Fix for ticket 2513: "Can't linkify" error when some links are shortened

When bogus SSL sites etc were hit through a shortening redirect, sometimes link resolution kinda blew up and the user would get a "Can't linkify" error, aborting their post.
Now catching this case and just passing through the URL without attempting to resolve it. Could benefit from an overall scrubbing of the freaky link/attachment code though...! :)

http://status.net/open-source/issues/2513

classes/File_redirection.php

@@ -210,6 +210,14 @@ class File_redirection extends Memcached_DataObject
                 } else if (is_string($redir_data)) {
                     // The file is a known redirect target.
                     $file = File::staticGet('url', $redir_data);
+                    if (empty($file)) {
+                        // @fixme should we save a new one?
+                        // this case was triggering sometimes for redirects
+                        // with unresolvable targets; found while fixing
+                        // "can't linkify" bugs with shortened links to
+                        // SSL sites with cert issues.
+                        return null;
+                    }
                     $file_id = $file->id;
                 }
             } else {

lib/util.php

@@ -830,7 +830,10 @@ function common_linkify($url) {
         } elseif (is_string($longurl_data)) {
             $longurl = $longurl_data;
         } else {
-            throw new ServerException("Can't linkify url '$url'");
+            // Unable to reach the server to verify contents, etc
+            // Just pass the link on through for now.
+            common_log(LOG_ERR, "Can't linkify url '$url'");
+            $longurl = $url;
         }
     }
     $attrs = array('href' => $canon, 'title' => $longurl, 'rel' => 'external');