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)