Question

我有多线程异步套接字侦听器。我想检查请求是否安全。但我想在AcceptCallBack方法中检查不是ReceiveCallBack。

我会这样做，因为我希望我的代码适用于HTTP和HTTPS。如果请求来自HTTPS，我将继续使用经过身份验证的SslStream而不是原始套接字。

这是我的代码：

using System;
using System.Net;
using System.Net.Sockets;
using System.Threading;
using System.Text;

namespace LearnRequestType
{
    class StackOverFlow
    {
        private static readonly ManualResetEvent _manualResetEvent = new ManualResetEvent(false);

        private void StartListening()
        {
            IPEndPoint localEndPoint = new IPEndPoint(IPAddress.Any, 9002);

            if (localEndPoint != null)
            {
                Socket listener = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);

                if (listener != null)
                {
                    listener.Bind(localEndPoint);
                    listener.Listen(10);

                    Console.WriteLine("Socket listener is running...");

                    listener.BeginAccept(new AsyncCallback(AcceptCallback), listener);
                }
            }
        }

        private void AcceptCallback(IAsyncResult ar)
        {
            _manualResetEvent.Set();

            Socket listener = (Socket)ar.AsyncState;

            Socket handler = listener.EndAccept(ar);

            StateObject state = new StateObject();
            state.workSocket = handler;

            // I want to understand if request comes from HTTP or HTTPS before this line.
            handler.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0, new AsyncCallback(ReceiveCallback), state);

            listener.BeginAccept(new AsyncCallback(AcceptCallback), listener);
        }

        private void ReceiveCallback(IAsyncResult result)
        {
            StateObject state = (StateObject)result.AsyncState;
            Socket handler = state.workSocket;

            string clientIP = ((IPEndPoint)handler.RemoteEndPoint).Address.ToString();

            int numBytesReceived = handler.EndReceive(result);

            if (!handler.Connected)
            {
                handler.Close();
                return;
            }

            // Read incoming data...
            if (numBytesReceived > 0)
            {
                state.sb.Append(Encoding.ASCII.GetString(state.buffer, 0, numBytesReceived));

                // Read incoming data line by line.
                string[] lines = state.sb.ToString().Split('\n');

                if (lines[lines.Length - 1] == "<EOF>")
                {
                    // We received all data. Do something...

                }
                else
                {
                    // We didn't receive all data. Continue reading...
                    handler.BeginReceive(state.buffer, 0, state.buffer.Length, SocketFlags.None, new AsyncCallback(ReceiveCallback), state);
                }
            }
        }
    }
}

public class StateObject
{
    public Socket workSocket = null;
    public const int BufferSize = 256;
    public byte[] buffer = new byte[BufferSize];
    public StringBuilder sb = new StringBuilder();
}

如果我更改AcceptCallBack方法和StateObject类：

private void AcceptCallback(IAsyncResult ar)
{
    _manualResetEvent.Set();

    Socket listener = (Socket)ar.AsyncState;

    Socket handler = listener.EndAccept(ar);

    try
    {
        sslStream = new SslStream(new NetworkStream(handler, true));

        // try to authenticate
        sslStream.AuthenticateAsServer(_cert, false, System.Security.Authentication.SslProtocols.Tls, true);

        state.workStream = sslStream;
        state.workStream.ReadTimeout = 100000;
        state.workStream.WriteTimeout = 100000;

        if (state.workStream.IsAuthenticated)
        {
            state.workStream.BeginRead(state.buffer, 0, StateObject.BufferSize, ReceiveCallback, state);
        }
    }
    catch (IOException ex)
    {
        // ıf we get handshake failed due to an unexpected packet format, this means incoming data is not HTTPS
        // Continue with socket not sslstream
        state.workSocket = handler;
        handler.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0, new AsyncCallback(ReceiveCallback), state);
    }

    StateObject state = new StateObject();
    state.workStream = handler;

    handler.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0, new AsyncCallback(ReceiveCallback), state);

    listener.BeginAccept(new AsyncCallback(AcceptCallback), listener);
}

public class StateObject
{
    public Socket workSocket = null;
    public SslStream workStream = null;
    public const int BufferSize = 1024;
    public byte[] buffer = new byte[BufferSize];
    public StringBuilder sb = new StringBuilder();
}

我可以决定传入的数据类型是HTTP还是HTTPS，但如果它是HTTP，它每次都会被catch块处理，因此会降低应用程序的性能。

还有其他办法吗？

Answer 1

如果我理解正确，您有一个端口，客户端可以使用HTTP或HTTPS进行连接，并且您希望在传输任何数据之前立即知道请求是如何进行的。

在从客户端接收数据之前无法知道这一点。 HTTP和HTTPS是TCP之上的协议，它们不能在较低的协议级别上工作，因此没有标志或任何可以说明使用哪种协议的东西。此外，HTTPS只是包含在TLS / SSL流中的普通HTTP流。

您必须根据使用的协议读取数据并确定。或者你必须有单独的HTTP和HTTPS端口，这将使这个变得微不足道。

要检测它是否为TLS / SSL，您可以查看几个字节并查看其中的内容。The TLS specification表示 Client Hello 数据包以协议开头版本，作为两个uint8发送。由于HTTP请求始终将动词作为第一个，因此您可以轻松检查前几个字节是否为字符，然后尝试SSLStream（如果不是）。

另请注意，如果您在套接字上启动SSLStream，它可能会从套接字中读取，这将占用HTTP请求的开头，而您无法正常处理它。

所以在你的Accept回调中使用这样的东西：

Socket handler = listener.EndAccept(ar);
byte[] tmp = new byte[2];
handler.Receive(tmp, 0, 2, SocketFlags.Peek);
if (!Char.IsLetter((char)tmp[0]) || !Char.IsLetter((char)tmp[1]))
{
  // Doesn't start with letters, so most likely not HTTP
} else {
  // Starts with letters, should be HTTP
}

如果您想确保它是TLS / SSL，可以查看this question on SO

检查请求是否来自套接字侦听器中的HTTP或HTTPS

1 个答案: