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PCAP_SETNONBLOCK

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, −1 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() will, if no packets are currently available to be read, return 0 immediately rather than blocking waiting for packets to arrive. pcap_loop() and pcap_next() will not work in ‘‘non-blocking’’ mode.

When first activated with pcap_activate() or opened with pcap_open_live() , 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, −1 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_loop(3PCAP), pcap_next_ex(3PCAP), pcap_geterr(3PCAP)

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