1.\" Copyright (c) 2003 Bruce M. Simpson. All rights reserved. 2.\" 3.\" Redistribution and use in source and binary forms, with or without 4.\" modification, are permitted provided that the following conditions 5.\" are met: 6.\" 1. Redistributions of source code must retain the above copyright 7.\" notice, this list of conditions and the following disclaimer. 8.\" 9.\" THIS SOFTWARE IS PROVIDED BY Bruce M. Simpson ``AS IS'' AND 10.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 11.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 12.\" ARE DISCLAIMED. IN NO EVENT SHALL Bruce M. Simpson BE LIABLE 13.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 14.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 15.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 16.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 17.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 18.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 19.\" SUCH DAMAGE. 20.\" 21.\" $FreeBSD$ 22.\" 23.Dd May 21, 2013 24.Dt GETIFMADDRS 3 25.Os 26.Sh NAME 27.Nm getifmaddrs 28.Nd get multicast group memberships 29.Sh SYNOPSIS 30.In ifaddrs.h 31.Ft int 32.Fn getifmaddrs "struct ifmaddrs **ifmap" 33.Ft void 34.Fn freeifmaddrs "struct ifmaddrs *ifmp" 35.Sh DESCRIPTION 36The 37.Fn getifmaddrs 38function stores a reference to a linked list of the multicast memberships 39on the local machine in the memory referenced by 40.Fa ifmap . 41The list consists of 42.Vt ifmaddrs 43structures, as defined in the include file 44.In ifaddrs.h . 45The 46.Vt ifmaddrs 47structure contains at least the following entries: 48.Bd -literal 49 struct ifmaddrs *ifma_next; /* Pointer to next struct */ 50 struct sockaddr *ifma_name; /* Interface name (AF_LINK) */ 51 struct sockaddr *ifma_addr; /* Multicast address */ 52 struct sockaddr *ifma_lladdr; /* Link-layer translation, if any */ 53.Ed 54.Pp 55The 56.Va ifma_next 57field contains a pointer to the next structure on the list. 58This field is 59.Dv NULL 60in last structure on the list. 61.Pp 62The 63.Va ifma_name 64field references an 65.Dv AF_LINK 66address structure, containing the name of the 67interface where the membership exists. 68.Pp 69The 70.Va ifma_addr 71references the address that this membership is for. 72.Pp 73The 74.Va ifma_lladdr 75field references a link-layer translation for the protocol-level address in 76.Va ifma_addr , 77if one is set, otherwise it is 78.Dv NULL . 79.Pp 80The data returned by 81.Fn getifmaddrs 82is dynamically allocated and should be freed using 83.Fn freeifmaddrs 84when no longer needed. 85.Sh RETURN VALUES 86.Rv -std getifmaddrs 87.Sh ERRORS 88The 89.Fn getifmaddrs 90may fail and set 91.Va errno 92for any of the errors specified for the library routines 93.Xr malloc 3 94or 95.Xr sysctl 3 . 96.Sh SEE ALSO 97.Xr sysctl 3 , 98.Xr networking 4 , 99.Xr ifconfig 8 100.Sh HISTORY 101The 102.Fn getifmaddrs 103function first appeared in 104.Fx 5.2 . 105.Sh BUGS 106If both 107.In net/if.h 108and 109.In ifaddrs.h 110are being included, 111.In net/if.h 112.Em must 113be included before 114.In ifaddrs.h . 115