粗糙的C#版HTTP代理 's

作者：云舒

前些时候一个无锡人在我博客留言，说我读再多的书，也改变不了我是个程序员的本质。或许它觉得它是在鄙视我，不过我到觉得它是在赞扬我——我真的算不上是个程序员，写代码的能力实在是太烂了——不过我会努力的。

说说这段代码的问题吧。首先是字符串切割的问题，要将客户端提交过来的GET，POST等原始请求切割，分离出主机名，端口，URL等数据。这里用正则匹配是最好的，遗憾的是我不擅长此道，所以使用了手动切割的办法，很笨重繁琐，但是毕竟它工作得很好。第二个问题是Keep-Alive的问题，这里我没有处理好。最开始我在http proxy里面修改客户端请求，强行将keep-alive修改为close，但是发现在某些站点的时候会出错。于是使用了类似select的方法读取数据，直到超时关闭两端的连接。我猜测，这里如果解析content-length会更好，但是略微繁琐了点，还是等我仔细阅读下RFC再看怎么修改吧。第三个是CONNECT方法的问题，这个到很简单，转发数据就行了，因此是这个代码中写得最好的一部分，用来登陆QQ还是不错的。

说实话，我不喜欢HTTP这种太宽松的协议，感觉灵活得让我难以把握。直接看代码吧，我加了很多debug信息，真的要用就去掉好了。调用这个类很简单，看main函数的实现就好了。为了方便贴代码，我写的时候就把三个类写到一个文件里面去了。顺便要说的是，虽然有类，但是没有任何面向对象的东西——这也再次证明，其实我算不上一个程序员，最多是个代码爱好者。

using System;  using System.Net;  using System.Net.Sockets;  using System.Text;  using System.IO;  using System.Threading;  using System.Collections;  namespace HttpProxy  {  public class HttpProxy  {  int ProxyPort;  /// <summary>  /// 代理服务器入口类构造函数  /// </summary>  /// <param name="Port">Http Proxy监听的端口</param>  public HttpProxy( int Port)  {  ProxyPort = Port;  }  /// <summary>  /// 启动Http代理服务器  /// </summary>  public void Start( )  {  TcpListener tcplistener = null;  try  {  // 开始监听端口  tcplistener = new TcpListener(Dns.GetHostAddresses(Dns.GetHostName())[0], ProxyPort);  tcplistener.Start();  Console.WriteLine("侦听端口号: " + ProxyPort.ToString());  }  catch (Exception e)  {  Console.WriteLine("启动代理服务器失败: " + e.Message);  }  while (true)  {  try  {  // 接受客户端连接  Socket socket = tcplistener.AcceptSocket();  HttpSession Session = new HttpSession(socket);  // 启动新线程，处理连接  Thread thread = new Thread(new ThreadStart(Session.Start));  thread.Start();  }  catch( Exception e )  {  Console.WriteLine("接受客户端连接异常: " + e.Message );  }  }  }  }  public class HttpSession  {  // 客户端socket  Socket ClientSocket;  // 设定编码  Encoding ASCII = Encoding.ASCII;  /// <summary>  /// 构造函数  /// </summary>  /// <param name="socket">客户端socket</param>  public HttpSession(Socket socket)  {  this.ClientSocket = socket;  }  public void Start()  {  // 客户端缓冲区，读取客户端命令  Byte[] ReadBuff = new byte[1024 * 10];  try  {  int Length = ClientSocket.Receive(ReadBuff);  // 没有读到数据  if (0 == Length)  {  Console.WriteLine("从客户端读取命令错误");  ClientSocket.Shutdown(SocketShutdown.Both);  ClientSocket.Close();  return;  }  }  // 读取出现异常  catch (Exception e)  {  Console.WriteLine("读取客户端异常: " + e.Message);  }  // 来自客户端的HTTP请求字符串  string ClientMsg = ASCII.GetString(ReadBuff);  // 根据rnrn截取请求行  string Line = ClientMsg.Substring(0, ClientMsg.IndexOf("rn"));  string[] CmdArray = Line.Split(' ');  // GET http://www.test.com:80/index.php HTTP/1.1  // CONNECT www.test.com:443 HTTP/1.1  string Cmd = CmdArray[0];  string RawUrl = CmdArray[1];  Console.WriteLine("原始请求: ", Line);  // CONNECT请求  if (Cmd == "CONNECT")  {  DoConnect(RawUrl);  }  // GET,POST和其他  else  {  DoOther(RawUrl, ClientMsg);  }  }  /// <summary>  /// 处理CONNECT命令，此处作用是支持QQ，MSN，以及多级代理串联等  /// </summary>  /// <param name="RawUrl"></param>  private void DoConnect( string RawUrl )  {  string[] Args = RawUrl.Split( ':' );  string Host = Args[0];  int Port = int.Parse(Args[1]);  Socket ServerSocket = null;  try  {  IPAddress[] IpList = Dns.GetHostEntry(Host).AddressList;  Console.WriteLine("尝试连接:", IpList[0], Port);  ServerSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);  ServerSocket.Connect(IpList[0], Port);  }  catch (Exception e)  {  Console.WriteLine("连接真实服务器异常: " + e.Message);  }  // 连接真实服务器成功  if (ServerSocket.Connected)  {  ClientSocket.Send( ASCII.GetBytes("HTTP/1.0 200 Connection establishedrnrn") );  }  else  {  ClientSocket.Shutdown(SocketShutdown.Both);  ClientSocket.Close();  }  // 开始转发数据  ForwardTcpData(ClientSocket, ServerSocket);  }  /// <summary>  /// 处理GET，POST等命令。使用了POLL，在代理服务器中强制去掉了Keep-Alive能力  /// </summary>  /// <param name="RawUrl"></param>  /// <param name="ClientMsg"></param>  public void DoOther(string RawUrl, string ClientMsg)  {  RawUrl = RawUrl.Substring(0 + "http://".Length);  int Port;  string Host;  string Url;  // 下面是分割处理请求，此处应该用正则匹配，不过我不擅长，因此手动切割，—_—!  int index1 = RawUrl.IndexOf(':');  // 没有端口  if (index1 == -1)  {  Port = 80;  int index2 = RawUrl.IndexOf('/');  // 没有目录  if (index2 == -1)  {  Host = RawUrl;  Url = "/";  }  else  {  Host = RawUrl.Substring(0, index2);  Url = RawUrl.Substring(index2);  }  }  else  {  int index2 = RawUrl.IndexOf('/');  // 没有目录  if (index2 == -1)  {  Host = RawUrl.Substring(0, index1);  Port = Int32.Parse(RawUrl.Substring(index1 + 1));  Url = "/";  }  else  {  // /出现在:之前，则说明:后面的不是端口  if (index2 < index1)  {  Host = RawUrl.Substring(0, index2);  Port = 80;  }  else  {  Host = RawUrl.Substring(0, index1);  Port = Int32.Parse(RawUrl.Substring(index1 + 1, index2 - index1 - 1));  }  Url = RawUrl.Substring(index2);  }  }  Console.WriteLine("Host is:, Port is:, Url is:", Host, Port, Url);  IPAddress[] address = null;  try  {  IPHostEntry IPHost = Dns.GetHostEntry(Host);  address = IPHost.AddressList;  Console.WriteLine("Web服务器IP地址: " + address[0]);  }  catch( Exception e )  {  Console.WriteLine( "解析服务器地址异常: " + e.Message );  }  Socket IPsocket = null;  try  {  // 连接到真实WEB服务器  IPEndPoint ipEndpoint = new IPEndPoint(address[0], Port);  IPsocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);  IPsocket.Connect(ipEndpoint);  // 对WEB服务器端传送HTTP请求命令，将原始HTTP请求中HTTP PROXY部分包装去掉  string ReqData = ClientMsg;  // 改写头中的URL,从http://www.test.com/index.php改为/index.php  ReqData = ReqData.Replace("http://"+RawUrl, Url);  // 按照rn切分HTTP头  string[] ReqArray = ReqData.Split(new string[1]{"rn"}, StringSplitOptions.None);  ReqData = "";  // 改写Keep-Alive等字段  for (int index = 0; index < ReqArray.Length; index++)  {  /*  if (ReqArray[index].StartsWith("Accept-Encoding:"))  {  ReqArray[index] = "Accept-Encoding: deflate";  }  */  if (ReqArray[index].StartsWith("Proxy-Connection:"))  {  ReqArray[index] = ReqArray[index].Replace("Proxy-Connection:", "Connection:");  //ReqArray[index] = "Connection: close";  }  /*  else if (ReqArray[index].StartsWith("Keep-Alive:"))  {  ReqArray[index] = "";  }  */  // 修改后的字段组合成请求  if( ReqArray[index] != "" )  {  ReqData = ReqData + ReqArray[index] + "rn";  }  }  ReqData = ReqData.Trim();  byte[] SendBuff = ASCII.GetBytes(ReqData);  IPsocket.Send(SendBuff);  }  catch( Exception e )  {  Console.WriteLine( "发送请求到服务器异常: " + e.Message );  }  // 使用Poll来判断完成，某些站点会出问题  while (true)  {  Byte[] RecvBuff = new byte[1024 * 20];  try  {  if( !IPsocket.Poll( 15 * 1000 * 1000, SelectMode.SelectRead ) )  {  Console.WriteLine("HTTP超时，关闭连接");  break;  }  }  catch (Exception e)  {  Console.WriteLine("Poll: " + e.Message);  break;  }  int Length = 0;  try  {  Length = IPsocket.Receive(RecvBuff);  if (0 == Length)  {  Console.WriteLine("服务端关闭");  break;  }  Console.WriteLine("从服务端收到字节", Length);  }  catch (Exception e)  {  Console.WriteLine("Recv: " + e.Message);  break;  }  try  {  Length = ClientSocket.Send(RecvBuff, Length, 0);  Console.WriteLine("发送字节到客户端", Length);  }  catch (Exception e)  {  Console.WriteLine("Send: " + e.Message);  }  }  /*  // 根据接收字节数来判断完成，某些站点会出问题  try  {  while (true)  {  Byte[] RecvBuff = new byte[1024 * 10];  int Length = IPsocket.Receive(RecvBuff);  if (Length <= 0)  {  Console.WriteLine("从服务端接收数据完成");  break;  }  Console.WriteLine("从服务端收到字节", Length);  Length = ClientSocket.Send(RecvBuff, Length, 0);  Console.WriteLine("发送字节到客户端", Length);  }  }  catch (Exception e)  {  Console.WriteLine(e.Message);  }  */  try  {  ClientSocket.Shutdown(SocketShutdown.Both);  ClientSocket.Close();  IPsocket.Shutdown(SocketShutdown.Both);  IPsocket.Close();  }  catch (Exception e)  {  //Console.WriteLine(e.Message);  }  }  /// <summary>  /// 在客户端和服务器之间中转数据  /// </summary>  /// <param name="client">客户端socket</param>  /// <param name="server">服务端socket</param>  private void ForwardTcpData(Socket client, Socket server)  {  ArrayList ReadList = new ArrayList(2);  while (true)  {  ReadList.Clear();  ReadList.Add(client);  ReadList.Add(server);  try  {  Socket.Select(ReadList, null, null, 1 * 1000 * 1000);  }  catch (SocketException e)  {  Console.WriteLine("Select error: " + e.Message);  break;  }  // 超时  if (ReadList.Count == 0)  {  //Console.WriteLine("Time out");  continue;  }  // 客户端可读  if (ReadList.Contains(client))  {  byte[] Recv = new byte[1024 * 10];  int Length = 0;  try  {  Length = client.Receive(Recv, Recv.Length, 0);  if (Length == 0)  {  Console.WriteLine("Client is disconnect.");  break;  }  Console.WriteLine(" Recv bytes from client", Length);  }  catch (Exception e)  {  Console.WriteLine("Read from client error: " + e.Message);  break;  }  try  {  Length = server.Send(Recv, Length, 0);  Console.WriteLine(" Write bytes to server", Length);  }  catch (Exception e)  {  Console.WriteLine("Write data to server error: " + e.Message);  break;  }  }  // 真实服务端可读  if (ReadList.Contains(server))  {  byte[] Recv = new byte[1024 * 10];  int Length = 0;  try  {  Length = server.Receive(Recv, Recv.Length, 0);  if (Length == 0)  {  Console.WriteLine("Server is disconnect");  break;  }  Console.WriteLine("Recv bytes from server", Length);  }  catch (Exception e)  {  Console.WriteLine("Read from server error: " + e.Message);  break;  }  try  {  Length = client.Send(Recv, Length, 0);  Console.WriteLine(" Write bytes to client", Length);  }  catch (Exception e)  {  Console.WriteLine("Write data to client error: " + e.Message);  break;  }  }  }  try  {  client.Shutdown(SocketShutdown.Both);  server.Shutdown(SocketShutdown.Both);  client.Close();  server.Close();  }  catch (Exception e)  {  Console.WriteLine(e.Message);  }  finally  {  Console.WriteLine("转发完毕");  }  }  }  public class MainClass  {  public static void Main()  {  const int Port = 8080;  HttpProxy Proxy = new HttpProxy(Port);  Proxy.Start();  }  }  }