feat(mobile): query DNS SVCB/HTTPS records

mobile/lib/services/api.service.dart

@@ -10,9 +10,10 @@ import 'package:logging/logging.dart';
 import 'package:openapi/api.dart';
 import 'package:http/http.dart';
 
+import 'package:dns_query_service.dart';
+
 class ApiService implements Authentication {
   late ApiClient _apiClient;
-
   late UsersApi usersApi;
   late AuthenticationApi authenticationApi;
   late OAuthApi oAuthApi;
@@ -31,7 +32,8 @@ class ApiService implements Authentication {
   late DownloadApi downloadApi;
   late TrashApi trashApi;
   late StacksApi stacksApi;
-
+  final DnsQueryService _dnsQueryService = DnsQueryService(); // Create DnsQueryService instance
+
   ApiService() {
     final endpoint = Store.tryGet(StoreKey.serverEndpoint);
     if (endpoint != null && endpoint.isNotEmpty) {
@@ -82,13 +84,25 @@ class ApiService implements Authentication {
   ///  host   - required
   ///  port   - optional (default: based on schema)
   ///  path   - optional
+  /// Resolve and set the API endpoint, with SRV record lookup based on domain
   Future<String> resolveEndpoint(String serverUrl) async {
     final url = sanitizeUrl(serverUrl);
 
     if (!await _isEndpointAvailable(serverUrl)) {
       throw ApiException(503, "Server is not reachable");
     }
 
+    // Get domain name from serverUrl
+    final domain = Uri.parse(serverUrl).host;
+
+    // Call DnsQueryService to fetch SRV records
+    try {
+      List<Map<String, dynamic>> srvRecords = await _dnsQueryService.fetchSrvRecords(domain);
+      _log.info('Fetched SRV records for domain $domain: $srvRecords');
+    } catch (e) {
+      _log.severe('Failed to fetch SRV records for domain $domain: $e');
+    }
+
     // Check for /.well-known/immich
     final wellKnownEndpoint = await _getWellKnownEndpoint(url);
     if (wellKnownEndpoint.isNotEmpty) return wellKnownEndpoint;

mobile/lib/services/dns_query_service.dart

@@ -0,0 +1,47 @@
+import 'dart:async';
+import 'package:basic_utils/basic_utils.dart';
+import 'package:logging/logging.dart';
+
+class DnsQueryService {
+	final Logger _log = Logger('DnsQueryService');
+
+	/// Validates the domain name format.
+  bool _isValidDomain(String domain) {
+	  final regex = RegExp(r'^([a-zA-Z0-9-]+\.)+[a-zA-Z]{2,}$');
+	  return regex.hasMatch(domain);
+  }
+
+	/// Fetch SRV records for a given domain.  
+	Future<List<Map<String, dynamic>>> fetchSrvRecords(String domain) async {
+	  if (!_isValidDomain(domain)) {
+			_log.warning('Invalid domain name: $domain');
+		  throw Exception('Invalid domain name: $domain');
+	  }
+
+		try {
+			_log.info('Attempting to fetch SRV records for domain: $domain');
+
+			// Perform the SRV record lookup
+			final srvRecords = await DnsUtils.lookupRecord(domain, RRecordType.SRV);
+
+			_log.info('Successfully fetched SRV records for domain: $domain');
+
+			// Transform the result into a list of maps
+			return srvRecords.map((record) {
+				return {
+					'priority': record.priority,
+					'weight': record.weight,
+					'port': record.port,
+					'target': record.target,
+				};
+			}).toList();
+		} catch (e, stackTrace) {
+			_log.severe(
+				'Failed to fetch SRV records for domain: $domain',
+				e,
+				stackTrace,
+			);
+			throw Exception('Failed to fetch SRV records: $e');
+		}
+	}
+}