C#使用Titanium.Web.Proxy做代理监控并修改网页

  • 2021年7月22日
  • 技术
介绍:

Titanium.Web.Proxy是用 C# 编写的轻量级 HTTP(S) 代理服务器,类似于转包工具Fiddler,但是比 Fiddler 强大很多。

特点:
  • 采用服务器连接池、证书缓存和缓冲池的多线程完全异步代理
  • 查看/修改/重定向/阻止请求和响应
  • 支持相互 SSL 认证、代理认证和自动上游代理检测
  • Windows 域的基于 HTTP 协议的 Kerberos/NTLM 身份验证
  • SOCKS4/5 代理支持
应用:

在访问指定域名网站中,对其网页进行注入对网页内容做修改

1,首先,使用Visual Studio 2019新建一个C#控制台应用程序的项目,在项目中使用使用NuGet引用 Titanium.Web.Proxy 包,注意NuGet的镜像源;

2,然后开始代码实现,在Program.cs中:

using System;
namespace WebProxy
{
    internal class Program
    {
        private static void Main(string[] args)
        {
            Proxy p = new();
            p.Start();
            Console.Read();
            p.Stop();
        }
    }
}

3,新建项目项Proxy.cs文件:

using System;
using System.Net;
using System.Threading;
using System.Threading.Tasks;
using Titanium.Web.Proxy;
using Titanium.Web.Proxy.EventArguments;
using Titanium.Web.Proxy.Models;

namespace WebProxy
{
    public class Proxy
    {
        private readonly SemaphoreSlim @lock = new(1);
        private readonly ProxyServer proxyServer;

        private readonly ExplicitProxyEndPoint explicitEndPoint;
        public const string LocalDomain = "www.baidu.com";

        public Proxy()
        {
            proxyServer = new ProxyServer();
            proxyServer.BeforeResponse += OnResponse;

            //绑定监听端口
            Random rnd = new Random();
            explicitEndPoint = new ExplicitProxyEndPoint(IPAddress.Any, 56801, true);
            Console.WriteLine("监听地址127.0.0.1:56801");

            //隧道请求连接前事件,HTTPS用
            explicitEndPoint.BeforeTunnelConnectRequest += ExplicitEndPoint_BeforeTunnelConnectRequest;

            //代理服务器注册监听地址
            proxyServer.AddEndPoint(explicitEndPoint);
        }

        public void Start()
        {
            Console.WriteLine("开始监听");
            proxyServer.Start();
            proxyServer.SetAsSystemHttpProxy(explicitEndPoint);
            proxyServer.SetAsSystemHttpsProxy(explicitEndPoint);
        }

        public void Stop()
        {
            if (proxyServer.ProxyRunning)
            {
                proxyServer.BeforeResponse -= OnResponse;
                explicitEndPoint.BeforeTunnelConnectRequest -= ExplicitEndPoint_BeforeTunnelConnectRequest;
                Console.WriteLine("结束监听");
                // 结束监听
                proxyServer.Stop();
            }
            else
            {
                Console.WriteLine("监听没开启");
            }

            try
            {
                proxyServer.DisableAllSystemProxies();
            }
            catch
            {
                Console.WriteLine("清除代理");
            }
            proxyServer.Dispose();
        }


        private async Task ExplicitEndPoint_BeforeTunnelConnectRequest(object sender, TunnelConnectSessionEventArgs e)
        {
            string hostname = e.HttpClient.Request.RequestUri.Host;
            await WaitMessage("Tunnel to: " + hostname);

            e.DecryptSsl = false;
            if (hostname.StartsWith(LocalDomain))
            {
                e.DecryptSsl = true;
            }
        }

        public async Task OnResponse(object sender, SessionEventArgs e)
        {
            var request = e.HttpClient.Request;
            if (request.Host.Contains(LocalDomain))
            {
                Console.WriteLine("code:" + e.HttpClient.Response.StatusCode);
                if (e.HttpClient.Request.Method == "GET")
                {
                    if (e.HttpClient.Response.StatusCode == 200)
                    {
                        if (e.HttpClient.Response.ContentType != null && e.HttpClient.Response.ContentType.Trim().ToLower().Contains("text/html"))
                        {
                            var doc = await e.GetResponseBodyAsString();

                            var t = e.HttpClient.Response.Headers.GetFirstHeader("Content-Security-Policy");
                            if (!string.IsNullOrEmpty(t?.Value))
                            {
                                e.HttpClient.Response.Headers.RemoveHeader(t);
                            }

                            //放到body
                            var index = doc.LastIndexOf("</body>", StringComparison.OrdinalIgnoreCase);
                            var temp = $"<script type=\"text/javascript\" ></script>";
                            TimeSpan ts = DateTime.Now - new DateTime(1970, 1, 1, 0, 0, 0, 0);
                            var time = Convert.ToInt64(ts.TotalSeconds).ToString();
                            temp += $"<script type=\"text/javascript\">alert(\"看到我了吗?\");</script>";
                            if (index > -1)
                            {
                                doc = doc.Insert(index, temp);
                                e.SetResponseBodyString(doc);
                            }
                        }
                    }
                }
            }
        }

        private async Task WaitMessage(string message)
        {
            await @lock.WaitAsync();
            Console.WriteLine(message);
            @lock.Release();
        }
    }
}

3,最后执行便可以开始抓包,在浏览器访问www.baidu.com后,效果如下:

注意:挂梯子时要使用系统代理才能抓到包

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