--- loncom/lonnet/perl/lonnet.pm	2009/02/08 20:28:52	1.985
+++ loncom/lonnet/perl/lonnet.pm	2009/02/18 06:54:22	1.987
@@ -1,7 +1,7 @@
 # The LearningOnline Network
 # TCP networking package
 #
-# $Id: lonnet.pm,v 1.985 2009/02/08 20:28:52 raeburn Exp $
+# $Id: lonnet.pm,v 1.987 2009/02/18 06:54:22 raeburn Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -74,6 +74,7 @@ use strict;
 use LWP::UserAgent();
 use HTTP::Date;
 use Image::Magick;
+use IO::Socket;
 
 # use Date::Parse;
 use vars qw(%perlvar %spareid %pr %prp $memcache %packagetab $tmpdir
@@ -150,7 +151,8 @@ sub logthis {
     my $now=time;
     my $local=localtime($now);
     if (open(my $fh,">>$execdir/logs/lonnet.log")) {
-	print $fh "$local ($$): $message\n";
+	my $logstring = $local. " ($$): ".$message."\n"; # Keep any \'s in string.
+	print $fh $logstring;
 	close($fh);
     }
     return 1;
@@ -526,7 +528,7 @@ sub appenv {
 # ----------------------------------------------------- Delete from Environment
 
 sub delenv {
-    my $delthis=shift;
+    my ($delthis,$regexp) = @_;
     if (($delthis=~/user\.role/) || ($delthis=~/user\.priv/)) {
         &logthis("<font color=\"blue\">WARNING: ".
                 "Attempt to delete from environment ".$delthis);
@@ -539,10 +541,17 @@ sub delenv {
 	tie(my %disk_env,'GDBM_File',$env{'user.environment'},
 	    (&GDBM_WRITER()|&GDBM_NOLOCK()),0640)) {
 	foreach my $key (keys(%disk_env)) {
-	    if ($key=~/^\Q$delthis\E/) { 
-		delete($env{$key});
-		delete($disk_env{$key});
-	    }
+	    if ($regexp) {
+                if ($key=~/^$delthis/) {
+                    delete($env{$key});
+                    delete($disk_env{$key});
+                } 
+            } else {
+                if ($key=~/^\Q$delthis\E/) {
+		    delete($env{$key});
+		    delete($disk_env{$key});
+	        }
+            }
 	}
 	untie(%disk_env);
     }
@@ -9010,6 +9019,23 @@ sub get_dns {
     }
 }
 
+#
+#  Given a DNS returns the loncapa host name for that DNS 
+# 
+sub host_from_dns {
+    my ($dns) = @_;
+    my @hosts;
+    my $ip;
+
+    $ip = gethostbyname($dns);	# Initial translation to IP is in net order.
+    if (length($ip) == 4) { 
+	$ip   = &IO::Socket::inet_ntoa($ip);
+	@hosts = get_hosts_from_ip($ip);
+	return $hosts[0];
+    }
+    return undef;
+}
+
 BEGIN {
 
 # ----------------------------------- Read loncapa.conf and loncapa_apache.conf
@@ -9289,9 +9315,11 @@ in the user's environment.db and in %env
 
 =item *
 X<delenv()>
-B<delenv($regexp)>: removes all items from the session
-environment file that matches the regular expression in $regexp. The
-values are also delted from the current processes %env.
+B<delenv($delthis,$regexp)>: removes all items from the session
+environment file that begin with $delthis. If the 
+optional second arg - $regexp - is true, $delthis is treated as a 
+regular expression, otherwise \Q$delthis\E is used. 
+The values are also deleted from the current processes %env.
 
 =item * get_env_multiple($name) 
 
@@ -9899,8 +9927,15 @@ dirlist($uri) : return directory list ba
 
 spareserver() : find server with least workload from spare.tab
 
+
+=item *
+
+host_from_dns($dns) : Returns the loncapa hostname corresponding to a DNS name or undef
+if there is no corresponding loncapa host.
+
 =back
 
+
 =head2 Apache Request
 
 =over 4