winpkf: stop starting packet reading in tunnel mode

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  • #4893

      winpkf question:

      If i set an adapter to TUNNEL mode and start reading packets in a loop this is fine.
      When i want to stop reading the packets i drop out of the loop.
      However, of course, the driver is still reading packets and as soon as the winpkf buffer is full tcp/ip stops for the whole PC.

      So what can i do:

      1. Put the adapter in to LISTEN mode – this does not appear to work. Do i have to keep reading packets??

      2. Drop out of the main loop in to a secondary loop which keep reading packets but re-creates them stright away.

      3. Unload the driver – not ideal as i have to keep loading, unloading every time it is started/stopped.

      Any other ideas?

      Thanks for any help, K.

      Vadim Smirnov

        Please pay attention to the routine below (it is available in PassThru and PacketSniffer samples), which actually stops WinpkFillter operations over the network interface and releases resources:

        void ReleaseInterface()
        // This function releases packets in the adapter queue and stops listening the interface
        ADAPTER_MODE Mode;

        Mode.dwFlags = 0;
        Mode.hAdapterHandle = (HANDLE)AdList.m_nAdapterHandle[iIndex];

        // Set NULL event to release previously set event object
        api.SetPacketEvent(AdList.m_nAdapterHandle[iIndex], NULL);

        // Close Event
        if (hEvent)
        CloseHandle ( hEvent );

        // Set default adapter mode

        // Empty adapter packets queue
        api.FlushAdapterPacketQueue (AdList.m_nAdapterHandle[iIndex]);

          Maybe i didnt express my question well.

          I do not want to close the filter driver, i just want to effectivly pause the processing of packets. So the are not processed any more, but processing can resume again.

          Is the best way to do this to close the driver as in the release interface example?

          thanks, K.

          Vadim Smirnov

            The code above do the following:

            1) Release event for packet indication.
            2) Set adapter into passthru mode (the state it was before you set TUNNEL mode).
            3) Flush packet queue associated with the adapter.

            For temporary stop filtering: 1 – is not necessary, 2 – should be be done, otherwise (if you exited the loop) the network will be forzen after all WinpkFilter internal buffers are used, 3 – should be done because if you have existed packet reading loop, to that moment you can have internal buffer pool exosted and the network frozen.

            So, in addition to exiting the loop you should set the default mode over the interface and flush its packet queue. If you want to restore filtering, then set tunnel mode and enter the loop again.


              Great thanks..!

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