PCAP_SETNONBLOCK(3PCAP) PCAP_SETNONBLOCK(3PCAP)
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); int pcap_getnonblock(pcap_t *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''.
errbuf is a buffer large enough to hold at least
PCAP_ERRBUF_SIZE chars.
In ``non-blocking'' mode, an attempt to read from the capture
descriptor with
pcap_dispatch(3PCAP) and
pcap_next_ex(3PCAP) will, if
no packets are currently available to be read, return
0 immediately
rather than blocking waiting for packets to arrive.
pcap_loop(3PCAP) will loop forever, consuming CPU time when no
packets are currently available;
pcap_dispatch() should be used
instead.
pcap_next(3PCAP) 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(3PCAP) or opened with
pcap_open_live(3PCAP), 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_setnonblock() return 0 on success,
PCAP_ERROR_NOT_ACTIVATED if
called on a capture handle that has been created but not activated,
and
PCAP_ERROR for other errors.
pcap_getnonblock() returns the
current ``non-blocking'' state of the capture descriptor on success;
it always returns
0 on ``savefiles''. It returns
PCAP_ERROR_NOT_ACTIVATED if called on a capture handle that has been
created but not activated, and
PCAP_ERROR for other errors. If
PCAP_ERROR is returned,
errbuf is filled in with an appropriate error
message.
SEE ALSO
pcap(3PCAP),
pcap_next_ex(3PCAP),
pcap_geterr(3PCAP) 30 November 2023 PCAP_SETNONBLOCK(3PCAP)
