--- loncom/lonnet/perl/lonnet.pm	2018/07/04 16:58:29	1.1378
+++ loncom/lonnet/perl/lonnet.pm	2018/08/14 18:29:33	1.1382
@@ -1,7 +1,7 @@
 # The LearningOnline Network
 # TCP networking package
 #
-# $Id: lonnet.pm,v 1.1378 2018/07/04 16:58:29 raeburn Exp $
+# $Id: lonnet.pm,v 1.1382 2018/08/14 18:29:33 raeburn Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -10041,12 +10041,25 @@ sub is_course {
     my ($cdom, $cnum) = scalar(@_) == 1 ? 
          ($_[0] =~ /^($match_domain)_($match_courseid)$/)  :  @_;
 
-    return unless $cdom and $cnum;
-
-    my %courses = &courseiddump($cdom, '.', 1, '.', '.', $cnum, undef, undef,
-        '.');
-
-    return unless(exists($courses{$cdom.'_'.$cnum}));
+    return unless (($cdom =~ /^$match_domain$/) && ($cnum =~ /^$match_courseid$/));
+    my $uhome=&homeserver($cnum,$cdom);
+    my $iscourse;
+    if (grep { $_ eq $uhome } current_machine_ids()) {
+        $iscourse = &LONCAPA::Lond::is_course($cdom,$cnum);
+    } else {
+        my $hashid = $cdom.':'.$cnum;
+        ($iscourse,my $cached) = &is_cached_new('iscourse',$hashid);
+        unless (defined($cached)) {
+            my %courses = &courseiddump($cdom, '.', 1, '.', '.',
+                                        $cnum,undef,undef,'.');
+            $iscourse = 0;
+            if (exists($courses{$cdom.'_'.$cnum})) {
+                $iscourse = 1;
+            }
+            &do_cache_new('iscourse',$hashid,$iscourse,3600);
+        }
+    }
+    return unless ($iscourse);
     return wantarray ? ($cdom, $cnum) : $cdom.'_'.$cnum;
 }
 
@@ -13519,15 +13532,17 @@ sub get_dns {
     }
 
     my %alldns;
-    open(my $config,"<","$perlvar{'lonTabDir'}/hosts.tab");
-    foreach my $dns (<$config>) {
-	next if ($dns !~ /^\^(\S*)/x);
-        my $line = $1;
-        my ($host,$protocol) = split(/:/,$line);
-        if ($protocol ne 'https') {
-            $protocol = 'http';
+    if (open(my $config,"<","$perlvar{'lonTabDir'}/hosts.tab")) {
+        foreach my $dns (<$config>) {
+	    next if ($dns !~ /^\^(\S*)/x);
+            my $line = $1;
+            my ($host,$protocol) = split(/:/,$line);
+            if ($protocol ne 'https') {
+                $protocol = 'http';
+            }
+	    $alldns{$host} = $protocol;
         }
-	$alldns{$host} = $protocol;
+        close($config);
     }
     while (%alldns) {
 	my ($dns) = sort { $b cmp $a } keys(%alldns);
@@ -13535,19 +13550,33 @@ sub get_dns {
         my $response = &LONCAPA::LWPReq::makerequest('',$request,'',\%perlvar,30,0);
         delete($alldns{$dns});
 	next if ($response->is_error());
-	my @content = split("\n",$response->content);
-	unless ($nocache) {
-	    &do_cache_new('dns',$url,\@content,30*24*60*60);
-	}
-	&$func(\@content,$hashref);
-	return;
+        if ($url eq '/adm/dns/loncapaCRL') {
+            return &$func($response);
+        } else {
+	    my @content = split("\n",$response->content);
+	    unless ($nocache) {
+	        &do_cache_new('dns',$url,\@content,30*24*60*60);
+	    }
+	    &$func(\@content,$hashref);
+            return;
+        }
+    }
+    my $which = (split('/',$url,4))[3];
+    if ($which eq 'loncapaCRL') {
+        my $diskfile = "$perlvar{'lonCertificateDirectory'}/$perlvar{'lonnetCertRevocationList'}";
+        if (-e $diskfile) {
+            &logthis("unable to contact DNS, on disk file $diskfile not updated");
+        } else {
+            &logthis("unable to contact DNS, no on disk file $diskfile available");
+        }
+    } else {
+        &logthis("unable to contact DNS defaulting to on disk file dns_$which.tab\n");
+        if (open(my $config,"<","$perlvar{'lonTabDir'}/dns_$which.tab")) {
+            my @content = <$config>;
+            close($config);
+            &$func(\@content,$hashref);
+        }
     }
-    close($config);
-    my $which = (split('/',$url))[3];
-    &logthis("unable to contact DNS defaulting to on disk file dns_$which.tab\n");
-    open($config,"<","$perlvar{'lonTabDir'}/dns_$which.tab");
-    my @content = <$config>;
-    &$func(\@content,$hashref);
     return;
 }
 
@@ -13607,6 +13636,79 @@ sub fetch_dns_checksums {
     return \%checksums;
 }
 
+sub fetch_crl_pemfile {
+    return &get_dns("/adm/dns/loncapaCRL",\&save_crl_pem,1,1);
+}
+
+sub save_crl_pem {
+    my ($response) = @_;
+    my ($msg,$hadchanges);
+    if (ref($response)) {
+        my $now = time;
+        my $lonca = $perlvar{'lonCertificateDirectory'}.'/'.$perlvar{'lonnetCertificateAuthority'};
+        my $tmpcrl = $tmpdir.'/'.$perlvar{'lonnetCertRevocationList'}.'_'.$now.'.'.$$.'.tmp';
+        if (open(my $fh,'>',"$tmpcrl")) {
+            print $fh $response->content;
+            close($fh);
+            if (-e $lonca) {
+                if (open(PIPE,"openssl crl -in $tmpcrl -inform pem -CAfile $lonca -noout 2>&1 |")) {
+                    my $check = <PIPE>;
+                    close(PIPE);
+                    chomp($check);
+                    if ($check eq 'verify OK') {
+                        my $dest = "$perlvar{'lonCertificateDirectory'}/$perlvar{'lonnetCertRevocationList'}";
+                        my $backup;
+                        if (-e $dest) {
+                            if (&File::Copy::move($dest,"$dest.bak")) {
+                                $backup = 'ok';
+                            }
+                        }
+                        if (&File::Copy::move($tmpcrl,$dest)) {
+                            $msg = 'ok';
+                            if ($backup) {
+                                my (%oldnums,%newnums);
+                                if (open(PIPE, "openssl crl -inform PEM -text -noout -in $dest.bak |grep 'Serial Number' |")) {
+                                    while (<PIPE>) {
+                                        $oldnums{(split(/:/))[1]} = 1;
+                                    }
+                                    close(PIPE);
+                                }
+                                if (open(PIPE, "openssl crl -inform PEM -text -noout -in $dest |grep 'Serial Number' |")) {
+                                    while(<PIPE>) {
+                                        $newnums{(split(/:/))[1]} = 1;
+                                    }
+                                    close(PIPE);
+                                }
+                                foreach my $key (sort {$b <=> $a } (keys(%newnums))) {
+                                    unless (exists($oldnums{$key})) {
+                                        $hadchanges = 1;
+                                        last;
+                                    }
+                                }
+                                unless ($hadchanges) {
+                                    foreach my $key (sort {$b <=> $a } (keys(%oldnums))) {
+                                        unless (exists($newnums{$key})) {
+                                            $hadchanges = 1;
+                                            last;
+                                        }
+                                    }
+                                }
+                            }
+                        }
+                    } else {
+                        unlink($tmpcrl);
+                    }
+                } else {
+                    unlink($tmpcrl);
+                }
+            } else {
+                unlink($tmpcrl);
+            }
+        }
+    }
+    return ($msg,$hadchanges);
+}
+
 # ------------------------------------------------------------ Read domain file
 {
     my $loaded;