File:  [LON-CAPA] / loncom / lonnet / perl / lonnet.pm
Revision 1.182: download - view: text, annotated - select for diffs
Wed Dec 5 14:48:28 2001 UTC (22 years, 5 months ago) by matthew
Branches: MAIN
CVS tags: HEAD
Added comment character ^\# for filetypes.tab

# The LearningOnline Network
# TCP networking package
#
# $Id: lonnet.pm,v 1.182 2001/12/05 14:48:28 matthew 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/
#
# 6/1/99,6/2,6/10,6/11,6/12,6/14,6/26,6/28,6/29,6/30,
# 7/1,7/2,7/9,7/10,7/12,7/14,7/15,7/19,
# 11/8,11/16,11/18,11/22,11/23,12/22,
# 01/06,01/13,02/24,02/28,02/29,
# 03/01,03/02,03/06,03/07,03/13,
# 04/05,05/29,05/31,06/01,
# 06/05,06/26 Gerd Kortemeyer
# 06/26 Ben Tyszka
# 06/30,07/15,07/17,07/18,07/20,07/21,07/22,07/25 Gerd Kortemeyer
# 08/14 Ben Tyszka
# 08/22,08/28,08/31,09/01,09/02,09/04,09/05,09/25,09/28,09/30 Gerd Kortemeyer
# 10/04 Gerd Kortemeyer
# 10/04 Guy Albertelli
# 10/06,10/09,10/10,10/11,10/14,10/20,10/23,10/25,10/26,10/27,10/28,10/29, 
# 10/30,10/31,
# 11/2,11/14,11/15,11/16,11/20,11/21,11/22,11/25,11/27,
# 12/02,12/12,12/13,12/14,12/28,12/29 Gerd Kortemeyer
# 05/01/01 Guy Albertelli
# 05/01,06/01,09/01 Gerd Kortemeyer
# 09/01 Guy Albertelli
# 09/01,10/01,11/01 Gerd Kortemeyer
# YEAR=2001
# 02/27/01 Scott Harrison
# 3/2 Gerd Kortemeyer
# 3/15,3/19 Scott Harrison
# 3/19,3/20 Gerd Kortemeyer
# 3/22,3/27,4/2,4/16,4/17 Scott Harrison
# 5/26,5/28 Gerd Kortemeyer
# 5/30 H. K. Ng
# 6/1 Gerd Kortemeyer
# July Guy Albertelli
# 8/4,8/7,8/8,8/9,8/11,8/16,8/17,8/18,8/20,8/23,9/20,9/21,9/26,
# 10/2 Gerd Kortemeyer
# 10/5,10/10,11/13,11/15 Scott Harrison
# 11/17,11/20,11/22,11/29 Gerd Kortemeyer
# 12/5 Matthew Hall
#
# $Id: lonnet.pm,v 1.182 2001/12/05 14:48:28 matthew Exp $
#
###

# Functions for use by content handlers:
#
# metadata_query(sql-query-string,custom-metadata-regex) : 
#                                    returns file handle of where sql and
#                                    regex results will be stored for query
# plaintext(short)   : plain text explanation of short term
# fileembstyle(ext)  : embed style in page for file extension
# filedescription(ext) : descriptor text for file extension
# allowed(short,url) : returns codes for allowed actions 
#                      F: full access
#                      U,I,K: authentication modes (cxx only)
#                      '': forbidden
#                      1: user needs to choose course
#                      2: browse allowed
# definerole(rolename,sys,dom,cou) : define a custom role rolename
#                      set privileges in format of lonTabs/roles.tab for
#                      system, domain and course level, 
# assignrole(udom,uname,url,role,end,start) : give a role to a user for the
#                      level given by url. Optional start and end dates
#                      (leave empty string or zero for "no date") 
# assigncustomrole (udom,uname,url,rdom,rnam,rolename,end,start) : give a
#                      custom role to a user for the level given by url.
#                      Specify name and domain of role author, and role name
# revokerole (udom,uname,url,role) : Revoke a role for url
# revokecustomrole (udom,uname,url,rdom,rnam,rolename) : Revoke a custom role
# appenv(hash)       : adds hash to session environment
# delenv(varname)    : deletes all environment entries starting with varname
# store(hashref,symb,courseid,udom,uname)
#                    : 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
# cstore(hashref,symb,courseid,udom,uname)
#                    : same as store but uses the critical interface to 
#                      guarentee a store
# restore(symb,courseid,udom,uname)
#                    : returns hash for this symb, all args are optional
#                      if they aren't given they will be derived from the 
#                      current enviroment
#
#
# for the next 6 functions udom and uname are optional
#         if supplied they use udom as the domain and uname
#         as the username for the function (supply a courseid
#         for the uname if you want a course database)
#         if not supplied it uses %ENV and looks at 
#         user. attribute for the values
#
# eget(namesp,arrayref,udom,uname)
#                    : returns hash with keys from array  reference filled
#                      in from namesp (encrypts the return communication)
# get(namesp,arrayref,udom,uname)
#                    : returns hash with keys from array  reference filled
#                      in from namesp
# dump(namesp,udom,uname) : dumps the complete namespace into a hash
# del(namesp,array,udom,uname)  : deletes keys out of array from namesp
# put(namesp,hash,udom,uname)   : stores hash in namesp
# cput(namesp,hash,udom,uname)  : critical put
#
#
# ssi(url,hash)      : does a complete request cycle on url to localhost, posts
#                      hash
# coursedescription(id) : returns and caches course description for id
# repcopy(filename)  : replicate file
# dirlist(url)       : gets a directory listing
# directcondval(index) : reading condition value of single condition from 
#                        state string
# condval(index)     : value of condition index based on state
# EXT(name)          : value of a variable
# symblist(map,hash) : Updates symbolic storage links
# symbread([filename]) : returns the data handle (filename optional)
# rndseed([symb,courseid,domain,uname])
#                    : returns a random seed, all arguments are optional,
#                      if they aren't sent it use the environment to derive
#                      them
#                      Note: if symb isn't sent and it can't get one from
#                      &symbread it will use the current time as it's return
# receipt()          : returns a receipt to be given out to users 
# getfile(filename)  : returns the contents of filename, or a -1 if it can't
#                      be found, replicates and subscribes to the file
# filelocation(dir,file) : returns a fairly clean absolute reference to file 
#                          from the directory dir
# hreflocation(dir,file) : same as filelocation, but for hrefs
# log(domain,user,home,msg) : write to permanent log for user
# usection(domain,user,courseid) : output of section name/number or '' for
#                                  "not in course" and '-1' for "no section"
# userenvironment(domain,user,what) : puts out any environment parameter 
#                                     for a user
# idput(domain,hash) : writes IDs for users from hash (name=>id,name=>id)
# idget(domain,array): returns hash with usernames (id=>name,id=>name) for
#                      an array of IDs
# idrget(domain,array): returns hash with IDs for usernames (name=>id,...) for
#                       an array of names
# metadata(file,entry): returns the metadata entry for a file. entry='keys'
#                       returns a comma separated list of keys
#

package Apache::lonnet;

use strict;
use Apache::File;
use LWP::UserAgent();
use HTTP::Headers;
use vars 
qw(%perlvar %hostname %homecache %hostip %spareid %hostdom %libserv %pr %prp %fe %fd $readit %metacache %packagetab %courselogs);
use IO::Socket;
use GDBM_File;
use Apache::Constants qw(:common :http);
use HTML::TokeParser;
use Fcntl qw(:flock);

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

sub logtouch {
    my $execdir=$perlvar{'lonDaemons'};
    unless (-e "$execdir/logs/lonnet.log") {
	my $fh=Apache::File->new(">>$execdir/logs/lonnet.log");
	close $fh;
    }
    my ($wwwuid,$wwwgid)=(getpwnam('www'))[2,3];
    chown($wwwuid,$wwwgid,$execdir.'/logs/lonnet.log');
}

sub logthis {
    my $message=shift;
    my $execdir=$perlvar{'lonDaemons'};
    my $now=time;
    my $local=localtime($now);
    my $fh=Apache::File->new(">>$execdir/logs/lonnet.log");
    print $fh "$local ($$): $message\n";
    return 1;
}

sub logperm {
    my $message=shift;
    my $execdir=$perlvar{'lonDaemons'};
    my $now=time;
    my $local=localtime($now);
    my $fh=Apache::File->new(">>$execdir/logs/lonnet.perm.log");
    print $fh "$now:$message:$local\n";
    return 1;
}

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

sub reply {
    my ($cmd,$server)=@_;
    my $answer=subreply($cmd,$server);
    if ($answer eq 'con_lost') { $answer=subreply($cmd,$server); }
    if (($answer=~/^refused/) || ($answer=~/^rejected/)) {
       &logthis("<font color=blue>WARNING:".
                " $cmd to $server returned $answer</font>");
    }
    return $answer;
}

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

sub reconlonc {
    my $peerfile=shift;
    &logthis("Trying to reconnect for $peerfile");
    my $loncfile="$perlvar{'lonDaemons'}/logs/lonc.pid";
    if (my $fh=Apache::File->new("$loncfile")) {
	my $loncpid=<$fh>;
        chomp($loncpid);
        if (kill 0 => $loncpid) {
	    &logthis("lonc at pid $loncpid responding, sending USR1");
            kill USR1 => $loncpid;
            sleep 1;
            if (-e "$peerfile") { return; }
            &logthis("$peerfile still not there, give it another try");
            sleep 5;
            if (-e "$peerfile") { return; }
            &logthis(
  "<font color=blue>WARNING: $peerfile still not there, giving up</font>");
        } else {
	    &logthis(
               "<font color=blue>WARNING:".
               " lonc at pid $loncpid not responding, giving up</font>");
        }
    } else {
     &logthis('<font color=blue>WARNING: lonc not running, giving up</font>');
    }
}

# ------------------------------------------------------ Critical communication

sub critical {
    my ($cmd,$server)=@_;
    unless ($hostname{$server}) {
        &logthis("<font color=blue>WARNING:".
               " Critical message to unknown server ($server)</font>");
        return 'no_such_host';
    }
    my $answer=reply($cmd,$server);
    if ($answer eq 'con_lost') {
        my $pingreply=reply('ping',$server);
	&reconlonc("$perlvar{'lonSockDir'}/$server");
        my $pongreply=reply('pong',$server);
        &logthis("Ping/Pong for $server: $pingreply/$pongreply");
        $answer=reply($cmd,$server);
        if ($answer eq 'con_lost') {
            my $now=time;
            my $middlename=$cmd;
            $middlename=substr($middlename,0,16);
            $middlename=~s/\W//g;
            my $dfilename=
             "$perlvar{'lonSockDir'}/delayed/$now.$middlename.$server";
            {
             my $dfh;
             if ($dfh=Apache::File->new(">$dfilename")) {
                print $dfh "$cmd\n";
	     }
            }
            sleep 2;
            my $wcmd='';
            {
	     my $dfh;
             if ($dfh=Apache::File->new("$dfilename")) {
                $wcmd=<$dfh>;
	     }
            }
            chomp($wcmd);
            if ($wcmd eq $cmd) {
		&logthis("<font color=blue>WARNING: ".
                         "Connection buffer $dfilename: $cmd</font>");
                &logperm("D:$server:$cmd");
	        return 'con_delayed';
            } else {
                &logthis("<font color=red>CRITICAL:"
                        ." Critical connection failed: $server $cmd</font>");
                &logperm("F:$server:$cmd");
                return 'con_failed';
            }
        }
    }
    return $answer;
}

# ---------------------------------------------------------- Append Environment

sub appenv {
    my %newenv=@_;
    map {
	if (($newenv{$_}=~/^user\.role/) || ($newenv{$_}=~/^user\.priv/)) {
            &logthis("<font color=blue>WARNING: ".
                "Attempt to modify environment ".$_." to ".$newenv{$_}
                .'</font>');
	    delete($newenv{$_});
        } else {
            $ENV{$_}=$newenv{$_};
        }
    } keys %newenv;

    my $lockfh;
    unless ($lockfh=Apache::File->new("$ENV{'user.environment'}")) {
       return 'error: '.$!;
    }
    unless (flock($lockfh,LOCK_EX)) {
         &logthis("<font color=blue>WARNING: ".
                  'Could not obtain exclusive lock in appenv: '.$!);
         $lockfh->close();
         return 'error: '.$!;
    }

    my @oldenv;
    {
     my $fh;
     unless ($fh=Apache::File->new("$ENV{'user.environment'}")) {
	return 'error: '.$!;
     }
     @oldenv=<$fh>;
     $fh->close();
    }
    for (my $i=0; $i<=$#oldenv; $i++) {
        chomp($oldenv[$i]);
        if ($oldenv[$i] ne '') {
           my ($name,$value)=split(/=/,$oldenv[$i]);
           unless (defined($newenv{$name})) {
	      $newenv{$name}=$value;
	   }
        }
    }
    {
     my $fh;
     unless ($fh=Apache::File->new(">$ENV{'user.environment'}")) {
	return 'error';
     }
     my $newname;
     foreach $newname (keys %newenv) {
	 print $fh "$newname=$newenv{$newname}\n";
     }
     $fh->close();
    }

    $lockfh->close();
    return 'ok';
}
# ----------------------------------------------------- Delete from Environment

sub delenv {
    my $delthis=shift;
    my %newenv=();
    if (($delthis=~/user\.role/) || ($delthis=~/user\.priv/)) {
        &logthis("<font color=blue>WARNING: ".
                "Attempt to delete from environment ".$delthis);
        return 'error';
    }
    my @oldenv;
    {
     my $fh;
     unless ($fh=Apache::File->new("$ENV{'user.environment'}")) {
	return 'error';
     }
     unless (flock($fh,LOCK_SH)) {
         &logthis("<font color=blue>WARNING: ".
                  'Could not obtain shared lock in delenv: '.$!);
         $fh->close();
         return 'error: '.$!;
     }
     @oldenv=<$fh>;
     $fh->close();
    }
    {
     my $fh;
     unless ($fh=Apache::File->new(">$ENV{'user.environment'}")) {
	return 'error';
     }
     unless (flock($fh,LOCK_EX)) {
         &logthis("<font color=blue>WARNING: ".
                  'Could not obtain exclusive lock in delenv: '.$!);
         $fh->close();
         return 'error: '.$!;
     }
     map {
	 unless ($_=~/^$delthis/) { print $fh $_; }
     } @oldenv;
     $fh->close();
    }
    return 'ok';
}

# ------------------------------ Find server with least workload from spare.tab

sub spareserver {
    my $tryserver;
    my $spareserver='';
    my $lowestserver=100;
    foreach $tryserver (keys %spareid) {
       my $answer=reply('load',$tryserver);
       if (($answer =~ /\d/) && ($answer<$lowestserver)) {
	   $spareserver="http://$hostname{$tryserver}";
           $lowestserver=$answer;
       }
    }    
    return $spareserver;
}

# ----------------------- Try to determine user's current authentication scheme

sub queryauthenticate {
    my ($uname,$udom)=@_;
    if (($perlvar{'lonRole'} eq 'library') && 
        ($udom eq $perlvar{'lonDefDomain'})) {
	my $answer=reply("encrypt:currentauth:$udom:$uname",
			 $perlvar{'lonHostID'});
	unless ($answer eq 'unknown_user' or $answer eq 'refused') {
	    if (length($answer)) {
		return $answer;
	    }
	    else {
	&logthis("User $uname at $udom lacks an authentication mechanism");
		return 'no_host';
	    }
	}
    }

    my $tryserver;
    foreach $tryserver (keys %libserv) {
	if ($hostdom{$tryserver} eq $udom) {
           my $answer=reply("encrypt:currentauth:$udom:$uname",$tryserver);
	   unless ($answer eq 'unknown_user' or $answer eq 'refused') {
	       if (length($answer)) {
		   return $answer;
	       }
	       else {
	   &logthis("User $uname at $udom lacks an authentication mechanism");
		   return 'no_host';
	       }
	   }
       }
    }
    &logthis("User $uname at $udom lacks an authentication mechanism");    
    return 'no_host';
}

# --------- Try to authenticate user from domain's lib servers (first this one)

sub authenticate {
    my ($uname,$upass,$udom)=@_;
    $upass=escape($upass);
    if (($perlvar{'lonRole'} eq 'library') && 
        ($udom eq $perlvar{'lonDefDomain'})) {
    my $answer=reply("encrypt:auth:$udom:$uname:$upass",$perlvar{'lonHostID'});
        if ($answer =~ /authorized/) {
              if ($answer eq 'authorized') {
                 &logthis("User $uname at $udom authorized by local server"); 
                 return $perlvar{'lonHostID'}; 
              }
              if ($answer eq 'non_authorized') {
                 &logthis("User $uname at $udom rejected by local server"); 
                 return 'no_host'; 
              }
	}
    }

    my $tryserver;
    foreach $tryserver (keys %libserv) {
	if ($hostdom{$tryserver} eq $udom) {
           my $answer=reply("encrypt:auth:$udom:$uname:$upass",$tryserver);
           if ($answer =~ /authorized/) {
              if ($answer eq 'authorized') {
                 &logthis("User $uname at $udom authorized by $tryserver"); 
                 return $tryserver; 
              }
              if ($answer eq 'non_authorized') {
                 &logthis("User $uname at $udom rejected by $tryserver");
                 return 'no_host';
              } 
	   }
       }
    }
    &logthis("User $uname at $udom could not be authenticated");    
    return 'no_host';
}

# ---------------------- Find the homebase for a user from domain's lib servers

sub homeserver {
    my ($uname,$udom)=@_;

    my $index="$uname:$udom";
    if ($homecache{$index}) { return "$homecache{$index}"; }

    my $tryserver;
    foreach $tryserver (keys %libserv) {
	if ($hostdom{$tryserver} eq $udom) {
           my $answer=reply("home:$udom:$uname",$tryserver);
           if ($answer eq 'found') { 
	      $homecache{$index}=$tryserver;
              return $tryserver; 
	   }
       }
    }    
    return 'no_host';
}

# ------------------------------------- Find the usernames behind a list of IDs

sub idget {
    my ($udom,@ids)=@_;
    my %returnhash=();
    
    my $tryserver;
    foreach $tryserver (keys %libserv) {
       if ($hostdom{$tryserver} eq $udom) {
	  my $idlist=join('&',@ids);
          $idlist=~tr/A-Z/a-z/; 
	  my $reply=&reply("idget:$udom:".$idlist,$tryserver);
          my @answer=();
          if (($reply ne 'con_lost') && ($reply!~/^error\:/)) {
	      @answer=split(/\&/,$reply);
          }                    ;
          my $i;
          for ($i=0;$i<=$#ids;$i++) {
              if ($answer[$i]) {
		  $returnhash{$ids[$i]}=$answer[$i];
              } 
          }
       }
    }    
    return %returnhash;
}

# ------------------------------------- Find the IDs behind a list of usernames

sub idrget {
    my ($udom,@unames)=@_;
    my %returnhash=();
    map {
        $returnhash{$_}=(&userenvironment($udom,$_,'id'))[1];
    } @unames;
    return %returnhash;
}

# ------------------------------- Store away a list of names and associated IDs

sub idput {
    my ($udom,%ids)=@_;
    my %servers=();
    map {
        my $uhom=&homeserver($_,$udom);
        if ($uhom ne 'no_host') {
            my $id=&escape($ids{$_});
            $id=~tr/A-Z/a-z/;
            my $unam=&escape($_);
	    if ($servers{$uhom}) {
		$servers{$uhom}.='&'.$id.'='.$unam;
            } else {
                $servers{$uhom}=$id.'='.$unam;
            }
            &critical('put:'.$udom.':'.$unam.':environment:id='.$id,$uhom);
        }
    } keys %ids;
    map {
        &critical('idput:'.$udom.':'.$servers{$_},$_);
    } keys %servers;
}

# ------------------------------------- Find the section of student in a course

sub usection {
    my ($udom,$unam,$courseid)=@_;
    $courseid=~s/\_/\//g;
    $courseid=~s/^(\w)/\/$1/;
    map {
        my ($key,$value)=split(/\=/,$_);
        $key=&unescape($key);
        if ($key=~/^$courseid(?:\/)*(\w+)*\_st$/) {
            my $section=$1;
            if ($key eq $courseid.'_st') { $section=''; }
	    my ($dummy,$end,$start)=split(/\_/,&unescape($value));
            my $now=time;
            my $notactive=0;
            if ($start) {
		if ($now<$start) { $notactive=1; }
            }
            if ($end) {
                if ($now>$end) { $notactive=1; }
            } 
            unless ($notactive) { return $section; }
        }
    } split(/\&/,&reply('dump:'.$udom.':'.$unam.':roles',
                        &homeserver($unam,$udom)));
    return '-1';
}

# ------------------------------------- Read an entry from a user's environment

sub userenvironment {
    my ($udom,$unam,@what)=@_;
    my %returnhash=();
    my @answer=split(/\&/,
                &reply('get:'.$udom.':'.$unam.':environment:'.join('&',@what),
                      &homeserver($unam,$udom)));
    my $i;
    for ($i=0;$i<=$#what;$i++) {
	$returnhash{$what[$i]}=&unescape($answer[$i]);
    }
    return %returnhash;
}

# ----------------------------- Subscribe to a resource, return URL if possible

sub subscribe {
    my $fname=shift;
    my $author=$fname;
    $author=~s/\/home\/httpd\/html\/res\/([^\/]*)\/([^\/]*).*/$1\/$2/;
    my ($udom,$uname)=split(/\//,$author);
    my $home=homeserver($uname,$udom);
    if (($home eq 'no_host') || ($home eq $perlvar{'lonHostID'})) { 
        return 'not_found'; 
    }
    my $answer=reply("sub:$fname",$home);
    if (($answer eq 'con_lost') || ($answer eq 'rejected')) {
	$answer.=' by '.$home;
    }
    return $answer;
}
    
# -------------------------------------------------------------- Replicate file

sub repcopy {
    my $filename=shift;
    $filename=~s/\/+/\//g;
    my $transname="$filename.in.transfer";
    if ((-e $filename) || (-e $transname)) { return OK; }
    my $remoteurl=subscribe($filename);
    if ($remoteurl =~ /^con_lost by/) {
	   &logthis("Subscribe returned $remoteurl: $filename");
           return HTTP_SERVICE_UNAVAILABLE;
    } elsif ($remoteurl eq 'not_found') {
	   &logthis("Subscribe returned not_found: $filename");
	   return HTTP_NOT_FOUND;
    } elsif ($remoteurl =~ /^rejected by/) {
	   &logthis("Subscribe returned $remoteurl: $filename");
           return FORBIDDEN;
    } elsif ($remoteurl eq 'directory') {
           return OK;
    } else {
           my @parts=split(/\//,$filename);
           my $path="/$parts[1]/$parts[2]/$parts[3]/$parts[4]";
           if ($path ne "$perlvar{'lonDocRoot'}/res") {
               &logthis("Malconfiguration for replication: $filename");
	       return HTTP_BAD_REQUEST;
           }
           my $count;
           for ($count=5;$count<$#parts;$count++) {
               $path.="/$parts[$count]";
               if ((-e $path)!=1) {
		   mkdir($path,0777);
               }
           }
           my $ua=new LWP::UserAgent;
           my $request=new HTTP::Request('GET',"$remoteurl");
           my $response=$ua->request($request,$transname);
           if ($response->is_error()) {
	       unlink($transname);
               my $message=$response->status_line;
               &logthis("<font color=blue>WARNING:"
                       ." LWP get: $message: $filename</font>");
               return HTTP_SERVICE_UNAVAILABLE;
           } else {
	       if ($remoteurl!~/\.meta$/) {
                  my $mrequest=new HTTP::Request('GET',$remoteurl.'.meta');
                  my $mresponse=$ua->request($mrequest,$filename.'.meta');
                  if ($mresponse->is_error()) {
		      unlink($filename.'.meta');
                      &logthis(
                     "<font color=yellow>INFO: No metadata: $filename</font>");
                  }
	       }
               rename($transname,$filename);
               return OK;
           }
    }
}

# --------------------------------------------------------- Server Side Include

sub ssi {

    my ($fn,%form)=@_;

    my $ua=new LWP::UserAgent;
    
    my $request;
    
    if (%form) {
      $request=new HTTP::Request('POST',"http://".$ENV{'HTTP_HOST'}.$fn);
      $request->content(join '&', map { "$_=$form{$_}" } keys %form);
    } else {
      $request=new HTTP::Request('GET',"http://".$ENV{'HTTP_HOST'}.$fn);
    }

    $request->header(Cookie => $ENV{'HTTP_COOKIE'});
    my $response=$ua->request($request);

    return $response->content;
}

# ------------------------------------------------------------------------- Log

sub log {
    my ($dom,$nam,$hom,$what)=@_;
    return critical("log:$dom:$nam:$what",$hom);
}

# ------------------------------------------------------------------ Course Log

sub flushcourselogs {
    &logthis('Flushing course log buffers');
    map {
        my $crsid=$_;
        if (&reply('log:'.$ENV{'course.'.$crsid.'.domain'}.':'.
		          $ENV{'course.'.$crsid.'.num'}.':'.
		           &escape($courselogs{$crsid}),
		          $ENV{'course.'.$crsid.'.home'}) eq 'ok') {
	    delete $courselogs{$crsid};
        } else {
            &logthis('Failed to flush log buffer for '.$crsid);
            if (length($courselogs{$crsid})>40000) {
               &logthis("<font color=blue>WARNING: Buffer for ".$crsid.
                        " exceeded maximum size, deleting.</font>");
               delete $courselogs{$crsid};
            }
        }        
    } keys %courselogs;
}

sub courselog {
    my $what=shift;
    $what=time.':'.$what;
    unless ($ENV{'request.course.id'}) { return ''; }
    if (defined $courselogs{$ENV{'request.course.id'}}) {
	$courselogs{$ENV{'request.course.id'}}.='&'.$what;
    } else {
	$courselogs{$ENV{'request.course.id'}}.=$what;
    }
    if (length($courselogs{$ENV{'request.course.id'}})>4048) {
	&flushcourselogs();
    }
}

sub courseacclog {
    my $fnsymb=shift;
    unless ($ENV{'request.course.id'}) { return ''; }
    my $what=$fnsymb.':'.$ENV{'user.name'}.':'.$ENV{'user.domain'};
    if ($what=~/(problem|exam|quiz|assess|survey|form)$/) {
	map {
            if ($_=~/^form\.(.*)/) {
		$what.=':'.$1.'='.$ENV{$_};
            }
        } keys %ENV;
    }
    &courselog($what);
}

# ----------------------------------------------------------- Check out an item

sub checkout {
    my ($symb,$tuname,$tudom,$tcrsid)=@_;
    my $now=time;
    my $lonhost=$perlvar{'lonHostID'};
    my $infostr=&escape(
                 $tuname.'&'.
                 $tudom.'&'.
                 $tcrsid.'&'.
                 $symb.'&'.
		 $now.'&'.$ENV{'REMOTE_ADDR'});
    my $token=&reply('tmpput:'.$infostr,$lonhost);
    if ($token=~/^error\:/) { 
        &logthis("<font color=blue>WARNING: ".
                "Checkout tmpput failed ".$tudom.' - '.$tuname.' - '.$symb.
                 "</font>");
        return ''; 
    }

    $token=~s/^(\d+)\_.*\_(\d+)$/$1\*$2\*$lonhost/;
    $token=~tr/a-z/A-Z/;

    my %infohash=('resource.0.outtoken' => $token,
                  'resource.0.checkouttime' => $now,
                  'resource.0.outremote' => $ENV{'REMOTE_ADDR'});

    unless (&cstore(\%infohash,$symb,$tcrsid,$tudom,$tuname) eq 'ok') {
       return '';
    } else {
        &logthis("<font color=blue>WARNING: ".
                "Checkout cstore failed ".$tudom.' - '.$tuname.' - '.$symb.
                 "</font>");
    }    

    if (&log($tudom,$tuname,&homeserver($tuname,$tudom),
                         &escape('Checkout '.$infostr.' - '.
                                                 $token)) ne 'ok') {
	return '';
    } else {
        &logthis("<font color=blue>WARNING: ".
                "Checkout log failed ".$tudom.' - '.$tuname.' - '.$symb.
                 "</font>");
    }
    return $token;
}

# ------------------------------------------------------------ Check in an item

sub checkin {
    my $token=shift;
    my $now=time;
    my ($ta,$tb,$lonhost)=split(/\*/,$token);
    $lonhost=~tr/A-Z/a-z/;
    my $dtoken=$ta.'_'.$hostip{$lonhost}.'_'.$tb;
    $dtoken=~s/\W/\_/g;
    my ($tuname,$tudom,$tcrsid,$symb,$chtim,$rmaddr)=
                 split(/\&/,&unescape(&reply('tmpget:'.$dtoken,$lonhost)));

    unless (($tuname) && ($tudom)) {
        &logthis('Check in '.$token.' ('.$dtoken.') failed');
        return '';
    }
    
    unless (&allowed('mgr',$tcrsid)) {
        &logthis('Check in '.$token.' ('.$dtoken.') unauthorized: '.
                 $ENV{'user.name'}.' - '.$ENV{'user.domain'});
        return '';
    }

    my %infohash=('resource.0.intoken' => $token,
                  'resource.0.checkintime' => $now,
                  'resource.0.inremote' => $ENV{'REMOTE_ADDR'});

    unless (&cstore(\%infohash,$symb,$tcrsid,$tudom,$tuname) eq 'ok') {
       return '';
    }    

    if (&log($tudom,$tuname,&homeserver($tuname,$tudom),
                         &escape('Checkin - '.$token)) ne 'ok') {
	return '';
    }

    return ($symb,$tuname,$tudom,$tcrsid);    
}

# --------------------------------------------- Set Expire Date for Spreadsheet

sub expirespread {
    my ($uname,$udom,$stype,$usymb)=@_;
    my $cid=$ENV{'request.course.id'}; 
    if ($cid) {
       my $now=time;
       my $key=$uname.':'.$udom.':'.$stype.':'.$usymb;
       return &reply('put:'.$ENV{'course.'.$cid.'.domain'}.':'.
                            $ENV{'course.'.$cid.'.num'}.
	        	    ':nohist_expirationdates:'.
                            &escape($key).'='.$now,
                            $ENV{'course.'.$cid.'.home'})
    }
    return 'ok';
}

# ----------------------------------------------------- Devalidate Spreadsheets

sub devalidate {
    my $symb=shift;
    my $cid=$ENV{'request.course.id'}; 
    if ($cid) {
	my $key=$ENV{'user.name'}.':'.$ENV{'user.domain'}.':';
        my $status=
	    &del('nohist_calculatedsheet',
		 [$key.'studentcalc'],
		 $ENV{'course.'.$cid.'.domain'},
		 $ENV{'course.'.$cid.'.num'})
		.' '.
	    &del('nohist_calculatedsheets_'.$cid,
		 [$key.'assesscalc:'.$symb]);
        unless ($status eq 'ok ok') {
           &logthis('Could not devalidate spreadsheet '.
                    $ENV{'user.name'}.' at '.$ENV{'user.domain'}.' for '.
		    $symb.': '.$status);
        }
    }
}

sub hash2str {
  my (%hash)=@_;
  my $result='';
  map { $result.=escape($_).'='.escape($hash{$_}).'&'; } keys %hash;
  $result=~s/\&$//;
  return $result;
}

sub str2hash {
  my ($string) = @_;
  my %returnhash;
  map {
    my ($name,$value)=split(/\=/,$_);
    $returnhash{&unescape($name)}=&unescape($value);
  } split(/\&/,$string);
  return %returnhash;
}

# -------------------------------------------------------------------Temp Store

sub tmpreset {
  my ($symb,$namespace,$domain,$stuname) = @_;
  if (!$symb) {
    $symb=&symbread();
    if (!$symb) { $symb= $ENV{'REQUEST_URI'}; }
  }
  $symb=escape($symb);

  if (!$namespace) { $namespace=$ENV{'request.state'}; }
  $namespace=~s/\//\_/g;
  $namespace=~s/\W//g;

  #FIXME needs to do something for /pub resources
  if (!$domain) { $domain=$ENV{'user.domain'}; }
  if (!$stuname) { $stuname=$ENV{'user.name'}; }
  my $path=$perlvar{'lonDaemons'}.'/tmp';
  my %hash;
  if (tie(%hash,'GDBM_File',
	  $path.'/tmpstore_'.$stuname.'_'.$domain.'_'.$namespace.'.db',
	  &GDBM_WRCREAT,0640)) {
    foreach my $key (keys %hash) {
      if ($key=~ /:$symb/) {
	delete($hash{$key});
      }
    }
  }
}

sub tmpstore {
  my ($storehash,$symb,$namespace,$domain,$stuname) = @_;

  if (!$symb) {
    $symb=&symbread();
    if (!$symb) { $symb= $ENV{'request.url'}; }
  }
  $symb=escape($symb);

  if (!$namespace) {
    # I don't think we would ever want to store this for a course.
    # it seems this will only be used if we don't have a course.
    #$namespace=$ENV{'request.course.id'};
    #if (!$namespace) {
      $namespace=$ENV{'request.state'};
    #}
  }
  $namespace=~s/\//\_/g;
  $namespace=~s/\W//g;
#FIXME needs to do something for /pub resources
  if (!$domain) { $domain=$ENV{'user.domain'}; }
  if (!$stuname) { $stuname=$ENV{'user.name'}; }
  my $now=time;
  my %hash;
  my $path=$perlvar{'lonDaemons'}.'/tmp';
  if (tie(%hash,'GDBM_File',
	  $path.'/tmpstore_'.$stuname.'_'.$domain.'_'.$namespace.'.db',
	  &GDBM_WRCREAT,0640)) {
    $hash{"version:$symb"}++;
    my $version=$hash{"version:$symb"};
    my $allkeys=''; 
    foreach my $key (keys(%$storehash)) {
      $allkeys.=$key.':';
      $hash{"$version:$symb:$key"}=$$storehash{$key};
    }
    $hash{"$version:$symb:timestamp"}=$now;
    $allkeys.='timestamp';
    $hash{"$version:keys:$symb"}=$allkeys;
    if (untie(%hash)) {
      return 'ok';
    } else {
      return "error:$!";
    }
  } else {
    return "error:$!";
  }
}

# -----------------------------------------------------------------Temp Restore

sub tmprestore {
  my ($symb,$namespace,$domain,$stuname) = @_;

  if (!$symb) {
    $symb=&symbread();
    if (!$symb) { $symb= $ENV{'request.url'}; }
  }
  $symb=escape($symb);

  if (!$namespace) { $namespace=$ENV{'request.state'}; }
  #FIXME needs to do something for /pub resources
  if (!$domain) { $domain=$ENV{'user.domain'}; }
  if (!$stuname) { $stuname=$ENV{'user.name'}; }

  my %returnhash;
  $namespace=~s/\//\_/g;
  $namespace=~s/\W//g;
  my %hash;
  my $path=$perlvar{'lonDaemons'}.'/tmp';
  if (tie(%hash,'GDBM_File',
	  $path.'/tmpstore_'.$stuname.'_'.$domain.'_'.$namespace.'.db',
	  &GDBM_READER,0640)) {
    my $version=$hash{"version:$symb"};
    $returnhash{'version'}=$version;
    my $scope;
    for ($scope=1;$scope<=$version;$scope++) {
      my $vkeys=$hash{"$scope:keys:$symb"};
      my @keys=split(/:/,$vkeys);
      my $key;
      $returnhash{"$scope:keys"}=$vkeys;
      foreach $key (@keys) {
	$returnhash{"$scope:$key"}=$hash{"$scope:$symb:$key"};
	$returnhash{"$key"}=$hash{"$scope:$symb:$key"};
      }
    }
    if (!(untie(%hash))) {
      return "error:$!";
    }
  } else {
    return "error:$!";
  }
  return %returnhash;
}

# ----------------------------------------------------------------------- Store

sub store {
    my ($storehash,$symb,$namespace,$domain,$stuname) = @_;
    my $home='';

    if ($stuname) { $home=&homeserver($stuname,$domain); }

    if (!$symb) { unless ($symb=&symbread()) { return ''; } }

    &devalidate($symb);

    $symb=escape($symb);
    if (!$namespace) { unless ($namespace=$ENV{'request.course.id'}) { return ''; } }
    if (!$domain) { $domain=$ENV{'user.domain'}; }
    if (!$stuname) { $stuname=$ENV{'user.name'}; }
    if (!$home) { $home=$ENV{'user.home'}; }
    my $namevalue='';
    map {
        $namevalue.=escape($_).'='.escape($$storehash{$_}).'&';
    } keys %$storehash;
    $namevalue=~s/\&$//;
    return reply("store:$domain:$stuname:$namespace:$symb:$namevalue","$home");
}

# -------------------------------------------------------------- Critical Store

sub cstore {
    my ($storehash,$symb,$namespace,$domain,$stuname) = @_;
    my $home='';

    if ($stuname) { $home=&homeserver($stuname,$domain); }

    if (!$symb) { unless ($symb=&symbread()) { return ''; } }

    &devalidate($symb);

    $symb=escape($symb);
    if (!$namespace) { unless ($namespace=$ENV{'request.course.id'}) { return ''; } }
    if (!$domain) { $domain=$ENV{'user.domain'}; }
    if (!$stuname) { $stuname=$ENV{'user.name'}; }
    if (!$home) { $home=$ENV{'user.home'}; }

    my $namevalue='';
    map {
        $namevalue.=escape($_).'='.escape($$storehash{$_}).'&';
    } keys %$storehash;
    $namevalue=~s/\&$//;
    return critical("store:$domain:$stuname:$namespace:$symb:$namevalue","$home");
}

# --------------------------------------------------------------------- Restore

sub restore {
    my ($symb,$namespace,$domain,$stuname) = @_;
    my $home='';

    if ($stuname) { $home=&homeserver($stuname,$domain); }

    if (!$symb) {
      unless ($symb=escape(&symbread())) { return ''; }
    } else {
      $symb=&escape($symb);
    }
    if (!$namespace) { unless ($namespace=$ENV{'request.course.id'}) { return ''; } }
    if (!$domain) { $domain=$ENV{'user.domain'}; }
    if (!$stuname) { $stuname=$ENV{'user.name'}; }
    if (!$home) { $home=$ENV{'user.home'}; }
    my $answer=&reply("restore:$domain:$stuname:$namespace:$symb","$home");

    my %returnhash=();
    map {
	my ($name,$value)=split(/\=/,$_);
        $returnhash{&unescape($name)}=&unescape($value);
    } split(/\&/,$answer);
    my $version;
    for ($version=1;$version<=$returnhash{'version'};$version++) {
       map {
          $returnhash{$_}=$returnhash{$version.':'.$_};
       } split(/\:/,$returnhash{$version.':keys'});
    }
    return %returnhash;
}

# ---------------------------------------------------------- Course Description

sub coursedescription {
    my $courseid=shift;
    $courseid=~s/^\///;
    $courseid=~s/\_/\//g;
    my ($cdomain,$cnum)=split(/\//,$courseid);
    my $chome=&homeserver($cnum,$cdomain);
    if ($chome ne 'no_host') {
       my %returnhash=&dump('environment',$cdomain,$cnum);
       if (!exists($returnhash{'con_lost'})) {
           my $normalid=$cdomain.'_'.$cnum;
           my %envhash=();
           $returnhash{'home'}= $chome;
	   $returnhash{'domain'} = $cdomain;
	   $returnhash{'num'} = $cnum;
           while (my ($name,$value) = each %returnhash) {
               $envhash{'course.'.$normalid.'.'.$name}=$value;
           }
           $returnhash{'url'}='/res/'.declutter($returnhash{'url'});
           $returnhash{'fn'}=$perlvar{'lonDaemons'}.'/tmp/'.
	       $ENV{'user.name'}.'_'.$cdomain.'_'.$cnum;
           $envhash{'course.'.$normalid.'.last_cache'}=time;
           $envhash{'course.'.$normalid.'.home'}=$chome;
           $envhash{'course.'.$normalid.'.domain'}=$cdomain;
           $envhash{'course.'.$normalid.'.num'}=$cnum;
           &appenv(%envhash);
           return %returnhash;
       }
    }
    return ();
}

# -------------------------------------------------------- Get user privileges

sub rolesinit {
    my ($domain,$username,$authhost)=@_;
    my $rolesdump=reply("dump:$domain:$username:roles",$authhost);
    if (($rolesdump eq 'con_lost') || ($rolesdump eq '')) { return ''; }
    my %allroles=();
    my %thesepriv=();
    my $now=time;
    my $userroles="user.login.time=$now\n";
    my $thesestr;

    if ($rolesdump ne '') {
        map {
	  if ($_!~/^rolesdef\&/) {
            my ($area,$role)=split(/=/,$_);
            $area=~s/\_\w\w$//;
            my ($trole,$tend,$tstart)=split(/_/,$role);
            $userroles.='user.role.'.$trole.'.'.$area.'='.
                        $tstart.'.'.$tend."\n";
            if ($tend!=0) {
	        if ($tend<$now) {
	            $trole='';
                } 
            }
            if ($tstart!=0) {
                if ($tstart>$now) {
                   $trole='';        
                }
            }
            if (($area ne '') && ($trole ne '')) {
	       my $spec=$trole.'.'.$area;
               my ($tdummy,$tdomain,$trest)=split(/\//,$area);
               if ($trole =~ /^cr\//) {
		   my ($rdummy,$rdomain,$rauthor,$rrole)=split(/\//,$trole);
                   my $homsvr=homeserver($rauthor,$rdomain);
                   if ($hostname{$homsvr} ne '') {
                      my $roledef=
			  reply("get:$rdomain:$rauthor:roles:rolesdef_$rrole",
                                $homsvr);
                      if (($roledef ne 'con_lost') && ($roledef ne '')) {
                         my ($syspriv,$dompriv,$coursepriv)=
			     split(/\_/,unescape($roledef));
 	                 $allroles{'cm./'}.=':'.$syspriv;
                         $allroles{$spec.'./'}.=':'.$syspriv;
                         if ($tdomain ne '') {
                             $allroles{'cm./'.$tdomain.'/'}.=':'.$dompriv;
                             $allroles{$spec.'./'.$tdomain.'/'}.=':'.$dompriv;
                             if ($trest ne '') {
		                $allroles{'cm.'.$area}.=':'.$coursepriv;
		                $allroles{$spec.'.'.$area}.=':'.$coursepriv;
                             }
	                 }
                      }
                   }
               } else {
	           $allroles{'cm./'}.=':'.$pr{$trole.':s'};
	           $allroles{$spec.'./'}.=':'.$pr{$trole.':s'};
                   if ($tdomain ne '') {
                     $allroles{'cm./'.$tdomain.'/'}.=':'.$pr{$trole.':d'};
                     $allroles{$spec.'./'.$tdomain.'/'}.=':'.$pr{$trole.':d'};
                      if ($trest ne '') {
		          $allroles{'cm.'.$area}.=':'.$pr{$trole.':c'};
		          $allroles{$spec.'.'.$area}.=':'.$pr{$trole.':c'};
                      }
	           }
	       }
            }
          } 
        } split(/&/,$rolesdump);
        my $adv=0;
        my $author=0;
        map {
            %thesepriv=();
            if (($_!~/^st/) && ($_!~/^ta/) && ($_!~/^cm/)) { $adv=1; }
            if (($_=~/^au/) || ($_=~/^ca/)) { $author=1; }
            map {
                if ($_ ne '') {
		    my ($privilege,$restrictions)=split(/&/,$_);
                    if ($restrictions eq '') {
			$thesepriv{$privilege}='F';
                    } else {
                        if ($thesepriv{$privilege} ne 'F') {
			    $thesepriv{$privilege}.=$restrictions;
                        }
                    }
                }
            } split(/:/,$allroles{$_});
            $thesestr='';
            map { $thesestr.=':'.$_.'&'.$thesepriv{$_}; } keys %thesepriv;
            $userroles.='user.priv.'.$_.'='.$thesestr."\n";
        } keys %allroles;            
        $userroles.='user.adv='.$adv."\n".
	            'user.author='.$author."\n";
        $ENV{'user.adv'}=$adv;
    }
    return $userroles;  
}

# --------------------------------------------------------------- get interface

sub get {
   my ($namespace,$storearr,$udomain,$uname)=@_;
   my $items='';
   map {
       $items.=escape($_).'&';
   } @$storearr;
   $items=~s/\&$//;
   if (!$udomain) { $udomain=$ENV{'user.domain'}; }
   if (!$uname) { $uname=$ENV{'user.name'}; }
   my $uhome=&homeserver($uname,$udomain);

   my $rep=&reply("get:$udomain:$uname:$namespace:$items",$uhome);
   my @pairs=split(/\&/,$rep);
   my %returnhash=();
   my $i=0;
   map {
      $returnhash{$_}=unescape($pairs[$i]);
      $i++;
   } @$storearr;
   return %returnhash;
}

# --------------------------------------------------------------- del interface

sub del {
   my ($namespace,$storearr,$udomain,$uname)=@_;
   my $items='';
   map {
       $items.=escape($_).'&';
   } @$storearr;
   $items=~s/\&$//;
   if (!$udomain) { $udomain=$ENV{'user.domain'}; }
   if (!$uname) { $uname=$ENV{'user.name'}; }
   my $uhome=&homeserver($uname,$udomain);

   return &reply("del:$udomain:$uname:$namespace:$items",$uhome);
}

# -------------------------------------------------------------- dump interface

sub dump {
   my ($namespace,$udomain,$uname)=@_;
   if (!$udomain) { $udomain=$ENV{'user.domain'}; }
   if (!$uname) { $uname=$ENV{'user.name'}; }
   my $uhome=&homeserver($uname,$udomain);
   my $rep=reply("dump:$udomain:$uname:$namespace",$uhome);
   my @pairs=split(/\&/,$rep);
   my %returnhash=();
   map {
      my ($key,$value)=split(/=/,$_);
      $returnhash{unescape($key)}=unescape($value);
   } @pairs;
   return %returnhash;
}

# --------------------------------------------------------------- put interface

sub put {
   my ($namespace,$storehash,$udomain,$uname)=@_;
   if (!$udomain) { $udomain=$ENV{'user.domain'}; }
   if (!$uname) { $uname=$ENV{'user.name'}; }
   my $uhome=&homeserver($uname,$udomain);
   my $items='';
   map {
       $items.=&escape($_).'='.&escape($$storehash{$_}).'&';
   } keys %$storehash;
   $items=~s/\&$//;
   return &reply("put:$udomain:$uname:$namespace:$items",$uhome);
}

# ------------------------------------------------------ critical put interface

sub cput {
   my ($namespace,$storehash,$udomain,$uname)=@_;
   if (!$udomain) { $udomain=$ENV{'user.domain'}; }
   if (!$uname) { $uname=$ENV{'user.name'}; }
   my $uhome=&homeserver($uname,$udomain);
   my $items='';
   map {
       $items.=escape($_).'='.escape($$storehash{$_}).'&';
   } keys %$storehash;
   $items=~s/\&$//;
   return &critical("put:$udomain:$uname:$namespace:$items",$uhome);
}

# -------------------------------------------------------------- eget interface

sub eget {
   my ($namespace,$storearr,$udomain,$uname)=@_;
   my $items='';
   map {
       $items.=escape($_).'&';
   } @$storearr;
   $items=~s/\&$//;
   if (!$udomain) { $udomain=$ENV{'user.domain'}; }
   if (!$uname) { $uname=$ENV{'user.name'}; }
   my $uhome=&homeserver($uname,$udomain);
   my $rep=&reply("eget:$udomain:$uname:$namespace:$items",$uhome);
   my @pairs=split(/\&/,$rep);
   my %returnhash=();
   my $i=0;
   map {
      $returnhash{$_}=unescape($pairs[$i]);
      $i++;
   } @$storearr;
   return %returnhash;
}

# ------------------------------------------------- Check for a user privilege

sub allowed {
    my ($priv,$uri)=@_;

    my $orguri=$uri;
    $uri=&declutter($uri);

# Free bre access to adm and meta resources

    if ((($uri=~/^adm\//) || ($uri=~/\.meta$/)) && ($priv eq 'bre')) {
	return 'F';
    }

# Free bre to public access

    if ($priv eq 'bre') {
	if (&metadata($uri,'copyright') eq 'public') { return 'F'; }
    }

    my $thisallowed='';
    my $statecond=0;
    my $courseprivid='';

# Course

    if ($ENV{'user.priv.'.$ENV{'request.role'}.'./'}=~/$priv\&([^\:]*)/) {
       $thisallowed.=$1;
    }

# Domain

    if ($ENV{'user.priv.'.$ENV{'request.role'}.'./'.(split(/\//,$uri))[0].'/'}
       =~/$priv\&([^\:]*)/) {
       $thisallowed.=$1;
    }

# Course: uri itself is a course
    my $courseuri=$uri;
    $courseuri=~s/\_(\d)/\/$1/;
    $courseuri=~s/^([^\/])/\/$1/;

    if ($ENV{'user.priv.'.$ENV{'request.role'}.'.'.$courseuri}
       =~/$priv\&([^\:]*)/) {
       $thisallowed.=$1;
    }

# Full access at system, domain or course-wide level? Exit.

    if ($thisallowed=~/F/) {
	return 'F';
    }

# If this is generating or modifying users, exit with special codes

    if (':csu:cdc:ccc:cin:cta:cep:ccr:cst:cad:cli:cau:cdg:cca:'=~/\:$priv\:/) {
	return $thisallowed;
    }
#
# Gathered so far: system, domain and course wide privileges
#
# Course: See if uri or referer is an individual resource that is part of 
# the course

    if ($ENV{'request.course.id'}) {
       $courseprivid=$ENV{'request.course.id'};
       if ($ENV{'request.course.sec'}) {
          $courseprivid.='/'.$ENV{'request.course.sec'};
       }
       $courseprivid=~s/\_/\//;
       my $checkreferer=1;
       my @uriparts=split(/\//,$uri);
       my $filename=$uriparts[$#uriparts];
       my $pathname=$uri;
       $pathname=~s/\/$filename$//;
       if ($ENV{'acc.res.'.$ENV{'request.course.id'}.'.'.$pathname}=~
           /\&$filename\:([\d\|]+)\&/) {
           $statecond=$1;
           if ($ENV{'user.priv.'.$ENV{'request.role'}.'./'.$courseprivid}
               =~/$priv\&([^\:]*)/) {
               $thisallowed.=$1;
               $checkreferer=0;
           }
       }
       
       if ($checkreferer) {
	  my $refuri=$ENV{'httpref.'.$orguri};

            unless ($refuri) {
                map {
		    if ($_=~/^httpref\..*\*/) {
			my $pattern=$_;
                        $pattern=~s/^httpref\.\/res\///;
                        $pattern=~s/\*/\[\^\/\]\+/g;
                        $pattern=~s/\//\\\//g;
                        if ($orguri=~/$pattern/) {
			    $refuri=$ENV{$_};
                        }
                    }
                } keys %ENV;
            }
         if ($refuri) { 
	  $refuri=&declutter($refuri);
          my @uriparts=split(/\//,$refuri);
          my $filename=$uriparts[$#uriparts];
          my $pathname=$refuri;
          $pathname=~s/\/$filename$//;
            if ($ENV{'acc.res.'.$ENV{'request.course.id'}.'.'.$pathname}=~
              /\&$filename\:([\d\|]+)\&/) {
              my $refstatecond=$1;
              if ($ENV{'user.priv.'.$ENV{'request.role'}.'./'.$courseprivid}
                  =~/$priv\&([^\:]*)/) {
                  $thisallowed.=$1;
                  $uri=$refuri;
                  $statecond=$refstatecond;
              }
          }
        }
       }
   }

#
# Gathered now: all privileges that could apply, and condition number
# 
#
# Full or no access?
#

    if ($thisallowed=~/F/) {
	return 'F';
    }

    unless ($thisallowed) {
        return '';
    }

# Restrictions exist, deal with them
#
#   C:according to course preferences
#   R:according to resource settings
#   L:unless locked
#   X:according to user session state
#

# Possibly locked functionality, check all courses
# Locks might take effect only after 10 minutes cache expiration for other
# courses, and 2 minutes for current course

    my $envkey;
    if ($thisallowed=~/L/) {
        foreach $envkey (keys %ENV) {
           if ($envkey=~/^user\.role\.(st|ta)\.([^\.]*)/) {
               my $courseid=$2;
               my $roleid=$1.'.'.$2;
               $courseid=~s/^\///;
               my $expiretime=600;
               if ($ENV{'request.role'} eq $roleid) {
		  $expiretime=120;
               }
	       my ($cdom,$cnum,$csec)=split(/\//,$courseid);
               my $prefix='course.'.$cdom.'_'.$cnum.'.';
               if ((time-$ENV{$prefix.'last_cache'})>$expiretime) {
		   &coursedescription($courseid);
               }
               if (($ENV{$prefix.'res.'.$uri.'.lock.sections'}=~/\,$csec\,/)
                || ($ENV{$prefix.'res.'.$uri.'.lock.sections'} eq 'all')) {
		   if ($ENV{$prefix.'res.'.$uri.'.lock.expire'}>time) {
                       &log($ENV{'user.domain'},$ENV{'user.name'},
                            $ENV{'user.host'},
                            'Locked by res: '.$priv.' for '.$uri.' due to '.
                            $cdom.'/'.$cnum.'/'.$csec.' expire '.
                            $ENV{$prefix.'priv.'.$priv.'.lock.expire'});
		       return '';
                   }
               }
               if (($ENV{$prefix.'priv.'.$priv.'.lock.sections'}=~/\,$csec\,/)
                || ($ENV{$prefix.'priv.'.$priv.'.lock.sections'} eq 'all')) {
		   if ($ENV{'priv.'.$priv.'.lock.expire'}>time) {
                       &log($ENV{'user.domain'},$ENV{'user.name'},
                            $ENV{'user.host'},
                            'Locked by priv: '.$priv.' for '.$uri.' due to '.
                            $cdom.'/'.$cnum.'/'.$csec.' expire '.
                            $ENV{$prefix.'priv.'.$priv.'.lock.expire'});
		       return '';
                   }
               }
	   }
       }
    }
   
#
# Rest of the restrictions depend on selected course
#

    unless ($ENV{'request.course.id'}) {
       return '1';
    }

#
# Now user is definitely in a course
#


# Course preferences

   if ($thisallowed=~/C/) {
       my $rolecode=(split(/\./,$ENV{'request.role'}))[0];
       if ($ENV{'course.'.$ENV{'request.course.id'}.'.'.$priv.'.roles.denied'}
	   =~/\,$rolecode\,/) {
           &log($ENV{'user.domain'},$ENV{'user.name'},$ENV{'user.host'},
                'Denied by role: '.$priv.' for '.$uri.' as '.$rolecode.' in '.
                $ENV{'request.course.id'});
           return '';
       }
   }

# Resource preferences

   if ($thisallowed=~/R/) {
       my $rolecode=(split(/\./,$ENV{'request.role'}))[0];
       my $filename=$perlvar{'lonDocRoot'}.'/res/'.$uri.'.meta';
       if (-e $filename) {
           my @content;
           {
	     my $fh=Apache::File->new($filename);
             @content=<$fh>;
	   }
           if (join('',@content)=~
                    /\<roledeny[^\>]*\>[^\<]*$rolecode[^\<]*\<\/roledeny\>/) {
	       &log($ENV{'user.domain'},$ENV{'user.name'},$ENV{'user.host'},
                    'Denied by role: '.$priv.' for '.$uri.' as '.$rolecode);
           return '';

           }
       }
   }

# Restricted by state?

   if ($thisallowed=~/X/) {
      if (&condval($statecond)) {
	 return '2';
      } else {
         return '';
      }
   }

   return 'F';
}

# ----------------------------------------------------------------- Define Role

sub definerole {
  if (allowed('mcr','/')) {
    my ($rolename,$sysrole,$domrole,$courole)=@_;
    map {
	my ($crole,$cqual)=split(/\&/,$_);
        if ($pr{'cr:s'}!~/$crole/) { return "refused:s:$crole"; }
        if ($pr{'cr:s'}=~/$crole\&/) {
	    if ($pr{'cr:s'}!~/$crole\&\w*$cqual/) { 
               return "refused:s:$crole&$cqual"; 
            }
        }
    } split('/',$sysrole);
    map {
	my ($crole,$cqual)=split(/\&/,$_);
        if ($pr{'cr:d'}!~/$crole/) { return "refused:d:$crole"; }
        if ($pr{'cr:d'}=~/$crole\&/) {
	    if ($pr{'cr:d'}!~/$crole\&\w*$cqual/) { 
               return "refused:d:$crole&$cqual"; 
            }
        }
    } split('/',$domrole);
    map {
	my ($crole,$cqual)=split(/\&/,$_);
        if ($pr{'cr:c'}!~/$crole/) { return "refused:c:$crole"; }
        if ($pr{'cr:c'}=~/$crole\&/) {
	    if ($pr{'cr:c'}!~/$crole\&\w*$cqual/) { 
               return "refused:c:$crole&$cqual"; 
            }
        }
    } split('/',$courole);
    my $command="encrypt:rolesput:$ENV{'user.domain'}:$ENV{'user.name'}:".
                "$ENV{'user.domain'}:$ENV{'user.name'}:".
	        "rolesdef_$rolename=".
                escape($sysrole.'_'.$domrole.'_'.$courole);
    return reply($command,$ENV{'user.home'});
  } else {
    return 'refused';
  }
}

# ---------------- Make a metadata query against the network of library servers

sub metadata_query {
    my ($query,$custom,$customshow)=@_;
    my %rhash;
    for my $server (keys %libserv) {
	unless ($custom or $customshow) {
	    my $reply=&reply("querysend:".&escape($query),$server);
	    $rhash{$server}=$reply;
	}
	else {
	    my $reply=&reply("querysend:".&escape($query).':'.
			     &escape($custom).':'.&escape($customshow),
			     $server);
	    $rhash{$server}=$reply;
	}
    }
    return \%rhash;
}

# ------------------------------------------------------------------ Plain Text

sub plaintext {
    my $short=shift;
    return $prp{$short};
}

# ------------------------------------------------------------------ Plain Text

sub fileembstyle {
    my $ending=lc(shift);
    return $fe{$ending};
}

# ------------------------------------------------------------ Description Text

sub filedescription {
    my $ending=lc(shift);
    return $fd{$ending};
}

# ----------------------------------------------------------------- Assign Role

sub assignrole {
    my ($udom,$uname,$url,$role,$end,$start)=@_;
    my $mrole;
    if ($role =~ /^cr\//) {
	unless (&allowed('ccr',$url)) {
           &logthis('Refused custom assignrole: '.
             $udom.' '.$uname.' '.$url.' '.$role.' '.$end.' '.$start.' by '.
		    $ENV{'user.name'}.' at '.$ENV{'user.domain'});
           return 'refused'; 
        }
        $mrole='cr';
    } else {
        my $cwosec=$url;
        $cwosec=~s/^\/(\w+)\/(\w+)\/.*/$1\/$2/;
        unless (&allowed('c'.$role,$cwosec)) { 
           &logthis('Refused assignrole: '.
             $udom.' '.$uname.' '.$url.' '.$role.' '.$end.' '.$start.' by '.
		    $ENV{'user.name'}.' at '.$ENV{'user.domain'});
           return 'refused'; 
        }
        $mrole=$role;
    }
    my $command="encrypt:rolesput:$ENV{'user.domain'}:$ENV{'user.name'}:".
                "$udom:$uname:$url".'_'."$mrole=$role";
    if ($end) { $command.='_'.$end; }
    if ($start) {
	if ($end) { 
           $command.='_'.$start; 
        } else {
           $command.='_0_'.$start;
        }
    }
    return &reply($command,&homeserver($uname,$udom));
}

# -------------------------------------------------- Modify user authentication
sub modifyuserauth {
    my ($udom,$uname,$umode,$upass)=@_;
    my $uhome=&homeserver($uname,$udom);
    &logthis('Call to modify user authentication'.$udom.', '.$uname.', '.
             $umode.' by '.$ENV{'user.name'}.' at '.$ENV{'user.domain'});  
    my $reply=&reply('encrypt:changeuserauth:'.$udom.':'.$uname.':'.$umode.':'.
		     &escape($upass),$uhome);
    unless ($reply eq 'ok') {
	return 'error: '.$reply;
    }   
    return 'ok';
}

# --------------------------------------------------------------- Modify a user


sub modifyuser {
    my ($udom,$uname,$uid,$umode,$upass,$first,$middle,$last,$gene)=@_;
    &logthis('Call to modify user '.$udom.', '.$uname.', '.$uid.', '.
             $umode.', '.$first.', '.$middle.', '.
	     $last.', '.$gene.' by '.
             $ENV{'user.name'}.' at '.$ENV{'user.domain'});  
    my $uhome=&homeserver($uname,$udom);
# ----------------------------------------------------------------- Create User
    if (($uhome eq 'no_host') && ($umode) && ($upass)) {
        my $unhome='';
	if ($ENV{'course.'.$ENV{'request.course.id'}.'.domain'} eq $udom) {
	    $unhome=$ENV{'course.'.$ENV{'request.course.id'}.'.home'};
        } else {
            my $tryserver;
            my $loadm=10000000;
            foreach $tryserver (keys %libserv) {
	       if ($hostdom{$tryserver} eq $udom) {
                  my $answer=reply('load',$tryserver);
                  if (($answer=~/\d+/) && ($answer<$loadm)) {
		      $loadm=$answer;
                      $unhome=$tryserver;
                  }
	       }
	    }
        }
        if (($unhome eq '') || ($unhome eq 'no_host')) {
	    return 'error: find home';
        }
        my $reply=&reply('encrypt:makeuser:'.$udom.':'.$uname.':'.$umode.':'.
                         &escape($upass),$unhome);
	unless ($reply eq 'ok') {
            return 'error: '.$reply;
        }   
        $uhome=&homeserver($uname,$udom);
        if (($uhome eq '') || ($uhome eq 'no_host') || ($uhome ne $unhome)) {
	    return 'error: verify home';
        }
    }
# ---------------------------------------------------------------------- Add ID
    if ($uid) {
       $uid=~tr/A-Z/a-z/;
       my %uidhash=&idrget($udom,$uname);
       if (($uidhash{$uname}) && ($uidhash{$uname}!~/error\:/)) {
	  unless ($uid eq $uidhash{$uname}) {
	      return 'error: mismatch '.$uidhash{$uname}.' versus '.$uid;
          }
       } else {
	  &idput($udom,($uname => $uid));
       }
    }
# -------------------------------------------------------------- Add names, etc
    my %names=&get('environment',
		   ['firstname','middlename','lastname','generation'],
		   $udom,$uname);
    if ($first)  { $names{'firstname'}  = $first; }
    if ($middle) { $names{'middlename'} = $middle; }
    if ($last)   { $names{'lastname'}   = $last; }
    if ($gene)   { $names{'generation'} = $gene; }
    my $reply = &put('environment', \%names, $udom,$uname);
    if ($reply ne 'ok') { return 'error: '.$reply; }
    &logthis('Success modifying user '.$udom.', '.$uname.', '.$uid.', '.
             $umode.', '.$first.', '.$middle.', '.
	     $last.', '.$gene.' by '.
             $ENV{'user.name'}.' at '.$ENV{'user.domain'});
    return 'ok';
}

# -------------------------------------------------------------- Modify student

sub modifystudent {
    my ($udom,$uname,$uid,$umode,$upass,$first,$middle,$last,$gene,$usec,
        $end,$start)=@_;
    my $cid='';
    unless ($cid=$ENV{'request.course.id'}) {
	return 'not_in_class';
    }
# --------------------------------------------------------------- Make the user
    my $reply=&modifyuser
	($udom,$uname,$uid,$umode,$upass,$first,$middle,$last,$gene);
    unless ($reply eq 'ok') { return $reply; }
    my $uhome=&homeserver($uname,$udom);
    if (($uhome eq '') || ($uhome eq 'no_host')) { 
	return 'error: no such user';
    }
# -------------------------------------------------- Add student to course list
    $reply=critical('put:'.$ENV{'course.'.$cid.'.domain'}.':'.
	              $ENV{'course.'.$cid.'.num'}.':classlist:'.
                      &escape($uname.':'.$udom).'='.
                      &escape($end.':'.$start),
	              $ENV{'course.'.$cid.'.home'});
    unless (($reply eq 'ok') || ($reply eq 'delayed')) {
	return 'error: '.$reply;
    }
# ---------------------------------------------------- Add student role to user
    my $uurl='/'.$cid;
    $uurl=~s/\_/\//g;
    if ($usec) {
	$uurl.='/'.$usec;
    }
    return &assignrole($udom,$uname,$uurl,'st',$end,$start);
}

# ------------------------------------------------- Write to course preferences

sub writecoursepref {
    my ($courseid,%prefs)=@_;
    $courseid=~s/^\///;
    $courseid=~s/\_/\//g;
    my ($cdomain,$cnum)=split(/\//,$courseid);
    my $chome=homeserver($cnum,$cdomain);
    if (($chome eq '') || ($chome eq 'no_host')) { 
	return 'error: no such course';
    }
    my $cstring='';
    map {
	$cstring.=escape($_).'='.escape($prefs{$_}).'&';
    } keys %prefs;
    $cstring=~s/\&$//;
    return reply('put:'.$cdomain.':'.$cnum.':environment:'.$cstring,$chome);
}

# ---------------------------------------------------------- Make/modify course

sub createcourse {
    my ($udom,$description,$url)=@_;
    $url=&declutter($url);
    my $cid='';
    unless (&allowed('ccc',$ENV{'user.domain'})) {
        return 'refused';
    }
    unless ($udom eq $ENV{'user.domain'}) {
        return 'refused';
    }
# ------------------------------------------------------------------- Create ID
   my $uname=substr($$.time,0,5).unpack("H8",pack("I32",time)).
       unpack("H2",pack("I32",int(rand(255)))).$perlvar{'lonHostID'};
# ----------------------------------------------- Make sure that does not exist
   my $uhome=&homeserver($uname,$udom);
   unless (($uhome eq '') || ($uhome eq 'no_host')) {
       $uname=substr($$.time,0,5).unpack("H8",pack("I32",time)).
        unpack("H2",pack("I32",int(rand(255)))).$perlvar{'lonHostID'};
       $uhome=&homeserver($uname,$udom);       
       unless (($uhome eq '') || ($uhome eq 'no_host')) {
           return 'error: unable to generate unique course-ID';
       } 
   }
# ------------------------------------------------------------- Make the course
    my $reply=&reply('encrypt:makeuser:'.$udom.':'.$uname.':none::',
                      $ENV{'user.home'});
    unless ($reply eq 'ok') { return 'error: '.$reply; }
    $uhome=&homeserver($uname,$udom);
    if (($uhome eq '') || ($uhome eq 'no_host')) { 
	return 'error: no such course';
    }
    &writecoursepref($udom.'_'.$uname,
                     ('description' => $description,
                      'url'         => $url));
    return '/'.$udom.'/'.$uname;
}

# ---------------------------------------------------------- Assign Custom Role

sub assigncustomrole {
    my ($udom,$uname,$url,$rdom,$rnam,$rolename,$end,$start)=@_;
    return &assignrole($udom,$uname,$url,'cr/'.$rdom.'/'.$rnam.'/'.$rolename,
                       $end,$start);
}

# ----------------------------------------------------------------- Revoke Role

sub revokerole {
    my ($udom,$uname,$url,$role)=@_;
    my $now=time;
    return &assignrole($udom,$uname,$url,$role,$now);
}

# ---------------------------------------------------------- Revoke Custom Role

sub revokecustomrole {
    my ($udom,$uname,$url,$rdom,$rnam,$rolename)=@_;
    my $now=time;
    return &assigncustomrole($udom,$uname,$url,$rdom,$rnam,$rolename,$now);
}

# ------------------------------------------------------------ Directory lister

sub dirlist {
    my $uri=shift;
    $uri=~s/^\///;
    $uri=~s/\/$//;
    my ($res,$udom,$uname,@rest)=split(/\//,$uri);
    if ($udom) {
     if ($uname) {
       my $listing=reply('ls:'.$perlvar{'lonDocRoot'}.'/'.$uri,
                      homeserver($uname,$udom));
       return split(/:/,$listing);
     } else {
       my $tryserver;
       my %allusers=();
       foreach $tryserver (keys %libserv) {
	  if ($hostdom{$tryserver} eq $udom) {
             my $listing=reply('ls:'.$perlvar{'lonDocRoot'}.'/res/'.$udom,
			       $tryserver);
             if (($listing ne 'no_such_dir') && ($listing ne 'empty')
              && ($listing ne 'con_lost')) {
                map {
                  my ($entry,@stat)=split(/&/,$_);
                  $allusers{$entry}=1;
                } split(/:/,$listing);
             }
	  }
       }
       my $alluserstr='';
       map {
           $alluserstr.=$_.'&user:';
       } sort keys %allusers;
       $alluserstr=~s/:$//;
       return split(/:/,$alluserstr);
     } 
   } else {
       my $tryserver;
       my %alldom=();
       foreach $tryserver (keys %libserv) {
	   $alldom{$hostdom{$tryserver}}=1;
       }
       my $alldomstr='';
       map {
          $alldomstr.=$perlvar{'lonDocRoot'}.'/res/'.$_.'&domain:';
       } sort keys %alldom;
       $alldomstr=~s/:$//;
       return split(/:/,$alldomstr);       
   }
}

# -------------------------------------------------------- Value of a Condition

sub directcondval {
    my $number=shift;
    if ($ENV{'user.state.'.$ENV{'request.course.id'}}) {
       return substr($ENV{'user.state.'.$ENV{'request.course.id'}},$number,1);
    } else {
       return 2;
    }
}

sub condval {
    my $condidx=shift;
    my $result=0;
    my $allpathcond='';
    map {
       if (defined($ENV{'acc.cond.'.$ENV{'request.course.id'}.'.'.$_})) {
	   $allpathcond.=
               '('.$ENV{'acc.cond.'.$ENV{'request.course.id'}.'.'.$_}.')|';
       }
    } split(/\|/,$condidx);
    $allpathcond=~s/\|$//;
    if ($ENV{'request.course.id'}) {
       if ($allpathcond) {
          my $operand='|';
	  my @stack;
          map {
              if ($_ eq '(') {
                 push @stack,($operand,$result)
              } elsif ($_ eq ')') {
                  my $before=pop @stack;
		  if (pop @stack eq '&') {
		      $result=$result>$before?$before:$result;
                  } else {
                      $result=$result>$before?$result:$before;
                  }
              } elsif (($_ eq '&') || ($_ eq '|')) {
                  $operand=$_;
              } else {
                  my $new=directcondval($_);
                  if ($operand eq '&') {
                     $result=$result>$new?$new:$result;
                  } else {
                     $result=$result>$new?$result:$new;
                  }                  
              }
          } ($allpathcond=~/(\d+|\(|\)|\&|\|)/g);
       }
    }
    return $result;
}

# --------------------------------------------------------- Value of a Variable

sub EXT {
    my ($varname,$symbparm)=@_;
    unless ($varname) { return ''; }
    my ($realm,$space,$qualifier,@therest)=split(/\./,$varname);
    my $rest;
    if ($therest[0]) {
       $rest=join('.',@therest);
    } else {
       $rest='';
    }
    my $qualifierrest=$qualifier;
    if ($rest) { $qualifierrest.='.'.$rest; }
    my $spacequalifierrest=$space;
    if ($qualifierrest) { $spacequalifierrest.='.'.$qualifierrest; }
    if ($realm eq 'user') {
# --------------------------------------------------------------- user.resource
	if ($space eq 'resource') {
	    my %restored=&restore();
            return $restored{$qualifierrest};
# ----------------------------------------------------------------- user.access
        } elsif ($space eq 'access') {
            return &allowed($qualifier,$rest);
# ------------------------------------------ user.preferences, user.environment
        } elsif (($space eq 'preferences') || ($space eq 'environment')) {
            return $ENV{join('.',('environment',$qualifierrest))};
# ----------------------------------------------------------------- user.course
        } elsif ($space eq 'course') {
            return $ENV{join('.',('request.course',$qualifier))};
# ------------------------------------------------------------------- user.role
        } elsif ($space eq 'role') {
            my ($role,$where)=split(/\./,$ENV{'request.role'});
            if ($qualifier eq 'value') {
		return $role;
            } elsif ($qualifier eq 'extent') {
                return $where;
            }
# ----------------------------------------------------------------- user.domain
        } elsif ($space eq 'domain') {
            return $ENV{'user.domain'};
# ------------------------------------------------------------------- user.name
        } elsif ($space eq 'name') {
            return $ENV{'user.name'};
# ---------------------------------------------------- Any other user namespace
        } else {
            my $item=($rest)?$qualifier.'.'.$rest:$qualifier;
            my %reply=&get($space,[$item]);
            return $reply{$item};
        }
    } elsif ($realm eq 'request') {
# ------------------------------------------------------------- request.browser
        if ($space eq 'browser') {
	    return $ENV{'browser.'.$qualifier};
# ------------------------------------------------------------ request.filename
        } else {
            return $ENV{'request.'.$spacequalifierrest};
        }
    } elsif ($realm eq 'course') {
# ---------------------------------------------------------- course.description
        return $ENV{'course.'.$ENV{'request.course.id'}.'.'.
                              $spacequalifierrest};
    } elsif ($realm eq 'resource') {
       if ($ENV{'request.course.id'}) {

#	   print '<br>'.$space.' - '.$qualifier.' - '.$spacequalifierrest;


# ----------------------------------------------------- Cascading lookup scheme
         my $symbp;
         if ($symbparm) {
            $symbp=$symbparm;
	 } else {
            $symbp=&symbread();
         }            
         my $mapp=(split(/\_\_\_/,$symbp))[0];

         my $symbparm=$symbp.'.'.$spacequalifierrest;
         my $mapparm=$mapp.'___(all).'.$spacequalifierrest;

         my $seclevel=
            $ENV{'request.course.id'}.'.['.
		$ENV{'request.course.sec'}.'].'.$spacequalifierrest;
         my $seclevelr=
            $ENV{'request.course.id'}.'.['.
		$ENV{'request.course.sec'}.'].'.$symbparm;
         my $seclevelm=
            $ENV{'request.course.id'}.'.['.
		$ENV{'request.course.sec'}.'].'.$mapparm;

         my $courselevel=
            $ENV{'request.course.id'}.'.'.$spacequalifierrest;
         my $courselevelr=
            $ENV{'request.course.id'}.'.'.$symbparm;
         my $courselevelm=
            $ENV{'request.course.id'}.'.'.$mapparm;

# ----------------------------------------------------------- first, check user
         my %resourcedata=get('resourcedata',
                           [$courselevelr,$courselevelm,$courselevel]);
         if (($resourcedata{$courselevelr}!~/^error\:/) &&
             ($resourcedata{$courselevelr}!~/^con_lost/)) {

         if ($resourcedata{$courselevelr}) { 
            return $resourcedata{$courselevelr}; }
         if ($resourcedata{$courselevelm}) { 
            return $resourcedata{$courselevelm}; }
         if ($resourcedata{$courselevel}) { return $resourcedata{$courselevel}; }

      } else {
	  if ($resourcedata{$courselevelr}!~/No such file/) {
	    &logthis("<font color=blue>WARNING:".
		   " Trying to get resource data for ".$ENV{'user.name'}." at "
                   .$ENV{'user.domain'}.": ".$resourcedata{$courselevelr}.
                 "</font>");
	  }
      }

# -------------------------------------------------------- second, check course

        my $reply=&reply('get:'.
              $ENV{'course.'.$ENV{'request.course.id'}.'.domain'}.':'.
              $ENV{'course.'.$ENV{'request.course.id'}.'.num'}.
	      ':resourcedata:'.
   &escape($seclevelr).'&'.&escape($seclevelm).'&'.&escape($seclevel).'&'.
   &escape($courselevelr).'&'.&escape($courselevelm).'&'.&escape($courselevel),
		   $ENV{'course.'.$ENV{'request.course.id'}.'.home'});
      if ($reply!~/^error\:/) {
	  map {
	      if ($_) { return &unescape($_); }
          } split(/\&/,$reply);
      }
      if (($reply=~/^con_lost/) || ($reply=~/^error\:/)) {
	  &logthis("<font color=blue>WARNING:".
                " Getting ".$reply." asking for ".$varname." for ".
                $ENV{'course.'.$ENV{'request.course.id'}.'.num'}.
                ' at '.
                $ENV{'course.'.$ENV{'request.course.id'}.'.domain'}.
                ' from '.
                $ENV{'course.'.$ENV{'request.course.id'}.'.home'}.
                 "</font>");
      }
# ------------------------------------------------------ third, check map parms
       my %parmhash=();
       my $thisparm='';       
       if (tie(%parmhash,'GDBM_File',
          $ENV{'request.course.fn'}.'_parms.db',&GDBM_READER,0640)) {
           $thisparm=$parmhash{$symbparm};
	   untie(%parmhash);
       }
       if ($thisparm) { return $thisparm; }
     }
     
# --------------------------------------------- last, look in resource metadata

      $spacequalifierrest=~s/\./\_/;
      my $metadata=&metadata($ENV{'request.filename'},$spacequalifierrest);
      if ($metadata) { return $metadata; }
      $metadata=&metadata($ENV{'request.filename'},
                                         'parameter_'.$spacequalifierrest);
      if ($metadata) { return $metadata; }

# ------------------------------------------------------------------ Cascade up

      unless ($space eq '0') {
          my ($part,$id)=split(/\_/,$space);
          if ($id) {
	      my $partgeneral=&EXT('resource.'.$part.'.'.$qualifierrest,
                                   $symbparm);
              if ($partgeneral) { return $partgeneral; }
          } else {
              my $resourcegeneral=&EXT('resource.0.'.$qualifierrest,
                                       $symbparm);
              if ($resourcegeneral) { return $resourcegeneral; }
          }
      }

# ---------------------------------------------------- Any other user namespace
    } elsif ($realm eq 'environment') {
# ----------------------------------------------------------------- environment
        return $ENV{'environment.'.$spacequalifierrest};
    } elsif ($realm eq 'system') {
# ----------------------------------------------------------------- system.time
	if ($space eq 'time') {
	    return time;
        }
    }
    return '';
}

# ---------------------------------------------------------------- Get metadata

sub metadata {
    my ($uri,$what,$liburi,$prefix,$depthcount)=@_;

    $uri=&declutter($uri);
    my $filename=$uri;
    $uri=~s/\.meta$//;
#
# Is the metadata already cached?
# Look at timestamp of caching
# Everything is cached by the main uri, libraries are never directly cached
#
    unless (abs($metacache{$uri.':cachedtimestamp'}-time)<600) {
#
# Is this a recursive call for a library?
#
        if ($liburi) {
	    $liburi=&declutter($liburi);
            $filename=$liburi;
        }
        my %metathesekeys=();
        unless ($filename=~/\.meta$/) { $filename.='.meta'; }
	my $metastring=&getfile($perlvar{'lonDocRoot'}.'/res/'.$filename);
        my $parser=HTML::TokeParser->new(\$metastring);
        my $token;
        undef %metathesekeys;
        while ($token=$parser->get_token) {
           if ($token->[0] eq 'S') {
	     if (defined($token->[2]->{'package'})) {
#
# This is a package - get package info
#
	      my $package=$token->[2]->{'package'};
	      my $keyroot='';
              if ($prefix) {
		  $keyroot.='_'.$prefix;
              } else {
                if (defined($token->[2]->{'part'})) { 
                   $keyroot.='_'.$token->[2]->{'part'}; 
	        }
	      }
              if (defined($token->[2]->{'id'})) { 
                 $keyroot.='_'.$token->[2]->{'id'}; 
	      }
              if ($metacache{$uri.':packages'}) {
                 $metacache{$uri.':packages'}.=','.$package.$keyroot;
              } else {
                 $metacache{$uri.':packages'}=$package.$keyroot;
	      }
              map {
		  if ($_=~/^$package\&/) {
		      my ($pack,$name,$subp)=split(/\&/,$_);
                      my $value=$packagetab{$_};
		      my $part=$keyroot;
                      $part=~s/^\_//;
                      if ($subp eq 'display') {
			  $value.=' [Part: '.$part.']';
                      }
                      my $unikey='parameter'.$keyroot.'_'.$name;
                      $metathesekeys{$unikey}=1;
                      $metacache{$uri.':'.$unikey.'.part'}=$part;
                      unless 
                       (defined($metacache{$uri.':'.$unikey.'.'.$subp})) {
                         $metacache{$uri.':'.$unikey.'.'.$subp}=$value;
		      }
                  }
              } keys %packagetab;
             } else {
#
# This is not a package - some other kind of start tag
# 
              my $entry=$token->[1];
              my $unikey;
              if ($entry eq 'import') {
                 $unikey='';
              } else {
                 $unikey=$entry;
	      }
              if ($prefix) {
		  $unikey.=$prefix;
              } else {
                if (defined($token->[2]->{'part'})) { 
                   $unikey.='_'.$token->[2]->{'part'}; 
	        }
	      }
              if (defined($token->[2]->{'id'})) { 
                 $unikey.='_'.$token->[2]->{'id'}; 
	      }

             if ($entry eq 'import') {
#
# Importing a library here
#                
		 if (defined($depthcount)) { $depthcount++; } else 
                                           { $depthcount=0; }
                 if ($depthcount<20) {
		     map {
                         $metathesekeys{$_}=1;
		     } split(/\,/,&metadata($uri,'keys',
                                  $parser->get_text('/import'),$unikey,
                                  $depthcount));
		 }
             } else { 

              if (defined($token->[2]->{'name'})) { 
                 $unikey.='_'.$token->[2]->{'name'}; 
	      }
              $metathesekeys{$unikey}=1;
              map {
		  $metacache{$uri.':'.$unikey.'.'.$_}=$token->[2]->{$_};
              } @{$token->[3]};
              unless (
                 $metacache{$uri.':'.$unikey}=$parser->get_text('/'.$entry)
		      ) { $metacache{$uri.':'.$unikey}=
			      $metacache{$uri.':'.$unikey.'.default'};
		      }
# end of not-a-package not-a-library import
	   }
# end of not-a-package start tag
	  }
# the next is the end of "start tag"
	 }
       }
       $metacache{$uri.':keys'}=join(',',keys %metathesekeys);
       $metacache{$uri.':cachedtimestamp'}=time;
# this is the end of "was not already recently cached
    }
    return $metacache{$uri.':'.$what};
}

# ------------------------------------------------- Update symbolic store links

sub symblist {
    my ($mapname,%newhash)=@_;
    $mapname=declutter($mapname);
    my %hash;
    if (($ENV{'request.course.fn'}) && (%newhash)) {
        if (tie(%hash,'GDBM_File',$ENV{'request.course.fn'}.'_symb.db',
                      &GDBM_WRCREAT,0640)) {
	    map {
                $hash{declutter($_)}=$mapname.'___'.$newhash{$_};
            } keys %newhash;
            if (untie(%hash)) {
		return 'ok';
            }
        }
    }
    return 'error';
}

# ------------------------------------------------------ Return symb list entry

sub symbread {
    my $thisfn=shift;
    unless ($thisfn) {
        if ($ENV{'request.symb'}) { return $ENV{'request.symb'}; }
	$thisfn=$ENV{'request.filename'};
    }
    $thisfn=declutter($thisfn);
    my %hash;
    my %bighash;
    my $syval='';
    if (($ENV{'request.course.fn'}) && ($thisfn)) {
        if (tie(%hash,'GDBM_File',$ENV{'request.course.fn'}.'_symb.db',
                      &GDBM_READER,0640)) {
	    $syval=$hash{$thisfn};
            untie(%hash);
        }
# ---------------------------------------------------------- There was an entry
        if ($syval) {
           unless ($syval=~/\_\d+$/) {
	       unless ($ENV{'form.request.prefix'}=~/\.(\d+)\_$/) {
                  &appenv('request.ambiguous' => $thisfn);
                  return '';
               }    
               $syval.=$1;
	   }
        } else {
# ------------------------------------------------------- Was not in symb table
           if (tie(%bighash,'GDBM_File',$ENV{'request.course.fn'}.'.db',
                            &GDBM_READER,0640)) {
# ---------------------------------------------- Get ID(s) for current resource
              my $ids=$bighash{'ids_/res/'.$thisfn};
              unless ($ids) { 
                 $ids=$bighash{'ids_/'.$thisfn};
              }
              if ($ids) {
# ------------------------------------------------------------------- Has ID(s)
                 my @possibilities=split(/\,/,$ids);
                 if ($#possibilities==0) {
# ----------------------------------------------- There is only one possibility
		     my ($mapid,$resid)=split(/\./,$ids);
                     $syval=declutter($bighash{'map_id_'.$mapid}).'___'.$resid;
                 } else {
# ------------------------------------------ There is more than one possibility
                     my $realpossible=0;
                     map {
			 my $file=$bighash{'src_'.$_};
                         if (&allowed('bre',$file)) {
         		    my ($mapid,$resid)=split(/\./,$_);
                            if ($bighash{'map_type_'.$mapid} ne 'page') {
				$realpossible++;
                                $syval=declutter($bighash{'map_id_'.$mapid}).
                                       '___'.$resid;
                            }
			 }
                     } @possibilities;
		     if ($realpossible!=1) { $syval=''; }
                 }
	      }
              untie(%bighash)
           } 
        }
        if ($syval) {
           return $syval.'___'.$thisfn; 
        }
    }
    &appenv('request.ambiguous' => $thisfn);
    return '';
}

# ---------------------------------------------------------- Return random seed

sub numval {
    my $txt=shift;
    $txt=~tr/A-J/0-9/;
    $txt=~tr/a-j/0-9/;
    $txt=~tr/K-T/0-9/;
    $txt=~tr/k-t/0-9/;
    $txt=~tr/U-Z/0-5/;
    $txt=~tr/u-z/0-5/;
    $txt=~s/\D//g;
    return int($txt);
}    

sub rndseed {
    my ($symb,$courseid,$domain,$username)=@_;
    if (!$symb) {
      unless ($symb=&symbread()) { return time; }
    }
    if (!$courseid) { $courseid=$ENV{'request.course.id'};}
    if (!$domain) {$domain=$ENV{'user.domain'};}
    if (!$username) {$username=$ENV{'user.name'};}
    {
      use integer;
      my $symbchck=unpack("%32C*",$symb) << 27;
      my $symbseed=numval($symb) << 22;
      my $namechck=unpack("%32C*",$username) << 17;
      my $nameseed=numval($username) << 12;
      my $domainseed=unpack("%32C*",$domain) << 7;
      my $courseseed=unpack("%32C*",$courseid);
      my $num=$symbseed+$nameseed+$domainseed+$courseseed+$namechck+$symbchck;
      #uncommenting these lines can break things!
      #&Apache::lonxml::debug("$symbseed:$nameseed;$domainseed|$courseseed;$namechck:$symbchck");
      #&Apache::lonxml::debug("rndseed :$num:$symb");
      return $num;
    }
}

sub ireceipt {
    my ($funame,$fudom,$fucourseid,$fusymb)=@_;
    my $cuname=unpack("%32C*",$funame);
    my $cudom=unpack("%32C*",$fudom);
    my $cucourseid=unpack("%32C*",$fucourseid);
    my $cusymb=unpack("%32C*",$fusymb);
    my $cunique=unpack("%32C*",$perlvar{'lonReceipt'});
    return unpack("%32C*",$perlvar{'lonHostID'}).'-'.
           ($cunique%$cuname+
            $cunique%$cudom+
            $cusymb%$cuname+
            $cusymb%$cudom+
            $cucourseid%$cuname+
            $cucourseid%$cudom);
}

sub receipt {
    return &ireceipt($ENV{'user.name'},$ENV{'user.domain'},
                     $ENV{'request.course.id'},&symbread());
}
  
# ------------------------------------------------------------ Serves up a file
# returns either the contents of the file or a -1
sub getfile {
  my $file=shift;
  &repcopy($file);
  if (! -e $file ) { return -1; };
  my $fh=Apache::File->new($file);
  my $a='';
  while (<$fh>) { $a .=$_; }
  return $a
}

sub filelocation {
  my ($dir,$file) = @_;
  my $location;
  $file=~ s/^\s*(\S+)\s*$/$1/; ## strip off leading and trailing spaces
  if ($file=~m:^/~:) { # is a contruction space reference
    $location = $file;
    $location =~ s:/~(.*?)/(.*):/home/$1/public_html/$2:;
  } else {
    $file=~s/^$perlvar{'lonDocRoot'}//;
    $file=~s:^/*res::;
    if ( !( $file =~ m:^/:) ) {
      $location = $dir. '/'.$file;
    } else {
      $location = '/home/httpd/html/res'.$file;
    }
  }
  $location=~s://+:/:g; # remove duplicate /
  while ($location=~m:/\.\./:) {$location=~ s:/[^/]+/\.\./:/:g;} #remove dir/..
  return $location;
}

sub hreflocation {
    my ($dir,$file)=@_;
    unless (($_=~/^http:\/\//i) || ($_=~/^\//)) {
       my $finalpath=filelocation($dir,$file);
       $finalpath=~s/^\/home\/httpd\/html//;
       return $finalpath;
    } else {
       return $file;
    }
}

# ------------------------------------------------------------- Declutters URLs

sub declutter {
    my $thisfn=shift;
    $thisfn=~s/^$perlvar{'lonDocRoot'}//;
    $thisfn=~s/^\///;
    $thisfn=~s/^res\///;
    return $thisfn;
}

# -------------------------------------------------------- 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;
}

# ================================================================ Main Program

BEGIN {
# ------------------------------------------------------------ Read access.conf
{
    my $config=Apache::File->new("/etc/httpd/conf/access.conf");

    while (my $configline=<$config>) {
        if ($configline =~ /PerlSetVar/) {
	   my ($dummy,$varname,$varvalue)=split(/\s+/,$configline);
           chomp($varvalue);
           $perlvar{$varname}=$varvalue;
        }
    }
}

# ------------------------------------------------------------- Read hosts file
{
    my $config=Apache::File->new("$perlvar{'lonTabDir'}/hosts.tab");

    while (my $configline=<$config>) {
       chomp($configline);
       my ($id,$domain,$role,$name,$ip)=split(/:/,$configline);
       $hostname{$id}=$name;
       $hostdom{$id}=$domain;
       $hostip{$id}=$ip;
       if ($role eq 'library') { $libserv{$id}=$name; }
    }
}

# ------------------------------------------------------ Read spare server file
{
    my $config=Apache::File->new("$perlvar{'lonTabDir'}/spare.tab");

    while (my $configline=<$config>) {
       chomp($configline);
       if (($configline) && ($configline ne $perlvar{'lonHostID'})) {
          $spareid{$configline}=1;
       }
    }
}
# ------------------------------------------------------------ Read permissions
{
    my $config=Apache::File->new("$perlvar{'lonTabDir'}/roles.tab");

    while (my $configline=<$config>) {
       chomp($configline);
      if ($configline) {
       my ($role,$perm)=split(/ /,$configline);
       if ($perm ne '') { $pr{$role}=$perm; }
      }
    }
}

# -------------------------------------------- Read plain texts for permissions
{
    my $config=Apache::File->new("$perlvar{'lonTabDir'}/rolesplain.tab");

    while (my $configline=<$config>) {
       chomp($configline);
      if ($configline) {
       my ($short,$plain)=split(/:/,$configline);
       if ($plain ne '') { $prp{$short}=$plain; }
      }
    }
}

# ---------------------------------------------------------- Read package table
{
    my $config=Apache::File->new("$perlvar{'lonTabDir'}/packages.tab");

    while (my $configline=<$config>) {
       chomp($configline);
       my ($short,$plain)=split(/:/,$configline);
       my ($pack,$name)=split(/\&/,$short);
       if ($plain ne '') {
          $packagetab{$pack.'&'.$name.'&name'}=$name; 
          $packagetab{$short}=$plain; 
       }
    }
}

# ------------------------------------------------------------- Read file types
{
    my $config=Apache::File->new("$perlvar{'lonTabDir'}/filetypes.tab");

    while (my $configline=<$config>) {
       next if (/^\#/);
       chomp($configline);
       my ($ending,$emb,@descr)=split(/\s+/,$configline);
       if ($descr[0] ne '') { 
         $fe{$ending}=lc($emb);
         $fd{$ending}=join(' ',@descr);
       }
    }
}

%metacache=();

$readit='done';
&logtouch();
&logthis('<font color=yellow>INFO: Read configuration</font>');
}

1;

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