pkgs/web_socket_conformance_tests/lib/src/protocol_server.dart

// Copyright (c) 2024, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

import 'dart:async';
import 'dart:convert';
import 'dart:io';

import 'package:crypto/crypto.dart';
import 'package:stream_channel/stream_channel.dart';

const _webSocketGuid = '258EAFA5-E914-47DA-95CA-C5AB0DC85B11';

/// Starts an WebSocket server that responds with a scripted subprotocol.
void hybridMain(StreamChannel<Object?> channel) async {
  late final HttpServer server;
  server = (await HttpServer.bind('localhost', 0))
    ..listen((request) async {
      final serverProtocol = request.requestedUri.queryParameters['protocol'];
      var key = request.headers.value('Sec-WebSocket-Key');
      var digest = sha1.convert('$key$_webSocketGuid'.codeUnits);
      var accept = base64.encode(digest.bytes);
      channel.sink.add(request.headers['Sec-WebSocket-Protocol']);
      request.response
        ..statusCode = HttpStatus.switchingProtocols
        ..headers.add(HttpHeaders.connectionHeader, 'Upgrade')
        ..headers.add(HttpHeaders.upgradeHeader, 'websocket')
        ..headers.add('Sec-WebSocket-Accept', accept);
      if (serverProtocol != null) {
        request.response.headers.add('Sec-WebSocket-Protocol', serverProtocol);
      }
      request.response.contentLength = 0;
      final socket = await request.response.detachSocket();
      final webSocket = WebSocket.fromUpgradedSocket(socket,
          protocol: serverProtocol, serverSide: true);
      webSocket.listen((e) async {
        webSocket.add(e);
        await webSocket.close();
      });
    });

  channel.sink.add(server.port);

  await channel
      .stream.first; // Any writes indicates that the server should exit.
  unawaited(server.close());
}