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PCAP_NEXT_EX(3PCAP)                                                                      PCAP_NEXT_EX(3PCAP)



NAME
       pcap_next_ex, pcap_next - read the next packet from a pcap_t

SYNOPSIS
       #include <pcap/pcap.h>

       int pcap_next_ex(pcap_t *p, struct pcap_pkthdr **pkt_header,
               const u_char **pkt_data);
       const u_char *pcap_next(pcap_t *p, struct pcap_pkthdr *h);

DESCRIPTION
       pcap_next_ex()  reads  the  next  packet and returns a success/failure indication.  If the packet was
       read without problems, the pointer pointed to by the pkt_header argument  is  set  to  point  to  the
       pcap_pkthdr  struct  for  the  packet,  and the pointer pointed to by the pkt_data argument is set to
       point to the data in the packet.  The struct pcap_pkthdr and the packet data are not to be  freed  by
       the  caller,  and  are not guaranteed to be valid after the next call to pcap_next_ex(), pcap_next(),
       pcap_loop(), or pcap_dispatch(); if the code needs them to remain valid, it must make a copy of them.

       pcap_next()  reads  the next packet (by calling pcap_dispatch() with a cnt of 1) and returns a u_char
       pointer to the data in that packet.  The packet data is not to be freed by the  caller,  and  is  not
       guaranteed  to be valid after the next call to pcap_next_ex(), pcap_next(), pcap_loop(), or pcap_dis-patch(); pcap_dispatch();
       patch(); if the code needs it to remain valid, it must make a copy of it.  The pcap_pkthdr  structure
       pointed to by h is filled in with the appropriate values for the packet.

RETURN VALUE
       pcap_next_ex()  returns 1 if the packet was read without problems, 0 if packets are being read from a
       live capture, and the timeout expired, -1 if an error occurred while reading the packet,  and  -2  if
       packets  are being read from a ``savefile'', and there are no more packets to read from the savefile.
       If -1 is returned, pcap_geterr() or pcap_perror() may be called with p as an  argument  to  fetch  or
       display the error text.

       pcap_next()  returns  a pointer to the packet data on success, and returns NULL if an error occurred,
       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 cap-ture capture
       ture  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
       occurred or not.

SEE ALSO
       pcap(3PCAP), pcap_geterr(3PCAP), pcap_dispatch(3PCAP)



                                                5 April 2008                             PCAP_NEXT_EX(3PCAP)