最近，在我的学校有关于http代理类的项目。因此，它的目的是当您在浏览器上键入url时，请求到达您的代理，在解压缩主机后，您重新创建新请求并请求到目标服务器，然后，您将从目标服务器接收数据并发送回浏览器渲染页面。
我创建了一个异步的http代理服务器类。在StateObject类中，我有两个socket，一个是workSocket来处理来自浏览器的新请求，另一个是destinationSocket来处理目标套接字。
在从浏览器向目标服务器发送新请求之前，我将destinationSocket和处理程序套接字存储到StateObject对象。通过这样做，在AsynCallBack ReceiveFromDestinationServer函数中，我可以检索destinationSocket以从目标服务器和workSocket接收数据，以将接收到的数据发送回浏览器。并且BeginReceive再次运行，直到收到的数据结束。
我在回调ReceiveFromDestinationServer方法的Socket中的Send方法中得到此异常。
请帮我修理一下。谢谢你的阅读。
这是我的代码：
public class ServerListerner
{
private const int TCPPort = 80;
private const string EOF = "\r\n";
// Thread signal.
public static ManualResetEvent allDone = new ManualResetEvent(false);
public void StartListening()
{
// Data buffer for incoming data.
byte[] bytes = new Byte[1024];
// Establish the local endpoint for the socket.
IPEndPoint localEndPoint = new IPEndPoint(IPAddress.Any, 9000);
// Create a TCP/IP socket.
Socket listener = new Socket(AddressFamily.InterNetwork,
SocketType.Stream, ProtocolType.Tcp );
// Bind the socket to the local endpoint and listen for incoming connections.
try {
listener.Bind(localEndPoint);
listener.Listen(100);
while (true) {
// Set the event to nonsignaled state.
allDone.Reset();
// Start an asynchronous socket to listen for connections.
listener.BeginAccept(new AsyncCallback(AcceptCallback), listener);
// Wait until a connection is made before continuing.
allDone.WaitOne();
}
} catch (Exception e) {
MessageBox.Show(e.ToString());
}
}
private void AcceptCallback(IAsyncResult ar) {
// Signal the main thread to continue.
allDone.Set();
// Get the socket that handles the client request.
Socket listener = (Socket) ar.AsyncState;
Socket handler = listener.EndAccept(ar);
// Create the state object.
StateObject state = new StateObject();
state.workSocket = handler;
// And begin receive data from client
handler.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
new AsyncCallback(ReadCallback), state);
}
private void ReadCallback(IAsyncResult ar)
{
String content = String.Empty;
// Retrieve the state object and the handler socket
// from the asynchronous state object.
StateObject state = (StateObject) ar.AsyncState;
Socket handler = state.workSocket;
// Read data from the client socket.
int bytesRead = handler.EndReceive(ar);
Thread.Sleep(10);
if (bytesRead > 0) {
// There might be more data, so store the data received so far.
state.sb.Append(Encoding.ASCII.GetString(state.buffer));
content = state.sb.ToString();
if(content != "")
{
// All the data has been read from the client.
// Change data to string array to easy access.
string[] requestLines = Regex.Split(content, EOF);
// Get remote host
string remoteHost = requestLines[0].Split(' ')[1].Replace("http://", "").Split('/')[0];
// Create a destination socket and connect to remote host at TCP port
Socket destinationSocket= new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
destinationSocket.Connect(remoteHost, TCPPort);
// Send the data to destination socket.
state.workSocket = handler;
state.destinationSocket = destinationSocket;
destinationSocket.Send(state.buffer);
destinationSocket.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0, new AsyncCallback(ReceiveFromDestinationServer), state);
} else {
// Not all data received. Get more.
handler.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
new AsyncCallback(ReadCallback), state);
}
}
}
private void ReceiveFromDestinationServer(IAsyncResult ar)
{
StateObject state = (StateObject)ar.AsyncState;
Socket destinationSocket = state.destinationServer;
Socket client = state.workSocket;
int bytesRead = destinationSocket.EndReceive(ar);
if (bytesRead > 0)
{
client.Send(state.buffer, bytesRead, SocketFlags.None);
destinationSocket.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0, new AsyncCallback(ReceiveFromDestinationServer), state);
}
else
{
// Exception here
destinationSocket.Shutdown(SocketShutdown.Both);
destinationSocket.Close();
client.Close();
}
}
}
更新：ReceiveFromDestinationServer函数 我在bytesRead之后添加了Thread.Sleep（10）。我认为睡眠很重要，当设置为10时，某些网站加载速度很快，有些网站只加载一些信息，当设置为100时，加载网站后，应用程序会自动退出。 但例外仍然存在。
答案 0 :(得分：0)
可能是远程主机未运行或未正在侦听您尝试连接的端口。您可能需要使用telnet检查服务器应用程序的状态
telnet ipaddr port
答案 1 :(得分：0)
我认为您的代码用于在客户端和服务器之间进行交互。 'AcceptCallback'中的'handler'是用于将字节发送回浏览器而不是发送到目的地的套接字
因此，您需要编写另一个工作对（异步）/一个（同步）套接字来实现http代理。首先，您应该明确请求和响应的样子。
浏览器首先发送给您：
browserIP ===> proxyIP
GET domainname.com
....
然后代理执行依赖：
proxyIP ===> domainname.com'sIP
GET domain name
....
在您的代理从domainname.com获得响应后，将其发送回browserIP。这就是你所做的，在.NET中你还需要处理一些特定于代理的http标头，比如X-forwarded-by。等。
但部分代码：
套接字侦听器=（套接字）ar.AsyncState;
Socket handler = listener.EndAccept（ar）; //这一行创建一个新的套接字只是为了将字节发送回浏览器：所以你的浏览器会收到与它的请求相同的回复。
// Create the state object.
StateObject state = new StateObject();
所以你需要创建另一个新的Socket和一对新的处理程序。真正将请求发送到目的地。在你创建它们之前。您需要获取目标的真实IP地址（您的代理不知道，您的客户端不知道目的地的IP地址[domainname.com]）