How to use Proxy with TcpClient.ConnectAsync()?

Question

HTTP proxy support in .NET does not actually support the lower level classes like TcpClient or Socket. But I want to connect a TCPServer (ip, port) through HTTP proxy that s

Answer 1

We have managed to implement it using .Net's Socket. Nuget package is called Filemail.ProxiedTcpClient. The code is pretty simple:

public static TcpClient CreateProxied(Uri proxy, Uri destination)
{
    var socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);

    socket.Connect(proxy.Host, proxy.Port);

    var connectMessage = Encoding.UTF8.GetBytes($"CONNECT {destination.Host}:{destination.Port} HTTP/1.1{Environment.NewLine}{Environment.NewLine}");
    socket.Send(connectMessage);

    byte[] receiveBuffer = new byte[1024];
    var received = socket.Receive(receiveBuffer);

    var response = ASCIIEncoding.ASCII.GetString(receiveBuffer, 0, received);

    if (!response.Contains("200 OK"))
    {
        throw new Exception($"Error connecting to proxy server {destination.Host}:{destination.Port}. Response: {response}");
    }

    return new TcpClient
    {
        Client = socket
    };
}

Contribute here: https://github.com/filemail/ProxiedTcpClient