164 lines
4.5 KiB
Groff
164 lines
4.5 KiB
Groff
.\" $NetBSD: getifaddrs.3,v 1.6 2001/09/16 02:54:17 wiz Exp $
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.\" BSDI getifaddrs.3,v 2.5 2000/02/23 14:51:59 dab Exp
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.\"
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.\" Copyright (c) 1995, 1999
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.\" Berkeley Software Design, Inc. 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 the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY Berkeley Software Design, Inc. ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL Berkeley Software Design, Inc. BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.Dd October 12, 1995
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.Dt GETIFADDRS 3
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.Sh NAME
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.Nm getifaddrs
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.Nd get interface addresses
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.Sh SYNOPSIS
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.Fd #include <sys/types.h>
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.Fd #include <sys/socket.h>
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.Fd #include <ifaddrs.h>
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.Ft int
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.Fn getifaddrs "struct ifaddrs **ifap"
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.Ft void
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.Fn freeifaddrs "struct ifaddrs *ifp"
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.Sh DESCRIPTION
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The
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.Fn getifaddrs
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function stores a reference to a linked list of the network interfaces
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on the local machine in the memory referenced by
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.Fa ifap .
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The list consists of
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.Nm ifaddrs
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structures, as defined in the include file
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.Aq Pa ifaddrs.h .
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The
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.Nm ifaddrs
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structure contains at least the following entries:
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.Bd -literal
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struct ifaddrs *ifa_next; /* Pointer to next struct */
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char *ifa_name; /* Interface name */
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u_int ifa_flags; /* Interface flags */
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struct sockaddr *ifa_addr; /* Interface address */
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struct sockaddr *ifa_netmask; /* Interface netmask */
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struct sockaddr *ifa_broadaddr; /* Interface broadcast address */
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struct sockaddr *ifa_dstaddr; /* P2P interface destination */
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void *ifa_data; /* Address specific data */
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.Ed
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.Pp
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The
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.Li ifa_next
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field contains a pointer to the next structure on the list.
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This field is
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.Dv NULL
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in last structure on the list.
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.Pp
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The
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.Li ifa_name
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field contains the interface name.
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.Pp
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The
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.Li ifa_flags
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field contains the interface flags, as set by
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.Xr ifconfig 8
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utility.
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.Pp
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The
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.Li ifa_addr
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field references either the address of the interface or the link level
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address of the interface, if one exists, otherwise it is NULL.
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(The
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.Li sa_family
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field of the
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.Li ifa_addr
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field should be consulted to determine the format of the
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.Li ifa_addr
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address.)
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.Pp
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The
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.Li ifa_netmask
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field references the netmask associated with
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.Li ifa_addr ,
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if one is set, otherwise it is NULL.
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.Pp
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The
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.Li ifa_broadaddr
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field,
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which should only be referenced for non-P2P interfaces,
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references the broadcast address associated with
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.Li ifa_addr ,
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if one exists, otherwise it is NULL.
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.Pp
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The
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.Li ifa_dstaddr
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field references the destination address on a P2P interface,
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if one exists, otherwise it is NULL.
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.Pp
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The
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.Li ifa_data
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field references address family specific data. For
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.Dv AF_LINK
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addresses it contains a pointer to the
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.Fa struct if_data
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.Pq as defined in include file Aq Pa net/if.h
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which contains various interface attributes and statistics.
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For all other address families, it contains a pointer to the
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.Fa struct ifa_data
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.Pq as defined in include file Aq Pa net/if.h
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which contains per-address interface statistics.
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.Pp
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The data returned by
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.Fn getifaddrs
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is dynamically allocated and should be freed using
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.Fn freeifaddrs
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when no longer needed.
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.Sh RETURN VALUES
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Upon successful completion, a value of 0 is returned.
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Otherwise, a value of -1 is returned and
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.Va errno
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is set to indicate the error.
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.Sh ERRORS
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The
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.Fn getifaddrs
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may fail and set
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.Va errno
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for any of the errors specified for the library routines
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.Xr ioctl 2 ,
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.Xr socket 2 ,
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.Xr malloc 3
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or
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.Xr sysctl 3 .
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.Sh SEE ALSO
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.Xr ioctl 2 ,
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.Xr socket 2 ,
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.Xr sysctl 3 ,
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.Xr networking 4 ,
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.Xr ifconfig 8
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.Sh HISTORY
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The
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.Nm
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implementation first appeared in
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.Bsx .
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.Sh BUGS
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If both
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.Aq Pa net/if.h
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and
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.Aq Pa ifaddrs.h
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are being included,
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.Aq Pa net/if.h
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.Em must
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be included before
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.Aq Pa ifaddrs.h .
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