--- loncom/lonnet/perl/lonnet.pm	2018/12/27 18:14:50	1.1397
+++ loncom/lonnet/perl/lonnet.pm	2018/12/27 20:10:56	1.1398
@@ -1,7 +1,7 @@
 # The LearningOnline Network
 # TCP networking package
 #
-# $Id: lonnet.pm,v 1.1397 2018/12/27 18:14:50 raeburn Exp $
+# $Id: lonnet.pm,v 1.1398 2018/12/27 20:10:56 raeburn Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -13358,7 +13358,7 @@ sub repcopy_userfile {
     my $request;
     $uri=~s/^\///;
     my $homeserver = &homeserver($cnum,$cdom);
-    my $hostname = &hostname($homeserver); 
+    my $hostname = &hostname($homeserver);
     my $protocol = $protocol{$homeserver};
     $protocol = 'http' if ($protocol ne 'https');
     $request=new HTTP::Request('GET',$protocol.'://'.$hostname.'/raw/'.$uri);
@@ -13560,6 +13560,44 @@ sub default_login_domain {
     return $domain;
 }
 
+sub uses_sts {
+    my ($ignore_cache) = @_;
+    my $lonhost = $perlvar{'lonHostID'};
+    my $hostname = &hostname($lonhost);
+    my $sts_on;
+    if ($protocol{$lonhost} eq 'https') {
+        my $cachetime = 12*3600;
+        if (!$ignore_cache) {
+            ($sts_on,my $cached)=&is_cached_new('stspolicy',$lonhost);
+            if (defined($cached)) {
+                return $sts_on;
+            }
+        }
+        my $url = $protocol{$lonhost}.'://'.$hostname.'/index.html';
+        my $request=new HTTP::Request('HEAD',$url);
+        my $response=&LONCAPA::LWPReq::makerequest($lonhost,$request,'',\%perlvar,'','','',1);
+        if ($response->is_success) {
+            my $has_sts = $response->header('Strict-Transport-Security');
+            if ($has_sts eq '') {
+                $sts_on = 0;
+            } else {
+                if ($has_sts =~ /\Qmax-age=\E(\d+)/) {
+                    my $maxage = $1;
+                    if ($maxage) {
+                        $sts_on = 1;
+                    } else {
+                        $sts_on = 0;
+                    }
+                } else {
+                    $sts_on = 0;
+                }
+            }
+            return &do_cache_new('stspolicy',$lonhost,$sts_on,$cachetime);
+        }
+    }
+    return;
+}
+
 # ------------------------------------------------------------- Declutters URLs
 
 sub declutter {