--- loncom/lonnet/perl/lonnet.pm	2017/08/23 22:46:38	1.1351
+++ loncom/lonnet/perl/lonnet.pm	2017/08/27 02:36:58	1.1352
@@ -1,7 +1,7 @@
 # The LearningOnline Network
 # TCP networking package
 #
-# $Id: lonnet.pm,v 1.1351 2017/08/23 22:46:38 raeburn Exp $
+# $Id: lonnet.pm,v 1.1352 2017/08/27 02:36:58 raeburn Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -3171,6 +3171,45 @@ sub externalssi {
     }
 }
 
+sub remove_stale_resfile {
+    my ($url) = @_;
+    my $stale;
+    if ($url=~m{^/res/($match_domain)/($match_username)/}) {
+        my $audom = $1;
+        my $auname = $2;
+        unless (($url =~ /\.\d+\.\w+$/) || ($url !~ m{^/res/lib/templates/})) {
+            my $homeserver = &homeserver($auname,$audom);
+            unless (($homeserver eq 'no_host') ||
+                    (grep { $_ eq $homeserver } &current_machine_ids())) {
+                my $fname = &filelocation('',$url);
+                if (-e $fname) {
+                    my $protocol = $protocol{$homeserver};
+                    $protocol = 'http' if ($protocol ne 'https');
+                    my $hostname = &hostname($homeserver);
+                    if ($hostname) {
+                        my $uri = &declutter($url);
+                        my $request=new HTTP::Request('HEAD',$protocol.'://'.$hostname.'/raw/'.$uri);
+                        my $response = &LONCAPA::LWPReq::makerequest($homeserver,$request,'',\%perlvar,5,0,1);
+                        if ($response->is_success()) {
+                            my $remmodtime = &HTTP::Date::str2time( $response->header('Last-modified') );
+                            my $locmodtime = (stat($fname))[9];
+                            if ($locmodtime < $remmodtime) {
+                                unlink($fname);
+                                if ($uri!~/\.meta$/) {
+                                    unlink($fname.'.meta');
+                                }
+                                &reply("unsub:$fname",$homeserver);
+                                $stale = 1;
+                            }
+                        }
+                    }
+                }
+            }
+        }
+    }
+    return $stale;
+}
+
 # -------------------------------- Allow a /uploaded/ URI to be vouched for
 
 sub allowuploaded {