我有一个异步 UDP 服务器类，在 IPAddress.Any 上绑定了一个套接字，我想知道接收到的数据包发送到哪个 IPAddress（...或接收到）。看来我不能只使用 Socket.LocalEndPoint 属性，因为它总是返回 0.0.0.0 （这是有道理的，因为它绑定到那个......）。
以下是我目前正在使用的代码中有趣的部分：
private Socket udpSock;
private byte[] buffer;
public void Starter(){
//Setup the socket and message buffer
udpSock = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
udpSock.Bind(new IPEndPoint(IPAddress.Any, 12345));
buffer = new byte[1024];
//Start listening for a new message.
EndPoint newClientEP = new IPEndPoint(IPAddress.Any, 0);
udpSock.BeginReceiveFrom(buffer, 0, buffer.Length, SocketFlags.None, ref newClientEP, DoReceiveFrom, udpSock);
}
private void DoReceiveFrom(IAsyncResult iar){
//Get the received message.
Socket recvSock = (Socket)iar.AsyncState;
EndPoint clientEP = new IPEndPoint(IPAddress.Any, 0);
int msgLen = recvSock.EndReceiveFrom(iar, ref clientEP);
byte[] localMsg = new byte[msgLen];
Array.Copy(buffer, localMsg, msgLen);
//Start listening for a new message.
EndPoint newClientEP = new IPEndPoint(IPAddress.Any, 0);
udpSock.BeginReceiveFrom(buffer, 0, buffer.Length, SocketFlags.None, ref newClientEP, DoReceiveFrom, udpSock);
//Handle the received message
Console.WriteLine("Recieved {0} bytes from {1}:{2} to {3}:{4}",
msgLen,
((IPEndPoint)clientEP).Address,
((IPEndPoint)clientEP).Port,
((IPEndPoint)recvSock.LocalEndPoint).Address,
((IPEndPoint)recvSock.LocalEndPoint).Port);
//Do other, more interesting, things with the received message.
}
如前所述，这总是打印如下一行：
从 127.0.0.1:1678 到 0.0.0.0:12345 收到 32 个字节
我希望它是这样的：
从 127.0.0.1:1678 到 127.0.0.1:12345 收到 32 个字节
提前感谢您对此的任何想法！ - 亚当
更新
好吧，我找到了一个解决方案，虽然我不喜欢它......基本上，我不是打开一个绑定到 IPAddress.Any 的单个 udp 套接字，而是为每个可用的 IPAddress 创建一个唯一的套接字。因此，新的 Starter 函数如下所示：
public void Starter(){
buffer = new byte[1024];
//create a new socket and start listening on the loopback address.
Socket lSock = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
lSock.Bind(new IPEndPoint(IPAddress.Parse("127.0.0.1"), 12345);
EndPoint ncEP = new IPEndPoint(IPAddress.Any, 0);
lSock.BeginReceiveFrom(buffer, 0, buffer.Length, SocketFlags.None, ref ncEP, DoReceiveFrom, lSock);
//create a new socket and start listening on each IPAddress in the Dns host.
foreach(IPAddress addr in Dns.GetHostEntry(Dns.GetHostName()).AddressList){
if(addr.AddressFamily != AddressFamily.InterNetwork) continue; //Skip all but IPv4 addresses.
Socket s = new Socket(addr.AddressFamily, SocketType.Dgram, ProtocolType.Udp);
s.Bind(new IPEndPoint(addr, 12345));
EndPoint newClientEP = new IPEndPoint(IPAddress.Any, 0);
s.BeginReceiveFrom(buffer, 0, buffer.Length, SocketFlags.None, ref newClientEP, DoReceiveFrom, s);
}
}
这只是为了说明这个概念，这个代码的最大问题是每个套接字都试图使用相同的缓冲区......这通常是一个坏主意......
必须有更好的解决方案；我的意思是，源和目标是 UDP 数据包头的一部分！哦，好吧，我想我会继续这样做，直到有更好的东西。