From 90e2f3452dc013ab8be397b1ceb0cb692b2c8751 Mon Sep 17 00:00:00 2001
From: John Crispin <john@phrozen.org>
Date: Tue, 25 Nov 2025 07:31:08 +0100
Subject: [PATCH] cloud_discovery: add standard FQDN fallback discovery

Add discovery method that attempts to resolve a standard FQDN when DHCP
discovery fails. This enables zero-touch provisioning in environments
where administrators configure DNS without modifying DHCP infrastructure.

The standard FQDN is configurable via STANDARD_FQDN constant (defaults
to "openwifi.network"). Administrators can configure their local DNS to
resolve this FQDN to their controller, allowing APs to discover the
controller automatically.

Discovery priority order:
1. EST enrollment (blocking)
2. DHCP discovery (Option 224/138)
3. Flash-based configuration
4. Standard FQDN resolution (NEW)
5. Cloud redirector service (internet-connected only)

The implementation uses the resolv module for DNS queries, performing
A record lookups. If resolution fails, discovery continues to the next
method. The standard FQDN method integrates with the existing discovery
block list mechanism to prevent repeated failed attempts.

Note: The boguspriv dnsmasq option may prevent FQDNs from resolving to
private IPs. Administrators should either use CG NAT Safe IP addresses
(100.64.0.0/10) or configure dnsmasq with rebind-domain-ok exceptions.

Signed-off-by: John Crispin <john@phrozen.org>
---
 .../files/usr/bin/cloud_discovery             | 33 ++++++++++++++++++-
 1 file changed, 32 insertions(+), 1 deletion(-)

diff --git a/feeds/tip/cloud_discovery/files/usr/bin/cloud_discovery b/feeds/tip/cloud_discovery/files/usr/bin/cloud_discovery
index 3cae790d3..90ad334a2 100755
--- a/feeds/tip/cloud_discovery/files/usr/bin/cloud_discovery
+++ b/feeds/tip/cloud_discovery/files/usr/bin/cloud_discovery
@@ -3,6 +3,7 @@
 'use strict';
 
 import { ulog_open, ulog, ULOG_SYSLOG, ULOG_STDIO, LOG_DAEMON, LOG_INFO } from 'log';
+import { query } from 'resolv';
 import * as libubus from 'ubus';
 import * as uloop from 'uloop';
 import * as libuci from 'uci';
@@ -17,8 +18,12 @@ const ORPHAN = 4;
 
 const DISCOVER_DHCP = "DHCP";
 const DISCOVER_FLASH = "FLASH";
+const DISCOVER_FQDN = "STANDARD_FQDN";
 const DISCOVER_LOOKUP = "OpenLAN";
 
+const STANDARD_FQDN = "openwifi.network";
+const STANDARD_FQDN_PORT = 15002;
+
 let ubus = libubus.connect();
 let uci = libuci.cursor();
 let state = DISCOVER;
@@ -229,6 +234,28 @@ function discover_flash() {
 	return 0;
 }
 
+function discover_standard_fqdn() {
+	ulog(LOG_INFO, `Trying standard FQDN: ${STANDARD_FQDN}\n`);
+
+	let result = query([STANDARD_FQDN], { type: ['A'] });
+	if (!result || !result[STANDARD_FQDN] || !result[STANDARD_FQDN].A) {
+		ulog(LOG_INFO, `Failed to resolve ${STANDARD_FQDN}\n`);
+		return false;
+	}
+
+	let address = result[STANDARD_FQDN].A[0];
+	ulog(LOG_INFO, `Resolved ${STANDARD_FQDN} to ${address}\n`);
+
+	if (gateway_write({ server: STANDARD_FQDN, port: STANDARD_FQDN_PORT, valid: false, hostname_validate: 1 })) {
+		ulog(LOG_INFO, `Discovered cloud via standard FQDN ${STANDARD_FQDN}\n`);
+		client_start();
+		set_state(VALIDATING);
+		return true;
+	}
+
+	return false;
+}
+
 function time_is_valid() {
 	let valid = !!fs.stat('/tmp/ntp.set');
 	if (!valid)
@@ -269,7 +296,7 @@ function interval_handler() {
 
 	case DISCOVER:
 		ulog(LOG_INFO, 'Starting discover\n');
-	
+
 		if (!time_is_valid())
 			return;
 
@@ -284,6 +311,10 @@ function interval_handler() {
 		if (!is_discover_method_blacked() && !discover_flash())
 			return;
 
+		discovery_method = DISCOVER_FQDN;
+		if (!is_discover_method_blacked() && discover_standard_fqdn())
+			return;
+
 		discovery_method = DISCOVER_LOOKUP;
 		redirector_lookup();