Sockets in C#: How to get the response stream?

Question

Hi

I'm trying to replace this:

void ProcessRequest(object listenerContext)
{
    var context = (HttpListenerContext)listenerContext;
    Uri URL = new Uri(context.Request.RawUrl);
    HttpWebRequest.DefaultWebProxy = null;
    HttpWebRequest httpWebRequest = (HttpWebRequest)WebRequest.Create(URL);
    httpWebRequest.Method = context.Request.HttpMethod;
    httpWebRequest.Headers.Clear();
    if (context.Request.UserAgent != null) httpWebRequest.UserAgent = context.Request.UserAgent;
    foreach (string headerKey in context.Request.Headers.AllKeys)
    {
        try { httpWebRequest.Headers.Set(headerKey, context.Request.Headers[headerKey]); }
            catch (Exception) { }
    }

    using (HttpWebResponse httpWebResponse = (HttpWebResponse)httpWebRequest.GetResponse())
    {
        Stream responseStream = httpWebResponse.GetResponseStream();
        if (httpWebResponse.ContentEncoding.ToLower().Contains("gzip"))
            responseStream = new GZipStream(responseStream, CompressionMode.Decompress);
        else if (httpWebResponse.ContentEncoding.ToLower().Contains("deflate"))
                responseStream = new DeflateStream(responseStream, CompressionMode.Decompress);

        MemoryStream memStream = new MemoryStream();

        byte[] respBuffer = new byte[4096];
        try
        {
            int bytesRead = responseStream.Read(respBuffer, 0, respBuffer.Length);
            while (bytesRead > 0)
            {
                memStream.Write(respBuffer, 0, bytesRead);
                bytesRead = responseStream.Read(respBuffer, 0, respBuffer.Length);
            }
        }
        finally
        {
            responseStream.Close();
        }

        byte[] msg = memStream.ToArray();

        context.Response.ContentLength64 = msg.Length;
        using (Stream strOut = context.Response.OutputStream)
        {
            strOut.Write(msg, 0, msg.Length);
        }
    }
    catch (Exception ex)
    {
        // Some error handling
    }
}

with sockets. This is what I have so far:

void ProcessRequest(object listenerContext)
{
    HttpListenerContext context = (HttpListenerContext)listenerContext;
    Uri URL = new Uri(context.Request.RawUrl);
    string getString = string.Format("GET {0} HTTP/1.1\r\nHost: {1}\r\nAccept-Encoding: gzip\r\n\r\n",
                context.Request.Url.PathAndQuery,
                context.Request.UserHostName);

    Socket socket = null;

    string[] hostAndPort;
    if (context.Request.UserHostName.Contains(":"))
    {
        hostAndPort = context.Request.UserHostName.Split(':');
    }
    else
    {
        hostAndPort = new string[] { context.Request.UserHostName, "80" };
    }

    IPHostEntry ipAddress = Dns.GetHostEntry(hostAndPort[0]);
    IPEndPoint ip = new IPEndPoint(IPAddress.Parse(ipAddress.AddressList[0].ToString()), int.Parse(hostAndPort[1]));
    socket = new Socket(ip.AddressFamily, SocketType.Stream, ProtocolType.Tcp);
    socket.Connect(ip);

BEGIN NEW CODE

Encoding ASCII = Encoding.ASCII;
Byte[] byteGetString = ASCII.GetBytes(getString);
Byte[] receiveByte = new Byte[256];
string response = string.Empty;
socket.Send(byteGetString, byteGetString.Length, 0);
Int32 bytes = socket.Receive(receiveByte, receiveByte.Length, 0);
response += ASCII.GetString(receiveByte, 0, bytes);
while (bytes > 0)
{
bytes = socket.Receive(receiveByte, receiveByte.Length, 0);
strPage = strPage + ASCII.GetString(receiveByte, 0, bytes);
}
socket.Close();

string separator = "\r\n\r\n";
string header = strPage.Substring(0,strPage.IndexOf(separator));
string content = strPage.Remove(0, strPage.IndexOf(separator) + 4);

byte[] byteResponse = ASCII.GetBytes(content);
context.Response.ContentLength64 = byteResponse .Length;
context.Response.OutputStream.Write(byteResponse , 0, byteResponse .Length);
context.Response.OutputStream.Close();

END NEW CODE

After connecting to the socket I don't know how to get the Stream response to decompress, and send back to context.Response.OutputStream

Any help will be appreciated. Thanks. Cheers.

EDIT 2: With this edit now seems to be working fine (same as HttpWebRequest at least). Do you find any error here?

EDIT 3: False alarm... Still can't get this working

EDIT 4: I needed to add the following lines to Scott's code ... because not always the first to bytes of reponseStream are the gzip magic number. The sequence seems to be: 0x0a (10), 0x1f (31), 0x8b (139). The last two are the gzip magic number. The first number was always before in my tests.

if (contentEncoding.Equals("gzip"))
{
    int magicNumber = 0;
    while (magicNumber != 10)
        magicNumber = responseStream.ReadByte();
    responseStream = new GZipStream(responseStream, CompressionMode.Decompress);
}

Answer 1

Socket, by definition, is the low level to access the network. You can even use datagram protocols with a socket. In that case a stream does not make sense at all.

While I'm not sure why are you doing what HttpWebRequest easily accomplishes, to read/write data to a socket, you use the Send/Receive methods. If you want to have a stream like access to a TCP socket, you should use the TcpClient/TcpListener classes which wrap a socket and provide a network stream for it.

Answer 2

There's also the NetworkStream class that takes a Socket as a parameter. ;)

Answer 3

Here's some code that works for me.

using System;
using System.Collections.Generic;
using System.IO;
using System.Net;
using System.Net.Sockets;
using System.Text;
using System.IO.Compression;

namespace HttpUsingSockets {
    public class Program {
        private static readonly Encoding DefaultEncoding = Encoding.ASCII;
        private static readonly byte[] LineTerminator = new byte[] { 13, 10 };

        public static void Main(string[] args) {
            var host = "stackoverflow.com";
            var url = "/questions/523930/sockets-in-c-how-to-get-the-response-stream";

            IPHostEntry ipAddress = Dns.GetHostEntry(host);
            var ip = new IPEndPoint(ipAddress.AddressList[0], 80);
            using (var socket = new Socket(ip.AddressFamily, SocketType.Stream, ProtocolType.Tcp)) {
                socket.Connect(ip);
                using (var n = new NetworkStream(socket)) {
                    SendRequest(n, new[] {"GET " + url + " HTTP/1.1", "Host: " + host, "Connection: Close", "Accept-Encoding: gzip"});

                    var headers = new Dictionary<string, string>();
                    while (true) {
                        var line = ReadLine(n);
                        if (line.Length == 0) {
                            break;
                        }
                        int index = line.IndexOf(':');
                        headers.Add(line.Substring(0, index), line.Substring(index + 2));
                    }

                    string contentEncoding;
                    if (headers.TryGetValue("Content-Encoding", out contentEncoding)) {
                        Stream responseStream = n;
                        if (contentEncoding.Equals("gzip")) {
                            responseStream = new GZipStream(responseStream, CompressionMode.Decompress);
                        }
                        else if (contentEncoding.Equals("deflate")) {
                            responseStream = new DeflateStream(responseStream, CompressionMode.Decompress);
                        }

                        var memStream = new MemoryStream();

                        var respBuffer = new byte[4096];
                        try {
                            int bytesRead = responseStream.Read(respBuffer, 0, respBuffer.Length);
                            while (bytesRead > 0) {
                                memStream.Write(respBuffer, 0, bytesRead);
                                bytesRead = responseStream.Read(respBuffer, 0, respBuffer.Length);
                            }
                        }
                        finally {
                            responseStream.Close();
                        }

                        var body = DefaultEncoding.GetString(memStream.ToArray());
                        Console.WriteLine(body);
                    }
                    else {
                        while (true) {
                            var line = ReadLine(n);
                            if (line == null) {
                                break;
                            }
                            Console.WriteLine(line);
                        }
                    }
                }
            }
        }

        static void SendRequest(Stream stream, IEnumerable<string> request) {
            foreach (var r in request) {
                var data = DefaultEncoding.GetBytes(r);
                stream.Write(data, 0, data.Length);
                stream.Write(LineTerminator, 0, 2);
            }
            stream.Write(LineTerminator, 0, 2);
            // Eat response
            var response = ReadLine(stream);
        }

        static string ReadLine(Stream stream) {
            var lineBuffer = new List<byte>();
            while (true) {
                int b = stream.ReadByte();
                if (b == -1) {
                    return null;
                }
                if (b == 10) {
                    break;
                }
                if (b != 13) {
                    lineBuffer.Add((byte)b);
                }
            }
            return DefaultEncoding.GetString(lineBuffer.ToArray());
        }
    }
}

You could substitute this for the Socket/NetworkStream and save a bit of work.

using (var client = new TcpClient(host, 80)) {
      using (var n = client.GetStream()) {
     }
}