
# with it for each version.  These resources are built up via the store
# command.
#
#  Parameters:
#     $cmd               - Command keyword.
#     $tail              - Remainder of the request which consists of:
#                          domain/user   - User and auth. domain.
#                          namespace     - name of resource database.
#                          rid           - Resource id.
#    $client             - socket open on the client.
#
# Returns:
#      1  indicating the caller should not yet exit.
# Side-effects:
#   Writes a reply to the client.
#   The reply is a string of the following shape:
#   version=current&version:keys=k1:k2...&1:k1=v1&1:k2=v2...
#    Where the 1 above represents version 1.
#    this continues for all pairs of keys in all versions.
#
#
#    
#
sub restore_handler {
    my ($cmd, $tail, $client) = @_;

    my $userinput = "$cmd:$tail";	# Only used for logging purposes.
    my ($udom,$uname,$namespace,$rid) = split(/:/,$tail);
    $namespace=~s/\//\_/g;
    $namespace = &LONCAPA::clean_username($namespace);

    chomp($rid);
    my $qresult='';
    my $hashref = &tie_user_hash($udom, $uname, $namespace, &GDBM_READER());
    if ($hashref) {
	my $version=$hashref->{"version:$rid"};
	$qresult.="version=$version&";
	my $scope;
	for ($scope=1;$scope<=$version;$scope++) {
	    my $vkeys=$hashref->{"$scope:keys:$rid"};
	    my @keys=split(/:/,$vkeys);
	    my $key;
	    $qresult.="$scope:keys=$vkeys&";
	    foreach $key (@keys) {
		$qresult.="$scope:$key=".$hashref->{"$scope:$rid:$key"}."&";
	    }                                  
	}
	if (&untie_user_hash($hashref)) {
	    $qresult=~s/\&$//;
	    &Reply( $client, \$qresult, $userinput);
	} else {
	    &Failure($client, "error: ".($!+0)." untie(GDBM) Failed ".
		    "while attempting restore\n", $userinput);
	}
    } else {
	&Failure($client, "error: ".($!+0)." tie(GDBM) Failed ".
		"while attempting restore\n", $userinput);
    }
  
    return 1;


}
&register_handler("restore", \&restore_handler, 0,1,0);

#
#   Add a chat message to a synchronous discussion board.
#
# Parameters:
#    $cmd                - Request keyword.
#    $tail               - Tail of the command. A colon separated list
#                          containing:
#                          cdom    - Domain on which the chat board lives
#                          cnum    - Course containing the chat board.
#                          newpost - Body of the posting.
#                          group   - Optional group, if chat board is only 
#                                    accessible in a group within the course 
#   $client              - Socket open on the client.
# Returns:
#   1    - Indicating caller should keep on processing.
#
# Side-effects:
#   writes a reply to the client.
#
#
sub send_chat_handler {
    my ($cmd, $tail, $client) = @_;

    
    my $userinput = "$cmd:$tail";

    my ($cdom,$cnum,$newpost,$group)=split(/\:/,$tail);
    &chat_add($cdom,$cnum,$newpost,$group);
    &Reply($client, "ok\n", $userinput);

    return 1;
}
&register_handler("chatsend", \&send_chat_handler, 0, 1, 0);

#
#   Retrieve the set of chat messages from a discussion board.
#
#  Parameters:
#    $cmd             - Command keyword that initiated the request.
#    $tail            - Remainder of the request after the command
#                       keyword.  In this case a colon separated list of
#                       chat domain    - Which discussion board.
#                       chat id        - Discussion thread(?)
#                       domain/user    - Authentication domain and username
#                                        of the requesting person.
#                       group          - Optional course group containing
#                                        the board.      
#   $client           - Socket open on the client program.
# Returns:
#    1     - continue processing
# Side effects:
#    Response is written to the client.
#
sub retrieve_chat_handler {
    my ($cmd, $tail, $client) = @_;


    my $userinput = "$cmd:$tail";

    my ($cdom,$cnum,$udom,$uname,$group)=split(/\:/,$tail);
    my $reply='';
    foreach (&get_chat($cdom,$cnum,$udom,$uname,$group)) {
	$reply.=&escape($_).':';
    }
    $reply=~s/\:$//;
    &Reply($client, \$reply, $userinput);


    return 1;
}
&register_handler("chatretr", \&retrieve_chat_handler, 0, 1, 0);

#
#  Initiate a query of an sql database.  SQL query repsonses get put in
#  a file for later retrieval.  This prevents sql query results from
#  bottlenecking the system.  Note that with loncnew, perhaps this is
#  less of an issue since multiple outstanding requests can be concurrently
#  serviced.
#
#  Parameters:
#     $cmd       - COmmand keyword that initiated the request.
#     $tail      - Remainder of the command after the keyword.
#                  For this function, this consists of a query and
#                  3 arguments that are self-documentingly labelled
#                  in the original arg1, arg2, arg3.
#     $client    - Socket open on the client.
# Return:
#    1   - Indicating processing should continue.
# Side-effects:
#    a reply is written to $client.
#
sub send_query_handler {
    my ($cmd, $tail, $client) = @_;


    my $userinput = "$cmd:$tail";

    my ($query,$arg1,$arg2,$arg3)=split(/\:/,$tail);
    $query=~s/\n*$//g;
    &Reply($client, "". &sql_reply("$clientname\&$query".
				"\&$arg1"."\&$arg2"."\&$arg3")."\n",
	  $userinput);
    
    return 1;
}
&register_handler("querysend", \&send_query_handler, 0, 1, 0);

#
#   Add a reply to an sql query.  SQL queries are done asyncrhonously.
#   The query is submitted via a "querysend" transaction.
#   There it is passed on to the lonsql daemon, queued and issued to
#   mysql.
#     This transaction is invoked when the sql transaction is complete
#   it stores the query results in flie and indicates query completion.
#   presumably local software then fetches this response... I'm guessing
#   the sequence is: lonc does a querysend, we ask lonsql to do it.
#   lonsql on completion of the query interacts with the lond of our
#   client to do a query reply storing two files:
#    - id     - The results of the query.
#    - id.end - Indicating the transaction completed. 
#    NOTE: id is a unique id assigned to the query and querysend time.
# Parameters:
#    $cmd        - Command keyword that initiated this request.
#    $tail       - Remainder of the tail.  In this case that's a colon
#                  separated list containing the query Id and the 
#                  results of the query.
#    $client     - Socket open on the client.
# Return:
#    1           - Indicating that we should continue processing.
# Side effects:
#    ok written to the client.
#
sub reply_query_handler {
    my ($cmd, $tail, $client) = @_;


    my $userinput = "$cmd:$tail";

    my ($id,$reply)=split(/:/,$tail); 
    my $store;
    my $execdir=$perlvar{'lonDaemons'};
    if ($store=IO::File->new(">$execdir/tmp/$id")) {
	$reply=~s/\&/\n/g;
	print $store $reply;
	close $store;
	my $store2=IO::File->new(">$execdir/tmp/$id.end");
	print $store2 "done\n";
	close $store2;
	&Reply($client, "ok\n", $userinput);
    } else {
	&Failure($client, "error: ".($!+0)
		." IO::File->new Failed ".
		"while attempting queryreply\n", $userinput);
    }
 

    return 1;
}
&register_handler("queryreply", \&reply_query_handler, 0, 1, 0);

#
#  Process the courseidput request.  Not quite sure what this means
#  at the system level sense.  It appears a gdbm file in the 
#  /home/httpd/lonUsers/$domain/nohist_courseids is tied and
#  a set of entries made in that database.
#
# Parameters:
#   $cmd      - The command keyword that initiated this request.
#   $tail     - Tail of the command.  In this case consists of a colon
#               separated list contaning the domain to apply this to and
#               an ampersand separated list of keyword=value pairs.
#               Each value is a colon separated list that includes:  
#               description, institutional code and course owner.
#               For backward compatibility with versions included
#               in LON-CAPA 1.1.X (and earlier) and 1.2.X, institutional
#               code and/or course owner are preserved from the existing 
#               record when writing a new record in response to 1.1 or 
#               1.2 implementations of lonnet::flushcourselogs().   
#                      
#   $client   - Socket open on the client.
# Returns:
#   1    - indicating that processing should continue
#
# Side effects:
#   reply is written to the client.
#
sub put_course_id_handler {
    my ($cmd, $tail, $client) = @_;


    my $userinput = "$cmd:$tail";

    my ($udom, $what) = split(/:/, $tail,2);
    chomp($what);
    my $now=time;
    my @pairs=split(/\&/,$what);

    my $hashref = &tie_domain_hash($udom, "nohist_courseids", &GDBM_WRCREAT());
    if ($hashref) {
	foreach my $pair (@pairs) {
            my ($key,$courseinfo) = split(/=/,$pair,2);
            $courseinfo =~ s/=/:/g;
            if (defined($hashref->{$key})) {
                my $value = &Apache::lonnet::thaw_unescape($hashref->{$key});
                if (ref($value) eq 'HASH') {
                    my @items = ('description','inst_code','owner','type');
                    my @new_items = split(/:/,$courseinfo,-1);
                    my %storehash; 
                    for (my $i=0; $i<@new_items; $i++) {
                        $storehash{$items[$i]} = &unescape($new_items[$i]);
                    }
                    $hashref->{$key} = 
                        &Apache::lonnet::freeze_escape(\%storehash);
                    my $unesc_key = &unescape($key);
                    $hashref->{&escape('lasttime:'.$unesc_key)} = $now;
                    next;
                }
            }
            my @current_items = split(/:/,$hashref->{$key},-1);
            shift(@current_items); # remove description
            pop(@current_items);   # remove last access
            my $numcurrent = scalar(@current_items);
            if ($numcurrent > 3) {
                $numcurrent = 3;
            }
            my @new_items = split(/:/,$courseinfo,-1);
            my $numnew = scalar(@new_items);
            if ($numcurrent > 0) {
                if ($numnew <= $numcurrent) { # flushcourselogs() from pre 2.2 
                    for (my $j=$numcurrent-$numnew; $j>=0; $j--) {
                        $courseinfo .= ':'.$current_items[$numcurrent-$j-1];
                    }
                }
            }
            $hashref->{$key}=$courseinfo.':'.$now;
	}
	if (&untie_domain_hash($hashref)) {
	    &Reply( $client, "ok\n", $userinput);
	} else {
	    &Failure($client, "error: ".($!+0)
		     ." untie(GDBM) Failed ".
		     "while attempting courseidput\n", $userinput);
	}
    } else {
	&Failure($client, "error: ".($!+0)
		 ." tie(GDBM) Failed ".
		 "while attempting courseidput\n", $userinput);
    }

    return 1;
}
&register_handler("courseidput", \&put_course_id_handler, 0, 1, 0);

sub put_course_id_hash_handler {
    my ($cmd, $tail, $client) = @_;
    my $userinput = "$cmd:$tail";
    my ($udom,$mode,$what) = split(/:/, $tail,3);
    chomp($what);
    my $now=time;
    my @pairs=split(/\&/,$what);
    my $hashref = &tie_domain_hash($udom, "nohist_courseids", &GDBM_WRCREAT());
    if ($hashref) {
        foreach my $pair (@pairs) {
            my ($key,$value)=split(/=/,$pair);
            my $unesc_key = &unescape($key);
            if ($mode ne 'timeonly') {
                if (!defined($hashref->{&escape('lasttime:'.$unesc_key)})) {
                    my $curritems = &Apache::lonnet::thaw_unescape($key); 
                    if (ref($curritems) ne 'HASH') {
                        my @current_items = split(/:/,$hashref->{$key},-1);
                        my $lasttime = pop(@current_items);
                        $hashref->{&escape('lasttime:'.$unesc_key)} = $lasttime;
                    } else {
                        $hashref->{&escape('lasttime:'.$unesc_key)} = '';
                    }
                } 
                $hashref->{$key} = $value;
            }
            if ($mode ne 'notime') {
                $hashref->{&escape('lasttime:'.$unesc_key)} = $now;
            }
        }
        if (&untie_domain_hash($hashref)) {
            &Reply($client, "ok\n", $userinput);
        } else {
            &Failure($client, "error: ".($!+0)." untie(GDBM) Failed ".
                     "while attempting courseidputhash\n", $userinput);
        }
    } else {
        &Failure( $client, "error: ".($!+0)." tie(GDBM) Failed ".
                  "while attempting courseidputhash\n", $userinput);
    }
    return 1;
}
&register_handler("courseidputhash", \&put_course_id_hash_handler, 0, 1, 0);

#  Retrieves the value of a course id resource keyword pattern
#  defined since a starting date.  Both the starting date and the
#  keyword pattern are optional.  If the starting date is not supplied it
#  is treated as the beginning of time.  If the pattern is not found,
#  it is treatred as "." matching everything.
#
#  Parameters:
#     $cmd     - Command keyword that resulted in us being dispatched.
#     $tail    - The remainder of the command that, in this case, consists
#                of a colon separated list of:
#                 domain   - The domain in which the course database is 
#                            defined.
#                 since    - Optional parameter describing the minimum
#                            time of definition(?) of the resources that
#                            will match the dump.
#                 description - regular expression that is used to filter
#                            the dump.  Only keywords matching this regexp
#                            will be used.
#                 institutional code - optional supplied code to filter 
#                            the dump. Only courses with an institutional code 
#                            that match the supplied code will be returned.
#                 owner    - optional supplied username and domain of owner to
#                            filter the dump.  Only courses for which the course
#                            owner matches the supplied username and/or domain
#                            will be returned. Pre-2.2.0 legacy entries from 
#                            nohist_courseiddump will only contain usernames.
#                 type     - optional parameter for selection 
#                 regexp_ok - if true, allow the supplied institutional code
#                            filter to behave as a regular expression.  
#                 rtn_as_hash - whether to return the information available for
#                            each matched item as a frozen hash of all 
#                            key, value pairs in the item's hash, or as a 
#                            colon-separated list of (in order) description,
#                            institutional code, and course owner.
#                 selfenrollonly - filter by courses allowing self-enrollment  
#                                  now or in the future (selfenrollonly = 1).
#                 catfilter - filter by course category, assigned to a course 
#                             using manually defined categories (i.e., not
#                             self-cataloging based on on institutional code).   
#                 showhidden - include course in results even if course  
#                              was set to be excluded from course catalog (DC only).
#                 caller -  if set to 'coursecatalog', courses set to be hidden
#                           from course catalog will be excluded from results (unless
#                           overridden by "showhidden".
#
#     $client  - The socket open on the client.
# Returns:
#    1     - Continue processing.
# Side Effects:
#   a reply is written to $client.
sub dump_course_id_handler {
    my ($cmd, $tail, $client) = @_;
    my $userinput = "$cmd:$tail";

    my ($udom,$since,$description,$instcodefilter,$ownerfilter,$coursefilter,
        $typefilter,$regexp_ok,$rtn_as_hash,$selfenrollonly,$catfilter,$showhidden,
        $caller) =split(/:/,$tail);
    my $now = time;
    if (defined($description)) {
	$description=&unescape($description);
    } else {
	$description='.';
    }
    if (defined($instcodefilter)) {
        $instcodefilter=&unescape($instcodefilter);
    } else {
        $instcodefilter='.';
    }
    my ($ownerunamefilter,$ownerdomfilter);
    if (defined($ownerfilter)) {
        $ownerfilter=&unescape($ownerfilter);
        if ($ownerfilter ne '.' && defined($ownerfilter)) {
            if ($ownerfilter =~ /^([^:]*):([^:]*)$/) {
                 $ownerunamefilter = $1;
                 $ownerdomfilter = $2;
            } else {
                $ownerunamefilter = $ownerfilter;
                $ownerdomfilter = '';
            }
        }
    } else {
        $ownerfilter='.';
    }

    if (defined($coursefilter)) {
        $coursefilter=&unescape($coursefilter);
    } else {
        $coursefilter='.';
    }
    if (defined($typefilter)) {
        $typefilter=&unescape($typefilter);
    } else {
        $typefilter='.';
    }
    if (defined($regexp_ok)) {
        $regexp_ok=&unescape($regexp_ok);
    }
    if (defined($catfilter)) {
        $catfilter=&unescape($catfilter);
    }
    my $unpack = 1;
    if ($description eq '.' && $instcodefilter eq '.' && $coursefilter eq '.' && 
        $typefilter eq '.') {
        $unpack = 0;
    }
    if (!defined($since)) { $since=0; }
    my $qresult='';
    my $hashref = &tie_domain_hash($udom, "nohist_courseids", &GDBM_WRCREAT());
    if ($hashref) {
	while (my ($key,$value) = each(%$hashref)) {
            my ($unesc_key,$lasttime_key,$lasttime,$is_hash,%val,
                %unesc_val,$selfenroll_end,$selfenroll_types);
            $unesc_key = &unescape($key);
            if ($unesc_key =~ /^lasttime:/) {
                next;
            } else {
                $lasttime_key = &escape('lasttime:'.$unesc_key);
            }
            if ($hashref->{$lasttime_key} ne '') {
                $lasttime = $hashref->{$lasttime_key};
                next if ($lasttime<$since);
            }
            my $items = &Apache::lonnet::thaw_unescape($value);
            if (ref($items) eq 'HASH') {
                $is_hash =  1;
                if ($unpack || !$rtn_as_hash) {
                    $unesc_val{'descr'} = $items->{'description'};
                    $unesc_val{'inst_code'} = $items->{'inst_code'};
                    $unesc_val{'owner'} = $items->{'owner'};
                    $unesc_val{'type'} = $items->{'type'};
                }
                $selfenroll_types = $items->{'selfenroll_types'};
                $selfenroll_end = $items->{'selfenroll_end_date'};
                if ($selfenrollonly) {
                    next if (!$selfenroll_types);
                    if (($selfenroll_end > 0) && ($selfenroll_end <= $now)) {
                        next;
                    }
                }
                if ($catfilter ne '') {
                    next if ($items->{'categories'} eq '');
                    my @categories = split('&',$items->{'categories'}); 
                    next if (@categories == 0);
                    my @subcats = split('&',$catfilter);
                    my $matchcat = 0;
                    foreach my $cat (@categories) {
                        if (grep(/^\Q$cat\E$/,@subcats)) {
                            $matchcat = 1;
                            last;
                        }
                    }
                    next if (!$matchcat);
                }
                if ($caller eq 'coursecatalog') {
                    if ($items->{'hidefromcat'} eq 'yes') {
                        next if !$showhidden;
                    }
                }
            } else {
                next if ($catfilter ne '');
                next if ($selfenrollonly); 
                $is_hash =  0;
                my @courseitems = split(/:/,$value);
                $lasttime = pop(@courseitems);
                if ($hashref->{$lasttime_key} eq '') {
                    next if ($lasttime<$since);
                }
	        ($val{'descr'},$val{'inst_code'},$val{'owner'},$val{'type'}) = @courseitems;
            }
            my $match = 1;
	    if ($description ne '.') {
                if (!$is_hash) {
                    $unesc_val{'descr'} = &unescape($val{'descr'});
                }
                if (eval{$unesc_val{'descr'} !~ /\Q$description\E/i}) {
                    $match = 0;
                }
            }
            if ($instcodefilter ne '.') {
                if (!$is_hash) {
                    $unesc_val{'inst_code'} = &unescape($val{'inst_code'});
                }
                if ($regexp_ok) {
                    if (eval{$unesc_val{'inst_code'} !~ /$instcodefilter/}) {
                        $match = 0;
                    }
                } else {
                    if (eval{$unesc_val{'inst_code'} !~ /\Q$instcodefilter\E/i}) {
                        $match = 0;
                    }
                }
	    }
            if ($ownerfilter ne '.') {
                if (!$is_hash) {
                    $unesc_val{'owner'} = &unescape($val{'owner'});
                }
                if (($ownerunamefilter ne '') && ($ownerdomfilter ne '')) {
                    if ($unesc_val{'owner'} =~ /:/) {
                        if (eval{$unesc_val{'owner'} !~ 
                             /\Q$ownerunamefilter\E:\Q$ownerdomfilter\E$/i}) {
                            $match = 0;
                        } 
                    } else {
                        if (eval{$unesc_val{'owner'} !~ /\Q$ownerunamefilter\E/i}) {
                            $match = 0;
                        }
                    }
                } elsif ($ownerunamefilter ne '') {
                    if ($unesc_val{'owner'} =~ /:/) {
                        if (eval{$unesc_val{'owner'} !~ /\Q$ownerunamefilter\E:[^:]+$/i}) {
                             $match = 0;
                        }
                    } else {
                        if (eval{$unesc_val{'owner'} !~ /\Q$ownerunamefilter\E/i}) {
                            $match = 0;
                        }
                    }
                } elsif ($ownerdomfilter ne '') {
                    if ($unesc_val{'owner'} =~ /:/) {
                        if (eval{$unesc_val{'owner'} !~ /^[^:]+:\Q$ownerdomfilter\E/}) {
                             $match = 0;
                        }
                    } else {
                        if ($ownerdomfilter ne $udom) {
                            $match = 0;
                        }
                    }
                }
            }
            if ($coursefilter ne '.') {
                if (eval{$unesc_key !~ /^$udom(_)\Q$coursefilter\E$/}) {
                    $match = 0;
                }
            }
            if ($typefilter ne '.') {
                if (!$is_hash) {
                    $unesc_val{'type'} = &unescape($val{'type'});
                }
                if ($unesc_val{'type'} eq '') {
                    if ($typefilter ne 'Course') {
                        $match = 0;
                    }
                } else {
                    if (eval{$unesc_val{'type'} !~ /^\Q$typefilter\E$/}) {
                        $match = 0;
                    }
                }
            }
            if ($match == 1) {
                if ($rtn_as_hash) {
                    if ($is_hash) {
                        $qresult.=$key.'='.$value.'&';
                    } else {
                        my %rtnhash = ( 'description' => &unescape($val{'descr'}),
                                        'inst_code' => &unescape($val{'inst_code'}),
                                        'owner'     => &unescape($val{'owner'}),
                                        'type'      => &unescape($val{'type'}),
                                      );
                        my $items = &Apache::lonnet::freeze_escape(\%rtnhash);
                        $qresult.=$key.'='.$items.'&';
                    }
                } else {
                    if ($is_hash) {
                        $qresult .= $key.'='.&escape($unesc_val{'descr'}).':'.
                                    &escape($unesc_val{'inst_code'}).':'.
                                    &escape($unesc_val{'owner'}).'&';
                    } else {
                        $qresult .= $key.'='.$val{'descr'}.':'.$val{'inst_code'}.
                                    ':'.$val{'owner'}.'&';
                    }
                }
            }
	}
	if (&untie_domain_hash($hashref)) {
	    chop($qresult);
	    &Reply($client, \$qresult, $userinput);
	} else {
	    &Failure($client, "error: ".($!+0)." untie(GDBM) Failed ".
		    "while attempting courseiddump\n", $userinput);
	}
    } else {
	&Failure($client, "error: ".($!+0)." tie(GDBM) Failed ".
		"while attempting courseiddump\n", $userinput);
    }
    return 1;
}
&register_handler("courseiddump", \&dump_course_id_handler, 0, 1, 0);

#
# Puts an unencrypted entry in a namespace db file at the domain level 
#
# Parameters:
#    $cmd      - The command that got us here.
#    $tail     - Tail of the command (remaining parameters).
#    $client   - File descriptor connected to client.
# Returns
#     0        - Requested to exit, caller should shut down.
#     1        - Continue processing.
#  Side effects:
#     reply is written to $client.
#
sub put_domain_handler {
    my ($cmd,$tail,$client) = @_;

    my $userinput = "$cmd:$tail";

    my ($udom,$namespace,$what) =split(/:/,$tail,3);
    chomp($what);
    my @pairs=split(/\&/,$what);
    my $hashref = &tie_domain_hash($udom, "$namespace", &GDBM_WRCREAT(),
                                   "P", $what);
    if ($hashref) {
        foreach my $pair (@pairs) {
            my ($key,$value)=split(/=/,$pair);
            $hashref->{$key}=$value;
        }
        if (&untie_domain_hash($hashref)) {
            &Reply($client, "ok\n", $userinput);
        } else {
            &Failure($client, "error: ".($!+0)." untie(GDBM) Failed ".
                     "while attempting putdom\n", $userinput);
        }
    } else {
        &Failure( $client, "error: ".($!+0)." tie(GDBM) Failed ".
                  "while attempting putdom\n", $userinput);
    }

    return 1;
}
&register_handler("putdom", \&put_domain_handler, 0, 1, 0);

# Unencrypted get from the namespace database file at the domain level.
# This function retrieves a keyed item from a specific named database in the
# domain directory.
#
# Parameters:
#   $cmd             - Command request keyword (get).
#   $tail            - Tail of the command.  This is a colon separated list
#                      consisting of the domain and the 'namespace' 
#                      which selects the gdbm file to do the lookup in,
#                      & separated list of keys to lookup.  Note that
#                      the values are returned as an & separated list too.
#   $client          - File descriptor open on the client.
# Returns:
#   1       - Continue processing.
#   0       - Exit.
#  Side effects:
#     reply is written to $client.
#

sub get_domain_handler {
    my ($cmd, $tail, $client) = @_;

    my $userinput = "$client:$tail";

    my ($udom,$namespace,$what)=split(/:/,$tail,3);
    chomp($what);
    my @queries=split(/\&/,$what);
    my $qresult='';
    my $hashref = &tie_domain_hash($udom, "$namespace", &GDBM_READER());
    if ($hashref) {
        for (my $i=0;$i<=$#queries;$i++) {
            $qresult.="$hashref->{$queries[$i]}&";
        }
        if (&untie_domain_hash($hashref)) {
            $qresult=~s/\&$//;
            &Reply($client, \$qresult, $userinput);
        } else {
            &Failure( $client, "error: ".($!+0)." untie(GDBM) Failed ".
                      "while attempting getdom\n",$userinput);
        }
    } else {
        &Failure($client, "error: ".($!+0)." tie(GDBM) Failed ".
                 "while attempting getdom\n",$userinput);
    }

    return 1;
}
&register_handler("getdom", \&get_domain_handler, 0, 1, 0);


#
#  Puts an id to a domains id database. 
#
#  Parameters:
#   $cmd     - The command that triggered us.
#   $tail    - Remainder of the request other than the command. This is a 
#              colon separated list containing:
#              $domain  - The domain for which we are writing the id.
#              $pairs  - The id info to write... this is and & separated list
#                        of keyword=value.
#   $client  - Socket open on the client.
#  Returns:
#    1   - Continue processing.
#  Side effects:
#     reply is written to $client.
#
sub put_id_handler {
    my ($cmd,$tail,$client) = @_;


    my $userinput = "$cmd:$tail";

    my ($udom,$what)=split(/:/,$tail);
    chomp($what);
    my @pairs=split(/\&/,$what);
    my $hashref = &tie_domain_hash($udom, "ids", &GDBM_WRCREAT(),
				   "P", $what);
    if ($hashref) {
	foreach my $pair (@pairs) {
	    my ($key,$value)=split(/=/,$pair);
	    $hashref->{$key}=$value;
	}
	if (&untie_domain_hash($hashref)) {
	    &Reply($client, "ok\n", $userinput);
	} else {
	    &Failure($client, "error: ".($!+0)." untie(GDBM) Failed ".
		     "while attempting idput\n", $userinput);
	}
    } else {
	&Failure( $client, "error: ".($!+0)." tie(GDBM) Failed ".
		  "while attempting idput\n", $userinput);
    }

    return 1;
}
&register_handler("idput", \&put_id_handler, 0, 1, 0);

#
#  Retrieves a set of id values from the id database.
#  Returns an & separated list of results, one for each requested id to the
#  client.
#
# Parameters:
#   $cmd       - Command keyword that caused us to be dispatched.
#   $tail      - Tail of the command.  Consists of a colon separated:
#               domain - the domain whose id table we dump
#               ids      Consists of an & separated list of
#                        id keywords whose values will be fetched.
#                        nonexisting keywords will have an empty value.
#   $client    - Socket open on the client.
#
# Returns:
#    1 - indicating processing should continue.
# Side effects:
#   An & separated list of results is written to $client.
#
sub get_id_handler {
    my ($cmd, $tail, $client) = @_;

    
    my $userinput = "$client:$tail";
    
    my ($udom,$what)=split(/:/,$tail);
    chomp($what);
    my @queries=split(/\&/,$what);
    my $qresult='';
    my $hashref = &tie_domain_hash($udom, "ids", &GDBM_READER());
    if ($hashref) {
	for (my $i=0;$i<=$#queries;$i++) {
	    $qresult.="$hashref->{$queries[$i]}&";
	}
	if (&untie_domain_hash($hashref)) {
	    $qresult=~s/\&$//;
	    &Reply($client, \$qresult, $userinput);
	} else {
	    &Failure( $client, "error: ".($!+0)." untie(GDBM) Failed ".
		      "while attempting idget\n",$userinput);
	}
    } else {
	&Failure($client, "error: ".($!+0)." tie(GDBM) Failed ".
		 "while attempting idget\n",$userinput);
    }
    
    return 1;
}
&register_handler("idget", \&get_id_handler, 0, 1, 0);

#
# Puts broadcast e-mail sent by Domain Coordinator in nohist_dcmail database 
#
# Parameters
#   $cmd       - Command keyword that caused us to be dispatched.
#   $tail      - Tail of the command.  Consists of a colon separated:
#               domain - the domain whose dcmail we are recording
#               email    Consists of key=value pair 
#                        where key is unique msgid
#                        and value is message (in XML)
#   $client    - Socket open on the client.
#
# Returns:
#    1 - indicating processing should continue.
# Side effects
#     reply is written to $client.
#
sub put_dcmail_handler {
    my ($cmd,$tail,$client) = @_;
    my $userinput = "$cmd:$tail";
                                                                                
    my ($udom,$what)=split(/:/,$tail);
    chomp($what);
    my $hashref = &tie_domain_hash($udom, "nohist_dcmail", &GDBM_WRCREAT());
    if ($hashref) {
        my ($key,$value)=split(/=/,$what);
        $hashref->{$key}=$value;
    }
    if (&untie_domain_hash($hashref)) {
        &Reply($client, "ok\n", $userinput);
    } else {
        &Failure($client, "error: ".($!+0)." untie(GDBM) Failed ".
                 "while attempting dcmailput\n", $userinput);
    }
    return 1;
}
&register_handler("dcmailput", \&put_dcmail_handler, 0, 1, 0);

#
# Retrieves broadcast e-mail from nohist_dcmail database
# Returns to client an & separated list of key=value pairs,
# where key is msgid and value is message information.
#
# Parameters
#   $cmd       - Command keyword that caused us to be dispatched.
#   $tail      - Tail of the command.  Consists of a colon separated:
#               domain - the domain whose dcmail table we dump
#               startfilter - beginning of time window 
#               endfilter - end of time window
#               sendersfilter - & separated list of username:domain 
#                 for senders to search for.
#   $client    - Socket open on the client.
#
# Returns:
#    1 - indicating processing should continue.
# Side effects
#     reply (& separated list of msgid=messageinfo pairs) is 
#     written to $client.
#
sub dump_dcmail_handler {
    my ($cmd, $tail, $client) = @_;
                                                                                
    my $userinput = "$cmd:$tail";
    my ($udom,$startfilter,$endfilter,$sendersfilter) = split(/:/,$tail);
    chomp($sendersfilter);
    my @senders = ();
    if (defined($startfilter)) {
        $startfilter=&unescape($startfilter);
    } else {
        $startfilter='.';
    }
    if (defined($endfilter)) {
        $endfilter=&unescape($endfilter);
    } else {
        $endfilter='.';
    }
    if (defined($sendersfilter)) {
        $sendersfilter=&unescape($sendersfilter);
	@senders = map { &unescape($_) } split(/\&/,$sendersfilter);
    }

    my $qresult='';
    my $hashref = &tie_domain_hash($udom, "nohist_dcmail", &GDBM_WRCREAT());
    if ($hashref) {
        while (my ($key,$value) = each(%$hashref)) {
            my $match = 1;
            my ($timestamp,$subj,$uname,$udom) = 
		split(/:/,&unescape(&unescape($key)),5); # yes, twice really
            $subj = &unescape($subj);
            unless ($startfilter eq '.' || !defined($startfilter)) {
                if ($timestamp < $startfilter) {
                    $match = 0;
                }
            }
            unless ($endfilter eq '.' || !defined($endfilter)) {
                if ($timestamp > $endfilter) {
                    $match = 0;
                }
            }
            unless (@senders < 1) {
                unless (grep/^$uname:$udom$/,@senders) {
                    $match = 0;
                }
            }
            if ($match == 1) {
                $qresult.=$key.'='.$value.'&';
            }
        }
        if (&untie_domain_hash($hashref)) {
            chop($qresult);
            &Reply($client, \$qresult, $userinput);
        } else {
            &Failure($client, "error: ".($!+0)." untie(GDBM) Failed ".
                    "while attempting dcmaildump\n", $userinput);
        }
    } else {
        &Failure($client, "error: ".($!+0)." tie(GDBM) Failed ".
                "while attempting dcmaildump\n", $userinput);
    }
    return 1;
}

&register_handler("dcmaildump", \&dump_dcmail_handler, 0, 1, 0);

#
# Puts domain roles in nohist_domainroles database
#
# Parameters
#   $cmd       - Command keyword that caused us to be dispatched.
#   $tail      - Tail of the command.  Consists of a colon separated:
#               domain - the domain whose roles we are recording  
#               role -   Consists of key=value pair
#                        where key is unique role
#                        and value is start/end date information
#   $client    - Socket open on the client.
#
# Returns:
#    1 - indicating processing should continue.
# Side effects
#     reply is written to $client.
#

sub put_domainroles_handler {
    my ($cmd,$tail,$client) = @_;

    my $userinput = "$cmd:$tail";
    my ($udom,$what)=split(/:/,$tail);
    chomp($what);
    my @pairs=split(/\&/,$what);
    my $hashref = &tie_domain_hash($udom, "nohist_domainroles", &GDBM_WRCREAT());
    if ($hashref) {
        foreach my $pair (@pairs) {
            my ($key,$value)=split(/=/,$pair);
            $hashref->{$key}=$value;
        }
        if (&untie_domain_hash($hashref)) {
            &Reply($client, "ok\n", $userinput);
        } else {
            &Failure($client, "error: ".($!+0)." untie(GDBM) Failed ".
                     "while attempting domroleput\n", $userinput);
        }
    } else {
        &Failure( $client, "error: ".($!+0)." tie(GDBM) Failed ".
                  "while attempting domroleput\n", $userinput);
    }
                                                                                  
    return 1;
}

&register_handler("domroleput", \&put_domainroles_handler, 0, 1, 0);

#
# Retrieves domain roles from nohist_domainroles database
# Returns to client an & separated list of key=value pairs,
# where key is role and value is start and end date information.
#
# Parameters
#   $cmd       - Command keyword that caused us to be dispatched.
#   $tail      - Tail of the command.  Consists of a colon separated:
#               domain - the domain whose domain roles table we dump
#   $client    - Socket open on the client.
#
# Returns:
#    1 - indicating processing should continue.
# Side effects
#     reply (& separated list of role=start/end info pairs) is
#     written to $client.
#
sub dump_domainroles_handler {
    my ($cmd, $tail, $client) = @_;
                                                                                           
    my $userinput = "$cmd:$tail";
    my ($udom,$startfilter,$endfilter,$rolesfilter) = split(/:/,$tail);
    chomp($rolesfilter);
    my @roles = ();
    if (defined($startfilter)) {
        $startfilter=&unescape($startfilter);
    } else {
        $startfilter='.';
    }
    if (defined($endfilter)) {
        $endfilter=&unescape($endfilter);
    } else {
        $endfilter='.';
    }
    if (defined($rolesfilter)) {
        $rolesfilter=&unescape($rolesfilter);
	@roles = split(/\&/,$rolesfilter);
    }
                                                                                           
    my $hashref = &tie_domain_hash($udom, "nohist_domainroles", &GDBM_WRCREAT());
    if ($hashref) {
        my $qresult = '';
        while (my ($key,$value) = each(%$hashref)) {
            my $match = 1;
            my ($start,$end) = split(/:/,&unescape($value));
            my ($trole,$uname,$udom,$runame,$rudom,$rsec) = split(/:/,&unescape($key));
            unless ($startfilter eq '.' || !defined($startfilter)) {
                if ($start >= $startfilter) {
                    $match = 0;
                }
            }
            unless ($endfilter eq '.' || !defined($endfilter)) {
                if ($end <= $endfilter) {
                    $match = 0;
                }
            }
            unless (@roles < 1) {
                unless (grep/^\Q$trole\E$/,@roles) {
                    $match = 0;
                }
            }
            if ($match == 1) {
                $qresult.=$key.'='.$value.'&';
            }
        }
        if (&untie_domain_hash($hashref)) {
            chop($qresult);
            &Reply($client, \$qresult, $userinput);
        } else {
            &Failure($client, "error: ".($!+0)." untie(GDBM) Failed ".
                    "while attempting domrolesdump\n", $userinput);
        }
    } else {
        &Failure($client, "error: ".($!+0)." tie(GDBM) Failed ".
                "while attempting domrolesdump\n", $userinput);
    }
    return 1;
}

&register_handler("domrolesdump", \&dump_domainroles_handler, 0, 1, 0);


#  Process the tmpput command I'm not sure what this does.. Seems to
#  create a file in the lonDaemons/tmp directory of the form $id.tmp
# where Id is the client's ip concatenated with a sequence number.
# The file will contain some value that is passed in.  Is this e.g.
# a login token?
#
# Parameters:
#    $cmd     - The command that got us dispatched.
#    $tail    - The remainder of the request following $cmd:
#               In this case this will be the contents of the file.
#    $client  - Socket connected to the client.
# Returns:
#    1 indicating processing can continue.
# Side effects:
#   A file is created in the local filesystem.
#   A reply is sent to the client.
sub tmp_put_handler {
    my ($cmd, $what, $client) = @_;

    my $userinput = "$cmd:$what";	# Reconstruct for logging.

    my ($record,$context) = split(/:/,$what);
    if ($context ne '') {
        chomp($context);
        $context = &unescape($context);
    }
    my ($id,$store);
    $tmpsnum++;
    if ($context eq 'resetpw') {
        $id = &md5_hex(&md5_hex(time.{}.rand().$$));
    } else {
        $id = $$.'_'.$clientip.'_'.$tmpsnum;
    }
    $id=~s/\W/\_/g;
    $record=~s/\n//g;
    my $execdir=$perlvar{'lonDaemons'};
    if ($store=IO::File->new(">$execdir/tmp/$id.tmp")) {
	print $store $record;
	close $store;
	&Reply($client, \$id, $userinput);
    } else {
	&Failure( $client, "error: ".($!+0)."IO::File->new Failed ".
		  "while attempting tmpput\n", $userinput);
    }
    return 1;
  
}
&register_handler("tmpput", \&tmp_put_handler, 0, 1, 0);

#   Processes the tmpget command.  This command returns the contents
#  of a temporary resource file(?) created via tmpput.
#
# Paramters:
#    $cmd      - Command that got us dispatched.
#    $id       - Tail of the command, contain the id of the resource
#                we want to fetch.
#    $client   - socket open on the client.
# Return:
#    1         - Inidcating processing can continue.
# Side effects:
#   A reply is sent to the client.
#
sub tmp_get_handler {
    my ($cmd, $id, $client) = @_;

    my $userinput = "$cmd:$id"; 
    

    $id=~s/\W/\_/g;
    my $store;
    my $execdir=$perlvar{'lonDaemons'};
    if ($store=IO::File->new("$execdir/tmp/$id.tmp")) {
	my $reply=<$store>;
	&Reply( $client, \$reply, $userinput);
	close $store;
    } else {
	&Failure( $client, "error: ".($!+0)."IO::File->new Failed ".
		  "while attempting tmpget\n", $userinput);
    }

    return 1;
}
&register_handler("tmpget", \&tmp_get_handler, 0, 1, 0);

#
#  Process the tmpdel command.  This command deletes a temp resource
#  created by the tmpput command.
#
# Parameters:
#   $cmd      - Command that got us here.
#   $id       - Id of the temporary resource created.
#   $client   - socket open on the client process.
#
# Returns:
#   1     - Indicating processing should continue.
# Side Effects:
#   A file is deleted
#   A reply is sent to the client.
sub tmp_del_handler {
    my ($cmd, $id, $client) = @_;
    
    my $userinput= "$cmd:$id";
    
    chomp($id);
    $id=~s/\W/\_/g;
    my $execdir=$perlvar{'lonDaemons'};
    if (unlink("$execdir/tmp/$id.tmp")) {
	&Reply($client, "ok\n", $userinput);
    } else {
	&Failure( $client, "error: ".($!+0)."Unlink tmp Failed ".
		  "while attempting tmpdel\n", $userinput);
    }
    
    return 1;

}
&register_handler("tmpdel", \&tmp_del_handler, 0, 1, 0);

#
#   Processes the setannounce command.  This command
#   creates a file named announce.txt in the top directory of
#   the documentn root and sets its contents.  The announce.txt file is
#   printed in its entirety at the LonCAPA login page.  Note:
#   once the announcement.txt fileis created it cannot be deleted.
#   However, setting the contents of the file to empty removes the
#   announcement from the login page of loncapa so who cares.
#
# Parameters:
#    $cmd          - The command that got us dispatched.
#    $announcement - The text of the announcement.
#    $client       - Socket open on the client process.
# Retunrns:
#   1             - Indicating request processing should continue
# Side Effects:
#   The file {DocRoot}/announcement.txt is created.
#   A reply is sent to $client.
#
sub set_announce_handler {
    my ($cmd, $announcement, $client) = @_;
  
    my $userinput    = "$cmd:$announcement";

    chomp($announcement);
    $announcement=&unescape($announcement);
    if (my $store=IO::File->new('>'.$perlvar{'lonDocRoot'}.
				'/announcement.txt')) {
	print $store $announcement;
	close $store;
	&Reply($client, "ok\n", $userinput);
    } else {
	&Failure($client, "error: ".($!+0)."\n", $userinput);
    }

    return 1;
}
&register_handler("setannounce", \&set_announce_handler, 0, 1, 0);

#
#  Return the version of the daemon.  This can be used to determine
#  the compatibility of cross version installations or, alternatively to
#  simply know who's out of date and who isn't.  Note that the version
#  is returned concatenated with the tail.
# Parameters:
#   $cmd        - the request that dispatched to us.
#   $tail       - Tail of the request (client's version?).
#   $client     - Socket open on the client.
#Returns:
#   1 - continue processing requests.
# Side Effects:
#   Replies with version to $client.
sub get_version_handler {
    my ($cmd, $tail, $client) = @_;

    my $userinput  = $cmd.$tail;
    
    &Reply($client, &version($userinput)."\n", $userinput);


    return 1;
}
&register_handler("version", \&get_version_handler, 0, 1, 0);

#  Set the current host and domain.  This is used to support
#  multihomed systems.  Each IP of the system, or even separate daemons
#  on the same IP can be treated as handling a separate lonCAPA virtual
#  machine.  This command selects the virtual lonCAPA.  The client always
#  knows the right one since it is lonc and it is selecting the domain/system
#  from the hosts.tab file.
# Parameters:
#    $cmd      - Command that dispatched us.
#    $tail     - Tail of the command (domain/host requested).
#    $socket   - Socket open on the client.
#
# Returns:
#     1   - Indicates the program should continue to process requests.
# Side-effects:
#     The default domain/system context is modified for this daemon.
#     a reply is sent to the client.
#
sub set_virtual_host_handler {
    my ($cmd, $tail, $socket) = @_;
  
    my $userinput  ="$cmd:$tail";

    &Reply($client, &sethost($userinput)."\n", $userinput);


    return 1;
}
&register_handler("sethost", \&set_virtual_host_handler, 0, 1, 0);

#  Process a request to exit:
#   - "bye" is sent to the client.
#   - The client socket is shutdown and closed.
#   - We indicate to the caller that we should exit.
# Formal Parameters:
#   $cmd                - The command that got us here.
#   $tail               - Tail of the command (empty).
#   $client             - Socket open on the tail.
# Returns:
#   0      - Indicating the program should exit!!
#
sub exit_handler {
    my ($cmd, $tail, $client) = @_;

    my $userinput = "$cmd:$tail";

    &logthis("Client $clientip ($clientname) hanging up: $userinput");
    &Reply($client, "bye\n", $userinput);
    $client->shutdown(2);        # shutdown the socket forcibly.
    $client->close();

    return 0;
}
&register_handler("exit", \&exit_handler, 0,1,1);
&register_handler("init", \&exit_handler, 0,1,1);
&register_handler("quit", \&exit_handler, 0,1,1);

#  Determine if auto-enrollment is enabled.
#  Note that the original had what I believe to be a defect.
#  The original returned 0 if the requestor was not a registerd client.
#  It should return "refused".
# Formal Parameters:
#   $cmd       - The command that invoked us.
#   $tail      - The tail of the command (Extra command parameters.
#   $client    - The socket open on the client that issued the request.
# Returns:
#    1         - Indicating processing should continue.
#
sub enrollment_enabled_handler {
    my ($cmd, $tail, $client) = @_;
    my $userinput = $cmd.":".$tail; # For logging purposes.

    
    my ($cdom) = split(/:/, $tail, 2);   # Domain we're asking about.

    my $outcome  = &localenroll::run($cdom);
    &Reply($client, \$outcome, $userinput);

    return 1;
}
&register_handler("autorun", \&enrollment_enabled_handler, 0, 1, 0);

#   Get the official sections for which auto-enrollment is possible.
#   Since the admin people won't know about 'unofficial sections' 
#   we cannot auto-enroll on them.
# Formal Parameters:
#    $cmd     - The command request that got us dispatched here.
#    $tail    - The remainder of the request.  In our case this
#               will be split into:
#               $coursecode   - The course name from the admin point of view.
#               $cdom         - The course's domain(?).
#    $client  - Socket open on the client.
# Returns:
#    1    - Indiciting processing should continue.
#
sub get_sections_handler {
    my ($cmd, $tail, $client) = @_;
    my $userinput = "$cmd:$tail";

    my ($coursecode, $cdom) = split(/:/, $tail);
    my @secs = &localenroll::get_sections($coursecode,$cdom);
    my $seclist = &escape(join(':',@secs));

    &Reply($client, \$seclist, $userinput);
    

    return 1;
}
&register_handler("autogetsections", \&get_sections_handler, 0, 1, 0);

#   Validate the owner of a new course section.  
#
# Formal Parameters:
#   $cmd      - Command that got us dispatched.
#   $tail     - the remainder of the command.  For us this consists of a
#               colon separated string containing:
#                  $inst    - Course Id from the institutions point of view.
#                  $owner   - Proposed owner of the course.
#                  $cdom    - Domain of the course (from the institutions
#                             point of view?)..
#   $client   - Socket open on the client.
#
# Returns:
#   1        - Processing should continue.
#
sub validate_course_owner_handler {
    my ($cmd, $tail, $client)  = @_;
    my $userinput = "$cmd:$tail";
    my ($inst_course_id, $owner, $cdom) = split(/:/, $tail);

    $owner = &unescape($owner);
    my $outcome = &localenroll::new_course($inst_course_id,$owner,$cdom);
    &Reply($client, \$outcome, $userinput);



    return 1;
}
&register_handler("autonewcourse", \&validate_course_owner_handler, 0, 1, 0);

#
#   Validate a course section in the official schedule of classes
#   from the institutions point of view (part of autoenrollment).
#
# Formal Parameters:
#   $cmd          - The command request that got us dispatched.
#   $tail         - The tail of the command.  In this case,
#                   this is a colon separated set of words that will be split
#                   into:
#                        $inst_course_id - The course/section id from the
#                                          institutions point of view.
#                        $cdom           - The domain from the institutions
#                                          point of view.
#   $client       - Socket open on the client.
# Returns:
#    1           - Indicating processing should continue.
#
sub validate_course_section_handler {
    my ($cmd, $tail, $client) = @_;
    my $userinput = "$cmd:$tail";
    my ($inst_course_id, $cdom) = split(/:/, $tail);

    my $outcome=&localenroll::validate_courseID($inst_course_id,$cdom);
    &Reply($client, \$outcome, $userinput);


    return 1;
}
&register_handler("autovalidatecourse", \&validate_course_section_handler, 0, 1, 0);

#
#   Validate course owner's access to enrollment data for specific class section. 
#   
#
# Formal Parameters:
#    $cmd     - The command request that got us dispatched.
#    $tail    - The tail of the command.   In this case this is a colon separated
#               set of words that will be split into:
#               $inst_class  - Institutional code for the specific class section   
#               $courseowner - The escaped username:domain of the course owner 
#               $cdom        - The domain of the course from the institution's
#                              point of view.
#    $client  - The socket open on the client.
# Returns:
#    1 - continue processing.
#

sub validate_class_access_handler {
    my ($cmd, $tail, $client) = @_;
    my $userinput = "$cmd:$tail";
    my ($inst_class,$ownerlist,$cdom) = split(/:/, $tail);
    my $owners = &unescape($ownerlist);
    my $outcome;
    eval {
	local($SIG{__DIE__})='DEFAULT';
	$outcome=&localenroll::check_section($inst_class,$owners,$cdom);
    };
    &Reply($client,\$outcome, $userinput);

    return 1;
}
&register_handler("autovalidateclass_sec", \&validate_class_access_handler, 0, 1, 0);

#
#   Create a password for a new LON-CAPA user added by auto-enrollment.
#   Only used for case where authentication method for new user is localauth
#
# Formal Parameters:
#    $cmd     - The command request that got us dispatched.
#    $tail    - The tail of the command.   In this case this is a colon separated
#               set of words that will be split into:
#               $authparam - An authentication parameter (localauth parameter).
#               $cdom      - The domain of the course from the institution's
#                            point of view.
#    $client  - The socket open on the client.
# Returns:
#    1 - continue processing.
#
sub create_auto_enroll_password_handler {
    my ($cmd, $tail, $client) = @_;
    my $userinput = "$cmd:$tail";

    my ($authparam, $cdom) = split(/:/, $userinput);

    my ($create_passwd,$authchk);
    ($authparam,
     $create_passwd,
     $authchk) = &localenroll::create_password($authparam,$cdom);

    &Reply($client, &escape($authparam.':'.$create_passwd.':'.$authchk)."\n",
	   $userinput);


    return 1;
}
&register_handler("autocreatepassword", \&create_auto_enroll_password_handler, 
		  0, 1, 0);

#   Retrieve and remove temporary files created by/during autoenrollment.
#
# Formal Parameters:
#    $cmd      - The command that got us dispatched.
#    $tail     - The tail of the command.  In our case this is a colon 
#                separated list that will be split into:
#                $filename - The name of the file to remove.
#                            The filename is given as a path relative to
#                            the LonCAPA temp file directory.
#    $client   - Socket open on the client.
#
# Returns:
#   1     - Continue processing.
sub retrieve_auto_file_handler {
    my ($cmd, $tail, $client)    = @_;
    my $userinput                = "cmd:$tail";

    my ($filename)   = split(/:/, $tail);

    my $source = $perlvar{'lonDaemons'}.'/tmp/'.$filename;
    if ( (-e $source) && ($filename ne '') ) {
	my $reply = '';
	if (open(my $fh,$source)) {
	    while (<$fh>) {
		chomp($_);
		$_ =~ s/^\s+//g;
		$_ =~ s/\s+$//g;
		$reply .= $_;
	    }
	    close($fh);
	    &Reply($client, &escape($reply)."\n", $userinput);

#   Does this have to be uncommented??!?  (RF).
#
#                                unlink($source);
	} else {
	    &Failure($client, "error\n", $userinput);
	}
    } else {
	&Failure($client, "error\n", $userinput);
    }
    

    return 1;
}
&register_handler("autoretrieve", \&retrieve_auto_file_handler, 0,1,0);

#
#   Read and retrieve institutional code format (for support form).
# Formal Parameters:
#    $cmd        - Command that dispatched us.
#    $tail       - Tail of the command.  In this case it conatins 
#                  the course domain and the coursename.
#    $client     - Socket open on the client.
# Returns:
#    1     - Continue processing.
#
sub get_institutional_code_format_handler {
    my ($cmd, $tail, $client)   = @_;
    my $userinput               = "$cmd:$tail";

    my $reply;
    my($cdom,$course) = split(/:/,$tail);
    my @pairs = split/\&/,$course;
    my %instcodes = ();
    my %codes = ();
    my @codetitles = ();
    my %cat_titles = ();
    my %cat_order = ();
    foreach (@pairs) {
	my ($key,$value) = split/=/,$_;
	$instcodes{&unescape($key)} = &unescape($value);
    }
    my $formatreply = &localenroll::instcode_format($cdom,
						    \%instcodes,
						    \%codes,
						    \@codetitles,
						    \%cat_titles,
						    \%cat_order);
    if ($formatreply eq 'ok') {
	my $codes_str = &Apache::lonnet::hash2str(%codes);
	my $codetitles_str = &Apache::lonnet::array2str(@codetitles);
	my $cat_titles_str = &Apache::lonnet::hash2str(%cat_titles);
	my $cat_order_str = &Apache::lonnet::hash2str(%cat_order);
	&Reply($client,
	       $codes_str.':'.$codetitles_str.':'.$cat_titles_str.':'
	       .$cat_order_str."\n",
	       $userinput);
    } else {
	# this else branch added by RF since if not ok, lonc will
	# hang waiting on reply until timeout.
	#
	&Reply($client, "format_error\n", $userinput);
    }
    
    return 1;
}
&register_handler("autoinstcodeformat",
		  \&get_institutional_code_format_handler,0,1,0);

sub get_institutional_defaults_handler {
    my ($cmd, $tail, $client)   = @_;
    my $userinput               = "$cmd:$tail";

    my $dom = $tail;
    my %defaults_hash;
    my @code_order;
    my $outcome;
    eval {
        local($SIG{__DIE__})='DEFAULT';
        $outcome = &localenroll::instcode_defaults($dom,\%defaults_hash,
                                                   \@code_order);
    };
    if (!$@) {
        if ($outcome eq 'ok') {
            my $result='';
            while (my ($key,$value) = each(%defaults_hash)) {
                $result.=&escape($key).'='.&escape($value).'&';
            }
            $result .= 'code_order='.&escape(join('&',@code_order));
            &Reply($client,\$result,$userinput);
        } else {
            &Reply($client,"error\n", $userinput);
        }
    } else {
        &Failure($client,"unknown_cmd\n",$userinput);
    }
}
&register_handler("autoinstcodedefaults",
                  \&get_institutional_defaults_handler,0,1,0);

sub get_institutional_user_rules {
    my ($cmd, $tail, $client)   = @_;
    my $userinput               = "$cmd:$tail";
    my $dom = &unescape($tail);
    my (%rules_hash,@rules_order);
    my $outcome;
    eval {
        local($SIG{__DIE__})='DEFAULT';
        $outcome = &localenroll::username_rules($dom,\%rules_hash,\@rules_order);
    };
    if (!$@) {
        if ($outcome eq 'ok') {
            my $result;
            foreach my $key (keys(%rules_hash)) {
                $result .= &escape($key).'='.&Apache::lonnet::freeze_escape($rules_hash{$key}).'&';
            }
            $result =~ s/\&$//;
            $result .= ':';
            if (@rules_order > 0) {
                foreach my $item (@rules_order) {
                    $result .= &escape($item).'&';
                }
            }
            $result =~ s/\&$//;
            &Reply($client,\$result,$userinput);
        } else {
            &Reply($client,"error\n", $userinput);
        }
    } else {
        &Failure($client,"unknown_cmd\n",$userinput);
    }
}
&register_handler("instuserrules",\&get_institutional_user_rules,0,1,0);

sub get_institutional_id_rules {
    my ($cmd, $tail, $client)   = @_;
    my $userinput               = "$cmd:$tail";
    my $dom = &unescape($tail);
    my (%rules_hash,@rules_order);
    my $outcome;
    eval {
        local($SIG{__DIE__})='DEFAULT';
        $outcome = &localenroll::id_rules($dom,\%rules_hash,\@rules_order);
    };
    if (!$@) {
        if ($outcome eq 'ok') {
            my $result;
            foreach my $key (keys(%rules_hash)) {
                $result .= &escape($key).'='.&Apache::lonnet::freeze_escape($rules_hash{$key}).'&';
            }
            $result =~ s/\&$//;
            $result .= ':';
            if (@rules_order > 0) {
                foreach my $item (@rules_order) {
                    $result .= &escape($item).'&';
                }
            }
            $result =~ s/\&$//;
            &Reply($client,\$result,$userinput);
        } else {
            &Reply($client,"error\n", $userinput);
        }
    } else {
        &Failure($client,"unknown_cmd\n",$userinput);
    }
}
&register_handler("instidrules",\&get_institutional_id_rules,0,1,0);

sub get_institutional_selfcreate_rules {
    my ($cmd, $tail, $client)   = @_;
    my $userinput               = "$cmd:$tail";
    my $dom = &unescape($tail);
    my (%rules_hash,@rules_order);
    my $outcome;
    eval {
        local($SIG{__DIE__})='DEFAULT';
        $outcome = &localenroll::selfcreate_rules($dom,\%rules_hash,\@rules_order);
    };
    if (!$@) {
        if ($outcome eq 'ok') {
            my $result;
            foreach my $key (keys(%rules_hash)) {
                $result .= &escape($key).'='.&Apache::lonnet::freeze_escape($rules_hash{$key}).'&';
            }
            $result =~ s/\&$//;
            $result .= ':';
            if (@rules_order > 0) {
                foreach my $item (@rules_order) {
                    $result .= &escape($item).'&';
                }
            }
            $result =~ s/\&$//;
            &Reply($client,\$result,$userinput);
        } else {
            &Reply($client,"error\n", $userinput);
        }
    } else {
        &Failure($client,"unknown_cmd\n",$userinput);
    }
}
&register_handler("instemailrules",\&get_institutional_selfcreate_rules,0,1,0);


sub institutional_username_check {
    my ($cmd, $tail, $client)   = @_;
    my $userinput               = "$cmd:$tail";
    my %rulecheck;
    my $outcome;
    my ($udom,$uname,@rules) = split(/:/,$tail);
    $udom = &unescape($udom);
    $uname = &unescape($uname);
    @rules = map {&unescape($_);} (@rules);
    eval {
        local($SIG{__DIE__})='DEFAULT';
        $outcome = &localenroll::username_check($udom,$uname,\@rules,\%rulecheck);
    };
    if (!$@) {
        if ($outcome eq 'ok') {
            my $result='';
            foreach my $key (keys(%rulecheck)) {
                $result.=&escape($key).'='.&Apache::lonnet::freeze_escape($rulecheck{$key}).'&';
            }
            &Reply($client,\$result,$userinput);
        } else {
            &Reply($client,"error\n", $userinput);
        }
    } else {
        &Failure($client,"unknown_cmd\n",$userinput);
    }
}
&register_handler("instrulecheck",\&institutional_username_check,0,1,0);

sub institutional_id_check {
    my ($cmd, $tail, $client)   = @_;
    my $userinput               = "$cmd:$tail";
    my %rulecheck;
    my $outcome;
    my ($udom,$id,@rules) = split(/:/,$tail);
    $udom = &unescape($udom);
    $id = &unescape($id);
    @rules = map {&unescape($_);} (@rules);
    eval {
        local($SIG{__DIE__})='DEFAULT';
        $outcome = &localenroll::id_check($udom,$id,\@rules,\%rulecheck);
    };
    if (!$@) {
        if ($outcome eq 'ok') {
            my $result='';
            foreach my $key (keys(%rulecheck)) {
                $result.=&escape($key).'='.&Apache::lonnet::freeze_escape($rulecheck{$key}).'&';
            }
            &Reply($client,\$result,$userinput);
        } else {
            &Reply($client,"error\n", $userinput);
        }
    } else {
        &Failure($client,"unknown_cmd\n",$userinput);
    }
}
&register_handler("instidrulecheck",\&institutional_id_check,0,1,0);

sub institutional_selfcreate_check {
    my ($cmd, $tail, $client)   = @_;
    my $userinput               = "$cmd:$tail";
    my %rulecheck;
    my $outcome;
    my ($udom,$email,@rules) = split(/:/,$tail);
    $udom = &unescape($udom);
    $email = &unescape($email);
    @rules = map {&unescape($_);} (@rules);
    eval {
        local($SIG{__DIE__})='DEFAULT';
        $outcome = &localenroll::selfcreate_check($udom,$email,\@rules,\%rulecheck);
    };
    if (!$@) {
        if ($outcome eq 'ok') {
            my $result='';
            foreach my $key (keys(%rulecheck)) {
                $result.=&escape($key).'='.&Apache::lonnet::freeze_escape($rulecheck{$key}).'&';
            }
            &Reply($client,\$result,$userinput);
        } else {
            &Reply($client,"error\n", $userinput);
        }
    } else {
        &Failure($client,"unknown_cmd\n",$userinput);
    }
}
&register_handler("instselfcreatecheck",\&institutional_selfcreate_check,0,1,0);

# Get domain specific conditions for import of student photographs to a course
#
# Retrieves information from photo_permission subroutine in localenroll.
# Returns outcome (ok) if no processing errors, and whether course owner is 
# required to accept conditions of use (yes/no).
#
#    
sub photo_permission_handler {
    my ($cmd, $tail, $client)   = @_;
    my $userinput               = "$cmd:$tail";
    my $cdom = $tail;
    my ($perm_reqd,$conditions);
    my $outcome;
    eval {
	local($SIG{__DIE__})='DEFAULT';
	$outcome = &localenroll::photo_permission($cdom,\$perm_reqd,
						  \$conditions);
    };
    if (!$@) {
	&Reply($client, &escape($outcome.':'.$perm_reqd.':'. $conditions)."\n",
	       $userinput);
    } else {
	&Failure($client,"unknown_cmd\n",$userinput);
    }
    return 1;
}
&register_handler("autophotopermission",\&photo_permission_handler,0,1,0);

#
# Checks if student photo is available for a user in the domain, in the user's
# directory (in /userfiles/internal/studentphoto.jpg).
# Uses localstudentphoto:fetch() to ensure there is an up to date copy of
# the student's photo.   

sub photo_check_handler {
    my ($cmd, $tail, $client)   = @_;
    my $userinput               = "$cmd:$tail";
    my ($udom,$uname,$pid) = split(/:/,$tail);
    $udom = &unescape($udom);
    $uname = &unescape($uname);
    $pid = &unescape($pid);
    my $path=&propath($udom,$uname).'/userfiles/internal/';
    if (!-e $path) {
        &mkpath($path);
    }
    my $response;
    my $result = &localstudentphoto::fetch($udom,$uname,$pid,\$response);
    $result .= ':'.$response;
    &Reply($client, &escape($result)."\n",$userinput);
    return 1;
}
&register_handler("autophotocheck",\&photo_check_handler,0,1,0);

#
# Retrieve information from localenroll about whether to provide a button     
# for users who have enbled import of student photos to initiate an 
# update of photo files for registered students. Also include 
# comment to display alongside button.  

sub photo_choice_handler {
    my ($cmd, $tail, $client) = @_;
    my $userinput             = "$cmd:$tail";
    my $cdom                  = &unescape($tail);
    my ($update,$comment);
    eval {
	local($SIG{__DIE__})='DEFAULT';
	($update,$comment)    = &localenroll::manager_photo_update($cdom);
    };
    if (!$@) {
	&Reply($client,&escape($update).':'.&escape($comment)."\n",$userinput);
    } else {
	&Failure($client,"unknown_cmd\n",$userinput);
    }
    return 1;
}
&register_handler("autophotochoice",\&photo_choice_handler,0,1,0);

#
# Gets a student's photo to exist (in the correct image type) in the user's 
# directory.
# Formal Parameters:
#    $cmd     - The command request that got us dispatched.
#    $tail    - A colon separated set of words that will be split into:
#               $domain - student's domain
#               $uname  - student username
#               $type   - image type desired
#    $client  - The socket open on the client.
# Returns:
#    1 - continue processing.

sub student_photo_handler {
    my ($cmd, $tail, $client) = @_;
    my ($domain,$uname,$ext,$type) = split(/:/, $tail);

    my $path=&propath($domain,$uname). '/userfiles/internal/';
    my $filename = 'studentphoto.'.$ext;
    if ($type eq 'thumbnail') {
        $filename = 'studentphoto_tn.'.$ext;
    }
    if (-e $path.$filename) {
	&Reply($client,"ok\n","$cmd:$tail");
	return 1;
    }
    &mkpath($path);
    my $file;
    if ($type eq 'thumbnail') {
	eval {
	    local($SIG{__DIE__})='DEFAULT';
	    $file=&localstudentphoto::fetch_thumbnail($domain,$uname);
	};
    } else {
        $file=&localstudentphoto::fetch($domain,$uname);
    }
    if (!$file) {
	&Failure($client,"unavailable\n","$cmd:$tail");
	return 1;
    }
    if (!-e $path.$filename) { &convert_photo($file,$path.$filename); }
    if (-e $path.$filename) {
	&Reply($client,"ok\n","$cmd:$tail");
	return 1;
    }
    &Failure($client,"unable_to_convert\n","$cmd:$tail");
    return 1;
}
&register_handler("studentphoto", \&student_photo_handler, 0, 1, 0);

sub inst_usertypes_handler {
    my ($cmd, $domain, $client) = @_;
    my $res;
    my $userinput = $cmd.":".$domain; # For logging purposes.
    my (%typeshash,@order,$result);
    eval {
	local($SIG{__DIE__})='DEFAULT';
	$result=&localenroll::inst_usertypes($domain,\%typeshash,\@order);
    };
    if ($result eq 'ok') {
        if (keys(%typeshash) > 0) {
            foreach my $key (keys(%typeshash)) {
                $res.=&escape($key).'='.&escape($typeshash{$key}).'&';
            }
        }
        $res=~s/\&$//;
        $res .= ':';
        if (@order > 0) {
            foreach my $item (@order) {
                $res .= &escape($item).'&';
            }
        }
        $res=~s/\&$//;
    }
    &Reply($client, \$res, $userinput);
    return 1;
}
&register_handler("inst_usertypes", \&inst_usertypes_handler, 0, 1, 0);

# mkpath makes all directories for a file, expects an absolute path with a
# file or a trailing / if just a dir is passed
# returns 1 on success 0 on failure
sub mkpath {
    my ($file)=@_;
    my @parts=split(/\//,$file,-1);
    my $now=$parts[0].'/'.$parts[1].'/'.$parts[2];
    for (my $i=3;$i<= ($#parts-1);$i++) {
	$now.='/'.$parts[$i]; 
	if (!-e $now) {
	    if  (!mkdir($now,0770)) { return 0; }
	}
    }
    return 1;
}

#---------------------------------------------------------------
#
#   Getting, decoding and dispatching requests:
#
#
#   Get a Request:
#   Gets a Request message from the client.  The transaction
#   is defined as a 'line' of text.  We remove the new line
#   from the text line.  
#
sub get_request {
    my $input = <$client>;
    chomp($input);

    &Debug("get_request: Request = $input\n");

    &status('Processing '.$clientname.':'.$input);

    return $input;
}
#---------------------------------------------------------------
#
#  Process a request.  This sub should shrink as each action
#  gets farmed out into a separat sub that is registered 
#  with the dispatch hash.  
#
# Parameters:
#    user_input   - The request received from the client (lonc).
# Returns:
#    true to keep processing, false if caller should exit.
#
sub process_request {
    my ($userinput) = @_;      # Easier for now to break style than to
                                # fix all the userinput -> user_input.
    my $wasenc    = 0;		# True if request was encrypted.
# ------------------------------------------------------------ See if encrypted
    # for command
    # sethost:<server>
    # <command>:<args>
    #   we just send it to the processor
    # for
    # sethost:<server>:<command>:<args>
    #  we do the implict set host and then do the command
    if ($userinput =~ /^sethost:/) {
	(my $cmd,my $newid,$userinput) = split(':',$userinput,3);
	if (defined($userinput)) {
	    &sethost("$cmd:$newid");
	} else {
	    $userinput = "$cmd:$newid";
	}
    }

    if ($userinput =~ /^enc/) {
	$userinput = decipher($userinput);
	$wasenc=1;
	if(!$userinput) {	# Cipher not defined.
	    &Failure($client, "error: Encrypted data without negotated key\n");
	    return 0;
	}
    }
    Debug("process_request: $userinput\n");
    
    #  
    #   The 'correct way' to add a command to lond is now to
    #   write a sub to execute it and Add it to the command dispatch
    #   hash via a call to register_handler..  The comments to that
    #   sub should give you enough to go on to show how to do this
    #   along with the examples that are building up as this code
    #   is getting refactored.   Until all branches of the
    #   if/elseif monster below have been factored out into
    #   separate procesor subs, if the dispatch hash is missing
    #   the command keyword, we will fall through to the remainder
    #   of the if/else chain below in order to keep this thing in 
    #   working order throughout the transmogrification.

    my ($command, $tail) = split(/:/, $userinput, 2);
    chomp($command);
    chomp($tail);
    $tail =~ s/(\r)//;		# This helps people debugging with e.g. telnet.
    $command =~ s/(\r)//;	# And this too for parameterless commands.
    if(!$tail) {
	$tail ="";		# defined but blank.
    }

    &Debug("Command received: $command, encoded = $wasenc");

    if(defined $Dispatcher{$command}) {

	my $dispatch_info = $Dispatcher{$command};
	my $handler       = $$dispatch_info[0];
	my $need_encode   = $$dispatch_info[1];
	my $client_types  = $$dispatch_info[2];
	Debug("Matched dispatch hash: mustencode: $need_encode "
	      ."ClientType $client_types");
      
	#  Validate the request:
      
	my $ok = 1;
	my $requesterprivs = 0;
	if(&isClient()) {
	    $requesterprivs |= $CLIENT_OK;
	}
	if(&isManager()) {
	    $requesterprivs |= $MANAGER_OK;
	}
	if($need_encode && (!$wasenc)) {
	    Debug("Must encode but wasn't: $need_encode $wasenc");
	    $ok = 0;
	}
	if(($client_types & $requesterprivs) == 0) {
	    Debug("Client not privileged to do this operation");
	    $ok = 0;
	}

	if($ok) {
	    Debug("Dispatching to handler $command $tail");
	    my $keep_going = &$handler($command, $tail, $client);
	    return $keep_going;
	} else {
	    Debug("Refusing to dispatch because client did not match requirements");
	    Failure($client, "refused\n", $userinput);
	    return 1;
	}

    }    

    print $client "unknown_cmd\n";
# -------------------------------------------------------------------- complete
    Debug("process_request - returning 1");
    return 1;
}
#
#   Decipher encoded traffic
#  Parameters:
#     input      - Encoded data.
#  Returns:
#     Decoded data or undef if encryption key was not yet negotiated.
#  Implicit input:
#     cipher  - This global holds the negotiated encryption key.
#
sub decipher {
    my ($input)  = @_;
    my $output = '';
    
    
    if($cipher) {
	my($enc, $enclength, $encinput) = split(/:/, $input);
	for(my $encidx = 0; $encidx < length($encinput); $encidx += 16) {
	    $output .= 
		$cipher->decrypt(pack("H16", substr($encinput, $encidx, 16)));
	}
	return substr($output, 0, $enclength);
    } else {
	return undef;
    }
}

#
#   Register a command processor.  This function is invoked to register a sub
#   to process a request.  Once registered, the ProcessRequest sub can automatically
#   dispatch requests to an appropriate sub, and do the top level validity checking
#   as well:
#    - Is the keyword recognized.
#    - Is the proper client type attempting the request.
#    - Is the request encrypted if it has to be.
#   Parameters:
#    $request_name         - Name of the request being registered.
#                           This is the command request that will match
#                           against the hash keywords to lookup the information
#                           associated with the dispatch information.
#    $procedure           - Reference to a sub to call to process the request.
#                           All subs get called as follows:
#                             Procedure($cmd, $tail, $replyfd, $key)
#                             $cmd    - the actual keyword that invoked us.
#                             $tail   - the tail of the request that invoked us.
#                             $replyfd- File descriptor connected to the client
#    $must_encode          - True if the request must be encoded to be good.
#    $client_ok            - True if it's ok for a client to request this.
#    $manager_ok           - True if it's ok for a manager to request this.
# Side effects:
#      - On success, the Dispatcher hash has an entry added for the key $RequestName
#      - On failure, the program will die as it's a bad internal bug to try to 
#        register a duplicate command handler.
#
sub register_handler {
    my ($request_name,$procedure,$must_encode,	$client_ok,$manager_ok)   = @_;

    #  Don't allow duplication#
   
    if (defined $Dispatcher{$request_name}) {
	die "Attempting to define a duplicate request handler for $request_name\n";
    }
    #   Build the client type mask:
    
    my $client_type_mask = 0;
    if($client_ok) {
	$client_type_mask  |= $CLIENT_OK;
    }
    if($manager_ok) {
	$client_type_mask  |= $MANAGER_OK;
    }
   
    #  Enter the hash:
      
    my @entry = ($procedure, $must_encode, $client_type_mask);
   
    $Dispatcher{$request_name} = \@entry;
   
}


#------------------------------------------------------------------




#
#  Convert an error return code from lcpasswd to a string value.
#
sub lcpasswdstrerror {
    my $ErrorCode = shift;
    if(($ErrorCode < 0) || ($ErrorCode > $lastpwderror)) {
	return "lcpasswd Unrecognized error return value ".$ErrorCode;
    } else {
	return $passwderrors[$ErrorCode];
    }
}

#
# Convert an error return code from lcuseradd to a string value:
#
sub lcuseraddstrerror {
    my $ErrorCode = shift;
    if(($ErrorCode < 0) || ($ErrorCode > $lastadderror)) {
	return "lcuseradd - Unrecognized error code: ".$ErrorCode;
    } else {
	return $adderrors[$ErrorCode];
    }
}

# grabs exception and records it to log before exiting
sub catchexception {
    my ($error)=@_;
    $SIG{'QUIT'}='DEFAULT';
    $SIG{__DIE__}='DEFAULT';
    &status("Catching exception");
    &logthis("<font color='red'>CRITICAL: "
     ."ABNORMAL EXIT. Child $$ for server ".$perlvar{'lonHostID'}." died through "
     ."a crash with this error msg->[$error]</font>");
    &logthis('Famous last words: '.$status.' - '.$lastlog);
    if ($client) { print $client "error: $error\n"; }
    $server->close();
    die($error);
}
sub timeout {
    &status("Handling Timeout");
    &logthis("<font color='red'>CRITICAL: TIME OUT ".$$."</font>");
    &catchexception('Timeout');
}
# -------------------------------- Set signal handlers to record abnormal exits


$SIG{'QUIT'}=\&catchexception;
$SIG{__DIE__}=\&catchexception;

# ---------------------------------- Read loncapa_apache.conf and loncapa.conf
&status("Read loncapa.conf and loncapa_apache.conf");
my $perlvarref=LONCAPA::Configuration::read_conf('loncapa.conf');
%perlvar=%{$perlvarref};
undef $perlvarref;

# ----------------------------- Make sure this process is running from user=www
my $wwwid=getpwnam('www');
if ($wwwid!=$<) {
   my $emailto="$perlvar{'lonAdmEMail'},$perlvar{'lonSysEMail'}";
   my $subj="LON: $currenthostid User ID mismatch";
   system("echo 'User ID mismatch.  lond must be run as user www.' |\
 mailto $emailto -s '$subj' > /dev/null");
   exit 1;
}

# --------------------------------------------- Check if other instance running

my $pidfile="$perlvar{'lonDaemons'}/logs/lond.pid";

if (-e $pidfile) {
   my $lfh=IO::File->new("$pidfile");
   my $pide=<$lfh>;
   chomp($pide);
   if (kill 0 => $pide) { die "already running"; }
}

# ------------------------------------------------------------- Read hosts file



# establish SERVER socket, bind and listen.
$server = IO::Socket::INET->new(LocalPort => $perlvar{'londPort'},
                                Type      => SOCK_STREAM,
                                Proto     => 'tcp',
                                Reuse     => 1,
                                Listen    => 10 )
  or die "making socket: $@\n";

# --------------------------------------------------------- Do global variables

# global variables

my %children               = ();       # keys are current child process IDs

sub REAPER {                        # takes care of dead children
    $SIG{CHLD} = \&REAPER;
    &status("Handling child death");
    my $pid;
    do {
	$pid = waitpid(-1,&WNOHANG());
	if (defined($children{$pid})) {
	    &logthis("Child $pid died");
	    delete($children{$pid});
	} elsif ($pid > 0) {
	    &logthis("Unknown Child $pid died");
	}
    } while ( $pid > 0 );
    foreach my $child (keys(%children)) {
	$pid = waitpid($child,&WNOHANG());
	if ($pid > 0) {
	    &logthis("Child $child - $pid looks like we missed it's death");
	    delete($children{$pid});
	}
    }
    &status("Finished Handling child death");
}

sub HUNTSMAN {                      # signal handler for SIGINT
    &status("Killing children (INT)");
    local($SIG{CHLD}) = 'IGNORE';   # we're going to kill our children
    kill 'INT' => keys %children;
    &logthis("Free socket: ".shutdown($server,2)); # free up socket
    my $execdir=$perlvar{'lonDaemons'};
    unlink("$execdir/logs/lond.pid");
    &logthis("<font color='red'>CRITICAL: Shutting down</font>");
    &status("Done killing children");
    exit;                           # clean up with dignity
}

sub HUPSMAN {                      # signal handler for SIGHUP
    local($SIG{CHLD}) = 'IGNORE';  # we're going to kill our children
    &status("Killing children for restart (HUP)");
    kill 'INT' => keys %children;
    &logthis("Free socket: ".shutdown($server,2)); # free up socket
    &logthis("<font color='red'>CRITICAL: Restarting</font>");
    my $execdir=$perlvar{'lonDaemons'};
    unlink("$execdir/logs/lond.pid");
    &status("Restarting self (HUP)");
    exec("$execdir/lond");         # here we go again
}

#
#  Reload the Apache daemon's state.
#  This is done by invoking /home/httpd/perl/apachereload
#  a setuid perl script that can be root for us to do this job.
#
sub ReloadApache {
    my $execdir = $perlvar{'lonDaemons'};
    my $script  = $execdir."/apachereload";
    system($script);
}

#
#   Called in response to a USR2 signal.
#   - Reread hosts.tab
#   - All children connected to hosts that were removed from hosts.tab
#     are killed via SIGINT
#   - All children connected to previously existing hosts are sent SIGUSR1
#   - Our internal hosts hash is updated to reflect the new contents of
#     hosts.tab causing connections from hosts added to hosts.tab to
#     now be honored.
#
sub UpdateHosts {
    &status("Reload hosts.tab");
    logthis('<font color="blue"> Updating connections </font>');
    #
    #  The %children hash has the set of IP's we currently have children
    #  on.  These need to be matched against records in the hosts.tab
    #  Any ip's no longer in the table get killed off they correspond to
    #  either dropped or changed hosts.  Note that the re-read of the table
    #  will take care of new and changed hosts as connections come into being.

    &Apache::lonnet::reset_hosts_info();

    foreach my $child (keys(%children)) {
	my $childip = $children{$child};
	if ($childip ne '127.0.0.1'
	    && !defined(&Apache::lonnet::get_hosts_from_ip($childip))) {
	    logthis('<font color="blue"> UpdateHosts killing child '
		    ." $child for ip $childip </font>");
	    kill('INT', $child);
	} else {
	    logthis('<font color="green"> keeping child for ip '
		    ." $childip (pid=$child) </font>");
	}
    }
    ReloadApache;
    &status("Finished reloading hosts.tab");
}


sub checkchildren {
    &status("Checking on the children (sending signals)");
    &initnewstatus();
    &logstatus();
    &logthis('Going to check on the children');
    my $docdir=$perlvar{'lonDocRoot'};
    foreach (sort keys %children) {
	#sleep 1;
        unless (kill 'USR1' => $_) {
	    &logthis ('Child '.$_.' is dead');
            &logstatus($$.' is dead');
	    delete($children{$_});
        } 
    }
    sleep 5;
    $SIG{ALRM} = sub { Debug("timeout"); 
		       die "timeout";  };
    $SIG{__DIE__} = 'DEFAULT';
    &status("Checking on the children (waiting for reports)");
    foreach (sort keys %children) {
        unless (-e "$docdir/lon-status/londchld/$_.txt") {
          eval {
            alarm(300);
	    &logthis('Child '.$_.' did not respond');
	    kill 9 => $_;
	    #$emailto="$perlvar{'lonAdmEMail'},$perlvar{'lonSysEMail'}";
	    #$subj="LON: $currenthostid killed lond process $_";
	    #my $result=`echo 'Killed lond process $_.' | mailto $emailto -s '$subj' > /dev/null`;
	    #$execdir=$perlvar{'lonDaemons'};
	    #$result=`/bin/cp $execdir/logs/lond.log $execdir/logs/lond.log.$_`;
	    delete($children{$_});
	    alarm(0);
	  }
        }
    }
    $SIG{ALRM} = 'DEFAULT';
    $SIG{__DIE__} = \&catchexception;
    &status("Finished checking children");
    &logthis('Finished Checking children');
}

# --------------------------------------------------------------------- Logging

sub logthis {
    my $message=shift;
    my $execdir=$perlvar{'lonDaemons'};
    my $fh=IO::File->new(">>$execdir/logs/lond.log");
    my $now=time;
    my $local=localtime($now);
    $lastlog=$local.': '.$message;
    print $fh "$local ($$): $message\n";
}

# ------------------------- Conditional log if $DEBUG true.
sub Debug {
    my $message = shift;
    if($DEBUG) {
	&logthis($message);
    }
}

#
#   Sub to do replies to client.. this gives a hook for some
#   debug tracing too:
#  Parameters:
#     fd      - File open on client.
#     reply   - Text to send to client.
#     request - Original request from client.
#
sub Reply {
    my ($fd, $reply, $request) = @_;
    if (ref($reply)) {
	print $fd $$reply;
	print $fd "\n";
	if ($DEBUG) { Debug("Request was $request  Reply was $$reply"); }
    } else {
	print $fd $reply;
	if ($DEBUG) { Debug("Request was $request  Reply was $reply"); }
    }
    $Transactions++;
}


#
#    Sub to report a failure.
#    This function:
#     -   Increments the failure statistic counters.
#     -   Invokes Reply to send the error message to the client.
# Parameters:
#    fd       - File descriptor open on the client
#    reply    - Reply text to emit.
#    request  - The original request message (used by Reply
#               to debug if that's enabled.
# Implicit outputs:
#    $Failures- The number of failures is incremented.
#    Reply (invoked here) sends a message to the 
#    client:
#
sub Failure {
    my $fd      = shift;
    my $reply   = shift;
    my $request = shift;
   
    $Failures++;
    Reply($fd, $reply, $request);      # That's simple eh?
}
# ------------------------------------------------------------------ Log status

sub logstatus {
    &status("Doing logging");
    my $docdir=$perlvar{'lonDocRoot'};
    {
	my $fh=IO::File->new(">$docdir/lon-status/londchld/$$.txt");
        print $fh $status."\n".$lastlog."\n".time."\n$keymode";
        $fh->close();
    }
    &status("Finished $$.txt");
    {
	open(LOG,">>$docdir/lon-status/londstatus.txt");
	flock(LOG,LOCK_EX);
	print LOG $$."\t".$clientname."\t".$currenthostid."\t"
	    .$status."\t".$lastlog."\t $keymode\n";
	flock(LOG,LOCK_UN);
	close(LOG);
    }
    &status("Finished logging");
}

sub initnewstatus {
    my $docdir=$perlvar{'lonDocRoot'};
    my $fh=IO::File->new(">$docdir/lon-status/londstatus.txt");
    my $now=time;
    my $local=localtime($now);
    print $fh "LOND status $local - parent $$\n\n";
    opendir(DIR,"$docdir/lon-status/londchld");
    while (my $filename=readdir(DIR)) {
        unlink("$docdir/lon-status/londchld/$filename");
    }
    closedir(DIR);
}

# -------------------------------------------------------------- Status setting

sub status {
    my $what=shift;
    my $now=time;
    my $local=localtime($now);
    $status=$local.': '.$what;
    $0='lond: '.$what.' '.$local;
}

# -------------------------------------------------------------- Talk to lonsql

sub sql_reply {
    my ($cmd)=@_;
    my $answer=&sub_sql_reply($cmd);
    if ($answer eq 'con_lost') { $answer=&sub_sql_reply($cmd); }
    return $answer;
}

sub sub_sql_reply {
    my ($cmd)=@_;
    my $unixsock="mysqlsock";
    my $peerfile="$perlvar{'lonSockDir'}/$unixsock";
    my $sclient=IO::Socket::UNIX->new(Peer    =>"$peerfile",
                                      Type    => SOCK_STREAM,
                                      Timeout => 10)
       or return "con_lost";
    print $sclient "$cmd:$currentdomainid\n";
    my $answer=<$sclient>;
    chomp($answer);
    if (!$answer) { $answer="con_lost"; }
    return $answer;
}

# --------------------------------------- Is this the home server of an author?

sub ishome {
    my $author=shift;
    $author=~s/\/home\/httpd\/html\/res\/([^\/]*)\/([^\/]*).*/$1\/$2/;
    my ($udom,$uname)=split(/\//,$author);
    my $proname=propath($udom,$uname);
    if (-e $proname) {
	return 'owner';
    } else {
        return 'not_owner';
    }
}

# ======================================================= Continue main program
# ---------------------------------------------------- Fork once and dissociate

my $fpid=fork;
exit if $fpid;
die "Couldn't fork: $!" unless defined ($fpid);

POSIX::setsid() or die "Can't start new session: $!";

# ------------------------------------------------------- Write our PID on disk

my $execdir=$perlvar{'lonDaemons'};
open (PIDSAVE,">$execdir/logs/lond.pid");
print PIDSAVE "$$\n";
close(PIDSAVE);
&logthis("<font color='red'>CRITICAL: ---------- Starting ----------</font>");
&status('Starting');



# ----------------------------------------------------- Install signal handlers


$SIG{CHLD} = \&REAPER;
$SIG{INT}  = $SIG{TERM} = \&HUNTSMAN;
$SIG{HUP}  = \&HUPSMAN;
$SIG{USR1} = \&checkchildren;
$SIG{USR2} = \&UpdateHosts;

#  Read the host hashes:
&Apache::lonnet::load_hosts_tab();

my $dist=`$perlvar{'lonDaemons'}/distprobe`;

# --------------------------------------------------------------
#   Accept connections.  When a connection comes in, it is validated
#   and if good, a child process is created to process transactions
#   along the connection.

while (1) {
    &status('Starting accept');
    $client = $server->accept() or next;
    &status('Accepted '.$client.' off to spawn');
    make_new_child($client);
    &status('Finished spawning');
}

sub make_new_child {
    my $pid;
#    my $cipher;     # Now global
    my $sigset;

    $client = shift;
    &status('Starting new child '.$client);
    &logthis('<font color="green"> Attempting to start child ('.$client.
	     ")</font>");    
    # block signal for fork
    $sigset = POSIX::SigSet->new(SIGINT);
    sigprocmask(SIG_BLOCK, $sigset)
        or die "Can't block SIGINT for fork: $!\n";

    die "fork: $!" unless defined ($pid = fork);

    $client->sockopt(SO_KEEPALIVE, 1); # Enable monitoring of
	                               # connection liveness.

    #
    #  Figure out who we're talking to so we can record the peer in 
    #  the pid hash.
    #
    my $caller = getpeername($client);
    my ($port,$iaddr);
    if (defined($caller) && length($caller) > 0) {
	($port,$iaddr)=unpack_sockaddr_in($caller);
    } else {
	&logthis("Unable to determine who caller was, getpeername returned nothing");
    }
    if (defined($iaddr)) {
	$clientip  = inet_ntoa($iaddr);
	Debug("Connected with $clientip");
    } else {
	&logthis("Unable to determine clientip");
	$clientip='Unavailable';
    }
    
    if ($pid) {
        # Parent records the child's birth and returns.
        sigprocmask(SIG_UNBLOCK, $sigset)
            or die "Can't unblock SIGINT for fork: $!\n";
        $children{$pid} = $clientip;
        &status('Started child '.$pid);
        return;
    } else {
        # Child can *not* return from this subroutine.
        $SIG{INT} = 'DEFAULT';      # make SIGINT kill us as it did before
        $SIG{CHLD} = 'DEFAULT'; #make this default so that pwauth returns 
                                #don't get intercepted
        $SIG{USR1}= \&logstatus;
        $SIG{ALRM}= \&timeout;
        $lastlog='Forked ';
        $status='Forked';

        # unblock signals
        sigprocmask(SIG_UNBLOCK, $sigset)
            or die "Can't unblock SIGINT for fork: $!\n";

#        my $tmpsnum=0;            # Now global
#---------------------------------------------------- kerberos 5 initialization
        &Authen::Krb5::init_context();
	unless (($dist eq 'fedora5') || ($dist eq 'fedora4') ||  
		($dist eq 'fedora6') || ($dist eq 'suse9.3')) {
	    &Authen::Krb5::init_ets();
	}

	&status('Accepted connection');
# =============================================================================
            # do something with the connection
# -----------------------------------------------------------------------------
	# see if we know client and 'check' for spoof IP by ineffective challenge

	my $outsideip=$clientip;
	if ($clientip eq '127.0.0.1') {
	    $outsideip=&Apache::lonnet::get_host_ip($perlvar{'lonHostID'});
	}

	my $clientrec=defined(&Apache::lonnet::get_hosts_from_ip($outsideip));
	my $ismanager=($managers{$outsideip}    ne undef);
	$clientname  = "[unknonwn]";
	if($clientrec) {	# Establish client type.
	    $ConnectionType = "client";
	    $clientname = (&Apache::lonnet::get_hosts_from_ip($outsideip))[-1];
	    if($ismanager) {
		$ConnectionType = "both";
	    }
	} else {
	    $ConnectionType = "manager";
	    $clientname = $managers{$outsideip};
	}
	my $clientok;

	if ($clientrec || $ismanager) {
	    &status("Waiting for init from $clientip $clientname");
	    &logthis('<font color="yellow">INFO: Connection, '.
		     $clientip.
		  " ($clientname) connection type = $ConnectionType </font>" );
	    &status("Connecting $clientip  ($clientname))"); 
	    my $remotereq=<$client>;
	    chomp($remotereq);
	    Debug("Got init: $remotereq");

	    if ($remotereq =~ /^init/) {
		&sethost("sethost:$perlvar{'lonHostID'}");
		#
		#  If the remote is attempting a local init... give that a try:
		#
		my ($i, $inittype) = split(/:/, $remotereq);

		# If the connection type is ssl, but I didn't get my
		# certificate files yet, then I'll drop  back to 
		# insecure (if allowed).
		
		if($inittype eq "ssl") {
		    my ($ca, $cert) = lonssl::CertificateFile;
		    my $kfile       = lonssl::KeyFile;
		    if((!$ca)   || 
		       (!$cert) || 
		       (!$kfile)) {
			$inittype = ""; # This forces insecure attempt.
			&logthis("<font color=\"blue\"> Certificates not "
				 ."installed -- trying insecure auth</font>");
		    } else {	# SSL certificates are in place so
		    }		# Leave the inittype alone.
		}

		if($inittype eq "local") {
		    my $key = LocalConnection($client, $remotereq);
		    if($key) {
			Debug("Got local key $key");
			$clientok     = 1;
			my $cipherkey = pack("H32", $key);
			$cipher       = new IDEA($cipherkey);
			print $client "ok:local\n";
			&logthis('<font color="green"'
				 . "Successful local authentication </font>");
			$keymode = "local"
		    } else {
			Debug("Failed to get local key");
			$clientok = 0;
			shutdown($client, 3);
			close $client;
		    }
		} elsif ($inittype eq "ssl") {
		    my $key = SSLConnection($client);
		    if ($key) {
			$clientok = 1;
			my $cipherkey = pack("H32", $key);
			$cipher       = new IDEA($cipherkey);
			&logthis('<font color="green">'
				 ."Successfull ssl authentication with $clientname </font>");
			$keymode = "ssl";
	     
		    } else {
			$clientok = 0;
			close $client;
		    }
	   
		} else {
		    my $ok = InsecureConnection($client);
		    if($ok) {
			$clientok = 1;
			&logthis('<font color="green">'
				 ."Successful insecure authentication with $clientname </font>");
			print $client "ok\n";
			$keymode = "insecure";
		    } else {
			&logthis('<font color="yellow">'
				  ."Attempted insecure connection disallowed </font>");
			close $client;
			$clientok = 0;
			
		    }
		}
	    } else {
		&logthis(
			 "<font color='blue'>WARNING: "
			 ."$clientip failed to initialize: >$remotereq< </font>");
		&status('No init '.$clientip);
	    }
	    
	} else {
	    &logthis(
		     "<font color='blue'>WARNING: Unknown client $clientip</font>");
	    &status('Hung up on '.$clientip);
	}
 
	if ($clientok) {
# ---------------- New known client connecting, could mean machine online again
	    if (&Apache::lonnet::get_host_ip($currenthostid) ne $clientip 
		&& $clientip ne '127.0.0.1') {
		&Apache::lonnet::reconlonc($clientname);
	    }
	    &logthis("<font color='green'>Established connection: $clientname</font>");
	    &status('Will listen to '.$clientname);
# ------------------------------------------------------------ Process requests
	    my $keep_going = 1;
	    my $user_input;
	    while(($user_input = get_request) && $keep_going) {
		alarm(120);
		Debug("Main: Got $user_input\n");
		$keep_going = &process_request($user_input);
		alarm(0);
		&status('Listening to '.$clientname." ($keymode)");	   
	    }

# --------------------------------------------- client unknown or fishy, refuse
	}  else {
	    print $client "refused\n";
	    $client->close();
	    &logthis("<font color='blue'>WARNING: "
		     ."Rejected client $clientip, closing connection</font>");
	}
    }            
    
# =============================================================================
    
    &logthis("<font color='red'>CRITICAL: "
	     ."Disconnect from $clientip ($clientname)</font>");    
    
    
    # this exit is VERY important, otherwise the child will become
    # a producer of more and more children, forking yourself into
    # process death.
    exit;
    
}
#
#   Determine if a user is an author for the indicated domain.
#
# Parameters:
#    domain          - domain to check in .
#    user            - Name of user to check.
#
# Return:
#     1             - User is an author for domain.
#     0             - User is not an author for domain.
sub is_author {
    my ($domain, $user) = @_;

    &Debug("is_author: $user @ $domain");

    my $hashref = &tie_user_hash($domain, $user, "roles",
				 &GDBM_READER());

    #  Author role should show up as a key /domain/_au

    my $key    = "/$domain/_au";
    my $value;
    if (defined($hashref)) {
	$value = $hashref->{$key};
    }

    if(defined($value)) {
	&Debug("$user @ $domain is an author");
    }

    return defined($value);
}
#
#   Checks to see if the input roleput request was to set
# an author role.  If so, invokes the lchtmldir script to set
# up a correct public_html 
# Parameters:
#    request   - The request sent to the rolesput subchunk.
#                We're looking for  /domain/_au
#    domain    - The domain in which the user is having roles doctored.
#    user      - Name of the user for which the role is being put.
#    authtype  - The authentication type associated with the user.
#
sub manage_permissions {
    my ($request, $domain, $user, $authtype) = @_;

    &Debug("manage_permissions: $request $domain $user $authtype");

    # See if the request is of the form /$domain/_au
    if($request =~ /^(\/\Q$domain\E\/_au)$/) { # It's an author rolesput...
	my $execdir = $perlvar{'lonDaemons'};
	my $userhome= "/home/$user" ;
	&logthis("system $execdir/lchtmldir $userhome $user $authtype");
	&Debug("Setting homedir permissions for $userhome");
	system("$execdir/lchtmldir $userhome $user $authtype");
    }
}


#
#  Return the full path of a user password file, whether it exists or not.
# Parameters:
#   domain     - Domain in which the password file lives.
#   user       - name of the user.
# Returns:
#    Full passwd path:
#
sub password_path {
    my ($domain, $user) = @_;
    return &propath($domain, $user).'/passwd';
}

#   Password Filename
#   Returns the path to a passwd file given domain and user... only if
#  it exists.
# Parameters:
#   domain    - Domain in which to search.
#   user      - username.
# Returns:
#   - If the password file exists returns its path.
#   - If the password file does not exist, returns undefined.
#
sub password_filename {
    my ($domain, $user) = @_;

    Debug ("PasswordFilename called: dom = $domain user = $user");

    my $path  = &password_path($domain, $user);
    Debug("PasswordFilename got path: $path");
    if(-e $path) {
	return $path;
    } else {
	return undef;
    }
}

#
#   Rewrite the contents of the user's passwd file.
#  Parameters:
#    domain    - domain of the user.
#    name      - User's name.
#    contents  - New contents of the file.
# Returns:
#   0    - Failed.
#   1    - Success.
#
sub rewrite_password_file {
    my ($domain, $user, $contents) = @_;

    my $file = &password_filename($domain, $user);
    if (defined $file) {
	my $pf = IO::File->new(">$file");
	if($pf) {
	    print $pf "$contents\n";
	    return 1;
	} else {
	    return 0;
	}
    } else {
	return 0;
    }

}

#
#   get_auth_type - Determines the authorization type of a user in a domain.

#     Returns the authorization type or nouser if there is no such user.
#
sub get_auth_type 
{

    my ($domain, $user)  = @_;

    Debug("get_auth_type( $domain, $user ) \n");
    my $proname    = &propath($domain, $user); 
    my $passwdfile = "$proname/passwd";
    if( -e $passwdfile ) {
	my $pf = IO::File->new($passwdfile);
	my $realpassword = <$pf>;
	chomp($realpassword);
	Debug("Password info = $realpassword\n");
	my ($authtype, $contentpwd) = split(/:/, $realpassword);
	Debug("Authtype = $authtype, content = $contentpwd\n");
	return "$authtype:$contentpwd";     
    } else {
	Debug("Returning nouser");
	return "nouser";
    }
}

#
#  Validate a user given their domain, name and password.  This utility
#  function is used by both  AuthenticateHandler and ChangePasswordHandler
#  to validate the login credentials of a user.
# Parameters:
#    $domain    - The domain being logged into (this is required due to
#                 the capability for multihomed systems.
#    $user      - The name of the user being validated.
#    $password  - The user's propoposed password.
#
# Returns:
#     1        - The domain,user,pasword triplet corresponds to a valid
#                user.
#     0        - The domain,user,password triplet is not a valid user.
#
sub validate_user {
    my ($domain, $user, $password, $checkdefauth) = @_;

    # Why negative ~pi you may well ask?  Well this function is about
    # authentication, and therefore very important to get right.
    # I've initialized the flag that determines whether or not I've 
    # validated correctly to a value it's not supposed to get.
    # At the end of this function. I'll ensure that it's not still that
    # value so we don't just wind up returning some accidental value
    # as a result of executing an unforseen code path that
    # did not set $validated.  At the end of valid execution paths,
    # validated shoule be 1 for success or 0 for failuer.

    my $validated = -3.14159;

    #  How we authenticate is determined by the type of authentication
    #  the user has been assigned.  If the authentication type is
    #  "nouser", the user does not exist so we will return 0.

    my $contents = &get_auth_type($domain, $user);
    my ($howpwd, $contentpwd) = split(/:/, $contents);

    my $null = pack("C",0);	# Used by kerberos auth types.

    if ($howpwd eq 'nouser') {
        if ($checkdefauth) {
            my %domdefaults = &Apache::lonnet::get_domain_defaults($domain);
            if ($domdefaults{'auth_def'} eq 'localauth') {
                $howpwd = $domdefaults{'auth_def'};
                $contentpwd = $domdefaults{'auth_arg_def'};
            } elsif ((($domdefaults{'auth_def'} eq 'krb4') || 
                      ($domdefaults{'auth_def'} eq 'krb5')) &&
                     ($domdefaults{'auth_arg_def'} ne '')) {
                $howpwd = $domdefaults{'auth_def'};
                $contentpwd = $domdefaults{'auth_arg_def'}; 
            }
        }
    } 
    if ($howpwd ne 'nouser') {
	if($howpwd eq "internal") { # Encrypted is in local password file.
	    $validated = (crypt($password, $contentpwd) eq $contentpwd);
	}
	elsif ($howpwd eq "unix") { # User is a normal unix user.
	    $contentpwd = (getpwnam($user))[1];
	    if($contentpwd) {
		if($contentpwd eq 'x') { # Shadow password file...
		    my $pwauth_path = "/usr/local/sbin/pwauth";
		    open PWAUTH,  "|$pwauth_path" or
			die "Cannot invoke authentication";
		    print PWAUTH "$user\n$password\n";
		    close PWAUTH;
		    $validated = ! $?;

		} else { 	         # Passwords in /etc/passwd. 
		    $validated = (crypt($password,
					$contentpwd) eq $contentpwd);
		}
	    } else {
		$validated = 0;
	    }
	}
	elsif ($howpwd eq "krb4") { # user is in kerberos 4 auth. domain.
	    if(! ($password =~ /$null/) ) {
		my $k4error = &Authen::Krb4::get_pw_in_tkt($user,
							   "",
							   $contentpwd,,
							   'krbtgt',
							   $contentpwd,
							   1,
							   $password);
		if(!$k4error) {
		    $validated = 1;
		} else {
		    $validated = 0;
		    &logthis('krb4: '.$user.', '.$contentpwd.', '.
			     &Authen::Krb4::get_err_txt($Authen::Krb4::error));
		}
	    } else {
		$validated = 0; # Password has a match with null.
	    }
	} elsif ($howpwd eq "krb5") { # User is in kerberos 5 auth. domain.
	    if(!($password =~ /$null/)) { # Null password not allowed.
		my $krbclient = &Authen::Krb5::parse_name($user.'@'
							  .$contentpwd);
		my $krbservice = "krbtgt/".$contentpwd."\@".$contentpwd;
		my $krbserver  = &Authen::Krb5::parse_name($krbservice);
		my $credentials= &Authen::Krb5::cc_default();
		$credentials->initialize(&Authen::Krb5::parse_name($user.'@'
                                                                 .$contentpwd));
                my $krbreturn;
                if (exists(&Authen::Krb5::get_init_creds_password)) {
                    $krbreturn = 
                        &Authen::Krb5::get_init_creds_password($krbclient,$password,
                                                               $krbservice);
                    $validated = (ref($krbreturn) eq 'Authen::Krb5::Creds');
                } else {
		    $krbreturn  = 
                        &Authen::Krb5::get_in_tkt_with_password($krbclient,$krbserver,
		 						$password,$credentials);
		    $validated = ($krbreturn == 1);
                }
		if (!$validated) {
		    &logthis('krb5: '.$user.', '.$contentpwd.', '.
			     &Authen::Krb5::error());
		}
	    } else {
		$validated = 0;
	    }
	} elsif ($howpwd eq "localauth") { 
	    #  Authenticate via installation specific authentcation method:
	    $validated = &localauth::localauth($user, 
					       $password, 
					       $contentpwd,
					       $domain);
	    if ($validated < 0) {
		&logthis("localauth for $contentpwd $user:$domain returned a $validated");
		$validated = 0;
	    }
	} else {			# Unrecognized auth is also bad.
	    $validated = 0;
	}
    } else {
	$validated = 0;
    }
    #
    #  $validated has the correct stat of the authentication:
    #

    unless ($validated != -3.14159) {
	#  I >really really< want to know if this happens.
	#  since it indicates that user authentication is badly
	#  broken in some code path.
        #
	die "ValidateUser - failed to set the value of validated $domain, $user $password";
    }
    return $validated;
}


sub addline {
    my ($fname,$hostid,$ip,$newline)=@_;
    my $contents;
    my $found=0;
    my $expr='^'.quotemeta($hostid).':'.quotemeta($ip).':';
    my $sh;
    if ($sh=IO::File->new("$fname.subscription")) {
	while (my $subline=<$sh>) {
	    if ($subline !~ /$expr/) {$contents.= $subline;} else {$found=1;}
	}
	$sh->close();
    }
    $sh=IO::File->new(">$fname.subscription");
    if ($contents) { print $sh $contents; }
    if ($newline) { print $sh $newline; }
    $sh->close();
    return $found;
}

sub get_chat {
    my ($cdom,$cname,$udom,$uname,$group)=@_;

    my @entries=();
    my $namespace = 'nohist_chatroom';
    my $namespace_inroom = 'nohist_inchatroom';
    if ($group ne '') {
        $namespace .= '_'.$group;
        $namespace_inroom .= '_'.$group;
    }
    my $hashref = &tie_user_hash($cdom, $cname, $namespace,
				 &GDBM_READER());
    if ($hashref) {
	@entries=map { $_.':'.$hashref->{$_} } sort(keys(%$hashref));
	&untie_user_hash($hashref);
    }
    my @participants=();
    my $cutoff=time-60;
    $hashref = &tie_user_hash($cdom, $cname, $namespace_inroom,
			      &GDBM_WRCREAT());
    if ($hashref) {
        $hashref->{$uname.':'.$udom}=time;
        foreach my $user (sort(keys(%$hashref))) {
	    if ($hashref->{$user}>$cutoff) {
		push(@participants, 'active_participant:'.$user);
            }
        }
        &untie_user_hash($hashref);
    }
    return (@participants,@entries);
}

sub chat_add {
    my ($cdom,$cname,$newchat,$group)=@_;
    my @entries=();
    my $time=time;
    my $namespace = 'nohist_chatroom';
    my $logfile = 'chatroom.log';
    if ($group ne '') {
        $namespace .= '_'.$group;
        $logfile = 'chatroom_'.$group.'.log';
    }
    my $hashref = &tie_user_hash($cdom, $cname, $namespace,
				 &GDBM_WRCREAT());
    if ($hashref) {
	@entries=map { $_.':'.$hashref->{$_} } sort(keys(%$hashref));
	my ($lastid)=($entries[$#entries]=~/^(\w+)\:/);
	my ($thentime,$idnum)=split(/\_/,$lastid);
	my $newid=$time.'_000000';
	if ($thentime==$time) {
	    $idnum=~s/^0+//;
	    $idnum++;
	    $idnum=substr('000000'.$idnum,-6,6);
	    $newid=$time.'_'.$idnum;
	}
	$hashref->{$newid}=$newchat;
	my $expired=$time-3600;
	foreach my $comment (keys(%$hashref)) {
	    my ($thistime) = ($comment=~/(\d+)\_/);
	    if ($thistime<$expired) {
		delete $hashref->{$comment};
	    }
	}
	{
	    my $proname=&propath($cdom,$cname);
	    if (open(CHATLOG,">>$proname/$logfile")) { 
		print CHATLOG ("$time:".&unescape($newchat)."\n");
	    }
	    close(CHATLOG);
	}
	&untie_user_hash($hashref);
    }
}

sub unsub {
    my ($fname,$clientip)=@_;
    my $result;
    my $unsubs = 0;		# Number of successful unsubscribes:


    # An old way subscriptions were handled was to have a 
    # subscription marker file:

    Debug("Attempting unlink of $fname.$clientname");
    if (unlink("$fname.$clientname")) {
	$unsubs++;		# Successful unsub via marker file.
    } 

    # The more modern way to do it is to have a subscription list
    # file:

    if (-e "$fname.subscription") {
	my $found=&addline($fname,$clientname,$clientip,'');
	if ($found) { 
	    $unsubs++;
	}
    } 

    #  If either or both of these mechanisms succeeded in unsubscribing a 
    #  resource we can return ok:

    if($unsubs) {
	$result = "ok\n";
    } else {
	$result = "not_subscribed\n";
    }

    return $result;
}

sub currentversion {
    my $fname=shift;
    my $version=-1;
    my $ulsdir='';
    if ($fname=~/^(.+)\/[^\/]+$/) {
       $ulsdir=$1;
    }
    my ($fnamere1,$fnamere2);
    # remove version if already specified
    $fname=~s/\.\d+\.(\w+(?:\.meta)*)$/\.$1/;
    # get the bits that go before and after the version number
    if ( $fname=~/^(.*\.)(\w+(?:\.meta)*)$/ ) {
	$fnamere1=$1;
	$fnamere2='.'.$2;
    }
    if (-e $fname) { $version=1; }
    if (-e $ulsdir) {
	if(-d $ulsdir) {
	    if (opendir(LSDIR,$ulsdir)) {
		my $ulsfn;
		while ($ulsfn=readdir(LSDIR)) {
# see if this is a regular file (ignore links produced earlier)
		    my $thisfile=$ulsdir.'/'.$ulsfn;
		    unless (-l $thisfile) {
			if ($thisfile=~/\Q$fnamere1\E(\d+)\Q$fnamere2\E$/) {
			    if ($1>$version) { $version=$1; }
			}
		    }
		}
		closedir(LSDIR);
		$version++;
	    }
	}
    }
    return $version;
}

sub thisversion {
    my $fname=shift;
    my $version=-1;
    if ($fname=~/\.(\d+)\.\w+(?:\.meta)*$/) {
	$version=$1;
    }
    return $version;
}

sub subscribe {
    my ($userinput,$clientip)=@_;
    my $result;
    my ($cmd,$fname)=split(/:/,$userinput,2);
    my $ownership=&ishome($fname);
    if ($ownership eq 'owner') {
# explitly asking for the current version?
        unless (-e $fname) {
            my $currentversion=&currentversion($fname);
	    if (&thisversion($fname)==$currentversion) {
                if ($fname=~/^(.+)\.\d+\.(\w+(?:\.meta)*)$/) {
		    my $root=$1;
                    my $extension=$2;
                    symlink($root.'.'.$extension,
                            $root.'.'.$currentversion.'.'.$extension);
                    unless ($extension=~/\.meta$/) {
                       symlink($root.'.'.$extension.'.meta',
                            $root.'.'.$currentversion.'.'.$extension.'.meta');
		    }
                }
            }
        }
	if (-e $fname) {
	    if (-d $fname) {
		$result="directory\n";
	    } else {
		if (-e "$fname.$clientname") {&unsub($fname,$clientip);}
		my $now=time;
		my $found=&addline($fname,$clientname,$clientip,
				   "$clientname:$clientip:$now\n");
		if ($found) { $result="$fname\n"; }
		# if they were subscribed to only meta data, delete that
                # subscription, when you subscribe to a file you also get
                # the metadata
		unless ($fname=~/\.meta$/) { &unsub("$fname.meta",$clientip); }
		$fname=~s/\/home\/httpd\/html\/res/raw/;
		$fname="http://".&Apache::lonnet::hostname($perlvar{'lonHostID'})."/".$fname;
		$result="$fname\n";
	    }
	} else {
	    $result="not_found\n";
	}
    } else {
	$result="rejected\n";
    }
    return $result;
}
#  Change the passwd of a unix user.  The caller must have
#  first verified that the user is a loncapa user.
#
# Parameters:
#    user      - Unix user name to change.
#    pass      - New password for the user.
# Returns:
#    ok    - if success
#    other - Some meaningfule error message string.
# NOTE:
#    invokes a setuid script to change the passwd.
sub change_unix_password {
    my ($user, $pass) = @_;

    &Debug("change_unix_password");
    my $execdir=$perlvar{'lonDaemons'};
    &Debug("Opening lcpasswd pipeline");
    my $pf = IO::File->new("|$execdir/lcpasswd > "
			   ."$perlvar{'lonDaemons'}"
			   ."/logs/lcpasswd.log");
    print $pf "$user\n$pass\n$pass\n";
    close $pf;
    my $err = $?;
    return ($err < @passwderrors) ? $passwderrors[$err] : 
	"pwchange_falure - unknown error";

    
}


sub make_passwd_file {
    my ($uname, $umode,$npass,$passfilename)=@_;
    my $result="ok";
    if ($umode eq 'krb4' or $umode eq 'krb5') {
	{
	    my $pf = IO::File->new(">$passfilename");
	    if ($pf) {
		print $pf "$umode:$npass\n";
	    } else {
		$result = "pass_file_failed_error";
	    }
	}
    } elsif ($umode eq 'internal') {
	my $salt=time;
	$salt=substr($salt,6,2);
	my $ncpass=crypt($npass,$salt);
	{
	    &Debug("Creating internal auth");
	    my $pf = IO::File->new(">$passfilename");
	    if($pf) {
		print $pf "internal:$ncpass\n"; 
	    } else {
		$result = "pass_file_failed_error";
	    }
	}
    } elsif ($umode eq 'localauth') {
	{
	    my $pf = IO::File->new(">$passfilename");
	    if($pf) {
		print $pf "localauth:$npass\n";
	    } else {
		$result = "pass_file_failed_error";
	    }
	}
    } elsif ($umode eq 'unix') {
	{
	    #
	    #  Don't allow the creation of privileged accounts!!! that would
	    #  be real bad!!!
	    #
	    my $uid = getpwnam($uname);
	    if((defined $uid) && ($uid == 0)) {
		&logthis(">>>Attempted to create privilged account blocked");
		return "no_priv_account_error\n";
	    }

	    my $execpath       ="$perlvar{'lonDaemons'}/"."lcuseradd";

	    my $lc_error_file  = $execdir."/tmp/lcuseradd".$$.".status";
	    {
		&Debug("Executing external: ".$execpath);
		&Debug("user  = ".$uname.", Password =". $npass);
		my $se = IO::File->new("|$execpath > $perlvar{'lonDaemons'}/logs/lcuseradd.log");
		print $se "$uname\n";
		print $se "$npass\n";
		print $se "$npass\n";
		print $se "$lc_error_file\n"; # Status -> unique file.
	    }
	    if (-r $lc_error_file) {
		&Debug("Opening error file: $lc_error_file");
		my $error = IO::File->new("< $lc_error_file");
		my $useraddok = <$error>;
		$error->close;
		unlink($lc_error_file);
		
		chomp $useraddok;
	
		if($useraddok > 0) {
		    my $error_text = &lcuseraddstrerror($useraddok);
		    &logthis("Failed lcuseradd: $error_text");
		    $result = "lcuseradd_failed:$error_text";
		}  else {
		    my $pf = IO::File->new(">$passfilename");
		    if($pf) {
			print $pf "unix:\n";
		    } else {
			$result = "pass_file_failed_error";
		    }
		}
	    }  else {
		&Debug("Could not locate lcuseradd error: $lc_error_file");
		$result="bug_lcuseradd_no_output_file";
	    }
	}
    } elsif ($umode eq 'none') {
	{
	    my $pf = IO::File->new("> $passfilename");
	    if($pf) {
		print $pf "none:\n";
	    } else {
		$result = "pass_file_failed_error";
	    }
	}
    } else {
	$result="auth_mode_error";
    }
    return $result;
}

sub convert_photo {
    my ($start,$dest)=@_;
    system("convert $start $dest");
}

sub sethost {
    my ($remotereq) = @_;
    my (undef,$hostid)=split(/:/,$remotereq);
    # ignore sethost if we are already correct
    if ($hostid eq $currenthostid) {
	return 'ok';
    }

    if (!defined($hostid)) { $hostid=$perlvar{'lonHostID'}; }
    if (&Apache::lonnet::get_host_ip($perlvar{'lonHostID'}) 
	eq &Apache::lonnet::get_host_ip($hostid)) {
	$currenthostid  =$hostid;
	$currentdomainid=&Apache::lonnet::host_domain($hostid);
	&logthis("Setting hostid to $hostid, and domain to $currentdomainid");
    } else {
	&logthis("Requested host id $hostid not an alias of ".
		 $perlvar{'lonHostID'}." refusing connection");
	return 'unable_to_set';
    }
    return 'ok';
}

sub version {
    my ($userinput)=@_;
    $remoteVERSION=(split(/:/,$userinput))[1];
    return "version:$VERSION";
}


# ----------------------------------- POD (plain old documentation, CPAN style)

=head1 NAME

lond - "LON Daemon" Server (port "LOND" 5663)

=head1 SYNOPSIS

Usage: B<lond>

Should only be run as user=www.  This is a command-line script which
is invoked by B<loncron>.  There is no expectation that a typical user
will manually start B<lond> from the command-line.  (In other words,
DO NOT START B<lond> YOURSELF.)

=head1 DESCRIPTION

There are two characteristics associated with the running of B<lond>,
PROCESS MANAGEMENT (starting, stopping, handling child processes)
and SERVER-SIDE ACTIVITIES (password authentication, user creation,
subscriptions, etc).  These are described in two large
sections below.

B<PROCESS MANAGEMENT>

Preforker - server who forks first. Runs as a daemon. HUPs.
Uses IDEA encryption

B<lond> forks off children processes that correspond to the other servers
in the network.  Management of these processes can be done at the
parent process level or the child process level.

B<logs/lond.log> is the location of log messages.

The process management is now explained in terms of linux shell commands,
subroutines internal to this code, and signal assignments:

=over 4

=item *

PID is stored in B<logs/lond.pid>

This is the process id number of the parent B<lond> process.

=item *

SIGTERM and SIGINT

Parent signal assignment:
 $SIG{INT}  = $SIG{TERM} = \&HUNTSMAN;

Child signal assignment:
 $SIG{INT}  = 'DEFAULT'; (and SIGTERM is DEFAULT also)
(The child dies and a SIGALRM is sent to parent, awaking parent from slumber
 to restart a new child.)

Command-line invocations:
 B<kill> B<-s> SIGTERM I<PID>
 B<kill> B<-s> SIGINT I<PID>

Subroutine B<HUNTSMAN>:
 This is only invoked for the B<lond> parent I<PID>.
This kills all the children, and then the parent.
The B<lonc.pid> file is cleared.

=item *

SIGHUP

Current bug:
 This signal can only be processed the first time
on the parent process.  Subsequent SIGHUP signals
have no effect.

Parent signal assignment:
 $SIG{HUP}  = \&HUPSMAN;

Child signal assignment:
 none (nothing happens)

Command-line invocations:
 B<kill> B<-s> SIGHUP I<PID>

Subroutine B<HUPSMAN>:
 This is only invoked for the B<lond> parent I<PID>,
This kills all the children, and then the parent.
The B<lond.pid> file is cleared.

=item *

SIGUSR1

Parent signal assignment:
 $SIG{USR1} = \&USRMAN;

Child signal assignment:
 $SIG{USR1}= \&logstatus;

Command-line invocations:
 B<kill> B<-s> SIGUSR1 I<PID>

Subroutine B<USRMAN>:
 When invoked for the B<lond> parent I<PID>,
SIGUSR1 is sent to all the children, and the status of
each connection is logged.

=item *

SIGUSR2

Parent Signal assignment:
    $SIG{USR2} = \&UpdateHosts

Child signal assignment:
    NONE


=item *

SIGCHLD

Parent signal assignment:
 $SIG{CHLD} = \&REAPER;

Child signal assignment:
 none

Command-line invocations:
 B<kill> B<-s> SIGCHLD I<PID>

Subroutine B<REAPER>:
 This is only invoked for the B<lond> parent I<PID>.
Information pertaining to the child is removed.
The socket port is cleaned up.

=back

B<SERVER-SIDE ACTIVITIES>

Server-side information can be accepted in an encrypted or non-encrypted
method.

=over 4

=item ping

Query a client in the hosts.tab table; "Are you there?"

=item pong

Respond to a ping query.

=item ekey

Read in encrypted key, make cipher.  Respond with a buildkey.

=item load

Respond with CPU load based on a computation upon /proc/loadavg.

=item currentauth

Reply with current authentication information (only over an
encrypted channel).

=item auth

Only over an encrypted channel, reply as to whether a user's
authentication information can be validated.

=item passwd

Allow for a password to be set.

=item makeuser

Make a user.

=item passwd

Allow for authentication mechanism and password to be changed.

=item home

Respond to a question "are you the home for a given user?"

=item update

Update contents of a subscribed resource.

=item unsubscribe

The server is unsubscribing from a resource.

=item subscribe

The server is subscribing to a resource.

=item log

Place in B<logs/lond.log>

=item put

stores hash in namespace

=item rolesputy

put a role into a user's environment

=item get

returns hash with keys from array
reference filled in from namespace

=item eget

returns hash with keys from array
reference filled in from namesp (encrypts the return communication)

=item rolesget

get a role from a user's environment

=item del

deletes keys out of array from namespace

=item keys

returns namespace keys

=item dump

dumps the complete (or key matching regexp) namespace into a hash

=item store

stores hash permanently
for this url; hashref needs to be given and should be a \%hashname; the
remaining args aren't required and if they aren't passed or are '' they will
be derived from the ENV

=item restore

returns a hash for a given url

=item querysend

Tells client about the lonsql process that has been launched in response
to a sent query.

=item queryreply

Accept information from lonsql and make appropriate storage in temporary
file space.

=item idput

Defines usernames as corresponding to IDs.  (These "IDs" are unique identifiers
for each student, defined perhaps by the institutional Registrar.)

=item idget

Returns usernames corresponding to IDs.  (These "IDs" are unique identifiers
for each student, defined perhaps by the institutional Registrar.)

=item tmpput

Accept and store information in temporary space.

=item tmpget

Send along temporarily stored information.

=item ls

List part of a user's directory.

=item pushtable

Pushes a file in /home/httpd/lonTab directory.  Currently limited to:
hosts.tab and domain.tab. The old file is copied to  *.tab.backup but
must be restored manually in case of a problem with the new table file.
pushtable requires that the request be encrypted and validated via
ValidateManager.  The form of the command is:
enc:pushtable tablename <tablecontents> \n
where pushtable, tablename and <tablecontents> will be encrypted, but \n is a 
cleartext newline.

=item Hanging up (exit or init)

What to do when a client tells the server that they (the client)
are leaving the network.

=item unknown command

If B<lond> is sent an unknown command (not in the list above),
it replys to the client "unknown_cmd".


=item UNKNOWN CLIENT

If the anti-spoofing algorithm cannot verify the client,
the client is rejected (with a "refused" message sent
to the client, and the connection is closed.

=back

=head1 PREREQUISITES

IO::Socket
IO::File
Apache::File
POSIX
Crypt::IDEA
LWP::UserAgent()
GDBM_File
Authen::Krb4
Authen::Krb5

=head1 COREQUISITES

=head1 OSNAMES

linux

=head1 SCRIPT CATEGORIES

Server/Process

=cut


=pod

=head1 LOG MESSAGES

The messages below can be emitted in the lond log.  This log is located
in ~httpd/perl/logs/lond.log  Many log messages have HTML encapsulation
to provide coloring if examined from inside a web page. Some do not.
Where color is used, the colors are; Red for sometihhng to get excited
about and to follow up on. Yellow for something to keep an eye on to
be sure it does not get worse, Green,and Blue for informational items.

In the discussions below, sometimes reference is made to ~httpd
when describing file locations.  There isn't really an httpd 
user, however there is an httpd directory that gets installed in the
place that user home directories go.  On linux, this is usually
(always?) /home/httpd.


Some messages are colorless.  These are usually (not always)
Green/Blue color level messages.

=over 2

=item (Red)  LocalConnection rejecting non local: <ip> ne 127.0.0.1

A local connection negotiation was attempted by
a host whose IP address was not 127.0.0.1.
The socket is closed and the child will exit.
lond has three ways to establish an encyrption
key with a client:

=over 2

=item local 

The key is written and read from a file.
This is only valid for connections from localhost.

=item insecure 

The key is generated by the server and
transmitted to the client.

=item  ssl (secure)

An ssl connection is negotiated with the client,
the key is generated by the server and sent to the 
client across this ssl connection before the
ssl connectionis terminated and clear text
transmission resumes.

=back

=item (Red) LocalConnection: caller is insane! init = <init> and type = <type>

The client is local but has not sent an initialization
string that is the literal "init:local"  The connection
is closed and the child exits.

=item Red CRITICAL Can't get key file <error>        

SSL key negotiation is being attempted but the call to
lonssl::KeyFile  failed.  This usually means that the
configuration file is not correctly defining or protecting
the directories/files lonCertificateDirectory or
lonnetPrivateKey
<error> is a string that describes the reason that
the key file could not be located.

=item (Red) CRITICAL  Can't get certificates <error>  

SSL key negotiation failed because we were not able to retrives our certificate
or the CA's certificate in the call to lonssl::CertificateFile
<error> is the textual reason this failed.  Usual reasons:

=over 2
       
=item Apache config file for loncapa  incorrect:
 
one of the variables 
lonCertificateDirectory, lonnetCertificateAuthority, or lonnetCertificate
undefined or incorrect

=item Permission error:

The directory pointed to by lonCertificateDirectory is not readable by lond

=item Permission error:

Files in the directory pointed to by lonCertificateDirectory are not readable by lond.

=item Installation error:                         

Either the certificate authority file or the certificate have not
been installed in lonCertificateDirectory.

=item (Red) CRITICAL SSL Socket promotion failed:  <err> 

The promotion of the connection from plaintext to SSL failed
<err> is the reason for the failure.  There are two
system calls involved in the promotion (one of which failed), 
a dup to produce
a second fd on the raw socket over which the encrypted data
will flow and IO::SOcket::SSL->new_from_fd which creates
the SSL connection on the duped fd.

=item (Blue)   WARNING client did not respond to challenge 

This occurs on an insecure (non SSL) connection negotiation request.
lond generates some number from the time, the PID and sends it to
the client.  The client must respond by echoing this information back.
If the client does not do so, that's a violation of the challenge
protocols and the connection will be failed.

=item (Red) No manager table. Nobody can manage!!    

lond has the concept of privileged hosts that
can perform remote management function such
as update the hosts.tab.   The manager hosts
are described in the 
~httpd/lonTabs/managers.tab file.
this message is logged if this file is missing.


=item (Green) Registering manager <dnsname> as <cluster_name> with <ipaddress>

Reports the successful parse and registration
of a specific manager. 

=item Green existing host <clustername:dnsname>  

The manager host is already defined in the hosts.tab
the information in that table, rather than the info in the
manager table will be used to determine the manager's ip.

=item (Red) Unable to craete <filename>                 

lond has been asked to create new versions of an administrative
file (by a manager).  When this is done, the new file is created
in a temp file and then renamed into place so that there are always
usable administrative files, even if the update fails.  This failure
message means that the temp file could not be created.
The update is abandoned, and the old file is available for use.

=item (Green) CopyFile from <oldname> to <newname> failed

In an update of administrative files, the copy of the existing file to a
backup file failed.  The installation of the new file may still succeed,
but there will not be a back up file to rever to (this should probably
be yellow).

=item (Green) Pushfile: backed up <oldname> to <newname>

See above, the backup of the old administrative file succeeded.

=item (Red)  Pushfile: Unable to install <filename> <reason>

The new administrative file could not be installed.  In this case,
the old administrative file is still in use.

=item (Green) Installed new < filename>.                      

The new administrative file was successfullly installed.                                               

=item (Red) Reinitializing lond pid=<pid>                    

The lonc child process <pid> will be sent a USR2 
signal.

=item (Red) Reinitializing self                                    

We've been asked to re-read our administrative files,and
are doing so.

=item (Yellow) error:Invalid process identifier <ident>  

A reinit command was received, but the target part of the 
command was not valid.  It must be either
'lond' or 'lonc' but was <ident>

=item (Green) isValideditCommand checking: Command = <command> Key = <key> newline = <newline>

Checking to see if lond has been handed a valid edit
command.  It is possible the edit command is not valid
in that case there are no log messages to indicate that.

=item Result of password change for  <username> pwchange_success

The password for <username> was
successfully changed.

=item Unable to open <user> passwd to change password

Could not rewrite the 
internal password file for a user

=item Result of password change for <user> : <result>
                                                                     
A unix password change for <user> was attempted 
and the pipe returned <result>  

=item LWP GET: <message> for <fname> (<remoteurl>)

The lightweight process fetch for a resource failed
with <message> the local filename that should
have existed/been created was  <fname> the
corresponding URI: <remoteurl>  This is emitted in several
places.

=item Unable to move <transname> to <destname>     

From fetch_user_file_handler - the user file was replicated but could not
be mv'd to its final location.

=item Looking for <domain> <username>              

From user_has_session_handler - This should be a Debug call instead
it indicates lond is about to check whether the specified user has a 
session active on the specified domain on the local host.

=item Client <ip> (<name>) hanging up: <input>     

lond has been asked to exit by its client.  The <ip> and <name> identify the
client systemand <input> is the full exit command sent to the server.

=item Red CRITICAL: ABNORMAL EXIT. child <pid> for server <hostname> died through a crass with this error->[<message>].
                                                 
A lond child terminated.  NOte that this termination can also occur when the
child receives the QUIT or DIE signals.  <pid> is the process id of the child,
<hostname> the host lond is working for, and <message> the reason the child died
to the best of our ability to get it (I would guess that any numeric value
represents and errno value).  This is immediately followed by

=item  Famous last words: Catching exception - <log> 

Where log is some recent information about the state of the child.

=item Red CRITICAL: TIME OUT <pid>                     

Some timeout occured for server <pid>.  THis is normally a timeout on an LWP
doing an HTTP::GET.

=item child <pid> died                              

The reaper caught a SIGCHILD for the lond child process <pid>
This should be modified to also display the IP of the dying child
$children{$pid}

=item Unknown child 0 died                           
A child died but the wait for it returned a pid of zero which really should not
ever happen. 

=item Child <which> - <pid> looks like we missed it's death 

When a sigchild is received, the reaper process checks all children to see if they are
alive.  If children are dying quite quickly, the lack of signal queuing can mean
that a signal hearalds the death of more than one child.  If so this message indicates
which other one died. <which> is the ip of a dead child

=item Free socket: <shutdownretval>                

The HUNTSMAN sub was called due to a SIGINT in a child process.  The socket is being shutdown.
for whatever reason, <shutdownretval> is printed but in fact shutdown() is not documented
to return anything. This is followed by: 

=item Red CRITICAL: Shutting down                       

Just prior to exit.

=item Free socket: <shutdownretval>                 

The HUPSMAN sub was called due to a SIGHUP.  all children get killsed, and lond execs itself.
This is followed by:

=item (Red) CRITICAL: Restarting                         

lond is about to exec itself to restart.

=item (Blue) Updating connections                        

(In response to a USR2).  All the children (except the one for localhost)
are about to be killed, the hosts tab reread, and Apache reloaded via apachereload.

=item (Blue) UpdateHosts killing child <pid> for ip <ip>   

Due to USR2 as above.

=item (Green) keeping child for ip <ip> (pid = <pid>)    

In response to USR2 as above, the child indicated is not being restarted because
it's assumed that we'll always need a child for the localhost.


=item Going to check on the children                

Parent is about to check on the health of the child processes.
Note that this is in response to a USR1 sent to the parent lond.
there may be one or more of the next two messages:

=item <pid> is dead                                 

A child that we have in our child hash as alive has evidently died.

=item  Child <pid> did not respond                   

In the health check the child <pid> did not update/produce a pid_.txt
file when sent it's USR1 signal.  That process is killed with a 9 signal, as it's
assumed to be hung in some un-fixable way.

=item Finished checking children                   
 
Master processs's USR1 processing is cojmplete.

=item (Red) CRITICAL: ------- Starting ------            

(There are more '-'s on either side).  Lond has forked itself off to 
form a new session and is about to start actual initialization.

=item (Green) Attempting to start child (<client>)       

Started a new child process for <client>.  Client is IO::Socket object
connected to the child.  This was as a result of a TCP/IP connection from a client.

=item Unable to determine who caller was, getpeername returned nothing
                                                  
In child process initialization.  either getpeername returned undef or
a zero sized object was returned.  Processing continues, but in my opinion,
this should be cause for the child to exit.

=item Unable to determine clientip                  

In child process initialization.  The peer address from getpeername was not defined.
The client address is stored as "Unavailable" and processing continues.

=item (Yellow) INFO: Connection <ip> <name> connection type = <type>
                                                  
In child initialization.  A good connectionw as received from <ip>.

=over 2

=item <name> 

is the name of the client from hosts.tab.

=item <type> 

Is the connection type which is either 

=over 2

=item manager 

The connection is from a manager node, not in hosts.tab

=item client  

the connection is from a non-manager in the hosts.tab

=item both

The connection is from a manager in the hosts.tab.

=back

=back

=item (Blue) Certificates not installed -- trying insecure auth

One of the certificate file, key file or
certificate authority file could not be found for a client attempting
SSL connection intiation.  COnnection will be attemptied in in-secure mode.
(this would be a system with an up to date lond that has not gotten a 
certificate from us).

=item (Green)  Successful local authentication            

A local connection successfully negotiated the encryption key. 
In this case the IDEA key is in a file (that is hopefully well protected).

=item (Green) Successful ssl authentication with <client>  

The client (<client> is the peer's name in hosts.tab), has successfully
negotiated an SSL connection with this child process.

=item (Green) Successful insecure authentication with <client>
                                                   

The client has successfully negotiated an  insecure connection withthe child process.

=item (Yellow) Attempted insecure connection disallowed    

The client attempted and failed to successfully negotiate a successful insecure
connection.  This can happen either because the variable londAllowInsecure is false
or undefined, or becuse the child did not successfully echo back the challenge
string.


=back


=cut

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