PCAP_SETNONBLOCK(3)

PCAP_SETNONBLOCK(3) | Library Functions Manual | PCAP_SETNONBLOCK(3)

# 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(3) will, if no packets are currently available to be read, return 0 immediately rather than blocking waiting for packets to arrive. pcap_loop(3) and pcap_next(3) will not work in ``non-blocking'' mode.

When first activated with pcap_activate(3) or opened with pcap_open_live(3) , 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 appropriate error message.

errbuf is assumed to be able to hold at least PCAP_ERRBUF_SIZE chars.

# SEE ALSO

pcap(3), pcap_next_ex(3), pcap_geterr(3)

25 July 2018 |