115 lines
3.0 KiB
Groff
115 lines
3.0 KiB
Groff
.\" Copyright (c) 2003 Bruce M. Simpson. 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 Bruce M. Simpson ``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 Bruce M. Simpson 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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.\"
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.\" $FreeBSD$
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.\"
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.Dd May 21, 2013
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.Dt GETIFMADDRS 3
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.Os
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.Sh NAME
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.Nm getifmaddrs
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.Nd get multicast group memberships
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.Sh SYNOPSIS
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.In ifaddrs.h
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.Ft int
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.Fn getifmaddrs "struct ifmaddrs **ifmap"
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.Ft void
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.Fn freeifmaddrs "struct ifmaddrs *ifmp"
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.Sh DESCRIPTION
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The
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.Fn getifmaddrs
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function stores a reference to a linked list of the multicast memberships
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on the local machine in the memory referenced by
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.Fa ifmap .
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The list consists of
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.Vt ifmaddrs
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structures, as defined in the include file
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.In ifaddrs.h .
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The
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.Vt ifmaddrs
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structure contains at least the following entries:
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.Bd -literal
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struct ifmaddrs *ifma_next; /* Pointer to next struct */
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struct sockaddr *ifma_name; /* Interface name (AF_LINK) */
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struct sockaddr *ifma_addr; /* Multicast address */
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struct sockaddr *ifma_lladdr; /* Link-layer translation, if any */
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.Ed
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.Pp
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The
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.Va ifma_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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.Va ifma_name
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field references an
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.Dv AF_LINK
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address structure, containing the name of the
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interface where the membership exists.
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.Pp
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The
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.Va ifma_addr
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references the address that this membership is for.
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.Pp
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The
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.Va ifma_lladdr
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field references a link-layer translation for the protocol-level address in
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.Va ifma_addr ,
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if one is set, otherwise it is
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.Dv NULL .
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.Pp
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The data returned by
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.Fn getifmaddrs
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is dynamically allocated and should be freed using
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.Fn freeifmaddrs
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when no longer needed.
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.Sh RETURN VALUES
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.Rv -std getifmaddrs
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.Sh ERRORS
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The
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.Fn getifmaddrs
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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 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 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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.Fn getifmaddrs
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function first appeared in
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.Fx 5.2 .
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.Sh BUGS
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If both
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.In net/if.h
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and
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.In ifaddrs.h
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are being included,
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.In net/if.h
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.Em must
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be included before
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.In ifaddrs.h .
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