#!/usr/bin/perl
# The LearningOnline Network
# lond "LON Daemon" Server (port "LOND" 5663)
#
# $Id: lond,v 1.84 2002/07/26 19:35:20 albertel 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/
#
# 5/26/99,6/4,6/10,6/11,6/14,6/15,6/26,6/28,6/30,
# 7/8,7/9,7/10,7/12,7/17,7/19,9/21,
# 10/7,10/8,10/9,10/11,10/13,10/15,11/4,11/16,
# 12/7,12/15,01/06,01/11,01/12,01/14,2/8,
# 03/07,05/31 Gerd Kortemeyer
# 06/26 Scott Harrison
# 06/29,06/30,07/14,07/15,07/17,07/20,07/25,09/18 Gerd Kortemeyer
# 12/05 Scott Harrison
# 12/05,12/13,12/29 Gerd Kortemeyer
# YEAR=2001
# Jan 01 Scott Harrison
# 02/12 Gerd Kortemeyer
# 03/15 Scott Harrison
# 03/24 Gerd Kortemeyer
# 04/02 Scott Harrison
# 05/11,05/28,08/30 Gerd Kortemeyer
# 9/30,10/22,11/13,11/15,11/16 Scott Harrison
# 11/26,11/27 Gerd Kortemeyer
# 12/20 Scott Harrison
# 12/22 Gerd Kortemeyer
# YEAR=2002
# 01/20/02,02/05 Gerd Kortemeyer
# 02/05 Guy Albertelli
# 02/07 Scott Harrison
# 02/12 Gerd Kortemeyer
# 02/19 Matthew Hall
# 02/25 Gerd Kortemeyer
# 05/11 Scott Harrison
###

# based on "Perl Cookbook" ISBN 1-56592-243-3
# preforker - server who forks first
# runs as a daemon
# HUPs
# uses IDEA encryption

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

use IO::Socket;
use IO::File;
use Apache::File;
use Symbol;
use POSIX;
use Crypt::IDEA;
use LWP::UserAgent();
use GDBM_File;
use Authen::Krb4;
use lib '/home/httpd/lib/perl/';
use localauth;

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

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

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

sub timeout {
    &logthis("<font color=ref>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_apache.conf and loncapa.conf");
my $perlvarref=LONCAPA::Configuration::read_conf('loncapa_apache.conf',
                                                 'loncapa.conf');
my %perlvar=%{$perlvarref};
undef $perlvarref;

# ----------------------------- Make sure this process is running from user=www
my $wwwid=getpwnam('www');
if ($wwwid!=$<) {
   $emailto="$perlvar{'lonAdmEMail'},$perlvar{'lonSysEMail'}";
   $subj="LON: $perlvar{'lonHostID'} 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"; }
}

$PREFORK=4; # number of children to maintain, at least four spare

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

open (CONFIG,"$perlvar{'lonTabDir'}/hosts.tab") || die "Can't read host file";

while ($configline=<CONFIG>) {
    my ($id,$domain,$role,$name,$ip)=split(/:/,$configline);
    chomp($ip); $ip=~s/\D+$//;
    $hostid{$ip}=$id;
    if ($id eq $perlvar{'lonHostID'}) { $thisserver=$name; }
    $PREFORK++;
}
close(CONFIG);

# 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

$MAX_CLIENTS_PER_CHILD  = 50;        # number of clients each child should 
                                    # process
%children               = ();       # keys are current child process IDs
$children               = 0;        # current number of children

sub REAPER {                        # takes care of dead children
    $SIG{CHLD} = \&REAPER;
    my $pid = wait;
    if (defined($children{$pid})) {
	&logthis("Child $pid died");
	$children --;
	delete $children{$pid};
    } else {
	&logthis("Unknown Child $pid died");
    }
}

sub HUNTSMAN {                      # signal handler for SIGINT
    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>");
    exit;                           # clean up with dignity
}

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

sub checkchildren {
    &initnewstatus();
    &logstatus();
    &logthis('Going to check on the children');
    $docdir=$perlvar{'lonDocRoot'};
    foreach (sort keys %children) {
	sleep 1;
        unless (kill 'USR1' => $_) {
	    &logthis ('Child '.$_.' is dead');
            &logstatus($$.' is dead');
        } 
    }
    sleep 5;
    foreach (sort keys %children) {
        unless (-e "$docdir/lon-status/londchld/$_.txt") {
	    &logthis('Child '.$_.' did not respond');
	    kill 9 => $_;
	    $emailto="$perlvar{'lonAdmEMail'},$perlvar{'lonSysEMail'}";
	    $subj="LON: $perlvar{'lonHostID'} 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 $execdir/logs/lond.log.$_`
        }
    }
}

# --------------------------------------------------------------------- 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);
    }
}
# ------------------------------------------------------------------ Log status

sub logstatus {
    my $docdir=$perlvar{'lonDocRoot'};
    {
    my $fh=IO::File->new(">>$docdir/lon-status/londstatus.txt");
    print $fh $$."\t".$status."\t".$lastlog."\n";
    $fh->close();
    }
    {
	my $fh=IO::File->new(">$docdir/lon-status/londchld/$$.txt");
        print $fh $status."\n".$lastlog."\n".time;
        $fh->close();
    }
}

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,"$docdir/lon-status/londchld");
    while ($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;
}

# -------------------------------------------------------- Escape Special Chars

sub escape {
    my $str=shift;
    $str =~ s/(\W)/"%".unpack('H2',$1)/eg;
    return $str;
}

# ----------------------------------------------------- Un-Escape Special Chars

sub unescape {
    my $str=shift;
    $str =~ s/%([a-fA-F0-9][a-fA-F0-9])/pack("C",hex($1))/eg;
    return $str;
}

# ----------------------------------------------------------- Send USR1 to lonc

sub reconlonc {
    my $peerfile=shift;
    &logthis("Trying to reconnect for $peerfile");
    my $loncfile="$perlvar{'lonDaemons'}/logs/lonc.pid";
    if (my $fh=IO::File->new("$loncfile")) {
	my $loncpid=<$fh>;
        chomp($loncpid);
        if (kill 0 => $loncpid) {
	    &logthis("lonc at pid $loncpid responding, sending USR1");
            kill USR1 => $loncpid;
            sleep 5;
            if (-e "$peerfile") { return; }
            &logthis("$peerfile still not there, give it another try");
            sleep 10;
            if (-e "$peerfile") { return; }
            &logthis(
 "<font color=blue>WARNING: $peerfile still not there, giving up</font>");
        } else {
	    &logthis(
              "<font color=red>CRITICAL: "
             ."lonc at pid $loncpid not responding, giving up</font>");
        }
    } else {
      &logthis('<font color=red>CRITICAL: lonc not running, giving up</font>');
    }
}

# -------------------------------------------------- Non-critical communication

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

sub reply {
  my ($cmd,$server)=@_;
  my $answer;
  if ($server ne $perlvar{'lonHostID'}) { 
    $answer=subreply($cmd,$server);
    if ($answer eq 'con_lost') {
	$answer=subreply("ping",$server);
        if ($answer ne $server) {
	    &logthis("sub reply: answer != server");
           &reconlonc("$perlvar{'lonSockDir'}/$server");
        }
        $answer=subreply($cmd,$server);
    }
  } else {
    $answer='self_reply';
  } 
  return $answer;
}

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

sub sqlreply {
    my ($cmd)=@_;
    my $answer=subsqlreply($cmd);
    if ($answer eq 'con_lost') { $answer=subsqlreply($cmd); }
    return $answer;
}

sub subsqlreply {
    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\n";
    my $answer=<$sclient>;
    chomp($answer);
    if (!$answer) { $answer="con_lost"; }
    return $answer;
}

# -------------------------------------------- Return path to profile directory

sub propath {
    my ($udom,$uname)=@_;
    $udom=~s/\W//g;
    $uname=~s/\W//g;
    my $subdir=$uname.'__';
    $subdir =~ s/(.)(.)(.).*/$1\/$2\/$3/;
    my $proname="$perlvar{'lonUsersDir'}/$udom/$subdir/$uname";
    return $proname;
} 

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

$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

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

# ------------------------------------------------------- Now we are on our own
    
# Fork off our children.
for (1 .. $PREFORK) {
    make_new_child();
}

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

&status('Forked children');

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

# And maintain the population.
while (1) {
    &status('Sleeping');
    sleep;                          # wait for a signal (i.e., child's death)
    &logthis('Woke up');
    &status('Woke up');
    for ($i = $children; $i < $PREFORK; $i++) {
        make_new_child();           # top up the child pool
    }
}

sub make_new_child {
    my $pid;
    my $cipher;
    my $sigset;
    &logthis("Attempting to start child");    
    # 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);
    
    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} = 1;
        $children++;
        &status('Started child '.$pid);
        return;
    } else {
        # Child can *not* return from this subroutine.
        $SIG{INT} = 'DEFAULT';      # make SIGINT kill us as it did before
        $SIG{USR1}= \&logstatus;
        $SIG{ALRM}= \&timeout;
        $lastlog='Forked ';
        $status='Forked';

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

        $tmpsnum=0;
    
        # handle connections until we've reached $MAX_CLIENTS_PER_CHILD
        for ($i=0; $i < $MAX_CLIENTS_PER_CHILD; $i++) {
            &status('Idle, waiting for connection');
            $client = $server->accept()     or last;
            &status('Accepted connection');
# =============================================================================
            # do something with the connection
# -----------------------------------------------------------------------------
            # see if we know client and check for spoof IP by challenge
            my $caller=getpeername($client);
            my ($port,$iaddr)=unpack_sockaddr_in($caller);
            my $clientip=inet_ntoa($iaddr);
            my $clientrec=($hostid{$clientip} ne undef);
            &logthis(
"<font color=yellow>INFO: Connection $i, $clientip ($hostid{$clientip})</font>"
            );
            &status("Connecting $clientip ($hostid{$clientip})"); 
            my $clientok;
            if ($clientrec) {
	      &status("Waiting for init from $clientip ($hostid{$clientip})");
	      my $remotereq=<$client>;
              $remotereq=~s/\W//g;
              if ($remotereq eq 'init') {
		  my $challenge="$$".time;
                  print $client "$challenge\n";
                  &status(
           "Waiting for challenge reply from $clientip ($hostid{$clientip})"); 
                  $remotereq=<$client>;
                  $remotereq=~s/\W//g;
                  if ($challenge eq $remotereq) {
		      $clientok=1;
                      print $client "ok\n";
                  } else {
		      &logthis(
 "<font color=blue>WARNING: $clientip did not reply challenge</font>");
                      &status('No challenge reply '.$clientip);
                  }
              } 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

	      &reconlonc("$perlvar{'lonSockDir'}/$hostid{$clientip}");
              &logthis(
       "<font color=green>Established connection: $hostid{$clientip}</font>");
              &status('Will listen to '.$hostid{$clientip});
# ------------------------------------------------------------ Process requests
              while (my $userinput=<$client>) {
                chomp($userinput);
		Debug("Request = $userinput\n");
                &status('Processing '.$hostid{$clientip}.': '.$userinput);
                my $wasenc=0;
                alarm(120);
# ------------------------------------------------------------ See if encrypted
		if ($userinput =~ /^enc/) {
		  if ($cipher) {
                    my ($cmd,$cmdlength,$encinput)=split(/:/,$userinput);
		    $userinput='';
                    for (my $encidx=0;$encidx<length($encinput);$encidx+=16) {
                       $userinput.=
			   $cipher->decrypt(
                            pack("H16",substr($encinput,$encidx,16))
                           );
		    }
		    $userinput=substr($userinput,0,$cmdlength);
                    $wasenc=1;
		}
	      }
	  
# ------------------------------------------------------------- Normal commands
# ------------------------------------------------------------------------ ping
		   if ($userinput =~ /^ping/) {
                       print $client "$perlvar{'lonHostID'}\n";
# ------------------------------------------------------------------------ pong
		   } elsif ($userinput =~ /^pong/) {
                       $reply=reply("ping",$hostid{$clientip});
                       print $client "$perlvar{'lonHostID'}:$reply\n"; 
# ------------------------------------------------------------------------ ekey
		   } elsif ($userinput =~ /^ekey/) {
                       my $buildkey=time.$$.int(rand 100000);
                       $buildkey=~tr/1-6/A-F/;
                       $buildkey=int(rand 100000).$buildkey.int(rand 100000);
                       my $key=$perlvar{'lonHostID'}.$hostid{$clientip};
                       $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;
                       print $client "$buildkey\n"; 
# ------------------------------------------------------------------------ load
		   } elsif ($userinput =~ /^load/) {
                       my $loadavg;
                       {
                          my $loadfile=IO::File->new('/proc/loadavg');
                          $loadavg=<$loadfile>;
                       }
                       $loadavg =~ s/\s.*//g;
                       my $loadpercent=100*$loadavg/$perlvar{'lonLoadLim'};
		       print $client "$loadpercent\n";
# ----------------------------------------------------------------- currentauth
		   } elsif ($userinput =~ /^currentauth/) {
		     if ($wasenc==1) {
                       my ($cmd,$udom,$uname)=split(/:/,$userinput);
		       my $result = GetAuthType($udom, $uname);
		       if($result eq "nouser") {
			   print $client "unknown_user\n";
		       }
		       else {
			   print $client "$result\n"
		       }
		     } else {
		       print $client "refused\n";
		     }
# ------------------------------------------------------------------------ auth
                   } elsif ($userinput =~ /^auth/) {
		     if ($wasenc==1) {
                       my ($cmd,$udom,$uname,$upass)=split(/:/,$userinput);
                       chomp($upass);
                       $upass=unescape($upass);
                       my $proname=propath($udom,$uname);
                       my $passfilename="$proname/passwd";
                       if (-e $passfilename) {
                          my $pf = IO::File->new($passfilename);
                          my $realpasswd=<$pf>;
                          chomp($realpasswd);
                          my ($howpwd,$contentpwd)=split(/:/,$realpasswd);
                          my $pwdcorrect=0;
                          if ($howpwd eq 'internal') {
			      $pwdcorrect=
				  (crypt($upass,$contentpwd) eq $contentpwd);
                          } elsif ($howpwd eq 'unix') {
                              $contentpwd=(getpwnam($uname))[1];
			      my $pwauth_path="/usr/local/sbin/pwauth";
			      unless ($contentpwd eq 'x') {
				  $pwdcorrect=
                                    (crypt($upass,$contentpwd) eq $contentpwd);
			      }
			      elsif (-e $pwauth_path) {
				  open PWAUTH, "|$pwauth_path" or
				      die "Cannot invoke authentication";
				  print PWAUTH "$uname\n$upass\n";
				  close PWAUTH;
				  $pwdcorrect=!$?;
			      }
                          } elsif ($howpwd eq 'krb4') {
                             $null=pack("C",0);
			     unless ($upass=~/$null/) {
                              $pwdcorrect=(
                                 Authen::Krb4::get_pw_in_tkt($uname,"",
                                        $contentpwd,'krbtgt',$contentpwd,1,
							     $upass) == 0);
			     } else { $pwdcorrect=0; }
                          } elsif ($howpwd eq 'localauth') {
			    $pwdcorrect=&localauth::localauth($uname,$upass,
							      $contentpwd);
			  }
                          if ($pwdcorrect) {
                             print $client "authorized\n";
                          } else {
                             print $client "non_authorized\n";
                          }  
		       } else {
                          print $client "unknown_user\n";
                       }
		     } else {
		       print $client "refused\n";
		     }
# ---------------------------------------------------------------------- passwd
                   } elsif ($userinput =~ /^passwd/) {
		     if ($wasenc==1) {
                       my 
                       ($cmd,$udom,$uname,$upass,$npass)=split(/:/,$userinput);
                       chomp($npass);
                       $upass=&unescape($upass);
                       $npass=&unescape($npass);
		       &logthis("Trying to change password for $uname");
		       my $proname=propath($udom,$uname);
                       my $passfilename="$proname/passwd";
                       if (-e $passfilename) {
			   my $realpasswd;
                          { my $pf = IO::File->new($passfilename);
			    $realpasswd=<$pf>; }
                          chomp($realpasswd);
                          my ($howpwd,$contentpwd)=split(/:/,$realpasswd);
                          if ($howpwd eq 'internal') {
			   if (crypt($upass,$contentpwd) eq $contentpwd) {
			     my $salt=time;
                             $salt=substr($salt,6,2);
			     my $ncpass=crypt($npass,$salt);
                             { my $pf = IO::File->new(">$passfilename");
 	  		       print $pf "internal:$ncpass\n"; }             
			     &logthis("Result of password change for $uname: pwchange_success");
                             print $client "ok\n";
                           } else {
                             print $client "non_authorized\n";
                           }
                          } elsif ($howpwd eq 'unix') {
			      # Unix means we have to access /etc/password
			      # one way or another.
			      # First: Make sure the current password is
			      #        correct
			      $contentpwd=(getpwnam($uname))[1];
			      my $pwdcorrect = "0";
			      my $pwauth_path="/usr/local/sbin/pwauth";
			      unless ($contentpwd eq 'x') {
				  $pwdcorrect=
                                    (crypt($upass,$contentpwd) eq $contentpwd);
			      } elsif (-e $pwauth_path) {
				  open PWAUTH, "|$pwauth_path" or
				      die "Cannot invoke authentication";
				  print PWAUTH "$uname\n$upass\n";
				  close PWAUTH;
				  $pwdcorrect=!$?;
			      }
			     if ($pwdcorrect) {
				 my $execdir=$perlvar{'lonDaemons'};
				 my $pf = IO::File->new("|$execdir/lcpasswd");
				 print $pf "$uname\n$npass\n$npass\n";
				 close $pf;
				 my $result = ($?>0 ? 'pwchange_failure' 
					       : 'ok');
				 &logthis("Result of password change for $uname: $result");
				 print $client "$result\n";
			     } else {
				 print $client "non_authorized\n";
			     }
			  } else {
                            print $client "auth_mode_error\n";
                          }  
		       } else {
                          print $client "unknown_user\n";
                       }
		     } else {
		       print $client "refused\n";
		     }
# -------------------------------------------------------------------- makeuser
                   } elsif ($userinput =~ /^makeuser/) {
		     Debug("Make user received");
    	             my $oldumask=umask(0077);
		     if ($wasenc==1) {
                       my 
                       ($cmd,$udom,$uname,$umode,$npass)=split(/:/,$userinput);
		       &Debug("cmd =".$cmd." $udom =".$udom.
				    " uname=".$uname);
                       chomp($npass);
                       $npass=&unescape($npass);
                       my $proname=propath($udom,$uname);
                       my $passfilename="$proname/passwd";
		       &Debug("Password file created will be:".
				    $passfilename);
                       if (-e $passfilename) {
			   print $client "already_exists\n";
                       } elsif ($udom ne $perlvar{'lonDefDomain'}) {
                           print $client "not_right_domain\n";
                       } else {
                           @fpparts=split(/\//,$proname);
                           $fpnow=$fpparts[0].'/'.$fpparts[1].'/'.$fpparts[2];
                           $fperror='';
                           for ($i=3;$i<=$#fpparts;$i++) {
                               $fpnow.='/'.$fpparts[$i]; 
                               unless (-e $fpnow) {
				   unless (mkdir($fpnow,0777)) {
                                      $fperror="error:$!";
                                   }
                               }
                           }
                           unless ($fperror) {
			     if ($umode eq 'krb4') {
                               { 
                                 my $pf = IO::File->new(">$passfilename");
 	  		         print $pf "krb4:$npass\n"; 
                               }             
                               print $client "ok\n";
                             } elsif ($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");
 	  		         print $pf "internal:$ncpass\n"; 
                               }
                               print $client "ok\n";
			     } elsif ($umode eq 'localauth') {
			       {
				 my $pf = IO::File->new(">$passfilename");
  	  		         print $pf "localauth:$npass\n";
			       }
			       print $client "ok\n";
			     } elsif ($umode eq 'unix') {
			       {
				 my $execpath="$perlvar{'lonDaemons'}/".
				              "lcuseradd";
				 {
				     &Debug("Executing external: ".
						  $execpath);
				     my $se = IO::File->new("|$execpath");
				     print $se "$uname\n";
				     print $se "$npass\n";
				     print $se "$npass\n";
				 }
                                 my $pf = IO::File->new(">$passfilename");
 	  		         print $pf "unix:\n"; 
			       }
			       print $client "ok\n";
			     } elsif ($umode eq 'none') {
                               { 
                                 my $pf = IO::File->new(">$passfilename");
 	  		         print $pf "none:\n"; 
                               }             
                               print $client "ok\n";
                             } else {
                               print $client "auth_mode_error\n";
                             }  
                           } else {
                               print $client "$fperror\n";
                           }
                       }
		     } else {
		       print $client "refused\n";
		     }
		     umask($oldumask);
# -------------------------------------------------------------- changeuserauth
                   } elsif ($userinput =~ /^changeuserauth/) {
		       &Debug("Changing authorization");
		      if ($wasenc==1) {
                       my 
                       ($cmd,$udom,$uname,$umode,$npass)=split(/:/,$userinput);
                       chomp($npass);
		       &Debug("cmd = ".$cmd." domain= ".$udom.
			      "uname =".$uname." umode= ".$umode);
                       $npass=&unescape($npass);
                       my $proname=propath($udom,$uname);
                       my $passfilename="$proname/passwd";
		       if ($udom ne $perlvar{'lonDefDomain'}) {
                           print $client "not_right_domain\n";
                       } else {
			   if ($umode eq 'krb4') {
                               { 
				   my $pf = IO::File->new(">$passfilename");
				   print $pf "krb4:$npass\n"; 
                               }             
                               print $client "ok\n";
			   } elsif ($umode eq 'internal') {
			       my $salt=time;
                               $salt=substr($salt,6,2);
			       my $ncpass=crypt($npass,$salt);
                               { 
				   my $pf = IO::File->new(">$passfilename");
				   print $pf "internal:$ncpass\n"; 
                               }
                               print $client "ok\n";
			   } elsif ($umode eq 'localauth') {
			       {
				   my $pf = IO::File->new(">$passfilename");
				   print $pf "localauth:$npass\n";
			       }
			       print $client "ok\n";
			   } elsif ($umode eq 'unix') {
			       {
				   my $execpath="$perlvar{'lonDaemons'}/".
				       "lcuseradd";
				   {
				       my $se = IO::File->new("|$execpath");
				       print $se "$uname\n";
				       print $se "$npass\n";
				       print $se "$npass\n";
				   }
				   my $pf = IO::File->new(">$passfilename");
				   print $pf "unix:\n"; 
			       }
			       print $client "ok\n";
			   } elsif ($umode eq 'none') {
                               { 
				   my $pf = IO::File->new(">$passfilename");
				   print $pf "none:\n"; 
                               }             
                               print $client "ok\n";
			   } else {
                               print $client "auth_mode_error\n";
			   }  
                       }
		     } else {
		       print $client "refused\n";
		     }
# ------------------------------------------------------------------------ home
                   } elsif ($userinput =~ /^home/) {
                       my ($cmd,$udom,$uname)=split(/:/,$userinput);
                       chomp($uname);
                       my $proname=propath($udom,$uname);
                       if (-e $proname) {
                          print $client "found\n";
                       } else {
			  print $client "not_found\n";
                       }
# ---------------------------------------------------------------------- update
                   } elsif ($userinput =~ /^update/) {
                       my ($cmd,$fname)=split(/:/,$userinput);
                       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);
                          $now=time;
                          $since=$now-$atime;
                          if ($since>$perlvar{'lonExpire'}) {
                              $reply=
                                    reply("unsub:$fname","$hostid{$clientip}");
                              unlink("$fname");
                          } else {
			     my $transname="$fname.in.transfer";
                             my $remoteurl=
                                    reply("sub:$fname","$hostid{$clientip}");
                             my $response;
                              {
                             my $ua=new LWP::UserAgent;
                             my $request=new HTTP::Request('GET',"$remoteurl");
                             $response=$ua->request($request,$transname);
			      }
                             if ($response->is_error()) {
				 unlink($transname);
                                 my $message=$response->status_line;
                                 &logthis(
                                  "LWP GET: $message for $fname ($remoteurl)");
                             } else {
	                         if ($remoteurl!~/\.meta$/) {
                                  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($fname.'.meta');
                                  }
	                         }
                                 rename($transname,$fname);
			     }
                          }
                          print $client "ok\n";
                        } else {
                          print $client "not_found\n";
                        }
		       } else {
			print $client "rejected\n";
                       }
# ----------------------------------------------------------------- unsubscribe
                   } elsif ($userinput =~ /^unsub/) {
                       my ($cmd,$fname)=split(/:/,$userinput);
                       if (-e $fname) {
			   print $client &unsub($client,$fname,$clientip);
                       } else {
			   print $client "not_found\n";
                       }
# ------------------------------------------------------------------- subscribe
                   } elsif ($userinput =~ /^sub/) {
		       print $client &subscribe($userinput,$clientip);
# ------------------------------------------------------------------------- log
                   } elsif ($userinput =~ /^log/) {
                       my ($cmd,$udom,$uname,$what)=split(/:/,$userinput);
                       chomp($what);
                       my $proname=propath($udom,$uname);
                       my $now=time;
                       {
			 my $hfh;
			 if ($hfh=IO::File->new(">>$proname/activity.log")) { 
                            print $hfh "$now:$hostid{$clientip}:$what\n";
                            print $client "ok\n"; 
			} else {
                            print $client "error:$!\n";
		        }
		       }
# ------------------------------------------------------------------------- put
                   } elsif ($userinput =~ /^put/) {
                      my ($cmd,$udom,$uname,$namespace,$what)
                          =split(/:/,$userinput);
                      $namespace=~s/\//\_/g;
                      $namespace=~s/\W//g;
                      if ($namespace ne 'roles') {
                       chomp($what);
                       my $proname=propath($udom,$uname);
                       my $now=time;
                       unless ($namespace=~/^nohist\_/) {
			   my $hfh;
			   if (
                             $hfh=IO::File->new(">>$proname/$namespace.hist")
			       ) { print $hfh "P:$now:$what\n"; }
		       }
                       my @pairs=split(/\&/,$what);
      if (tie(%hash,'GDBM_File',"$proname/$namespace.db",&GDBM_WRCREAT,0640)) {
                           foreach $pair (@pairs) {
			       ($key,$value)=split(/=/,$pair);
                               $hash{$key}=$value;
                           }
			   if (untie(%hash)) {
                              print $client "ok\n";
                           } else {
                              print $client "error:$!\n";
                           }
                       } else {
                           print $client "error:$!\n";
                       }
		      } else {
                          print $client "refused\n";
                      }
# -------------------------------------------------------------------- rolesput
                   } elsif ($userinput =~ /^rolesput/) {
		       &Debug("rolesput");
		    if ($wasenc==1) {
                       my ($cmd,$exedom,$exeuser,$udom,$uname,$what)
                          =split(/:/,$userinput);
		       &Debug("cmd = ".$cmd." exedom= ".$exedom.
				    "user = ".$exeuser." udom=".$udom.
				    "what = ".$what);
                       my $namespace='roles';
                       chomp($what);
                       my $proname=propath($udom,$uname);
                       my $now=time;
                       {
			   my $hfh;
			   if (
                             $hfh=IO::File->new(">>$proname/$namespace.hist")
			       ) { 
                                  print $hfh "P:$now:$exedom:$exeuser:$what\n";
                                 }
		       }
                       my @pairs=split(/\&/,$what);
      if (tie(%hash,'GDBM_File',"$proname/$namespace.db",&GDBM_WRCREAT,0640)) {
                           foreach $pair (@pairs) {
			       ($key,$value)=split(/=/,$pair);
			       &ManagePermissions($key, $udom, $uname,
						  &GetAuthType( $udom, 
								$uname));
                               $hash{$key}=$value;
			       
                           }
			   if (untie(%hash)) {
                              print $client "ok\n";
                           } else {
                              print $client "error:$!\n";
                           }
                       } else {
                           print $client "error:$!\n";
                       }
		      } else {
                          print $client "refused\n";
                      }
# ------------------------------------------------------------------------- get
                   } elsif ($userinput =~ /^get/) {
                       my ($cmd,$udom,$uname,$namespace,$what)
                          =split(/:/,$userinput);
                       $namespace=~s/\//\_/g;
                       $namespace=~s/\W//g;
                       chomp($what);
                       my @queries=split(/\&/,$what);
                       my $proname=propath($udom,$uname);
                       my $qresult='';
      if (tie(%hash,'GDBM_File',"$proname/$namespace.db",&GDBM_READER,0640)) {
                           for ($i=0;$i<=$#queries;$i++) {
                               $qresult.="$hash{$queries[$i]}&";
                           }
			   if (untie(%hash)) {
		              $qresult=~s/\&$//;
                              print $client "$qresult\n";
                           } else {
                              print $client "error:$!\n";
                           }
                       } else {
                           print $client "error:$!\n";
                       }
# ------------------------------------------------------------------------ eget
                   } elsif ($userinput =~ /^eget/) {
                       my ($cmd,$udom,$uname,$namespace,$what)
                          =split(/:/,$userinput);
                       $namespace=~s/\//\_/g;
                       $namespace=~s/\W//g;
                       chomp($what);
                       my @queries=split(/\&/,$what);
                       my $proname=propath($udom,$uname);
                       my $qresult='';
      if (tie(%hash,'GDBM_File',"$proname/$namespace.db",&GDBM_READER,0640)) {
                           for ($i=0;$i<=$#queries;$i++) {
                               $qresult.="$hash{$queries[$i]}&";
                           }
			   if (untie(%hash)) {
		              $qresult=~s/\&$//;
                              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)));
                                }
                                print $client "enc:$cmdlength:$encqresult\n";
			      } else {
			        print $client "error:no_key\n";
                              }
                           } else {
                              print $client "error:$!\n";
                           }
                       } else {
                           print $client "error:$!\n";
                       }
# ------------------------------------------------------------------------- del
                   } elsif ($userinput =~ /^del/) {
                       my ($cmd,$udom,$uname,$namespace,$what)
                          =split(/:/,$userinput);
                       $namespace=~s/\//\_/g;
                       $namespace=~s/\W//g;
                       chomp($what);
                       my $proname=propath($udom,$uname);
                       my $now=time;
                       unless ($namespace=~/^nohist\_/) {
			   my $hfh;
			   if (
                             $hfh=IO::File->new(">>$proname/$namespace.hist")
			       ) { print $hfh "D:$now:$what\n"; }
		       }
                       my @keys=split(/\&/,$what);
      if (tie(%hash,'GDBM_File',"$proname/$namespace.db",&GDBM_WRCREAT,0640)) {
                           foreach $key (@keys) {
                               delete($hash{$key});
                           }
			   if (untie(%hash)) {
                              print $client "ok\n";
                           } else {
                              print $client "error:$!\n";
                           }
                       } else {
                           print $client "error:$!\n";
                       }
# ------------------------------------------------------------------------ keys
                   } elsif ($userinput =~ /^keys/) {
                       my ($cmd,$udom,$uname,$namespace)
                          =split(/:/,$userinput);
                       $namespace=~s/\//\_/g;
                       $namespace=~s/\W//g;
                       my $proname=propath($udom,$uname);
                       my $qresult='';
      if (tie(%hash,'GDBM_File',"$proname/$namespace.db",&GDBM_READER,0640)) {
                           foreach $key (keys %hash) {
                               $qresult.="$key&";
                           }
			   if (untie(%hash)) {
		              $qresult=~s/\&$//;
                              print $client "$qresult\n";
                           } else {
                              print $client "error:$!\n";
                           }
                       } else {
                           print $client "error:$!\n";
                       }
# ------------------------------------------------------------------------ dump
                   } elsif ($userinput =~ /^dump/) {
                       my ($cmd,$udom,$uname,$namespace,$regexp)
                          =split(/:/,$userinput);
                       $namespace=~s/\//\_/g;
                       $namespace=~s/\W//g;
                       if (defined($regexp)) {
                          $regexp=&unescape($regexp);
		       } else {
                          $regexp='.';
		       }
                       my $proname=propath($udom,$uname);
                       my $qresult='';
      if (tie(%hash,'GDBM_File',"$proname/$namespace.db",&GDBM_READER,0640)) {
                           foreach $key (keys %hash) {
                               if (eval('$key=~/$regexp/')) {
                                  $qresult.="$key=$hash{$key}&";
			       }
                           }
			   if (untie(%hash)) {
		              $qresult=~s/\&$//;
                              print $client "$qresult\n";
                           } else {
                              print $client "error:$!\n";
                           }
                       } else {
                           print $client "error:$!\n";
                       }
# ----------------------------------------------------------------------- store
                   } elsif ($userinput =~ /^store/) {
                      my ($cmd,$udom,$uname,$namespace,$rid,$what)
                          =split(/:/,$userinput);
                      $namespace=~s/\//\_/g;
                      $namespace=~s/\W//g;
                      if ($namespace ne 'roles') {
                       chomp($what);
                       my $proname=propath($udom,$uname);
                       my $now=time;
                       unless ($namespace=~/^nohist\_/) {
			   my $hfh;
			   if (
                             $hfh=IO::File->new(">>$proname/$namespace.hist")
			       ) { print $hfh "P:$now:$rid:$what\n"; }
		       }
                       my @pairs=split(/\&/,$what);
                         
    if (tie(%hash,'GDBM_File',"$proname/$namespace.db",&GDBM_WRCREAT,0640)) {
                           my @previouskeys=split(/&/,$hash{"keys:$rid"});
                           my $key;
                           $hash{"version:$rid"}++;
                           my $version=$hash{"version:$rid"};
                           my $allkeys=''; 
                           foreach $pair (@pairs) {
			       ($key,$value)=split(/=/,$pair);
                               $allkeys.=$key.':';
                               $hash{"$version:$rid:$key"}=$value;
                           }
                           $hash{"$version:$rid:timestamp"}=$now;
                           $allkeys.='timestamp';
                           $hash{"$version:keys:$rid"}=$allkeys;
			   if (untie(%hash)) {
                              print $client "ok\n";
                           } else {
                              print $client "error:$!\n";
                           }
                       } else {
                           print $client "error:$!\n";
                       }
		      } else {
                          print $client "refused\n";
                      }
# --------------------------------------------------------------------- restore
                   } elsif ($userinput =~ /^restore/) {
                       my ($cmd,$udom,$uname,$namespace,$rid)
                          =split(/:/,$userinput);
                       $namespace=~s/\//\_/g;
                       $namespace=~s/\W//g;
                       chomp($rid);
                       my $proname=propath($udom,$uname);
                       my $qresult='';
      if (tie(%hash,'GDBM_File',"$proname/$namespace.db",&GDBM_READER,0640)) {
                	   my $version=$hash{"version:$rid"};
                           $qresult.="version=$version&";
                           my $scope;
                           for ($scope=1;$scope<=$version;$scope++) {
			      my $vkeys=$hash{"$scope:keys:$rid"};
                              my @keys=split(/:/,$vkeys);
                              my $key;
                              $qresult.="$scope:keys=$vkeys&";
                              foreach $key (@keys) {
	     $qresult.="$scope:$key=".$hash{"$scope:$rid:$key"}."&";
                              }                                  
                           }
			   if (untie(%hash)) {
		              $qresult=~s/\&$//;
                              print $client "$qresult\n";
                           } else {
                              print $client "error:$!\n";
                           }
                       } else {
                           print $client "error:$!\n";
                       }
# ------------------------------------------------------------------- querysend
                   } elsif ($userinput =~ /^querysend/) {
                       my ($cmd,$query,
			   $arg1,$arg2,$arg3)=split(/\:/,$userinput);
		       $query=~s/\n*$//g;
		       print $client "".
			       sqlreply("$hostid{$clientip}\&$query".
					"\&$arg1"."\&$arg2"."\&$arg3")."\n";
# ------------------------------------------------------------------ queryreply
                   } elsif ($userinput =~ /^queryreply/) {
                       my ($cmd,$id,$reply)=split(/:/,$userinput); 
		       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;
			   print $client "ok\n";
		       }
		       else {
			   print $client "error:$!\n";
		       }
# ----------------------------------------------------------------------- idput
                   } elsif ($userinput =~ /^idput/) {
                       my ($cmd,$udom,$what)=split(/:/,$userinput);
                       chomp($what);
                       $udom=~s/\W//g;
                       my $proname="$perlvar{'lonUsersDir'}/$udom/ids";
                       my $now=time;
                       {
			   my $hfh;
			   if (
                             $hfh=IO::File->new(">>$proname.hist")
			       ) { print $hfh "P:$now:$what\n"; }
		       }
                       my @pairs=split(/\&/,$what);
                 if (tie(%hash,'GDBM_File',"$proname.db",&GDBM_WRCREAT,0640)) {
                           foreach $pair (@pairs) {
			       ($key,$value)=split(/=/,$pair);
                               $hash{$key}=$value;
                           }
			   if (untie(%hash)) {
                              print $client "ok\n";
                           } else {
                              print $client "error:$!\n";
                           }
                       } else {
                           print $client "error:$!\n";
                       }
# ----------------------------------------------------------------------- idget
                   } elsif ($userinput =~ /^idget/) {
                       my ($cmd,$udom,$what)=split(/:/,$userinput);
                       chomp($what);
                       $udom=~s/\W//g;
                       my $proname="$perlvar{'lonUsersDir'}/$udom/ids";
                       my @queries=split(/\&/,$what);
                       my $qresult='';
                 if (tie(%hash,'GDBM_File',"$proname.db",&GDBM_READER,0640)) {
                           for ($i=0;$i<=$#queries;$i++) {
                               $qresult.="$hash{$queries[$i]}&";
                           }
			   if (untie(%hash)) {
		              $qresult=~s/\&$//;
                              print $client "$qresult\n";
                           } else {
                              print $client "error:$!\n";
                           }
                       } else {
                           print $client "error:$!\n";
                       }
# ---------------------------------------------------------------------- tmpput
                   } elsif ($userinput =~ /^tmpput/) {
                       my ($cmd,$what)=split(/:/,$userinput);
		       my $store;
                       $tmpsnum++;
                       my $id=$$.'_'.$clientip.'_'.$tmpsnum;
                       $id=~s/\W/\_/g;
                       $what=~s/\n//g;
                       my $execdir=$perlvar{'lonDaemons'};
                       if ($store=IO::File->new(">$execdir/tmp/$id.tmp")) {
			   print $store $what;
			   close $store;
			   print $client "$id\n";
		       }
		       else {
			   print $client "error:$!\n";
		       }

# ---------------------------------------------------------------------- tmpget
                   } elsif ($userinput =~ /^tmpget/) {
                       my ($cmd,$id)=split(/:/,$userinput);
                       chomp($id);
                       $id=~s/\W/\_/g;
                       my $store;
                       my $execdir=$perlvar{'lonDaemons'};
                       if ($store=IO::File->new("$execdir/tmp/$id.tmp")) {
                           my $reply=<$store>;
			   print $client "$reply\n";
                           close $store;
		       }
		       else {
			   print $client "error:$!\n";
		       }

# -------------------------------------------------------------------------- ls
                   } elsif ($userinput =~ /^ls/) {
                       my ($cmd,$ulsdir)=split(/:/,$userinput);
                       my $ulsout='';
                       my $ulsfn;
                       if (-e $ulsdir) {
                           if(-d $ulsdir) {
                               if (opendir(LSDIR,$ulsdir)) {
                                   while ($ulsfn=readdir(LSDIR)) {
                                       my @ulsstats=stat($ulsdir.'/'.$ulsfn);
                                       $ulsout.=$ulsfn.'&'.
                                                join('&',@ulsstats).':';
                                   }
                                   closedir(LSDIR);
                               }
                           } else {
                               my @ulsstats=stat($ulsdir);
                               $ulsout.=$ulsfn.'&'.join('&',@ulsstats).':';
                           }
                       } else {
                          $ulsout='no_such_dir';
                       }
                       if ($ulsout eq '') { $ulsout='empty'; }
                       print $client "$ulsout\n";
# ------------------------------------------------------------------ Hanging up
                   } elsif (($userinput =~ /^exit/) ||
                            ($userinput =~ /^init/)) {
                       &logthis(
      "Client $clientip ($hostid{$clientip}) hanging up: $userinput");
                       print $client "bye\n";
                       $client->close();
		       last;
# ------------------------------------------------------------- unknown command
                   } else {
                       # unknown command
                       print $client "unknown_cmd\n";
                   }
# -------------------------------------------------------------------- complete
		   alarm(0);
                   &status('Listening to '.$hostid{$clientip});
	       }
# --------------------------------------------- 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 $clientip ($hostid{$clientip})</font>");    
        # tidy up gracefully and finish
    
        $server->close();

        # this exit is VERY important, otherwise the child will become
        # a producer of more and more children, forking yourself into
        # process death.
        exit;
    }
}


#
#   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 ManagePermissions
{
    my $request = shift;
    my $domain  = shift;
    my $user    = shift;
    my $authtype= shift;

    # See if the request is of the form /$domain/_au

    if($request =~ /^(\/$domain\/_au)$/) { # It's an author rolesput...
	my $execdir = $perlvar{'lonDaemons'};
	my $userhome= "/home/$user" ;
	Debug("system $execdir/lchtmldir $userhome $system $authtype");
	system("$execdir/lchtmldir $userhome $user $authtype");
    }
}
#
#   GetAuthType - Determines the authorization type of a user in a domain.

#     Returns the authorization type or nouser if there is no such user.
#
sub GetAuthType 
{
    my $domain = shift;
    my $user   = shift;

    Debug("GetAuthType( $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");
	my $availinfo = '';
	if($authtype eq 'krb4') {
	    $availinfo = $contentpwd;
	}

	return "$authtype:$availinfo";
    }
    else {
	Debug("Returning nouser");
	return "nouser";
    }
}

sub addline {
    my ($fname,$hostid,$ip,$newline)=@_;
    my $contents;
    my $found=0;
    my $expr='^'.$hostid.':'.$ip.':';
    $expr =~ s/\./\\\./g;
    if ($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 unsub {
    my ($fname,$clientip)=@_;
    my $result;
    if (unlink("$fname.$hostid{$clientip}")) {
	$result="ok\n";
    } else {
	$result="not_subscribed\n";
    }
    if (-e "$fname.subscription") {
	my $found=&addline($fname,$hostid{$clientip},$clientip,'');
	if ($found) { $result="ok\n"; }
    } else {
	if ($result != "ok\n") { $result="not_subscribed\n"; }
    }
    return $result;
}

sub subscribe {
    my ($userinput,$clientip)=@_;
    my $result;
    my ($cmd,$fname)=split(/:/,$userinput);
    my $ownership=&ishome($fname);
    if ($ownership eq 'owner') {
	if (-e $fname) {
	    if (-d $fname) {
		$result="directory\n";
	    } else {
		if (-e "$fname.$hostid{$clientip}") {&unsub($fname,$clientip);}
		$now=time;
		my $found=&addline($fname,$hostid{$clientip},$clientip,
				   "$hostid{$clientip}:$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/;
		$fname="http://$thisserver/".$fname;
		$result="$fname\n";
	    }
	} else {
	    $result="not_found\n";
	}
    } else {
	$result="rejected\n";
    }
    return $result;
}
# ----------------------------------- 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 *

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 rolesput

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 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
Symbol
POSIX
Crypt::IDEA
LWP::UserAgent()
GDBM_File
Authen::Krb4

=head1 COREQUISITES

=head1 OSNAMES

linux

=head1 SCRIPT CATEGORIES

Server/Process

=cut