Titanium Web Proxy

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

Report bugs or raise issues here. For programming help use StackOverflow with the tag Titanium-Web-Proxy.

Features

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

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

Note to contributors

Road map

Fix outstanding bugs
Support reading request and response body as stream #823
Stop throwing new exceptions #634
Support HTTP 2.0

Collaborators

The owner of this project, justcoding121, is considered to be inactive from this project due to his busy work schedule. However, we have a collaborator listed below who time and again shows up to maintain this project. Please create pull requests prioritizing bug fixes for the attention of collaborators.

honfika

Development environment

Windows

Visual Studio Code as IDE for .NET
Visual Studio 2022 as IDE for .NET Framework/.NET

Mac OS

Visual Studio Code as IDE for .NET
Visual Studio 2022 as IDE for Mono

Linux

Visual Studio Code as IDE for .NET
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.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

License

justcoding121/titanium-web-proxy

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