90 lines
3.0 KiB
Plaintext
90 lines
3.0 KiB
Plaintext
.\" Copyright (c) 1994, 1996, 1997
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that: (1) source code distributions
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.\" retain the above copyright notice and this paragraph in its entirety, (2)
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.\" distributions including binary code include the above copyright notice and
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.\" this paragraph in its entirety in the documentation or other materials
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.\" provided with the distribution, and (3) all advertising materials mentioning
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.\" features or use of this software display the following acknowledgement:
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.\" ``This product includes software developed by the University of California,
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.\" Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
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.\" the University nor the names of its contributors may be used to endorse
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.\" or promote products derived from this software without specific prior
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.\" written permission.
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.\" THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
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.\" WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
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.\" MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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.\"
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.TH PCAP_COMPILE 3PCAP "22 August 2018"
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.SH NAME
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pcap_compile \- compile a filter expression
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.SH SYNOPSIS
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.nf
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.ft B
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#include <pcap/pcap.h>
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.ft
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.LP
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.ft B
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int pcap_compile(pcap_t *p, struct bpf_program *fp,
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.ti +8
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const char *str, int optimize, bpf_u_int32 netmask);
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.ft
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.fi
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.SH DESCRIPTION
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.B pcap_compile()
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is used to compile the string
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.I str
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into a filter program. See
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.BR pcap-filter (@MAN_MISC_INFO@)
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for the syntax of that string.
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.I program
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is a pointer to a
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.I bpf_program
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struct and is filled in by
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.BR pcap_compile() .
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.I optimize
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controls whether optimization on the resulting code is performed.
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.I netmask
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specifies the IPv4 netmask of the network on which packets are being
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captured; it is used only when checking for IPv4 broadcast addresses in
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the filter program. If the netmask of the network on which packets are
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being captured isn't known to the program, or if packets are being
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captured on the Linux "any" pseudo-interface that can capture on more
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than one network, a value of
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.B PCAP_NETMASK_UNKNOWN
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can be supplied; tests
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for IPv4 broadcast addresses will fail to compile, but all other tests in
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the filter program will be OK.
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.LP
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NOTE: in libpcap 1.8.0 and later,
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.B pcap_compile()
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can be used in multiple threads within a single process. However, in
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earlier versions of libpcap, it is
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.I not
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safe to use
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.B pcap_compile()
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in multiple threads in a single process without some form of mutual
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exclusion allowing only one thread to call it at any given time.
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.SH RETURN VALUE
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.B pcap_compile()
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returns 0 on success and
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.B PCAP_ERROR
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on failure. If
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.B PCAP_ERROR
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is returned,
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.B pcap_geterr(3PCAP)
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or
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.B pcap_perror(3PCAP)
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may be called with
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.I p
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as an argument to fetch or display the error text.
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.SH BACKWARD COMPATIBILITY
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.PP
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The
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.B PCAP_NETMASK_UNKNOWN
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constant became available in libpcap release 1.1.0.
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.SH SEE ALSO
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pcap(3PCAP), pcap_setfilter(3PCAP), pcap_freecode(3PCAP),
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