pcap_compile(3pcap) — Linux manual page
PCAP_COMPILE(3PCAP) PCAP_COMPILE(3PCAP)
NAME
pcap_compile - compile a filter expression
SYNOPSIS
#include <pcap/pcap.h>
int pcap_compile(pcap_t *p, struct bpf_program *fp,
const char *str, int optimize, bpf_u_int32 netmask);
DESCRIPTION
pcap_compile() is used to compile the string str into a filter
program. See pcap-filter(7) for the syntax of that string. fp
is a pointer to a bpf_program struct and is filled in by
pcap_compile(). optimize controls whether optimization on the
resulting code is performed. 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 PCAP_NETMASK_UNKNOWN
can be supplied; tests for IPv4 broadcast addresses will fail to
compile, but all other tests in the filter program will be OK.
NOTE: in libpcap 1.8.0 and later, pcap_compile() can be used in
multiple threads within a single process. However, in earlier
versions of libpcap, it is not safe to use pcap_compile() in
multiple threads in a single process without some form of mutual
exclusion allowing only one thread to call it at any given time.
RETURN VALUE
pcap_compile() returns 0 on success and PCAP_ERROR on failure. If
PCAP_ERROR is returned, pcap_geterr(3PCAP) or pcap_perror(3PCAP)
may be called with p as an argument to fetch or display the error
text.
BACKWARD COMPATIBILITY
The PCAP_NETMASK_UNKNOWN constant became available in libpcap
release 1.1.0.
SEE ALSO
pcap(3PCAP), pcap_setfilter(3PCAP), pcap_freecode(3PCAP)
COLOPHON
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 2024-06-14.
(At that time, the date of the most recent commit that was found
in the repository was 2024-06-04.) If you discover any rendering
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