[Winpcap-users] Re: Winpcap-users Digest, Vol 25, Issue 14

[Gianluca Varenni]

The limitation in using threads is the same one you have with classes: you should not call the pcap_ functions on the *same* pcap_t handle from multiple threads. You can safely use multiple threads each one dealing with a different pcap_t handle.
pcap_findalldevs is thread-safe, if it hangs then it's a bug.

Have a nice day
GV
  ----- Original Message ----- 
  From: Hardik Shah 
  To: winpcap-users at winpcap.org 
  Sent: Friday, April 20, 2007 9:19 AM
  Subject: [Winpcap-users] Re: Winpcap-users Digest, Vol 25, Issue 14


  try using entercriticalsection before starting anythread.if i m not wrong no two thread can access the same stuff at kernel level.


  --------------------------------

  Hardik Shah
  mobile:- 9827634991
  phone:- +91-0731-2570516 



  ----- Original Message ----
  From: "winpcap-users-request at winpcap.org" <winpcap-users-request at winpcap.org>
  To: winpcap-users at winpcap.org
  Sent: Friday, 20 April, 2007 5:30:50 PM
  Subject: Winpcap-users Digest, Vol 25, Issue 14


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  Today's Topics:

     1. Problem with threading (Avelino Martins)


  ----------------------------------------------------------------------

  Message: 1
  Date: Thu, 19 Apr 2007 21:18:42 +0000
  From: Avelino Martins <martins_ajc at msn.com>
  Subject: [Winpcap-users] Problem with threading
  To: <winpcap-users at winpcap.org>
  Message-ID: <BAY117-W18EBF90F0362E266B52C688C570 at phx.gbl>
  Content-Type: text/plain; charset="iso-8859-1"

  Hello all, 
  despite all the threads i readed about issues on threading problems, i couldn't get to a conclusion at the specific issue of the function 
  pcap_findalldevs() hanging when called from a child thread, take the simple example:

  #include <pcap.h>
  #pragma comment(lib, "Wpcap.lib")

  void GetINetDevice()
  {
       pcap_if_t* alldevs;
       char errbuf[PCAP_ERRBUF_SIZE+1];

       /* Retrieve the device list */
       if(pcap_findalldevs(&alldevs, errbuf) == -1)
       {
            printf("Error in pcap_findalldevs: %s\n", errbuf);
            exit(1);
       }
       // Could not create thread
       MessageBox(NULL, "Sucess","",MB_OK);

       // Free the device list 
       pcap_freealldevs(alldevs);
  }


  int main()
  { 
       DWORD m_dwThreadID;
       HANDLE m_hThread;
       m_hThread = CreateThread(0,
                                               0,
                                               (LPTHREAD_START_ROUTINE)GetINetDevice,
                                               NULL,
                                               0,
                                               &m_dwThreadID);
       if(!m_hThread)
       {
            // Could not create thread
            MessageBox(NULL, "Thread error","",MB_OK);
       }
       return 0;
  }

  Is anyone able to tell me if the fact of the app hangs/exits on pcap_findalldevs(), is a known issue at winpcap, and if there is any workaround?

  Best Regards
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