Unobtanium Web Proxy

A lightweight HTTP(S) proxy server written in C# NET8.0.

Report bugs or raise issues here.

Project reboot

This project is a reboot of the original Titanium-Web-Proxy project. The original project was last updated two years ago, has been archived by the author on July 9th 2023 and has been inactive since then. This project aims to continue the development of the original project and provide a stable and reliable proxy server library for .NET developers.

Announcement Reboot discussion Issues

Reboot focus

• net8.0 only (no support for older versions of .NET!)
• Support for ILogger See #4
• Support for diagnostic events using ActivitySource and Activity See #3
• Using the latest .NET features like Span<T> and Memory<T> to improve performance
• Update dependencies to the latest versions
• TLS 1.2 and TLS 1.3 only support
• Event-handlers with HttpRequestMessage and HttpResponseMessage, to greatly improve the portability of the library See #6
• HttpClient as the default client, and using the IHttpClientFactory to handle pooling of the clients
• Testing, testing, testing!

Features

• API Documentation
• Wiki & Contribution guidelines
• Multithreaded and asynchronous proxy employing server connection pooling, certificate cache, and buffer pooling
• View, modify, redirect and block requests or responses
• Supports mutual SSL authentication, proxy authentication & automatic upstream proxy detection
• Supports kerberos, NTLM authentication over HTTP protocols on windows domain controlled networks
• SOCKS4/5 Proxy support

Installation

Package on NuGet, Unobtanium.Web.Proxy will be a partial drop-in replacement for Titanium.Web.Proxy, if you're on NET8.0 or higher.

dotnet add package Unobtanium.Web.Proxy

Supports

• .NET 8.0 and above

As stated above, this project is a reboot of the original project. Expect things to change, everything marked as obsolete in the original project will be removed in this project. And until this is v1.0.0, expect breaking changes.

Collaborators

The owner of this project, justcoding121, is considered to be inactive from this project due to his busy work schedule. See project reboot for more information.

Previous contributors:

• justcoding121 owner
• honfika

Current contributors:

• svrooij

You contributions are more then welcome! Let's make this project great again!

Development environment

Since this is a dotnet project I would suggest to use Visual Studio 2022 or Visual Studio Code as your development environment. The project is set up to use the dotnet CLI, so you can also use that to build and run the project.

Usage

Refer the Unobtanium.Web.Proxy in your project and check one of the example projects.

Setup HTTP proxy:

using Titanium.Web.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.BeforeTunnelConnectRequest += OnBeforeTunnelConnectRequest;

// 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.BeforeTunnelConnectRequest -= OnBeforeTunnelConnectRequest;
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.Headers;

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

        // Get/Set request body as string
        string bodyString = await e.GetRequestBodyAsString();
        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.Headers;

    //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.StatusCode == 200)
        {
            if (e.HttpClient.Response.ContentType != null && e.HttpClient.Response.ContentType.Trim().ToLower().Contains("text/html"))
            {
                byte[] bodyBytes = await e.GetResponseBody();
                e.SetResponseBody(bodyBytes);

                string body = await e.GetResponseBodyAsString();
                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.CompletedTask;
}

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

Console example application screenshot

GUI example application screenshot