#!/usr/local/bin/php
<?php
/**
 * Author 2025 Etienne Girault <etienne.girault@gmail.com>
 * OPNsense CARP event script
 * - Enables/disables the WAN interface only when needed
 * - Avoids reapplying config when CARP triggers multiple times
 */

require_once("config.inc");
require_once("interfaces.inc");
require_once("util.inc");
require_once("system.inc");

// Read CARP event arguments
$subsystem = !empty($argv[1]) ? $argv[1] : '';
$type = !empty($argv[2]) ? $argv[2] : '';

// Accept only MASTER/BACKUP events
if (!in_array($type, ['MASTER', 'BACKUP'])) {
    // Ignore CARP INIT, DEMOTED, etc.
    exit(0);
}

// Validate subsystem name format, expected pattern: <ifname>@<vhid>
if (!preg_match('/^[a-z0-9_]+@\S+$/i', $subsystem)) {
    log_error("Malformed subsystem argument: '{$subsystem}'.");
    exit(0);
}

// Only react to the primary VHID
list($vhid, $iface) = explode('@', $subsystem);
$primary_vhid = '1'; //

if ($vhid !== $primary_vhid) {
    exit(0); // ignore events from other VHIDs
}

// Interface key to manage
$ifkey = 'wan';
// Determine whether WAN interface is currently enabled
$ifkey_enabled = !empty($config['interfaces'][$ifkey]['enable']) ? true : false;

// MASTER event
if ($type === "MASTER") {
    // Enable WAN only if it's currently disabled
    if (!$ifkey_enabled) {
        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.");
    }

// BACKUP event
} else {
    // Disable WAN only if it's currently enabled
    if ($ifkey_enabled) {
        log_msg("CARP event: switching to '$type', disabling interface '$ifkey'.", LOG_WARNING);
        unset($config['interfaces'][$ifkey]['enable']);
        write_config("disable interface '$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.");
    }
}