+----------------------------------------------------------------------------+ | | | This man page documents libpcap version 1.10.1. | | | | Your system may have a different version installed, possibly with some | | local modifications. To achieve the best results, please make sure this | | version of this man page suits your needs. If necessary, try to look for | | a different version on this web site or in the man pages available in your | | installation. | | | +----------------------------------------------------------------------------+ PCAP_SETNONBLOCK(3PCAP) PCAP_SETNONBLOCK(3PCAP) NAME pcap_setnonblock, pcap_getnonblock - set or get the state of non-block- ing mode on a capture device SYNOPSIS #include 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 non- block 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 descrip- tor with pcap_dispatch(3PCAP) and pcap_next_ex(3PCAP) will, if no pack- ets 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; pacp_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_getnonblock() returns the current ``non-blocking'' state of the capture descriptor; it always returns 0 on ``savefiles''. If there is an error, PCAP_ERROR is returned and errbuf is filled in with an appro- priate error message. errbuf is assumed to be able to hold at least PCAP_ERRBUF_SIZE chars. SEE ALSO pcap(3PCAP), pcap_next_ex(3PCAP), pcap_geterr(3PCAP) 25 July 2018 PCAP_SETNONBLOCK(3PCAP)