[英]C# UDP Socket: Get receiver address
我有一个异步UDP服务器类,其中一个套接字绑定在IPAddress.Any上,我想知道收到的数据包被发送到哪个IP地址(...或收到)。 看来我不能只使用Socket.LocalEndPoint属性,因为它总是返回0.0.0.0(这是有意义的,因为它绑定到那个......)。
以下是我目前使用的代码的有趣部分:
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,这总是打印一条线,如:
从127.0.0.1:1678到0.0.0.0:12345收到32个字节
而且我希望它是这样的:
从127.0.0.1:1678到127.0.0.1:12345收到32个字节
在此先感谢您对此的任何想法! - 亚当
UPDATE
好吧,我找到了一个解决方案,虽然我不喜欢它......基本上,我没有打开绑定到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功能如下所示:
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,这个代码最大的问题就是每个套接字试图使用相同的缓冲区......这通常是一个坏主意......
必须有一个更好的解决方案; 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。
我刚遇到同样的问题。 我没有看到使用ReceiveFrom
或其异步变体来检索接收数据包的目标地址的方法。
但是...如果您使用ReceiveMessageFrom
或其变体,您将获得IPPacketInformation
(通过ReceiveMessageFrom
和EndReceiveMessageFrom
的引用,或作为传递给ReceiveMessageFromAsync
的回调的SocketAsyncEventArgs
的属性)。 该对象将包含接收数据包的IP地址和接口号。
(注意,此代码尚未经过测试,因为我使用的是ReceiveMessageFromAsync
而不是伪造的假开始/结束调用。)
private void ReceiveCallback(IAsyncResult iar)
{
IPPacketInformation packetInfo;
EndPoint remoteEnd = new IPEndPoint(IPAddress.Any, 0);
SocketFlags flags = SocketFlags.None;
Socket sock = (Socket) iar.AsyncState;
int received = sock.EndReceiveMessageFrom(iar, ref flags, ref remoteEnd, out packetInfo);
Console.WriteLine(
"{0} bytes received from {1} to {2}",
received,
remoteEnd,
packetInfo.Address
);
}
请注意,你应该叫显然SetSocketOption(SocketOptionLevel.IP, SocketOptionName.PacketInformation, true)
如设置插座, 在你面前的一部分Bind
它 。 ... ReceiveMessageFrom ...方法将为您设置它,但您可能只会看到在设置选项后Windows看到的任何数据包的有效信息。 (在实践中,这不是一个问题 - 但是如果/如果它曾经发生过,原因将是一个谜。最好完全防止它。)
我认为如果你绑定到127.0.0.1而不是IPAddress.Any你会得到你想要的行为。
0.0.0.0故意意味着“每个可用的IP地址”,并且它在字面上是由你的绑定语句引起的。
从该套接字获取地址的一种方法是将其连接到发送方。 一旦你这样做,你将能够获得本地地址(或至少一个可路由到发送者),但是,你只能从连接的端点接收消息。
要取消连接,您需要再次使用connect,这次指定一个AF_UNSPEC
系列的AF_UNSPEC
。 不幸的是,我不知道如何在C#中实现这一目标。
(免责声明:我从未写过一行C#,这一般适用于Winsock)
关于缓冲区问题,请尝试以下操作:
创建一个名为StateObject的类来存储您想要在回调中拥有的任何数据,并使用缓冲区,如果您需要它还包括套接字(因为我看到您当前正在将udpSock作为stateObject传递)。 将新创建的对象传递给异步方法,然后您将在回调中访问它。
public void Starter(){
StateObject state = new StateObject();
//set any values in state you need here.
//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(state.buffer, 0, state.buffer.Length, SocketFlags.None, ref ncEP, DoReceiveFrom, state);
//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);
StateObject objState = new StateObject();
s.BeginReceiveFrom(objState.buffer, 0, objState.buffer.length, SocketFlags.None, ref newClientEP, DoReceiveFrom, objState);
}
}
在搜索这个问题时,我发现:
http://msdn.microsoft.com/en-us/library/system.net.sockets.socket.beginreceivefrom.aspx
然后,您可以像使用udpSock和缓冲区一样从AsyncState转换StateObject,以及您需要存储的任何其他数据。
我想现在唯一的问题是如何以及在何处存储数据,但由于我不知道您的实现,我无法帮助那里。
亚当
这没有经过测试......试试吧
private void DoReceiveFrom(IAsyncResult iar){
//Get the received message.
Socket recvSock = (Socket)iar.AsyncState;
//EndPoint clientEP = new IPEndPoint(IPAddress.Any, 0);
Socket clientEP = recvSock.EndAccept(iar);
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)recvSock.RemoteEndPoint).Address,
((IPEndPoint)recvSock.RemoteEndPoint).Port,
((IPEndPoint)recvSock.LocalEndPoint).Address,
((IPEndPoint)recvSock.LocalEndPoint).Port);
//Do other, more interesting, things with the received message.
*/
Console.WriteLine("Recieved {0} bytes from {1}:{2} to {3}",
msgLen,
((IPEndPoint)recvSock.RemoteEndPoint).Address,
((IPEndPoint)recvSock.RemoteEndPoint).Port,
clientEP.RemoteEP.ToString();
}
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.