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; 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.
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 appropriate error message.
errbuf is assumed to be able to hold at least PCAP_ERRBUF_SIZE
This page is part of the libpcap (packet capture library)
project. Information about the project can be found at
⟨http://www.tcpdump.org/⟩. If you have a bug report for this
manual page, see ⟨http://www.tcpdump.org/#patches⟩. This page
was obtained from the project's upstream Git repository
⟨https://github.com/the-tcpdump-group/libpcap.git⟩ on 2021-04-01.
(At that time, the date of the most recent commit that was found
in the repository was 2021-03-31.) If you discover any rendering
problems in this HTML version of the page, or you believe there
is a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
25 July 2018 PCAP_SETNONBLOCK(3PCAP)