c# - UDP Socket BeginReceive() (Find IpAddress)

Question

I'm trying to receive UDP Packets on this port: 8070

I have a program for sending UDP packets and I will receive data in another program (Receiver) but I can't find the sender IP address! i'm using socket and my code is this:

    Socket UdpListener = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
    IPEndPoint ipep = new IPEndPoint(IPAddress.Any, 8070);
    byte[] buf = new byte[1000];

    public Form1()
    {
        InitializeComponent();
        UdpListener.SetSocketOption(SocketOptionLevel.IP, SocketOptionName.PacketInformation, true);
        UdpListener.Bind(ipep);


    }

    private void button1_Click(object sender, EventArgs e)
    {
        UdpListener.BeginReceive(buf, 0, buf.Length, SocketFlags.None, new AsyncCallback(OnRecv), UdpListener);


    }

    private void OnRecv(IAsyncResult ar)
    {
        UdpListener.EndReceive(ar);

        UdpListener.BeginReceive(buf, 0, buf.Length, SocketFlags.None, new AsyncCallback(OnRecv), UdpListener);
    }

I Will Receive Data but how can I find Sender IP Address?

i tried this:

Socket s = (Socket)ar.AsyncState;
        MessageBox.Show(s.RemoteEndPoint.ToString());

but I get this Error:

A request to send or receive data was disallowed because the socket is not connected and (when sending on a datagram socket using a sendto call) no address was supplied

Rob Rob · Accepted Answer · 2014-02-27T08:14:21

You should use UdpListener.BeginReceiveFrom instead of UdpListener.BeginReceive as it offers a reference to the sending endpoint.

Further information: http://msdn.microsoft.com/en-us/library/system.net.sockets.socket.beginreceivefrom%28v=vs.110%29.aspx

c# - UDP Socket BeginReceive() (Find IpAddress)

1 Answers