--- loncom/lond	2011/04/05 15:49:27	1.467.2.2
+++ loncom/lond	2012/04/11 21:32:28	1.490
@@ -2,7 +2,7 @@
 # The LearningOnline Network
 # lond "LON Daemon" Server (port "LOND" 5663)
 #
-# $Id: lond,v 1.467.2.2 2011/04/05 15:49:27 raeburn Exp $
+# $Id: lond,v 1.490 2012/04/11 21:32:28 droeschl Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -15,6 +15,7 @@
 #
 # 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.
 #
@@ -33,6 +34,7 @@ use strict;
 use lib '/home/httpd/lib/perl/';
 use LONCAPA;
 use LONCAPA::Configuration;
+use LONCAPA::Lond;
 
 use IO::Socket;
 use IO::File;
@@ -52,13 +54,14 @@ use LONCAPA::lonlocal;
 use LONCAPA::lonssl;
 use Fcntl qw(:flock);
 use Apache::lonnet;
+use Mail::Send;
 
 my $DEBUG = 0;		       # Non zero to enable debug log entries.
 
 my $status='';
 my $lastlog='';
 
-my $VERSION='$Revision: 1.467.2.2 $'; #' stupid emacs
+my $VERSION='$Revision: 1.490 $'; #' stupid emacs
 my $remoteVERSION;
 my $currenthostid="default";
 my $currentdomainid;
@@ -90,6 +93,8 @@ my %managers;			# Ip -> manager names
 
 my %perlvar;			# Will have the apache conf defined perl vars.
 
+my $dist;
+
 #
 #   The hash below is used for command dispatching, and is therefore keyed on the request keyword.
 #    Each element of the hash contains a reference to an array that contains:
@@ -419,8 +424,11 @@ sub ReadManagerTable {
 
    my $tablename = $perlvar{'lonTabDir'}."/managers.tab";
    if (!open (MANAGERS, $tablename)) {
-      logthis('<font color="red">No manager table.  Nobody can manage!!</font>');
-      return;
+       my $hostname = &Apache::lonnet::hostname($perlvar{'lonHostID'});
+       if (&Apache::lonnet::is_LC_dns($hostname)) {
+           &logthis('<font color="red">No manager table.  Nobody can manage!!</font>');
+       }
+       return;
    }
    while(my $host = <MANAGERS>) {
       chomp($host);
@@ -445,7 +453,7 @@ sub ReadManagerTable {
          }
       } else {
          logthis('<font color="green"> existing host'." $host</font>\n");
-         $managers{&Apache::lonnet::get_host_ip($host)} = $host;  # Use info from cluster tab if clumemeber
+         $managers{&Apache::lonnet::get_host_ip($host)} = $host;  # Use info from cluster tab if cluster memeber
       }
    }
 }
@@ -507,7 +515,8 @@ sub AdjustHostContents {
     my $me        = $perlvar{'lonHostID'};
 
     foreach my $line (split(/\n/,$contents)) {
-	if(!(($line eq "") || ($line =~ /^ *\#/) || ($line =~ /^ *$/))) {
+	if(!(($line eq "") || ($line =~ /^ *\#/) || ($line =~ /^ *$/) ||
+             ($line =~ /^\s*\^/))) {
 	    chomp($line);
 	    my ($id,$domain,$role,$name,$ip,$maxcon,$idleto,$mincon)=split(/:/,$line);
 	    if ($id eq $me) {
@@ -595,11 +604,8 @@ sub InstallFile {
 #
 #   ConfigFileFromSelector: converts a configuration file selector
 #                 into a configuration file pathname.
-#                 It's probably no longer necessary to preserve
-#                 special handling of hosts or domain as those
-#                 files have been superceded by dns_hosts, dns_domain.
-#                 The default action is just to prepend the directory
-#                 and append .tab
+#                 Supports the following file selectors: 
+#                 hosts, domain, dns_hosts, dns_domain  
 #
 #
 #  Parameters:
@@ -612,15 +618,11 @@ sub ConfigFileFromSelector {
     my $tablefile;
 
     my $tabledir = $perlvar{'lonTabDir'}.'/';
-    if ($selector eq "hosts") {
-	$tablefile = $tabledir."hosts.tab";
-    } elsif ($selector eq "domain") {
-	$tablefile = $tabledir."domain.tab";
-    } else {
+    if (($selector eq "hosts") || ($selector eq "domain") || 
+        ($selector eq "dns_hosts") || ($selector eq "dns_domain")) {
 	$tablefile =  $tabledir.$selector.'.tab';
     }
     return $tablefile;
-
 }
 #
 #   PushFile:  Called to do an administrative push of a file.
@@ -646,6 +648,8 @@ sub PushFile {
     #  supported:
     #   hosts.tab  ($filename eq host).
     #   domain.tab ($filename eq domain).
+    #   dns_hosts.tab ($filename eq dns_host).
+    #   dns_domain.tab ($filename eq dns_domain). 
     # Construct the destination filename or reject the request.
     #
     # lonManage is supposed to ensure this, however this session could be
@@ -677,11 +681,31 @@ sub PushFile {
 	return "error:$!";
     } else {
 	&logthis('<font color="green"> Installed new '.$tablefile
-		 ."</font>");
-
+		 ." - transaction by: $clientname ($clientip)</font>");
+        my $adminmail = $perlvar{'lonAdmEMail'};
+        my $admindom = &Apache::lonnet::host_domain($perlvar{'lonHostID'});
+        if ($admindom ne '') {
+            my %domconfig =
+                &Apache::lonnet::get_dom('configuration',['contacts'],$admindom);
+            if (ref($domconfig{'contacts'}) eq 'HASH') {
+                if ($domconfig{'contacts'}{'adminemail'} ne '') {
+                    $adminmail = $domconfig{'contacts'}{'adminemail'};
+                }
+            }
+        }
+        if ($adminmail =~ /^[^\@]+\@[^\@]+$/) {
+            my $msg = new Mail::Send;
+            $msg->to($adminmail);
+            $msg->subject('LON-CAPA DNS update on '.$perlvar{'lonHostID'});
+            $msg->add('Content-type','text/plain; charset=UTF-8');
+            if (my $fh = $msg->open()) {
+                print $fh 'Update to '.$tablefile.' from Cluster Manager '.
+                          "$clientname ($clientip)\n";
+                $fh->close;
+            }
+        }
     }
 
-
     #  Indicate success:
  
     return "ok";
@@ -1620,6 +1644,74 @@ sub ls3_handler {
 }
 &register_handler("ls3", \&ls3_handler, 0, 1, 0);
 
+sub read_lonnet_global {
+    my ($cmd,$tail,$client) = @_;
+    my $userinput = "$cmd:$tail";
+    my $requested = &Apache::lonnet::thaw_unescape($tail);
+    my $result;
+    my %packagevars = (
+                        spareid => \%Apache::lonnet::spareid,
+                        perlvar => \%Apache::lonnet::perlvar,
+                      );
+    my %limit_to = (
+                    perlvar => {
+                                 lonOtherAuthen => 1,
+                                 lonBalancer    => 1,
+                                 lonVersion     => 1,
+                                 lonSysEMail    => 1,
+                                 lonHostID      => 1,
+                                 lonRole        => 1,
+                                 lonDefDomain   => 1,
+                                 lonLoadLim     => 1,
+                                 lonUserLoadLim => 1,
+                               }
+                  );
+    if (ref($requested) eq 'HASH') {
+        foreach my $what (keys(%{$requested})) {
+            my $response;
+            my $items = {};
+            if (exists($packagevars{$what})) {
+                if (ref($limit_to{$what}) eq 'HASH') {
+                    foreach my $varname (keys(%{$packagevars{$what}})) {
+                        if ($limit_to{$what}{$varname}) {
+                            $items->{$varname} = $packagevars{$what}{$varname};
+                        }
+                    }
+                } else {
+                    $items = $packagevars{$what};
+                }
+                if ($what eq 'perlvar') {
+                    if (!exists($packagevars{$what}{'lonBalancer'})) {
+                        if ($dist =~ /^(centos|rhes|fedora|scientific)/) {
+                            my $othervarref=LONCAPA::Configuration::read_conf('httpd.conf');
+                            if (ref($othervarref) eq 'HASH') {
+                                $items->{'lonBalancer'} = $othervarref->{'lonBalancer'};
+                            }
+                        }
+                    }
+                }
+                $response = &Apache::lonnet::freeze_escape($items);
+            }
+            $result .= &escape($what).'='.$response.'&';
+        }
+    }
+    $result =~ s/\&$//;
+    &Reply($client,\$result,$userinput);
+    return 1;
+}
+&register_handler("readlonnetglobal", \&read_lonnet_global, 0, 1, 0);
+
+sub server_devalidatecache_handler {
+    my ($cmd,$tail,$client) = @_;
+    my $userinput = "$cmd:$tail";
+    my ($name,$id) = map { &unescape($_); } split(/:/,$tail);
+    &Apache::lonnet::devalidate_cache_new($name,$id);
+    my $result = 'ok';
+    &Reply($client,\$result,$userinput);
+    return 1;
+}
+&register_handler("devalidatecache", \&server_devalidatecache_handler, 0, 1, 0);
+
 sub server_timezone_handler {
     my ($cmd,$tail,$client) = @_;
     my $userinput = "$cmd:$tail";
@@ -1668,6 +1760,15 @@ sub server_homeID_handler {
 }
 &register_handler("serverhomeID", \&server_homeID_handler, 0, 1, 0);
 
+sub server_distarch_handler {
+    my ($cmd,$tail,$client) = @_;
+    my $userinput = "$cmd:$tail";
+    my $reply = &distro_and_arch();
+    &Reply($client,\$reply,$userinput);
+    return 1;
+}
+&register_handler("serverdistarch", \&server_distarch_handler, 0, 1, 0);
+
 #   Process a reinit request.  Reinit requests that either
 #   lonc or lond be reinitialized so that an updated 
 #   host.tab or domain.tab can be processed.
@@ -1973,7 +2074,7 @@ sub add_user_handler {
 		    ."makeuser";
 	    }
 	    unless ($fperror) {
-		my $result=&make_passwd_file($uname, $umode,$npass, $passfilename);
+		my $result=&make_passwd_file($uname,$udom,$umode,$npass, $passfilename);
 		&Reply($client,\$result, $userinput);     #BUGBUG - could be fail
 	    } else {
 		&Failure($client, \$fperror, $userinput);
@@ -2048,7 +2149,7 @@ sub change_authentication_handler {
 		    &Failure($client, \$result);
 		}
 	    } else {
-		my $result=&make_passwd_file($uname, $umode,$npass,$passfilename);
+		my $result=&make_passwd_file($uname,$udom,$umode,$npass,$passfilename);
 		#
 		#  If the current auth mode is internal, and the old auth mode was
 		#  unix, or krb*,  and the user is an author for this domain,
@@ -2248,7 +2349,10 @@ sub fetch_user_file_handler {
 
 	my $destname=$udir.'/'.$ufile;
 	my $transname=$udir.'/'.$ufile.'.in.transit';
-	my $remoteurl='http://'.$clientip.'/userfiles/'.$fname;
+        my $clientprotocol=$Apache::lonnet::protocol{$clientname};
+        $clientprotocol = 'http' if ($clientprotocol ne 'https');
+	my $clienthost = &Apache::lonnet::hostname($clientname);
+	my $remoteurl=$clientprotocol.'://'.$clienthost.'/userfiles/'.$fname;
 	my $response;
 	Debug("Remote URL : $remoteurl Transfername $transname Destname: $destname");
 	alarm(120);
@@ -3142,6 +3246,12 @@ sub dump_profile_database {
 #                                             that is matched against
 #                                             database keywords to do
 #                                             selective dumps.
+#                               range       - optional range of entries
+#                                             e.g., 10-20 would return the
+#                                             10th to 19th items, etc.  
+#                               extra       - optional ref to hash of
+#                                             additional args. currently
+#                                             skipcheck is only key used.   
 #   $client                   - Channel open on the client.
 # Returns:
 #    1    - Continue processing.
@@ -3151,6 +3261,15 @@ sub dump_profile_database {
 sub dump_with_regexp {
     my ($cmd, $tail, $client) = @_;
 
+    #TODO encapsulate $clientname and $clientversion in a object.
+    my $res = LONCAPA::Lond::dump_with_regexp($cmd, $tail, $clientname, $clientversion);
+    
+    if ($res =~ /^error:/) {
+        Failure($client, \$res, "$cmd:$tail");
+    } else {
+        Reply($client, \$res, "$cmd:$tail");
+    }
+    return 1;
 
     my $userinput = "$cmd:$tail";
 
@@ -3176,12 +3295,26 @@ sub dump_with_regexp {
     if ($hashref) {
         my $qresult='';
 	my $count=0;
+#
+# When dump is for roles.db, determine if LON-CAPA version checking is needed.
+# Sessions on 2.10 and later will include skipcheck => 1 in extra args ref,
+# to indicate no version checking is needed (in this case, checking occurs
+# on the server hosting the user session, when constructing the roles/courses 
+# screen).
+# 
         if ($extra ne '') {
             $extra = &Apache::lonnet::thaw_unescape($extra);
             $skipcheck = $extra->{'skipcheck'};
         }
         my @ids = &Apache::lonnet::current_machine_ids();
         my (%homecourses,$major,$minor,$now);
+# 
+# If dump is for roles.db from a pre-2.10 server, determine the LON-CAPA   
+# version on the server which requested the data. For LON-CAPA 2.9, the  
+# client session will have sent its LON-CAPA version when initiating the
+# connection. For LON-CAPA 2.8 and older, the version is retrieved from
+# the global %loncaparevs in lonnet.pm.
+# 
         if (($namespace eq 'roles') && (!$skipcheck)) {
             my $loncaparev = $clientversion;
             if ($loncaparev eq '') {
@@ -3199,8 +3332,18 @@ sub dump_with_regexp {
                     my $cdom = $1;
                     my $cnum = $2;
                     unless ($skipcheck) {
-                        my ($role,$end,$start) = split(/\_/,$value);
-                        if (!$end || $end > $now) {
+                        my ($role,$roleend,$rolestart) = split(/\_/,$value);
+                        if (!$roleend || $roleend > $now) {
+#
+# For active course roles, check that requesting server is running a LON-CAPA
+# version which meets any version requirements for the course. Do not include
+# the role amongst the results returned if the requesting server's version is
+# too old.
+#
+# This determination is handled differently depending on whether the course's 
+# homeserver is the current server, or whether it is a different server.
+# In both cases, the course's version requirement needs to be retrieved.
+# 
                             next unless (&releasereqd_check($cnum,$cdom,$key,$value,$major,
                                                             $minor,\%homecourses,\@ids));
                         }
@@ -3223,9 +3366,16 @@ sub dump_with_regexp {
 	    }
 	}
 	if (&untie_user_hash($hashref)) {
+#
+# If dump is for roles.db from a pre-2.10 server, check if the LON-CAPA
+# version requirements for courses for which the current server is the home
+# server permit course roles to be usable on the client server hosting the
+# user's session. If so, include those role results in the data returned to  
+# the client server.
+#
             if (($namespace eq 'roles') && (!$skipcheck)) {
                 if (keys(%homecourses) > 0) {
-                    $qresult .= &check_homecourses(\%homecourses,$udom,$regexp,$count,
+                    $qresult .= &check_homecourses(\%homecourses,$regexp,$count,
                                                    $range,$start,$end,$major,$minor);
                 }
             }
@@ -3895,7 +4045,7 @@ sub dump_course_id_handler {
         $creationcontext = '.';
     }
     my $unpack = 1;
-    if ($description eq '.' && $instcodefilter eq '.' && $coursefilter eq '.' && 
+    if ($description eq '.' && $instcodefilter eq '.' && $ownerfilter eq '.' && 
         $typefilter eq '.') {
         $unpack = 0;
     }
@@ -5008,7 +5158,7 @@ sub validate_course_owner_handler {
     my ($cmd, $tail, $client)  = @_;
     my $userinput = "$cmd:$tail";
     my ($inst_course_id, $owner, $cdom, $coowners) = split(/:/, $tail);
-
+    
     $owner = &unescape($owner);
     $coowners = &unescape($coowners);
     my $outcome = &localenroll::new_course($inst_course_id,$owner,$cdom,$coowners);
@@ -5999,7 +6149,7 @@ if (-e $pidfile) {
 $server = IO::Socket::INET->new(LocalPort => $perlvar{'londPort'},
                                 Type      => SOCK_STREAM,
                                 Proto     => 'tcp',
-                                ReuseAddr => 1,
+                                ReuseAddr     => 1,
                                 Listen    => 10 )
   or die "making socket: $@\n";
 
@@ -6062,9 +6212,13 @@ sub HUPSMAN {                      # sig
 #  a setuid perl script that can be root for us to do this job.
 #
 sub ReloadApache {
-    my $execdir = $perlvar{'lonDaemons'};
-    my $script  = $execdir."/apachereload";
-    system($script);
+# --------------------------- Handle case of another apachereload process (locking)
+    if (&LONCAPA::try_to_lock('/tmp/lock_apachereload')) {
+        my $execdir = $perlvar{'lonDaemons'};
+        my $script  = $execdir."/apachereload";
+        system($script);
+        unlink('/tmp/lock_apachereload'); #  Remove the lock file.
+    }
 }
 
 #
@@ -6175,6 +6329,9 @@ sub Debug {
 #     reply   - Text to send to client.
 #     request - Original request from client.
 #
+#NOTE $reply must be terminated by exactly *one* \n. If $reply is a reference
+#this is done automatically ($$reply must not contain any \n in this case). 
+#If $reply is a string the caller has to ensure this.
 sub Reply {
     my ($fd, $reply, $request) = @_;
     if (ref($reply)) {
@@ -6328,7 +6485,14 @@ $SIG{USR2} = \&UpdateHosts;
 &Apache::lonnet::load_hosts_tab();
 my %iphost = &Apache::lonnet::get_iphost(1);
 
-my $dist=`$perlvar{'lonDaemons'}/distprobe`;
+$dist=`$perlvar{'lonDaemons'}/distprobe`;
+
+my $arch = `uname -i`;
+chomp($arch);
+if ($arch eq 'unknown') {
+    $arch = `uname -m`;
+    chomp($arch);
+}
 
 # --------------------------------------------------------------
 #   Accept connections.  When a connection comes in, it is validated
@@ -6396,13 +6560,12 @@ sub make_new_child {
                                 #don't get intercepted
         $SIG{USR1}= \&logstatus;
         $SIG{ALRM}= \&timeout;
-
-        #
-        # Block sigpipe as it gets thrownon socket disconnect and we want to
-        # deal with that as a read faiure instead.
-        #
-        my $blockset = POSIX::SigSet->new(SIGPIPE);
-        sigprocmask(SIG_BLOCK, $blockset);
+	#
+	# Block sigpipe as it gets thrownon socket disconnect and we want to 
+	# deal with that as a read faiure instead.
+	#
+	my $blockset = POSIX::SigSet->new(SIGPIPE);
+	sigprocmask(SIG_BLOCK, $blockset);
 
         $lastlog='Forked ';
         $status='Forked';
@@ -6604,22 +6767,29 @@ sub is_author {
 
     #  Author role should show up as a key /domain/_au
 
-    my $key    = "/$domain/_au";
     my $value;
-    if (defined($hashref)) {
-	$value = $hashref->{$key};
-    }
+    if ($hashref) {
 
-    if(defined($value)) {
-	&Debug("$user @ $domain is an author");
+	my $key    = "/$domain/_au";
+	if (defined($hashref)) {
+	    $value = $hashref->{$key};
+	    if(!untie_user_hash($hashref)) {
+		return 'error: ' .  ($!+0)." untie (GDBM) Failed";
+	    }
+	}
+	
+	if(defined($value)) {
+	    &Debug("$user @ $domain is an author");
+	}
+    } else {
+	return 'error: '.($!+0)." tie (GDBM) Failed";
     }
 
     return defined($value);
 }
 #
 #   Checks to see if the input roleput request was to set
-# an author role.  If so, invokes the lchtmldir script to set
-# up a correct public_html 
+# an author role.  If so, creates construction space 
 # Parameters:
 #    request   - The request sent to the rolesput subchunk.
 #                We're looking for  /domain/_au
@@ -6629,16 +6799,15 @@ sub is_author {
 #
 sub manage_permissions {
     my ($request, $domain, $user, $authtype) = @_;
-
-    &Debug("manage_permissions: $request $domain $user $authtype");
-
     # See if the request is of the form /$domain/_au
     if($request =~ /^(\/\Q$domain\E\/_au)$/) { # It's an author rolesput...
-	my $execdir = $perlvar{'lonDaemons'};
-	my $userhome= "/home/$user" ;
-	&logthis("system $execdir/lchtmldir $userhome $user $authtype");
-	&Debug("Setting homedir permissions for $userhome");
-	system("$execdir/lchtmldir $userhome $user $authtype");
+        my $path=$perlvar{'lonDocRoot'}."/priv/$domain";
+        unless (-e $path) {        
+           mkdir($path);
+        }
+        unless (-e $path.'/'.$user) {
+           mkdir($path.'/'.$user);
+        }
     }
 }
 
@@ -7127,7 +7296,9 @@ sub subscribe {
                 # the metadata
 		unless ($fname=~/\.meta$/) { &unsub("$fname.meta",$clientip); }
 		$fname=~s/\/home\/httpd\/html\/res/raw/;
-		$fname="http://".&Apache::lonnet::hostname($perlvar{'lonHostID'})."/".$fname;
+                my $protocol = $Apache::lonnet::protocol{$perlvar{'lonHostID'}};
+                $protocol = 'http' if ($protocol ne 'https');
+		$fname=$protocol.'://'.&Apache::lonnet::hostname($perlvar{'lonHostID'})."/".$fname;
 		$result="$fname\n";
 	    }
 	} else {
@@ -7169,7 +7340,7 @@ sub change_unix_password {
 
 
 sub make_passwd_file {
-    my ($uname, $umode,$npass,$passfilename)=@_;
+    my ($uname,$udom,$umode,$npass,$passfilename)=@_;
     my $result="ok";
     if ($umode eq 'krb4' or $umode eq 'krb5') {
 	{
@@ -7210,7 +7381,7 @@ sub make_passwd_file {
 	    #
 	    my $uid = getpwnam($uname);
 	    if((defined $uid) && ($uid == 0)) {
-		&logthis(">>>Attempted to create privilged account blocked");
+		&logthis(">>>Attempt to create privileged account blocked");
 		return "no_priv_account_error\n";
 	    }
 
@@ -7222,6 +7393,7 @@ sub make_passwd_file {
 		&Debug("user  = ".$uname.", Password =". $npass);
 		my $se = IO::File->new("|$execpath > $perlvar{'lonDaemons'}/logs/lcuseradd.log");
 		print $se "$uname\n";
+                print $se "$udom\n";
 		print $se "$npass\n";
 		print $se "$npass\n";
 		print $se "$lc_error_file\n"; # Status -> unique file.
@@ -7315,6 +7487,20 @@ sub get_usersession_config {
     return;
 }
 
+#
+# releasereqd_check() will determine if a LON-CAPA version (defined in the
+# $major,$minor args passed) is not too old to allow use of a role in a 
+# course ($cnum,$cdom args passed), if at least one of the following applies: 
+# (a) the course is a Community, (b) the course's home server is *not* the
+# current server, or (c) cached course information is not stale. 
+#
+# For the case where none of these apply, the course is added to the 
+# $homecourse hash ref (keys = courseIDs, values = array of a hash of roles).
+# The $homecourse hash ref is for courses for which the current server is the 
+# home server.  LON-CAPA version requirements are checked elsewhere for the
+# items in $homecourse.
+#
+
 sub releasereqd_check {
     my ($cnum,$cdom,$key,$value,$major,$minor,$homecourses,$ids) = @_;
     my $home = &Apache::lonnet::homeserver($cnum,$cdom);
@@ -7344,10 +7530,18 @@ sub releasereqd_check {
         if (ref($ids) eq 'ARRAY') {
             if (grep(/^\Q$home\E$/,@{$ids})) {
                 if (ref($homecourses) eq 'HASH') {
-                    if (ref($homecourses->{$hashid}) eq 'ARRAY') {
-                        push(@{$homecourses->{$hashid}},{$key=>$value});
+                    if (ref($homecourses->{$cdom}) eq 'HASH') {
+                        if (ref($homecourses->{$cdom}{$cnum}) eq 'HASH') {
+                            if (ref($homecourses->{$cdom}{$cnum}) eq 'ARRAY') {
+                                push(@{$homecourses->{$cdom}{$cnum}},{$key=>$value});
+                            } else {
+                                $homecourses->{$cdom}{$cnum} = [{$key=>$value}];
+                            }
+                        } else {
+                            $homecourses->{$cdom}{$cnum} = [{$key=>$value}];
+                        }
                     } else {
-                        $homecourses->{$hashid} = [{$key=>$value}];
+                        $homecourses->{$cdom}{$cnum} = [{$key=>$value}];
                     }
                 }
                 return;
@@ -7366,6 +7560,17 @@ sub releasereqd_check {
     return 1;
 }
 
+# 
+# get_courseinfo_hash() is used to retrieve course information from the db
+# file: nohist_courseids.db for a course for which the current server is *not*
+# the home server.
+#
+# A hash of a hash will be retrieved. The outer hash contains a single key --
+# courseID -- for the course for which the data are being requested.
+# The contents of the inner hash, for that single item in the outer hash
+# are returned (and cached in memcache for 10 minutes).
+# 
+
 sub get_courseinfo_hash {
     my ($cnum,$cdom,$home) = @_;
     my %info;
@@ -7391,43 +7596,64 @@ sub get_courseinfo_hash {
     return;
 }
 
+#
+# check_homecourses() will retrieve course information for those courses which
+# are keys of the $homecourses hash ref (first arg). The nohist_courseids.db 
+# GDBM file is tied and course information for each course retrieved. Last   
+# visit (lasttime key) is also retrieved for each, and cached values updated  
+# for any courses last visited less than 24 hours ago. Cached values are also
+# updated for any courses included in the $homecourses hash ref.
+#
+# The reason for the 24 hours constraint is that the cron entry in 
+# /etc/cron.d/loncapa for /home/httpd/perl/refresh_courseids_db.pl causes 
+# cached course information to be updated nightly for courses with activity
+# within the past 24 hours.
+#
+# Role information for the user (included in a ref to an array of hashes as the
+# value for each key in $homecourses) is appended to the result returned by the
+# routine, which will in turn be appended to the string returned to the client
+# hosting the user's session.
+# 
+
 sub check_homecourses {
-    my ($homecourses,$udom,$regexp,$count,$range,$start,$end,$major,$minor) = @_;
+    my ($homecourses,$regexp,$count,$range,$start,$end,$major,$minor) = @_;
     my ($result,%addtocache);
     my $yesterday = time - 24*3600; 
     if (ref($homecourses) eq 'HASH') {
         my (%okcourses,%courseinfo,%recent);
-        my $hashref = &tie_domain_hash($udom, "nohist_courseids", &GDBM_WRCREAT());
-        if ($hashref) {
-            while (my ($key,$value) = each(%$hashref)) {
-                my $unesc_key = &unescape($key);
-                if ($unesc_key =~ /^lasttime:(\w+)$/) {
-                    my $cid = $1;
-                    $cid =~ s/_/:/;
-                    if ($value > $yesterday ) {
-                        $recent{$cid} = 1;
+        foreach my $domain (keys(%{$homecourses})) {
+            my $hashref = 
+                &tie_domain_hash($domain, "nohist_courseids", &GDBM_WRCREAT());
+            if (ref($hashref) eq 'HASH') {
+                while (my ($key,$value) = each(%$hashref)) {
+                    my $unesc_key = &unescape($key);
+                    if ($unesc_key =~ /^lasttime:(\w+)$/) {
+                        my $cid = $1;
+                        $cid =~ s/_/:/;
+                        if ($value > $yesterday ) {
+                            $recent{$cid} = 1;
+                        }
+                        next;
                     }
-                    next;
-                }
-                my $items = &Apache::lonnet::thaw_unescape($value);
-                if (ref($items) eq 'HASH') {
-                    my $hashid = $unesc_key;
-                    $hashid =~ s/_/:/;
-                    $courseinfo{$hashid} = $items;
-                    if (ref($homecourses->{$hashid}) eq 'ARRAY') {
-                        my ($reqdmajor,$reqdminor) = split(/\./,$items->{'releaserequired'});
-                        if (&useable_role($reqdmajor,$reqdminor,$major,$minor)) {
-                            $okcourses{$hashid} = 1;
+                    my $items = &Apache::lonnet::thaw_unescape($value);
+                    if (ref($items) eq 'HASH') {
+                        my ($cdom,$cnum) = split(/_/,$unesc_key);
+                        my $hashid = $cdom.':'.$cnum; 
+                        $courseinfo{$hashid} = $items;
+                        if (ref($homecourses->{$cdom}{$cnum}) eq 'ARRAY') {
+                            my ($reqdmajor,$reqdminor) = split(/\./,$items->{'releaserequired'});
+                            if (&useable_role($reqdmajor,$reqdminor,$major,$minor)) {
+                               $okcourses{$hashid} = 1;
+                            }
                         }
                     }
                 }
+                unless (&untie_domain_hash($hashref)) {
+                    &logthis("Failed to untie tied hash for nohist_courseids.db for $domain");
+                }
+            } else {
+                &logthis("Failed to tie hash for nohist_courseids.db for $domain");
             }
-            unless (&untie_domain_hash($hashref)) {
-                &logthis('Failed to untie tied hash for nohist_courseids.db');
-            }
-        } else {
-            &logthis('Failed to tie hash for nohist_courseids.db');
-            return;
         }
         foreach my $hashid (keys(%recent)) {
             my ($result,$cached)=&Apache::lonnet::is_cached_new('courseinfo',$hashid);
@@ -7435,13 +7661,20 @@ sub check_homecourses {
                 &Apache::lonnet::do_cache_new('courseinfo',$hashid,$courseinfo{$hashid},600);
             }
         }
-        foreach my $hashid (keys(%{$homecourses})) {
-            next if ($recent{$hashid});
-            &Apache::lonnet::do_cache_new('courseinfo',$hashid,$courseinfo{$hashid},600);
+        foreach my $cdom (keys(%{$homecourses})) {
+            if (ref($homecourses->{$cdom}) eq 'HASH') {
+                foreach my $cnum (keys(%{$homecourses->{$cdom}})) {
+                    my $hashid = $cdom.':'.$cnum;
+                    next if ($recent{$hashid});
+                    &Apache::lonnet::do_cache_new('courseinfo',$hashid,$courseinfo{$hashid},600);
+                }
+            }
         }
         foreach my $hashid (keys(%okcourses)) {
-            if (ref($homecourses->{$hashid}) eq 'ARRAY') {
-                foreach my $role (@{$homecourses->{$hashid}}) {
+            my ($cdom,$cnum) = split(/:/,$hashid);
+            if ((ref($homecourses->{$cdom}) eq 'HASH') &&  
+                (ref($homecourses->{$cdom}{$cnum}) eq 'ARRAY')) {
+                foreach my $role (@{$homecourses->{$cdom}{$cnum}}) {
                     if (ref($role) eq 'HASH') {
                         while (my ($key,$value) = each(%{$role})) {
                             if ($regexp eq '.') {
@@ -7467,6 +7700,12 @@ sub check_homecourses {
     return $result;
 }
 
+#
+# useable_role() will compare the LON-CAPA version required by a course with 
+# the version available on the client server.  If the client server's version
+# is compatible, 1 will be returned.
+#
+
 sub useable_role {
     my ($reqdmajor,$reqdminor,$major,$minor) = @_; 
     if ($reqdmajor ne '' && $reqdminor ne '') {
@@ -7477,6 +7716,10 @@ sub useable_role {
     return 1;
 }
 
+sub distro_and_arch {
+    return $dist.':'.$arch;
+}
+
 # ----------------------------------- POD (plain old documentation, CPAN style)
 
 =head1 NAME
@@ -7801,6 +8044,8 @@ Authen::Krb5
 
 =head1 COREQUISITES
 
+none
+
 =head1 OSNAMES
 
 linux
@@ -7888,9 +8133,9 @@ or the CA's certificate in the call to l
 <error> is the textual reason this failed.  Usual reasons:
 
 =over 2
-       
+
 =item Apache config file for loncapa  incorrect:
- 
+
 one of the variables 
 lonCertificateDirectory, lonnetCertificateAuthority, or lonnetCertificate
 undefined or incorrect
@@ -8009,7 +8254,7 @@ Could not rewrite the
 internal password file for a user
 
 =item Result of password change for <user> : <result>
-                                                                     
+
 A unix password change for <user> was attempted 
 and the pipe returned <result>  
 
@@ -8038,7 +8283,7 @@ lond has been asked to exit by its clien
 client systemand <input> is the full exit command sent to the server.
 
 =item Red CRITICAL: ABNORMAL EXIT. child <pid> for server <hostname> died through a crass with this error->[<message>].
-                                                 
+
 A lond child terminated.  NOte that this termination can also occur when the
 child receives the QUIT or DIE signals.  <pid> is the process id of the child,
 <hostname> the host lond is working for, and <message> the reason the child died
@@ -8122,7 +8367,7 @@ file when sent it's USR1 signal.  That p
 assumed to be hung in some un-fixable way.
 
 =item Finished checking children                   
- 
+
 Master processs's USR1 processing is cojmplete.
 
 =item (Red) CRITICAL: ------- Starting ------            
@@ -8136,7 +8381,7 @@ Started a new child process for <client>
 connected to the child.  This was as a result of a TCP/IP connection from a client.
 
 =item Unable to determine who caller was, getpeername returned nothing
-                                                  
+
 In child process initialization.  either getpeername returned undef or
 a zero sized object was returned.  Processing continues, but in my opinion,
 this should be cause for the child to exit.
@@ -8147,7 +8392,7 @@ In child process initialization.  The pe
 The client address is stored as "Unavailable" and processing continues.
 
 =item (Yellow) INFO: Connection <ip> <name> connection type = <type>
-                                                  
+
 In child initialization.  A good connectionw as received from <ip>.
 
 =over 2
@@ -8197,7 +8442,7 @@ The client (<client> is the peer's name
 negotiated an SSL connection with this child process.
 
 =item (Green) Successful insecure authentication with <client>
-                                                   
+
 
 The client has successfully negotiated an  insecure connection withthe child process.