If you're logged in as a client, stay that way

When following a link from an email, if you are already signed in to the
help desk as a client, you should just be redirected to the new ticket.

include/class.client.php

@@ -149,6 +149,10 @@ abstract class TicketUser {
         return $this->_guest;
     }
 
+    function getUserId() {
+        return $this->user->getId();
+    }
+
     abstract function getTicketId();
     abstract function getTicket();
 }

view.php

@@ -16,14 +16,23 @@
 **********************************************************************/
 require_once('client.inc.php');
 
+$errors = array();
+// Check if the client is already signed in. Don't corrupt their session!
+if ($_GET['auth']
+        && $thisclient
+        && ($u = TicketUser::lookupByToken($_GET['auth']))
+        && ($u->getUserId() == $thisclient->getId())
+) {
+    Http::redirect('tickets.php?id='.$u->getTicketId());
+}
 // Try autologin the user
 // Authenticated user can be of type ticket owner or collaborator
-$errors = array();
-if (isset($_GET['auth']) || isset($_GET['t']))
+elseif (isset($_GET['auth']) || isset($_GET['t'])) {
     // TODO: Consider receiving an AccessDenied object
     $user =  UserAuthenticationBackend::processSignOn($errors, false);
+}
 
-if ($user && $user->getTicketId())
+if (@$user && is_object($user) && $user->getTicketId())
     Http::redirect('tickets.php?id='.$user->getTicketId());
 
 $nav = new UserNav();