A reverse proxy tool written in C# that can cache web pages locally

<%@ WebHandler Language="C#" Class="proxy" %>
  
using System;
using System.Web;
using System.Net;
using System.Text;
using System.IO;
using System.Collections.Generic;
using System.Configuration;
  
  
  
/// <summary>
/// 把http headers 和 http 响应的内容 分别存储在 /proxy/header/ 和 /proxy/body/ 中
/// 分层次创建目录
/// </summary>
public class proxy : IHttpHandler
{
  
    HttpResponse Response;
    HttpRequest Request;
    HttpApplicationState Application;
    HttpServerUtility Server;
  
    static string proxyCacheFolder = ConfigurationManager.AppSettings["proxyCacheFolder"];
    static string proxyDomain = ConfigurationManager.AppSettings["proxyDomain"];
    static string proxyReferer = ConfigurationManager.AppSettings["proxyReferer"];
    bool proxyCacheDirectAccess = ConfigurationManager.AppSettings["proxyCacheDirectAccess"] == "true";
    int proxyCacheSeconds = int.Parse(ConfigurationManager.AppSettings["proxyCacheSeconds"]);
  
  
  
    public void ProcessRequest(HttpContext context)
    {
        Response = context.Response;
        Request = context.Request;
        Application = context.Application;
        Server = context.Server;
  
        string path = context.Request.RawUrl;
        bool delCache = path.IndexOf("?del") > 0;
        if (delCache)
        {
            path = path.Replace("?del", string.Empty);
            DeleteCacheFile(path);
            return;
        }
  
  
        bool allowCache = Request.QueryString["cache"] == "true";
        string seconds = Request.QueryString["seconds"] ?? string.Empty;
        if (!int.TryParse(seconds, out proxyCacheSeconds))
        {
            proxyCacheSeconds = 3600;
        }
  
        if (allowCache)
        {
  
            EchoData(path);
        }
        else
        {
  
            WebClient wc = new WebClient();
            wc.Headers.Set("Referer", proxyReferer);
            byte[] buffer = wc.DownloadData(proxyDomain + path);
            Response.ContentType = wc.ResponseHeaders["Content-Type"];
            foreach (string key in wc.ResponseHeaders.AllKeys)
            {
  
                Response.Headers.Set(key, wc.ResponseHeaders[key]);
            }
            wc.Dispose();
            Response.OutputStream.Write(buffer, 0, buffer.Length);
        }
  
  
  
    }
  
  
    /// <summary>
    /// 清理失效的缓存
    /// </summary>
    /// <param name="d"></param>
    void ClearTimeoutCache(DirectoryInfo d)
    {
        if (d.Exists)
        {
            FileInfo[] files = d.GetFiles();
            foreach (FileInfo file in files)
            {
                TimeSpan timeSpan = DateTime.Now - file.LastAccessTime;
                if (timeSpan.TotalSeconds > proxyCacheSeconds)
                {
                    file.Delete();
                }
            }
        }
    }
  
    string GetCacheFolderPath(string hash)
    {
        string s = string.Empty;
        for (int i = 0; i <= 2; i++)
        {
            s += hash[i] + "/";
        }
  
        return s;
    }
  
    /// <summary>
    /// 读取缓存的header 并输出
    /// </summary>
    /// <param name="cacheHeaderPath"></param>
    void EchoCacheHeader(string cacheHeaderPath)
    {
        string[] headers = File.ReadAllLines(cacheHeaderPath);
        for (int i = 0; i < headers.Length; i++)
        {
            string[] headerKeyValue = headers[i].Split(&#39;:&#39;);
            if (headerKeyValue.Length == 2)
            {
                if (headerKeyValue[0] == "Content-Type")
                {
                    Response.ContentType = headerKeyValue[1];
                }
                Response.Headers.Set(headerKeyValue[0], headerKeyValue[1]);
            }
  
        }
  
    }
  
  
  
    void DeleteCacheFile(string path)
    {
        string absFolder = Server.MapPath(proxyCacheFolder);
        string hash = GetHashString(path);
  
        string folder = GetCacheFolderPath(hash);
  
        string cacheBodyPath = absFolder + "/body/" + folder + hash;
        string cacheHeaderPath = absFolder + "/header/" + folder + hash;
  
        FileInfo cacheBody = new FileInfo(cacheBodyPath);
        FileInfo cacheHeader = new FileInfo(cacheHeaderPath);
  
        if (cacheBody.Exists)
        {
            cacheBody.Delete();
        }
  
        if (cacheHeader.Exists)
        {
            cacheHeader.Delete();
        }
  
        Response.Write("delete cache file Success!\r\n" + path);
    }
  
    /// <summary>
    /// 输出缓存
    /// </summary>
    /// <param name="cacheHeaderPath">缓存header 的文件路径</param>
    /// <param name="cacheBodyPath">缓存 body 的文件路径</param>
    /// <param name="ifTimeout">是否进行判断文件过期</param>
    /// <returns>是否输出成功</returns>
    bool EchoCacheFile(string cacheHeaderPath, string cacheBodyPath, bool ifTimeout)
    {
        FileInfo cacheBody = new FileInfo(cacheBodyPath);
        FileInfo cacheHeader = new FileInfo(cacheHeaderPath);
  
        ClearTimeoutCache(cacheBody.Directory);
        ClearTimeoutCache(cacheHeader.Directory);
  
        if (cacheBody.Exists && cacheHeader.Exists)
        {
  
            if (ifTimeout)
            {
                TimeSpan timeSpan = DateTime.Now - cacheBody.LastWriteTime;
                if (timeSpan.TotalSeconds < proxyCacheSeconds)
                {
                    EchoCacheHeader(cacheHeaderPath);
  
                    Response.TransmitFile(cacheBodyPath);
                    return true;
                }
            }
            else
            {
                EchoCacheHeader(cacheHeaderPath);
  
                Response.TransmitFile(cacheBodyPath);
                return true;
            }
  
        }
  
        return false;
    }
  
    void EchoData(string path)
    {
  
        string absFolder = Server.MapPath(proxyCacheFolder);
        string hash = GetHashString(path);
  
        string folder = GetCacheFolderPath(hash);
  
        string cacheBodyPath = absFolder + "/body/" + folder + hash;
        string cacheHeaderPath = absFolder + "/header/" + folder + hash;
  
        bool success;
        if (proxyCacheDirectAccess)
        {
            success = EchoCacheFile(cacheHeaderPath, cacheBodyPath, false);
            if (!success)
            {
                Response.Write("直接从缓存读取失败!");
            }
            return;
        }
  
        success = EchoCacheFile(cacheHeaderPath, cacheBodyPath, true);
  
        if (success)
        {
            return;
        }
  
  
  
  
        //更新Cache File
        string ApplicationKey = "CacheList";
        List<string> List = null;
  
  
        if (Application[ApplicationKey] == null)
        {           
            Application.Lock();
            Application[ApplicationKey] = List = new List<string>(1000);
            Application.UnLock();
        }
        else
        {
  
            List = (List<string>)Application[ApplicationKey];
  
        }
  
  
        //判断是否已有另一个进程正在更新Cache File
        if (List.Contains(hash))
        {
            success = EchoCacheFile(cacheHeaderPath, cacheBodyPath, false);
            if (success)
            {
                return;
            }
            else
            {
  
                WebClient wc = new WebClient();
                wc.Headers.Set("Referer", proxyReferer);
                //主体内容
                byte[] data = wc.DownloadData(proxyDomain + path);
  
                //处理header
                Response.ContentType = wc.ResponseHeaders["Content-Type"];
                foreach (string key in wc.ResponseHeaders.AllKeys)
                {
                    Response.Headers.Set(key, wc.ResponseHeaders[key]);
                }
                wc.Dispose();
                Response.BinaryWrite(data);
                  
            }
        }
        else
        {
  
            
   
  
            WebClient wc = new WebClient();
            wc.Headers.Set("Referer", proxyReferer);
            StringBuilder headersb = new StringBuilder();
  
            List.Add(hash);
            //主体内容
            byte[] data = wc.DownloadData(proxyDomain + path);
  
  
  
  
  
            //处理header
  
            Response.ContentType = wc.ResponseHeaders["Content-Type"];
            foreach (string key in wc.ResponseHeaders.AllKeys)
            {
                headersb.Append(key);
                headersb.Append(":");
                headersb.Append(wc.ResponseHeaders[key]);
                headersb.Append("\r\n");
                Response.Headers.Set(key, wc.ResponseHeaders[key]);
            }
            wc.Dispose();
  
            string headers = headersb.ToString().Trim();
            if (!Directory.Exists(absFolder + "/header/" + folder))
            {
                Directory.CreateDirectory(absFolder + "/header/" + folder);
            }
  
            StreamWriter sw = File.CreateText(absFolder + "/header/" + folder + hash);
            sw.Write(headers);
            sw.Close();
            sw.Dispose();
  
  
            //处理缓存内容
            if (!Directory.Exists(absFolder + "/body/" + folder))
            {
                Directory.CreateDirectory(absFolder + "/body/" + folder);
            }
  
            FileStream fs = File.Create(absFolder + "/body/" + folder + hash);
            fs.Write(data, 0, data.Length);
            fs.Close();
            fs.Dispose();
  
            List.Remove(hash);
              
            
  
            Response.BinaryWrite(data);
        }
    }
  
  
  
  
    string GetHashString(string path)
    {
        string md5 = GetMd5Str(path);
        return md5;
    }
  
  
    static string GetMd5Str(string ConvertString)
    {
        System.Security.Cryptography.MD5CryptoServiceProvider md5 = new System.Security.Cryptography.MD5CryptoServiceProvider();
        string t2 = BitConverter.ToString(md5.ComputeHash(UTF8Encoding.Default.GetBytes(ConvertString)), 4, 8);
        t2 = t2.Replace("-", "");
  
        return t2;
    }
  
  
    public bool IsReusable
    {
        get
        {
            return false;
        }
    }
  
}

<?xml version="1.0"?>
<configuration>
  <configSections>
    <section name="RewriterConfig" type="URLRewriter.Config.RewriterConfigSerializerSectionHandler, URLRewriter"/>  
  </configSections>
  <RewriterConfig>
    <Rules>
  
  
        
      <RewriterRule>
        <LookFor>~/.*$</LookFor>
        <SendTo>
        <!--cache=true 设置此路径进行缓存-->
          <![CDATA[~/proxy.ashx?cache=true&seconds=30]]>
        </SendTo>
      </RewriterRule>
  
      <RewriterRule>
        <LookFor>~/ajax/.*$</LookFor>
        <SendTo>
        <!--cache=false 设置此路径不允许缓存-->
          <![CDATA[~/proxy.ashx?cache=false]]>
        </SendTo>
      </RewriterRule>
        
    </Rules>
  </RewriterConfig>
  
  <appSettings>
      
    <!--#反向代理设置 start-->
  
    <!--设置站点-->
    <add key="proxyDomain" value="http://127.0.0.1:12123/"/>
  
    <!--缓存文件夹-->
    <add key="proxyCacheFolder" value="/proxyCache/"/>
  
    <!--缓存时长-->
    <add key="proxyCacheSeconds" value="3600"/>
  
    <!--设置不再判断缓存文件是否超时，直接从缓存读取-->
    <add key="proxyCacheDirectAccess" value="false"/>
  
    <!--设置反向代理Referer-->
    <add key="proxyReferer" value="http://www.www.com/"/>
    <!--#反向代理设置 end-->
      
      
  </appSettings>
    
  <system.webServer>
    <modules runAllManagedModulesForAllRequests="true">
      <add type="URLRewriter.ModuleRewriter, URLRewriter" name="ModuleRewriter"/>
    </modules>
  </system.webServer>
  
  <system.web>
    <compilation debug="true"/>
  </system.web>
    
</configuration>