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.Dd May 21, 2013 22.Dt GETIFMADDRS 3 23.Os 24.Sh NAME 25.Nm getifmaddrs 26.Nd get multicast group memberships 27.Sh SYNOPSIS 28.In ifaddrs.h 29.Ft int 30.Fn getifmaddrs "struct ifmaddrs **ifmap" 31.Ft void 32.Fn freeifmaddrs "struct ifmaddrs *ifmp" 33.Sh DESCRIPTION 34The 35.Fn getifmaddrs 36function stores a reference to a linked list of the multicast memberships 37on the local machine in the memory referenced by 38.Fa ifmap . 39The list consists of 40.Vt ifmaddrs 41structures, as defined in the include file 42.In ifaddrs.h . 43The 44.Vt ifmaddrs 45structure contains at least the following entries: 46.Bd -literal 47 struct ifmaddrs *ifma_next; /* Pointer to next struct */ 48 struct sockaddr *ifma_name; /* Interface name (AF_LINK) */ 49 struct sockaddr *ifma_addr; /* Multicast address */ 50 struct sockaddr *ifma_lladdr; /* Link-layer translation, if any */ 51.Ed 52.Pp 53The 54.Va ifma_next 55field contains a pointer to the next structure on the list. 56This field is 57.Dv NULL 58in last structure on the list. 59.Pp 60The 61.Va ifma_name 62field references an 63.Dv AF_LINK 64address structure, containing the name of the 65interface where the membership exists. 66.Pp 67The 68.Va ifma_addr 69references the address that this membership is for. 70.Pp 71The 72.Va ifma_lladdr 73field references a link-layer translation for the protocol-level address in 74.Va ifma_addr , 75if one is set, otherwise it is 76.Dv NULL . 77.Pp 78The data returned by 79.Fn getifmaddrs 80is dynamically allocated and should be freed using 81.Fn freeifmaddrs 82when no longer needed. 83.Sh RETURN VALUES 84.Rv -std getifmaddrs 85.Sh ERRORS 86The 87.Fn getifmaddrs 88may fail and set 89.Va errno 90for any of the errors specified for the library routines 91.Xr malloc 3 92or 93.Xr sysctl 3 . 94.Sh SEE ALSO 95.Xr sysctl 3 , 96.Xr networking 4 , 97.Xr ifconfig 8 98.Sh HISTORY 99The 100.Fn getifmaddrs 101function first appeared in 102.Fx 5.2 . 103.Sh BUGS 104If both 105.In net/if.h 106and 107.In ifaddrs.h 108are being included, 109.In net/if.h 110.Em must 111be included before 112.In ifaddrs.h . 113