Use fiddler as a https reverse proxy - timeout occurs

Question

I am trying to create a reverse proxy using Fiddler.Core which we can use to replay third party requests over http(s).

The lib works great for http, for for https, I seem to be lacking a step, as replaying the response simply seems to timeout.

Here is the code for the specs:

[TestClass]
public class Verify_basic_proxy_functionality
{
    WebClient WC;
    Proxy SUT;

    [TestInitialize]
    public void Init()
    {
        SUT = new Proxy();
        SUT.InsertSession(Url:"http://proxy/ping",ResponseBody:"pong");
        var uri = SUT.Startup(9100,IsRecording: false);
        WC = new WebClient() { Proxy = new WebProxy(uri)};
    }

    [TestMethod]
    public void Ping_should_return_pong()
    {
        WC.DownloadString("http://proxy/ping").ShouldBe("pong");
    }

    [TestMethod]
    [ExpectedException(typeof(WebException))]
    public void Pang_should_return_error()
    {
        WC.DownloadString("http://proxy/pang");
    }

    [TestMethod]
    public void Http_reverse_proxy_should_work()
    {
        SUT.IsRecording = true;
        var http_url = "http://httpbin.org/ip";
        var initial_result = WC.DownloadString(http_url);
        initial_result.ShouldContain("origin");
        SUT.IsRecording = false;
        var result = WC.DownloadString(http_url);
        result.ShouldBe(initial_result);
    }

    // This one fails with a timeout... Probably need to close the connection or similar?
    [TestMethod]
    public void Https_reverse_proxy_should_work()
    {
        SUT.IsRecording = true;
        var https_url = "https://httpbin.org/ip"; 
        var initial_result = WC.DownloadString(https_url);
        initial_result.ShouldContain("origin");
        SUT.IsRecording = false;
        var result = WC.DownloadString(https_url);
        result.ShouldBe(initial_result);
    }
}

The code for the proxy can be found over at this gist: https://gist.github.com/ToJans/5082560

I think I might need to add an extra step for https (i.e. encoding). AFAIK fiddler.core ignores certificate errors as I intercept the OnValidateServerCertificate and always return true.

Who can tell me what I am doing wrong here?

Answer 1

Well, a collegue of mine pointed me to a flaw in my thinking; when doing replay for SSL you should not record/replay the CONNECT!!!

MITM proxy works now.....