PCAP_SETNONBLOCK(3PCAP) PCAP_SETNONBLOCK(3PCAP)
pcap_setnonblock, pcap_getnonblock - set or get the state of non-
blocking mode on a capture device
#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);
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.
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.
pcap(3PCAP), pcap_next_ex(3PCAP), pcap_geterr(3PCAP)
30 November 2023 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)