custom scrub rules need to be first

The custom scrub rules on the normalization settings page effectively
cannot be reached since the standard interface scrub rules are listed
first.

This patch swaps that order around so that custom scrub rules get
evaluated first.

src/etc/inc/filter.inc

@@ -570,26 +570,7 @@ function filter_generate_scrubing(&$FilterIflist)
 
     $scrubrules = '';
 
-    /* scrub per interface options */
-    if (empty($config['system']['scrub_interface_disable'])) {
-        foreach ($FilterIflist as $scrubif => $scrubcfg) {
-            if (isset($scrubcfg['virtual']) || empty($scrubcfg['descr'])) {
-                continue;
-            } else {
-                /* set up MSS clamping */
-                if (!empty($scrubcfg['mss']) && is_numeric($scrubcfg['mss']) &&
-                    !in_array($scrubcfg['if'], array('pppoe', 'pptp', 'l2tp'))) {
-                    $mssclamp = "max-mss " . (intval($scrubcfg['mss'] - 40));
-                } else {
-                    $mssclamp = '';
-                }
-                $scrubnodf = !empty($config['system']['scrubnodf']) ? "no-df" : "";
-                $scrubrnid = !empty($config['system']['scrubrnid']) ? "random-id" : "";
-                $scrubrules .= "scrub on \${$scrubcfg['descr']} all {$scrubnodf} {$scrubrnid} {$mssclamp}\n";
-            }
-        }
-    }
-
+    /* custom rules must be first */
     if (!empty($config['filter']['scrub']['rule'])) {
         foreach ($config['filter']['scrub']['rule'] as $scrub_rule) {
             if (!isset($scrub_rule['disabled'])) {
@@ -634,6 +615,26 @@ function filter_generate_scrubing(&$FilterIflist)
         }
     }
 
+    /* scrub per interface options */
+    if (empty($config['system']['scrub_interface_disable'])) {
+        foreach ($FilterIflist as $scrubif => $scrubcfg) {
+            if (isset($scrubcfg['virtual']) || empty($scrubcfg['descr'])) {
+                continue;
+            } else {
+                /* set up MSS clamping */
+                if (!empty($scrubcfg['mss']) && is_numeric($scrubcfg['mss']) &&
+                    !in_array($scrubcfg['if'], array('pppoe', 'pptp', 'l2tp'))) {
+                    $mssclamp = "max-mss " . (intval($scrubcfg['mss'] - 40));
+                } else {
+                    $mssclamp = '';
+                }
+                $scrubnodf = !empty($config['system']['scrubnodf']) ? "no-df" : "";
+                $scrubrnid = !empty($config['system']['scrubrnid']) ? "random-id" : "";
+                $scrubrules .= "scrub on \${$scrubcfg['descr']} all {$scrubnodf} {$scrubrnid} {$mssclamp}\n";
+            }
+        }
+    }
+
     return $scrubrules;
 }