Question

Following on from the post How to create a simple proxy in C#? I have been playing around with implementing a basic proxy.

Where I am getting stuck and confused is trying to issue a WebRequest with the information provided in the original request.

Using the following code.

WebRequest webRequest = WebRequest.Create("http://www.google.com");

(webRequest as HttpWebRequest).UserAgent = "MOZILLA/5.0 (WINDOWS NT 6.1; WOW64) APPLEWEBKIT/537.1 (KHTML, LIKE GECKO) CHROME/21.0.1180.75 SAFARI/537.1";
webRequest.Method = "GET";

WebResponse webResponse = webRequest.GetResponse();
Stream responseStream = webResponse.GetResponseStream();
byte[] responseBytes = responseStream.ReadFully();

I can successfully issue a request and return the page content.

However when I put it inside a Proxy request (IE: TcpListener) like such.

TcpListener _listener = new TcpListener(IPAddress.Any, 1234);
this._listener.Start();
byte[] bytes = new byte[1024];
while (true)
{
    TcpClient client = this._listener.AcceptTcpClient();
    NetworkStream networkStream = client.GetStream();
    int i = networkStream.Read(bytes, 0, bytes.Length);
    while (i != 0)
    {
        string data = System.Text.Encoding.ASCII.GetString(bytes, 0, i);
        RequestHeader header = new RequestHeader(data.ToUpper());
        WebRequest webRequest = WebRequest.Create(header.URL);
        (webRequest as HttpWebRequest).UserAgent = header.UserAgent;
        webRequest.Method = "GET";
        WebResponse webResponse = webRequest.GetResponse(); //It gets here and never returns
        Stream responseStream = webResponse.GetResponseStream();
        byte[] responseBytes = responseStream.ReadFully();
        networkStream.Write(responseBytes, 0, responseBytes.Length);
        i = networkStream.Read(bytes, 0, bytes.Length);
    }
    client.Close();
}

It blocks at the line WebResponse webResponse = webRequest.GetResponse(); and never returns.

This has definitely got nothing to do with the data provided by the RequestHeader class I created as I’ve also tried hardcoding the values.

I’m assuming I’m missing something fundamental about the way sockets work in such a scenario and the approach required. Hopefully someone can clarify for me.

Answer 1

So it turned out to be a proxy issue.

Basically for testing I needed to set the machine proxy to 127.0.0.1:1234 or similar.

This in turn was being used in the default settings when initializing a WebRequest.

So all I needed to do in the end was the following to bypass the proxy.

(webRequest as HttpWebRequest).UserAgent = header.UserAgent;
webRequest.Method = "GET";
webRequest.Proxy = null; //Adding this line cleared the proxy.