[Winpcap-users] Checking whether adapter is alive

[Loris Degioanni]

Thanks Bryan,
I'll give a look at it probably next weekend.

Loris


Bryan Kadzban wrote:
> Loris Degioanni wrote:
>> Bryan, Shmuel,
>> do you have a small snippet of code that we can use to replicate the
>> problem? That would allow us to debug it more easily.
> 
> Well, my program (not sure about Shmuel's) runs this type of code.  I
> have a .Net OO wrapper around the whole thing, but these are the API
> calls it makes:
> 
> // start of setup
> PacketGetAdapterNames(...);    // get size of buffer
> //  allocate a buffer
> PacketGetAdapterNames(...);    // get adapter list into the buffer
> 
> for each "name" in the list returned {
>     handle = PacketOpenAdapter(name);
> 
>     // Get OID_GEN_PHYSICAL_MEDIUM using PacketRequest on "handle", and
>     //  filter out non-wireless cards.
>     //  If not filtered, add handle to the list of handles.
> }
> // end of setup
> 
> every second, for each item in the list of handles, do {
>     PACKET_OID_DATA *req = malloc(whatever);
>     req->Oid = OID_802_11_BSSID_LIST;
>     req->Length = // what I passed to malloc
>     PacketRequest(handle, 0, req);
>     // (Actually, I do this, with increasing buffer sizes, until
>     //  PacketRequest doesn't fail with the "buffer too short" status.)
> 
>     // Display all APs in range, indicating the signal strength of
>     //  each, based on the list returned by this OID
> }
> 
> This "every second" loop runs (with only one device) fine, until the
> device in question gets disabled.  Then it BSODs.  (It may also BSOD if
> other devices on the same machine get disabled, I don't remember.  I do
> know it blue-screens if any device options get changed, though.)  You
> can reproduce it by either removing a USB NIC while the loop is running
> (if you have a USB NIC), or disabling the device in device manager (but
> this may not be possible).
> 
> The *easy* way to trigger the BSOD is to go into device manager, open up
> the properties of the NIC device that you have open in the loop (again,
> or perhaps any other one, I don't remember for sure anymore), go to the
> Advanced tab, change the value of any of the options there, and hit OK.
> The machine will BSOD on the first call into PacketRequest after you hit
> OK.
> 
> I also have a memory dump file from one of the blue screens, but I'm
> guessing it's probably too large to send via email (it's 512MB).
> 
> Thanks!
> 
>> A simple workaround, if the frequency of the calls to PacketRequest()
>> is not high, is closing and reopening the adapter every time. The
>> adapter should just not open if the card is removed.
> 
> Hmm.  One open and close per second might get to be a bit much, I don't
> know...
> 
> 
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