--- rat/lonpageflip.pm	2017/02/20 18:29:33	1.93
+++ rat/lonpageflip.pm	2017/02/25 19:40:29	1.94
@@ -2,7 +2,7 @@
 #
 # Page flip handler
 #
-# $Id: lonpageflip.pm,v 1.93 2017/02/20 18:29:33 raeburn Exp $
+# $Id: lonpageflip.pm,v 1.94 2017/02/25 19:40:29 raeburn Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -314,6 +314,7 @@ sub handler {
   my %multichoicehash=();
   my ($redirecturl,$redirectsymb,$enc,$anchor);
   my $next='';
+  my $hostname = $r->hostname();
   my @possibilities=();
    &Apache::loncommon::get_unprocessed_cgi($ENV{'QUERY_STRING'},['postdata']);
   if (($env{'form.postdata'})&&($env{'request.course.fn'})) {
@@ -334,8 +335,8 @@ sub handler {
       } elsif ($direction eq 'firstanswerable') {
           my $furl = &first_answerable_ressymb();
           my $usehttp = &check_for_syllabus(\$furl);
-          if ($usehttp) {
-              $furl='http://'.$ENV{'SERVER_NAME'}.$furl;
+          if (($usehttp) && ($hostname ne '')) {
+              $furl='http://'.$hostname.$furl;
           } else {
               $furl=&Apache::lonnet::absolute_url().$furl;
           }
@@ -387,8 +388,8 @@ sub handler {
       if ($direction eq 'firstres') {
 	  my $furl=&first_accessible_resource();
           my $usehttp = &check_for_syllabus(\$furl);
-          if ($usehttp) {
-              $furl='http://'.$ENV{'SERVER_NAME'}.$furl;
+          if (($usehttp) && ($hostname ne '')) {
+              $furl='http://'.$hostname.$furl;
           } else {
               $furl=&Apache::lonnet::absolute_url().$furl;
           }
@@ -418,8 +419,8 @@ sub handler {
          } else {
 	    $newloc='/adm/navmaps';
          }
-         if ($usehttp) {
-             $newloc='http://'.$ENV{'SERVER_NAME'}.$newloc;
+         if (($usehttp) && ($hostname ne '')) {
+             $newloc='http://'.$hostname.$newloc;
          } else {
              $newloc=&Apache::lonnet::absolute_url().$newloc
          }
@@ -529,8 +530,8 @@ sub handler {
                   my ($redirect, $url) = &Apache::loncommon::critical_redirect(300);
                   unless ($redirect) {
                       my $usehttp = &check_for_syllabus(\$redirecturl);
-                      if ($usehttp) {
-                          $url='http://'.$ENV{'SERVER_NAME'}.$redirecturl;
+                      if (($usehttp) && ($hostname ne '')) {
+                          $url='http://'.$hostname.$redirecturl;
                       } else {
                           $url=&Apache::lonnet::absolute_url().$redirecturl;
                       }
@@ -584,8 +585,8 @@ ENDSTART
                      foreach my $id (@possibilities) {
                         my $src = $multichoicehash{'src_'.$id};
                         my $usehttp = &check_for_syllabus(\$src);
-                        if ($usehttp) {
-                            $src = 'http://'.$ENV{'SERVER_NAME'}.$src;
+                        if (($usehttp) && ($hostname ne '')) {
+                            $src = 'http://'.$hostname.$src;
                         }
                         $r->print(
                               '<tr><td><a href="'.