On Aug 24, 2010, at 5:11 AM, Tim mizas wrote:
> What kind of FD does pcap_get_selectable_fd return?
It returns either
1) the same FD that pcap_fileno() returns, if select() is supported on
it
or
2) -1, if select() is *not* supported on it (which is the case in, for
example, FreeBSD 4.3 and 4.4, as well as for the DAG cards).
> I thought it was a socket's,
There is no guarantee whatsoever that the value returned by pcap_fileno() or
pcap_get_selectable_fd() is a socket.
> but when I tried to do a recv on it,
If it *were* a socket, and you did a recv() on it, unless you used MSG_PEEK you
would remove the packet from the socket queue, so libpcap wouldn't see that
packet.
I'm also not sure what would happen if it were a socket on Linux where
memory-mapped capturing is being done.
(I.e., don't do a recv() on it unless you fully understand what libpcap is
doing.)
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