WebSocketTransport.cs

// <copyright file="WebSocketTransport.cs" company="Selenium Committers">
// Licensed to the Software Freedom Conservancy (SFC) under one
// or more contributor license agreements.  See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership.  The SFC licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License.  You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License.
// </copyright>

using System;
using System.IO;
using System.Net.WebSockets;
using System.Threading.Tasks;
using System.Threading;
using System.Text.Json;
using System.Text;
using OpenQA.Selenium.Internal.Logging;
using System.Text.Json.Serialization;

#nullable enable

namespace OpenQA.Selenium.BiDi.Communication.Transport;

class WebSocketTransport(Uri _uri) : ITransport, IDisposable
{
    private readonly static ILogger _logger = Log.GetLogger<WebSocketTransport>();

    private readonly ClientWebSocket _webSocket = new();
    private readonly ArraySegment<byte> _receiveBuffer = new(new byte[1024 * 8]);

    private readonly SemaphoreSlim _socketSendSemaphoreSlim = new(1, 1);

    public async Task ConnectAsync(CancellationToken cancellationToken)
    {
        await _webSocket.ConnectAsync(_uri, cancellationToken).ConfigureAwait(false);
    }

    public async Task<T> ReceiveAsJsonAsync<T>(JsonSerializerContext jsonSerializerContext, CancellationToken cancellationToken)
    {
        using var ms = new MemoryStream();

        WebSocketReceiveResult result;

        do
        {
            result = await _webSocket.ReceiveAsync(_receiveBuffer, cancellationToken).ConfigureAwait(false);

            await ms.WriteAsync(_receiveBuffer.Array!, _receiveBuffer.Offset, result.Count, cancellationToken).ConfigureAwait(false);
        }
        while (!result.EndOfMessage);

        ms.Seek(0, SeekOrigin.Begin);

        if (_logger.IsEnabled(LogEventLevel.Trace))
        {
            _logger.Trace($"BiDi RCV << {Encoding.UTF8.GetString(ms.ToArray())}");
        }

        var res = await JsonSerializer.DeserializeAsync(ms, typeof(T), jsonSerializerContext, cancellationToken).ConfigureAwait(false);

        return (T)res!;
    }

    public async Task SendAsJsonAsync<TCommand>(TCommand command, JsonSerializerContext jsonSerializerContext, CancellationToken cancellationToken)
        where TCommand : Command
    {
        var buffer = JsonSerializer.SerializeToUtf8Bytes(command, typeof(TCommand), jsonSerializerContext);

        await _socketSendSemaphoreSlim.WaitAsync(cancellationToken);

        try
        {
            if (_logger.IsEnabled(LogEventLevel.Trace))
            {
                _logger.Trace($"BiDi SND >> {Encoding.UTF8.GetString(buffer)}");
            }

            await _webSocket.SendAsync(new ArraySegment<byte>(buffer), WebSocketMessageType.Text, true, cancellationToken).ConfigureAwait(false);
        }
        finally
        {
            _socketSendSemaphoreSlim.Release();
        }
    }

    public void Dispose()
    {
        _webSocket.Dispose();
    }
}