PCAP_NEXT_EX(3) Library Functions Manual PCAP_NEXT_EX(3)
pcap_next_ex, pcap_next - read the next packet from a pcap_t
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);
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.
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
pcap_pkthdr structure pointed to by h is filled in with the appropriate
values for the packet.
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 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.
pcap(3), pcap_geterr(3), pcap_dispatch(3)
5 April 2008 PCAP_NEXT_EX(3)