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.\" @(#) $Header: /tcpdump/master/libpcap/pcap_findalldevs.3pcap,v 1.3 2008-04-06 02:53:22 guy Exp $
.\"
.\" Copyright (c) 1994, 1996, 1997
.\" The Regents of the University of California. All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that: (1) source code distributions
.\" retain the above copyright notice and this paragraph in its entirety, (2)
.\" distributions including binary code include the above copyright notice and
.\" this paragraph in its entirety in the documentation or other materials
.\" provided with the distribution, and (3) all advertising materials mentioning
.\" features or use of this software display the following acknowledgement:
.\" ``This product includes software developed by the University of California,
.\" Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
.\" the University nor the names of its contributors may be used to endorse
.\" or promote products derived from this software without specific prior
.\" written permission.
.\" THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
.\" WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
.\" MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
.\"
.TH PCAP_FINDALLDEVS 3PCAP "22 August 2010"
.SH NAME
pcap_findalldevs, pcap_freealldevs \- get a list of capture devices, and
free that list
.SH SYNOPSIS
.nf
.ft B
#include <pcap/pcap.h>
.ft
.LP
.nf
.ft B
char errbuf[PCAP_ERRBUF_SIZE];
.ft
.LP
.ft B
int pcap_findalldevs(pcap_if_t **alldevsp, char *errbuf);
void pcap_freealldevs(pcap_if_t *alldevs);
.ft
.fi
.SH DESCRIPTION
.B pcap_findalldevs()
constructs a list of network devices that can be opened with
.B pcap_create()
and
.B pcap_activate()
or with
.BR pcap_open_live() .
(Note that there may be network devices that cannot be opened by the
process calling
.BR pcap_findalldevs() ,
because, for example, that process might not have sufficient privileges
to open them for capturing; if so, those devices will not appear on the
list.)
.I alldevsp
is set to point to the first element of the list; each element of the
list is of type
.BR pcap_if_t ,
and has the following members:
.RS
.TP
.B next
if not
.BR NULL ,
a pointer to the next element in the list;
.B NULL
for the last element of the list
.TP
.B name
a pointer to a string giving a name for the device to pass to
.B pcap_open_live()
.TP
.B description
if not
.BR NULL ,
a pointer to a string giving a human-readable description of the device
.TP
.B addresses
a pointer to the first element of a list of addresses for the interface
.TP
.B flags
interface flags:
.RS
.TP
.B PCAP_IF_LOOPBACK
set if the interface is a loopback interface
.RE
.RE
.PP
Each element of the list of addresses is of type
.BR pcap_addr_t ,
and has the following members:
.RS
.TP
.B next
if not
.BR NULL ,
a pointer to the next element in the list;
.B NULL
for the last element of the list
.TP
.B addr
a pointer to a
.B "struct sockaddr"
containing an address
.TP
.B netmask
if not
.BR NULL ,
a pointer to a
.B "struct sockaddr"
that contains the netmask corresponding to the address pointed to by
.B addr
.TP
.B broadaddr
if not
.BR NULL ,
a pointer to a
.B "struct sockaddr"
that contains the broadcast address corresponding to the address pointed
to by
.BR addr ;
may be null if the interface doesn't support broadcasts
.TP
.B dstaddr
if not
.BR NULL ,
a pointer to a
.B "struct sockaddr"
that contains the destination address corresponding to the address pointed
to by
.BR addr ;
may be null if the interface isn't a point-to-point interface
.RE
.PP
Note that not all the addresses in the list of addresses are
necessarily IPv4 or IPv6 addresses - you must check the
.B sa_family
member of the
.B "struct sockaddr"
before interpreting the contents of the address.
.PP
The list of devices must be freed with
.BR pcap_freealldevs() ,
whch frees the list pointed to by
.IR alldevs .
.SH RETURN VALUE
.B pcap_findalldevs()
returns 0 on success and \-1 on failure.
If \-1 is returned,
.I errbuf
is filled in with an appropriate error message.
.I errbuf
is assumed to be able to hold at least
.B PCAP_ERRBUF_SIZE
chars.
.SH SEE ALSO
pcap(3PCAP), pcap_create(3PCAP), pcap_activate(3PCAP),
pcap_open_live(3PCAP)
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