Titanium Web Proxy

A lightweight HTTP(S) proxy server written in C#.

Kindly report only issues/bugs here. For programming help or questions use StackOverflow with the tag Titanium-Web-Proxy.

• API Documentation
• Wiki & Contribution guidelines

Features

• Multi-threaded fully asynchronous proxy employing server connection pooling, certificate cache, and buffer pooling
• View/modify/redirect/block requests and responses
• Supports mutual SSL authentication, proxy authentication & automatic upstream proxy detection
• Kerberos/NTLM authentication over HTTP protocols for windows domain

Installation

Install by nuget

For beta releases on beta branch

Install-Package Titanium.Web.Proxy -Pre

For stable releases on stable branch

Install-Package Titanium.Web.Proxy

Supports

• .Net Standard 2.0 or above
• .Net Framework 4.5 or above

Development environment

Windows

• Visual Studio Code as IDE for .NET core
• Visual Studio 2017 as IDE for .NET framework/.NET core

Mac OS

• Visual Studio Code as IDE for .NET core
• Visual Studio 2017 as IDE for Mono

Linux

• Visual Studio Code as IDE for .NET core
• Mono develop as IDE for Mono

Usage

Refer the HTTP Proxy Server library in your project and look up the test project to learn usage.

Setup HTTP proxy:

var proxyServer = new ProxyServer();

//locally trust root certificate used by this proxy 
proxyServer.CertificateManager.TrustRootCertificate = true;

//optionally set the Certificate Engine
//Under Mono only BouncyCastle will be supported
//proxyServer.CertificateManager.CertificateEngine = Network.CertificateEngine.BouncyCastle;

proxyServer.BeforeRequest += OnRequest;
proxyServer.BeforeResponse += OnResponse;
proxyServer.ServerCertificateValidationCallback += OnCertificateValidation;
proxyServer.ClientCertificateSelectionCallback += OnCertificateSelection;


var explicitEndPoint = new ExplicitProxyEndPoint(IPAddress.Any, 8000, true)
{
//Use self-issued generic certificate on all https requests
//Optimizes performance by not creating a certificate for each https-enabled domain
//Useful when certificate trust is not required by proxy clients
//GenericCertificate = new X509Certificate2(Path.Combine(System.IO.Path.GetDirectoryName(System.Reflection.Assembly.GetExecutingAssembly().Location), "genericcert.pfx"), "password")
};

//Fired when a CONNECT request is received
explicitEndPoint.BeforeTunnelConnect += OnBeforeTunnelConnect;

//An explicit endpoint is where the client knows about the existence of a proxy
//So client sends request in a proxy friendly manner
proxyServer.AddEndPoint(explicitEndPoint);
proxyServer.Start();

//Transparent endpoint is useful for reverse proxy (client is not aware of the existence of proxy)
//A transparent endpoint usually requires a network router port forwarding HTTP(S) packets or DNS
//to send data to this endPoint
var transparentEndPoint = new TransparentProxyEndPoint(IPAddress.Any, 8001, true)
{
	//Generic Certificate hostname to use
	//when SNI is disabled by client
	GenericCertificateName = "google.com"
};

proxyServer.AddEndPoint(transparentEndPoint);

//proxyServer.UpStreamHttpProxy = new ExternalProxy() { HostName = "localhost", Port = 8888 };
//proxyServer.UpStreamHttpsProxy = new ExternalProxy() { HostName = "localhost", Port = 8888 };

foreach (var endPoint in proxyServer.ProxyEndPoints)
Console.WriteLine("Listening on '{0}' endpoint at Ip {1} and port: {2} ",
    endPoint.GetType().Name, endPoint.IpAddress, endPoint.Port);

//Only explicit proxies can be set as system proxy!
proxyServer.SetAsSystemHttpProxy(explicitEndPoint);
proxyServer.SetAsSystemHttpsProxy(explicitEndPoint);

//wait here (You can use something else as a wait function, I am using this as a demo)
Console.Read();

//Unsubscribe & Quit
explicitEndPoint.BeforeTunnelConnect -= OnBeforeTunnelConnect;
proxyServer.BeforeRequest -= OnRequest;
proxyServer.BeforeResponse -= OnResponse;
proxyServer.ServerCertificateValidationCallback -= OnCertificateValidation;
proxyServer.ClientCertificateSelectionCallback -= OnCertificateSelection;

proxyServer.Stop();
	

Sample request and response event handlers

private async Task OnBeforeTunnelConnectRequest(object sender, TunnelConnectSessionEventArgs e)
{
    string hostname = e.HttpClient.Request.RequestUri.Host;

    if (hostname.Contains("dropbox.com"))
    {
         //Exclude Https addresses you don't want to proxy
         //Useful for clients that use certificate pinning
         //for example dropbox.com
         e.DecryptSsl = false;
    }
}

public async Task OnRequest(object sender, SessionEventArgs e)
{
    Console.WriteLine(e.HttpClient.Request.Url);

    ////read request headers
    var requestHeaders = e.HttpClient.Request.RequestHeaders;

    var method = e.HttpClient.Request.Method.ToUpper();
    if ((method == "POST" || method == "PUT" || method == "PATCH"))
    {
	//Get/Set request body bytes
	byte[] bodyBytes = await e.GetRequestBody();
	await e.SetRequestBody(bodyBytes);

	//Get/Set request body as string
	string bodyString = await e.GetRequestBodyAsString();
	await e.SetRequestBodyString(bodyString);
	
	//store request 
	//so that you can find it from response handler 
  	e.UserData = e.HttpClient.Request;
    }

    //To cancel a request with a custom HTML content
    //Filter URL
    if (e.HttpClient.Request.RequestUri.AbsoluteUri.Contains("google.com"))
    {
	e.Ok("<!DOCTYPE html>" +
	      "<html><body><h1>" +
	      "Website Blocked" +
	      "</h1>" +
	      "<p>Blocked by titanium web proxy.</p>" +
	      "</body>" +
	      "</html>");
    }
    //Redirect example
    if (e.HttpClient.Request.RequestUri.AbsoluteUri.Contains("wikipedia.org"))
    {
	e.Redirect("https://www.paypal.com");
    }
}

//Modify response
public async Task OnResponse(object sender, SessionEventArgs e)
{
    //read response headers
    var responseHeaders = e.HttpClient.Response.ResponseHeaders;

    //if (!e.ProxySession.Request.Host.Equals("medeczane.sgk.gov.tr")) return;
    if (e.HttpClient.Request.Method == "GET" || e.HttpClient.Request.Method == "POST")
    {
	if (e.HttpClient.Response.ResponseStatusCode == "200")
	{
	    if (e.HttpClient.Response.ContentType!=null && e.HttpClient.Response.ContentType.Trim().ToLower().Contains("text/html"))
	    {
		byte[] bodyBytes = await e.GetResponseBody();
		await e.SetResponseBody(bodyBytes);

		string body = await e.GetResponseBodyAsString();
		await e.SetResponseBodyString(body);
	    }
	}
    }
    
    if(e.UserData!=null)
    {
	    //access request from UserData property where we stored it in RequestHandler
	    var request = (Request)e.UserData;
    }
    
}

/// Allows overriding default certificate validation logic
public Task OnCertificateValidation(object sender, CertificateValidationEventArgs e)
{
    //set IsValid to true/false based on Certificate Errors
    if (e.SslPolicyErrors == System.Net.Security.SslPolicyErrors.None)
	e.IsValid = true;

    return Task.FromResult(0);
}

/// Allows overriding default client certificate selection logic during mutual authentication
public Task OnCertificateSelection(object sender, CertificateSelectionEventArgs e)
{
    //set e.clientCertificate to override
    return Task.FromResult(0);
}

Note to contributors

Road map

• Support HTTP 2.0

Collaborators

• honfika

Console example application screenshot

GUI example application screenshot