推荐一个比FiddlerCore好用的HTTP(S)代理服务器

为什么不用FiddlerCore？

说到FiddlerCore大家可能会比较陌生，那么它哥Fiddler就比较熟悉了；抓包、模拟低带宽、修改请求我平时比较常用。Fiddler的本质就是一个HTTP代理服务器。
FiddlerCore是Fiddler去除了UI的核心组件，可以用于二次开发。如下图所示：

Fiddler主要有以下几点感觉很别扭：

1. API命名不规范、属性/字段混用。
   .NET中普遍采用Pascal命名规范，而Fiddler的命名就像个大杂烩。例如：public成员用字段，CONFIG类名，oSession参数名
2. 不支持异步。所有的回调都是同步。
3. 框架设计不合理，不支持多实例，大量使用了静态方法。所有方法都堆到了Session类中不易于扩展，起码Request/Response也得分开啊。

单就以上几点我感觉这框架完全没有设计可言，如果没有别的选择FiddlerCore我或许就将就用了，好在Github上已经有人先一步重新实现了FiddlerCore

Titanium-Web-Proxy介绍

一个跨平台、轻量级、低内存、高性能的HTTP(S)代理服务器，开发语言为C#

https://github.com/justcoding121/Titanium-Web-Proxy

功能特性

1. 支持HTTP(S)与HTTP 1.1的大部分功能
2. 支持redirect/block/update 请求
3. 支持更新Response
4. 支持HTTP承载的WebSocket
5. Support mutual SSL authentication
6. 完全异步的代理
7. 支持代理授权与自动代理检测
8. Kerberos/NTLM authentication over HTTP protocols for windows domain

使用

安装NuGet包

Install-Package Titanium.Web.Proxy

支持

• .Net Standard 1.6或更高
• .Net Framework 4.5或更高

设置HTTP代理

var proxyServer = new ProxyServer();

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

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

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


var explicitEndPoint = new ExplicitProxyEndPoint(IPAddress.Any, 8000, true)
{
//Exclude HTTPS addresses you don't want to proxy
//Useful for clients that use certificate pinning
//for example dropbox.com
// ExcludedHttpsHostNameRegex = new List<string>() { "google.com", "dropbox.com" }

//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")
};

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

proxyServer.Stop();

简单的请求与响应处理

//To access requestBody from OnResponse handler
private IDictionary<Guid, string> requestBodyHistory 
        = new ConcurrentDictionary<Guid, string>();

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

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

    var method = e.WebSession.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 Body/request headers etc with request Id as key
	//so that you can find it from response handler using request Id
  	requestBodyHistory[e.Id] = bodyString;
    }

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

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

    //if (!e.ProxySession.Request.Host.Equals("medeczane.sgk.gov.tr")) return;
    if (e.WebSession.Request.Method == "GET" || e.WebSession.Request.Method == "POST")
    {
	if (e.WebSession.Response.ResponseStatusCode == "200")
	{
	    if (e.WebSession.Response.ContentType!=null && e.WebSession.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);
	    }
	}
    }
    
    //access request body/request headers etc by looking up using requestId
    if(requestBodyHistory.ContainsKey(e.Id))
    {
	var requestBody = requestBodyHistory[e.Id];
    }
}

/// 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);
}

未来路线图

• 支持HTTP 2.0
• 支持Socks协议