Re: pcap_next returns "Didn't grab packet"

[Guy Harris <gharris () sonic net>]

On Mon, Dec 16, 2002 at 12:07:02PM -0800, Guy Harris wrote:
> "pcap_next()" returns a null pointer if "pcap_dispatch()" returns a
> value <= 0.  To quote the current CVS version of the libpcap man page:

And to quote the now-current version, with a change I checked in to make
this clearer:

       pcap_next()  reads  the  next packet (by calling pcap_dis-
       patch() with a cnt of 1) and returns a u_char  pointer  to
       the data in that packet.  (The pcap_pkthdr struct for that
       packet is not supplied.)  NULL is  returned  if  an  error
       occured,  or  if  no packets were read from a live capture
       (if, for example, they were discarded because they  didn't
       pass the packet filter, or if, on platforms that support a
       read timeout that starts before any  packets  arrive,  the
       timeout  expires before any packets arrive, or if the file
       descriptor for the capture device is in non-blocking  mode
       and  no  packets were available to be read), or if no more
       packets are available in a  ``savefile.''   Unfortunately,
       there  is  no way to determine whether an error occured or
       not.
-
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