Multi-Threading on sockets C#

Question

I am trying to capture network packets from several IPs at the same time using threads, but i get this exception "An operation on a socket could not be performed because the system lacked sufficient buffer space or because a queue was full". I am new to threads and sockets. Exception come from "mainSocket.BeginReceive(_data, 0, _data.Length, SocketFlags.None, OnReceive, null);"

         IPHostEntry HosyEntry = Dns.GetHostEntry((Dns.GetHostName()));
         if (HosyEntry.AddressList.Length > 0)
         {
             foreach (IPAddress ip in HosyEntry.AddressList)
             {
                 if (ip.IsIPv6LinkLocal == false)
                 {
                     SetIp ipAdd = new SetIp();
                     ipAdd.SetIpAdd(ip);    
                 }
             }
         }

    class SetIp
{
    private Socket mainSocket;                         
    private byte[] _data = new byte[4096];

    public void SetIpAdd(IPAddress address)
    {

        mainSocket = new Socket(AddressFamily.InterNetwork, SocketType.Raw, ProtocolType.IP);
        mainSocket.Bind(new IPEndPoint(address, 0));

         Thread MyThread = new Thread(new ThreadStart(() =>{
             while (true)
             {

                 mainSocket.SetSocketOption(SocketOptionLevel.IP, SocketOptionName.HeaderIncluded, true);
                 byte[] byTrue = new byte[] { 1, 0, 0, 0 };
                 byte[] byOut = new byte[] { 1, 0, 0, 0 };

                 mainSocket.IOControl(IOControlCode.ReceiveAll, byTrue, byOut);


                 mainSocket.BeginReceive(_data, 0, _data.Length, SocketFlags.None, OnReceive, null);


             } }));

         MyThread.Start();
     }

    private void OnReceive(IAsyncResult ar)
    {

        var received = mainSocket.EndReceive(ar);
        Parse(_data, received);
        mainSocket.BeginReceive(_data, 0, _data.Length, SocketFlags.None, OnReceive, null);

    }

    private void Parse(byte[] data, int size)
    {
        IPHeader ipHeader = new IPHeader(data, size);
        Console.WriteLine( ipHeader.SourceIP.ToString());
    }

Right, and I'm asking you to show it as part of your code. :) — Haney
Typically speaking, it is not apprpriate to edit the question when an answer solves the problem. Now your original question no longer applies as you edited the code to fix the issue. Might be a good idea to undo your edit and post a separate answer so it's not confusing. — theMayer

usr usr · Accepted Answer · 2014-05-01T14:58:21

You are calling BeginReceive infinitely often in a hot loop. This causes infinitely many IOs to queue up.

Probably, you want to use synchronous IO because it is simpler to use. Alternatively, only issue the next reado nce the last one has completed.

Multi-Threading on sockets C#

2 Answers