From 568c514d3f99fad82d15b1661234aaee43220ae2 Mon Sep 17 00:00:00 2001
From: Vezpi <etienne.girault@gmail.com>
Date: Mon, 8 Jun 2026 06:57:26 +0000
Subject: [PATCH] fix: use file lock

---
 opnsense/10-wan | 25 ++++++++++++++++++++++++-
 1 file changed, 24 insertions(+), 1 deletion(-)

diff --git a/opnsense/10-wan b/opnsense/10-wan
index 6f7fab4..0373bb1 100644
--- a/opnsense/10-wan
+++ b/opnsense/10-wan
@@ -40,17 +40,36 @@ if ($vhid !== $primary_vhid) {
 $ifkey = 'wan';
 // Determine whether WAN interface is currently enabled
 $ifkey_enabled = !empty($config['interfaces'][$ifkey]['enable']) ? true : false;
+// Lock file to prevent interface flapping
+$lock_file = '/tmp/carp_wan_disable_lock';
+$lock_default_age = 5;
+$lock_max_age = 10;
 
 // MASTER event
 if ($type === "MASTER") {
     // Enable WAN only if it's currently disabled
     if (!$ifkey_enabled) {
+        // Check if lock file is present
+        if (file_exists($lock_file)) {
+            $lock_age = time() - (int)file_get_contents($lock_file);
+            if ($lock_age < $lock_max_age) {
+                log_msg("CARP event: WAN disable lock present ({$lock_age}s old), waiting...");
+                $elapsed = 0;
+                while (file_exists($lock_file) && $elapsed < 5000) {
+                    usleep(500000);
+                    $elapsed += 500;
+                }
+            } else {
+                log_msg("CARP event: removing stale WAN disable lock.");
+                @unlink($lock_file);
+            }
+        }
         log_msg("CARP event: switching to '$type', enabling interface '$ifkey'.", LOG_WARNING);
         $config['interfaces'][$ifkey]['enable'] = '1';
         write_config("enable interface '$ifkey' due CARP event '$type'", false);
         interface_configure(false, $ifkey, false, false);
     } else {
-        log_msg("CARP event: already '$type' for interface '$ifkey', nothing to do.");
+        log_msg("CARP event: already 'MASTER' for interface '$ifkey', nothing to do.");
     }
 
 // BACKUP event
@@ -61,6 +80,10 @@ if ($type === "MASTER") {
         unset($config['interfaces'][$ifkey]['enable']);
         write_config("disable interface '$ifkey' due CARP event '$type'", false);
         interface_configure(false, $ifkey, false, false);
+        // Create lock file
+        file_put_contents($lock_file, time());
+        sleep($lock_default_age);
+        @unlink($lock_file);
     } else {
         log_msg("CARP event: already '$type' for interface '$ifkey', nothing to do.");
     }