使用代理访问web

http://support.microsoft.com/kb/307023

/* * REVERSE PROXY SERVER - IIS HTTP HANDLER - C# .NET v2.0 *  * FILE NAME    :    Program.cs *  * DATE CREATED :    March 26, 2007, 16:15:05 * CREATED BY   :    Gunasekaran Paramesh *  * LAST UPDATED :    April 16, 2007, 3:10:09 PM * UPDATED BY   :    Gunasekaran Paramesh *  * DESCRIPTION  :    Implementation of Reverse Proxy Server through IIS HTTP                      handler in C# .NET v2.0*/using System;using System.IO;using System.Net;using System.Web;using System.Text;using System.Web.Mail;using System.Collections;using System.Configuration;using System.Web.SessionState;using System.DirectoryServices;namespace TryHTTPHandler{public class SyncHandler : IHttpHandler, IRequiresSessionState{    public bool IsReusable { get { return true; } }    // Process incoming request    public void ProcessRequest(HttpContext Context)    {                    string ServerURL = "";                    try        {            // Parsing incoming URL and extracting original server URL            char[] URL_Separator = { '/' };            string[] URL_List = Context.Request.Url.AbsoluteUri.Remove(0,                 7).Split(URL_Separator);            ServerURL = "http://" +                 URL_List[2].Remove(URL_List[2].Length - 5, 5) + @"/";            string URLPrefix = @"/" + URL_List[1] + @"/" +                 URL_List[2]; // Eg. "/handler/stg2web.sync";            for ( int i = 3; i < URL_List.Length; i++ )                ServerURL += URL_List[i] + @"/";            ServerURL = ServerURL.Remove(ServerURL.Length -1, 1);            WriteLog(ServerURL + " (" +                 Context.Request.Url.ToString() + ")");            // Extracting POST data from incoming request            Stream RequestStream = Context.Request.InputStream;            byte[] PostData = new byte[Context.Request.InputStream.Length];            RequestStream.Read(PostData, 0,                (int) Context.Request.InputStream.Length);            // Creating proxy web request            HttpWebRequest ProxyRequest = (                HttpWebRequest) WebRequest.Create(ServerURL);            if ( ConfigurationManager.AppSettings["UpchainProxy"] ==                 "true" )                ProxyRequest.Proxy = new WebProxy(                    ConfigurationManager.AppSettings["Proxy"], true);            ProxyRequest.Method = Context.Request.HttpMethod;            ProxyRequest.UserAgent = Context.Request.UserAgent;                            CookieContainer ProxyCookieContainer = new CookieContainer();            ProxyRequest.CookieContainer = new CookieContainer();            ProxyRequest.CookieContainer.Add(                ProxyCookieContainer.GetCookies(new Uri(ServerURL)));            ProxyRequest.KeepAlive = true;            //For POST, write the post data extracted from the incoming request            if ( ProxyRequest.Method == "POST" )            {                ProxyRequest.ContentType =                     "application/x-www-form-urlencoded";                ProxyRequest.ContentLength = PostData.Length;                Stream ProxyRequestStream = ProxyRequest.GetRequestStream();                ProxyRequestStream.Write(PostData, 0, PostData.Length);                ProxyRequestStream.Close();            }            // Getting response from the proxy request                            HttpWebResponse ProxyResponse = (                HttpWebResponse) ProxyRequest.GetResponse();            if (ProxyRequest.HaveResponse)            {                // Handle cookies                foreach(Cookie ReturnCookie in ProxyResponse.Cookies)                {                    bool CookieFound = false;                    foreach(Cookie OldCookie in                         ProxyCookieContainer.GetCookies(new Uri(ServerURL)))                    {                        if (ReturnCookie.Name.Equals(OldCookie.Name))                        {                            OldCookie.Value = ReturnCookie.Value;                            CookieFound = true;                        }                    }                    if (!CookieFound)                        ProxyCookieContainer.Add(ReturnCookie);                }            }            Stream StreamResponse = ProxyResponse.GetResponseStream();            int ResponseReadBufferSize = 256;            byte[] ResponseReadBuffer = new byte[ResponseReadBufferSize];            MemoryStream MemoryStreamResponse = new MemoryStream();            int ResponseCount = StreamResponse.Read(ResponseReadBuffer, 0,                 ResponseReadBufferSize);            while ( ResponseCount > 0 )            {                MemoryStreamResponse.Write(ResponseReadBuffer, 0,                     ResponseCount);                ResponseCount = StreamResponse.Read(ResponseReadBuffer, 0,                     ResponseReadBufferSize);            }            byte[] ResponseData = MemoryStreamResponse.ToArray();            string ResponseDataString = Encoding.ASCII.GetString(ResponseData);            // While rendering HTML, parse and modify the URLs present            if ( ProxyResponse.ContentType.StartsWith("text/html") )            {                HTML.ParseHTML Parser = new HTML.ParseHTML();                Parser.Source = ResponseDataString;                                    while( !Parser.Eof() )                {                    char ch = Parser.Parse();                    if ( ch == 0 )                    {                        HTML.AttributeList Tag = Parser.GetTag();                        if ( Tag["href"] != null )                        {                            if ( Tag["href"].Value.StartsWith(                                @"/") )                            {                                WriteLog("URL " +                                      Tag["href"].Value +                                     " modified to " + URLPrefix +                                     Tag["href"].Value);                                ResponseDataString =                                     ResponseDataString.Replace(                                    "/"" +                                     Tag["href"].Value +                                     "/"", "/"" +                                     URLPrefix + Tag["href"].Value +                                     "/"");                            }                        }                        if ( Tag["src"] != null )                        {                            if ( Tag["src"].Value.StartsWith(                                @"/") )                            {                                WriteLog("URL " +                                      Tag["src"].Value +                                     " modified to " +                                     URLPrefix + Tag["src"].Value);                                ResponseDataString =                                     ResponseDataString.Replace(                                    "/"" +                                     Tag["src"].Value +                                     "/"", "/"" +                                     URLPrefix + Tag["src"].Value +                                     "/"");                            }                        }                    }                }                Context.Response.Write(ResponseDataString);            }            else                Context.Response.OutputStream.Write(ResponseData, 0,                     ResponseData.Length);            MemoryStreamResponse.Close();            StreamResponse.Close();            ProxyResponse.Close();        }        catch ( Exception Ex )        {            Context.Response.Write(Ex.Message.ToString());            WriteLog("An error has occurred while requesting the URL                 " + ServerURL + "(" +                 Context.Request.Url.ToString() + ")/n" +                 Ex.ToString());        }    }            // Write debug log message    private void WriteLog(string Message)    {        FileStream FS = new FileStream(ConfigurationManager.AppSettings[            "Log"], FileMode.Append, FileAccess.Write);        string DateTimeString = DateTime.Now.ToString();        Message = "[" + DateTimeString + "] " + Message +             "/n";        byte[] FileBuffer = Encoding.ASCII.GetBytes(Message);        FS.Write(FileBuffer, 0, (int)FileBuffer.Length);        FS.Flush(); FS.Close();    }}}