PCAP_SETNONBLOCK

Section: Misc. Reference Manual Pages (3PCAP)
Updated: 18 October 2014
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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''. If there is an error, -1 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() will, if no packets are currently available to be read, return 0 immediately rather than blocking waiting for packets to arrive. pcap_loop() and pcap_next() will not work in ``non-blocking'' mode.

When first activated with pcap_activate() or opened with pcap_open_live() , 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 there is an error, -1 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.