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.TH PCAP_COMPILE 3PCAP "5 April 2008"
.SH NAME
pcap_compile \- compile a filter expression
.SH SYNOPSIS
.nf
.ft B
#include <pcap/pcap.h>
.ft
.LP
.ft B
int pcap_compile(pcap_t *p, struct bpf_program *fp,
.ti +8
const char *str, int optimize, bpf_u_int32 netmask);
.ft
.fi
.SH DESCRIPTION
.B pcap_compile()
is used to compile the string
.I str
into a filter program.  See
.BR pcap-filter (7)
for the syntax of that string.
.I program
is a pointer to a
.I bpf_program
struct and is filled in by
.BR pcap_compile() .
.I optimize
controls whether optimization on the resulting code is performed.
.I netmask
specifies the IPv4 netmask of the network on which packets are being
captured; it is used only when checking for IPv4 broadcast addresses in
the filter program.  If the netmask of the network on which packets are
being captured isn't known to the program, or if packets are being
captured on the Linux "any" pseudo-interface that can capture on more
than one network, a value of 0 can be supplied; tests for IPv4 broadcast
addreses won't be done correctly, but all other tests in the filter
program will be OK.
.SH RETURN VALUE
.B pcap_compile()
returns 0 on success and \-1 on failure.
If \-1 is returned,
.B pcap_geterr()
or
.B pcap_perror()
may be called with
.I p
as an argument to fetch or display the error text.
.SH SEE ALSO
pcap(3PCAP), pcap_setfilter(3PCAP), pcap_freecode(3PCAP),
pcap_geterr(3PCAP), pcap-filter(7)