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, 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(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_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(3PCAP), pcap_next_ex(3PCAP), pcap_geterr(3PCAP)

                                           5 March 2022                   PCAP_SETNONBLOCK(3PCAP)