Sunday, May 02, 2010

Sockets in C#: How to make a HEAD request

this sample have been taken from: http://stackoverflow.com/questions/523930/sockets-in-c-how-to-get-the-response-stream and only one single line needed to be adapted to make a HTTP HEAD request instead of a get



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 Program2
{
private static readonly Encoding DefaultEncoding = Encoding.ASCII;
private static readonly byte[] LineTerminator = new byte[] { 13, 10 };

public static void Main2()
{
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" });
SendRequest(n, new[] { "HEAD " + 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));
}

Console.WriteLine("Headers: ");

foreach (string key in headers.Keys)
{
Console.WriteLine("{0}: {1} ", key, headers[key]);
}

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());
}
}
}

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