PCAP_SETNONBLOCK(3) PCAP_SETNONBLOCK(3)
NAME
pcap_setnonblock, pcap_getnonblock - set or get the state of non-blocking
mode on a capture device
SYNOPSIS
#include <pcap/pcap.h>
char errbuf[PCAP_ERRBUF_SIZE];
int pcap_setnonblock(pcap_t *p, int nonblock, char *errbuf);
pcap_getnonblock(3) *p, char *errbuf);
DESCRIPTION
pcap_setnonblock() puts a capture handle into ``non-blocking'' mode, or
takes it out of ``non-blocking'' mode, depending on whether the nonblock
argument is non-zero or zero. It has no effect on ``savefiles''. If
there is an error, PCAP_ERROR is returned and errbuf is filled in with an
appropriate error message; otherwise, 0 is returned.
In ``non-blocking'' mode, an attempt to read from the capture descriptor
with pcap_dispatch(3) and pcap_next_ex(3) will, if no packets are
currently available to be read, return 0 immediately rather than blocking
waiting for packets to arrive.
pcap_loop(3) will loop forever, consuming CPU time when no packets
are currently available; pcap_dispatch() should be used instead.
pcap_next(3) will return NULL if there are no packets currently
available to read; this is indistinguishable from an error, so
pcap_next_ex() should be used instead.
When first activated with pcap_activate(3) or opened with
pcap_open_live(3), a capture handle is not in ``non-blocking mode'';
a call to pcap_setnonblock() is required in order to put it into ``non-
blocking'' mode.
RETURN VALUE
pcap_getnonblock() returns the current ``non-blocking'' state of the
capture descriptor; it always returns 0 on ``savefiles''. If called on a
capture handle that has been created but not activated,
PCAP_ERROR_NOT_ACTIVATED is returned. If there is another error,
PCAP_ERROR is returned and errbuf is filled in with an appropriate error
message.
errbuf is assumed to be able to hold at least PCAP_ERRBUF_SIZE chars.
SEE ALSO
pcap(3), pcap_next_ex(3), pcap_geterr(3)
5 March 2022 PCAP_SETNONBLOCK(3)
libpcap 1.10.2 - Generated Mon Jan 2 05:45:44 CST 2023