Realtime: Unable to build WebSocket connection through Tor proxy

[nns52k]

Describe the bug

Unable to create a WebSocket connection to access Realtime on an .onion server.

To Reproduce

1. Have a working Tor serving Supabase.
2. Run this Dart script:

import 'dart:io';
import 'package:http/io_client.dart';
import 'package:supabase/supabase.dart';
import 'package:socks5_proxy/socks_client.dart';

void main(List<String> arguments) async {
  HttpClient httpClient = await connectTorProxy(9050);
  final supabase = SupabaseClient(
    'http://your_onion_address.onion',
    'your_anon_key',
    httpClient: IOClient(httpClient),
  );
  await listenToATable(supabase);
}
Future<HttpClient> connectTorProxy(int portNumber) async {
  final httpClient = HttpClient();
  SocksTCPClient.assignToHttpClient(httpClient, [
    ProxySettings(InternetAddress.loopbackIPv4, portNumber),
  ]);
  return httpClient;
}
Future<void> listenToATable(SupabaseClient supabase) async {
  final SupabaseQueryBuilder queryBuilder = supabase.from('countries'); // Assume we have SQL table `countries`.
  final SupabaseStreamFilterBuilder streamFilterBuilder = queryBuilder.stream(primaryKey: ['id']);
  streamFilterBuilder.listen((List<Map<String, dynamic>> resultSet) {
    print(supabase.realtime.isConnected);
    printResultSet(resultSet);
  });
}
void printResultSet(List<Map<String, dynamic>> resultSet, {bool hasRowSeparator = true}) {
  for (Map<String, dynamic> row in resultSet) {
    row.forEach((String columnName, dynamic columnValue) {
      print('$columnName: $columnValue');
    });
    if (hasRowSeparator) print('----------');
  }
}

Expected behavior

Whenever the SQL table countries in the server is changed, our Dart script shall receive an update, but because of the bug, it doesn't. There is no WebSocket connection between our client app and the .onion server providing Supabase.

Version (please complete the following information):
On Linux/macOS

├── supabase 2.1.2
│   ├── functions_client 2.1.0
│   ├── gotrue 2.6.1
│   ├── postgrest 2.1.1
│   ├── realtime_client 2.0.4
│   ├── storage_client 2.0.1

Additional context

According to Tor Project: FAQ | Tor onion services: How do I access onion services?, the client shan't lookup .onion address. Please note that the top-level domain is .onion. It will doom to fail to lookup .onion address, because .onion is only recognizable by Tor Network. The client shall simply pass the .onion address to Tor proxy without looking up the .onion address in advance.

When running the above code example that reproduces the bug, it will throw this exception:

SocketException (SocketException: Failed host lookup: 'your_onion_address.onion' (OS Error: Name or service not known, errno = -2))

The callstack of the DNS lookup that causes the exception is as follows:

_NativeSocket.staggeredLookup.<anonymous closure>.lookupAddresses (~/.local/packages/flutter/bin/cache/dart-sdk/lib/_internal/vm/bin/socket_patch.dart:633)
_NativeSocket.staggeredLookup.<anonymous closure> (~/.local/packages/flutter/bin/cache/dart-sdk/lib/_internal/vm/bin/socket_patch.dart:655)
_runGuarded (~/.local/packages/flutter/bin/cache/dart-sdk/lib/async/stream_controller.dart:823)
_StreamController._subscribe.<anonymous closure> (~/.local/packages/flutter/bin/cache/dart-sdk/lib/async/stream_controller.dart:702)
_BufferingStreamSubscription._guardCallback (~/.local/packages/flutter/bin/cache/dart-sdk/lib/async/stream_impl.dart:415)
_StreamController._subscribe (~/.local/packages/flutter/bin/cache/dart-sdk/lib/async/stream_controller.dart:701)
_ControllerStream._createSubscription (~/.local/packages/flutter/bin/cache/dart-sdk/lib/async/stream_controller.dart:836)
_StreamImpl.listen (~/.local/packages/flutter/bin/cache/dart-sdk/lib/async/stream_impl.dart:471)
_NativeSocket.tryConnectToResolvedAddresses (~/.local/packages/flutter/bin/cache/dart-sdk/lib/_internal/vm/bin/socket_patch.dart:966)
_NativeSocket.startConnect.<anonymous closure> (~/.local/packages/flutter/bin/cache/dart-sdk/lib/_internal/vm/bin/socket_patch.dart:740)
<asynchronous gap> (Unknown Source:0)
_RawSocket.startConnect.<anonymous closure> (~/.local/packages/flutter/bin/cache/dart-sdk/lib/_internal/vm/bin/socket_patch.dart:1915)
<asynchronous gap> (Unknown Source:0)
Socket._startConnect.<anonymous closure> (~/.local/packages/flutter/bin/cache/dart-sdk/lib/_internal/vm/bin/socket_patch.dart:2140)
<asynchronous gap> (Unknown Source:0)
_ConnectionTarget.connect.<anonymous closure> (~/.local/packages/flutter/bin/cache/dart-sdk/lib/_http/http_impl.dart:2490)
<asynchronous gap> (Unknown Source:0)
_HttpClient._openUrl.<anonymous closure> (~/.local/packages/flutter/bin/cache/dart-sdk/lib/_http/http_impl.dart:2787)
<asynchronous gap> (Unknown Source:0)
_WebSocketImpl.connect.<anonymous closure> (~/.local/packages/flutter/bin/cache/dart-sdk/lib/_http/websocket_impl.dart:1021)
<asynchronous gap> (Unknown Source:0)
_WebSocketImpl.connect.<anonymous closure> (~/.local/packages/flutter/bin/cache/dart-sdk/lib/_http/websocket_impl.dart:1048)
<asynchronous gap> (Unknown Source:0)
new IOWebSocketChannel.connect.<anonymous closure> (~/.pub-cache/hosted/pub.dev/web_socket_channel-2.4.5/lib/io.dart:90)
<asynchronous gap> (Unknown Source:0)

[nns52k]

There is no way to pass a HttpClient to WebSocketChannel like what we can do to SupabaseClient, but defining HttpOverrides.createHttpClient and running all Supabase code in a HttpOverrides.runZoned is a workaround.