1.\" $KAME: getifaddrs.3,v 1.4 2000/05/17 14:13:14 itojun Exp $ 2.\" BSDI getifaddrs.3,v 2.5 2000/02/23 14:51:59 dab Exp 3.\" 4.\" Copyright (c) 1995, 1999 5.\" Berkeley Software Design, Inc. All rights reserved. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 13.\" THIS SOFTWARE IS PROVIDED BY Berkeley Software Design, Inc. ``AS IS'' AND 14.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 15.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 16.\" ARE DISCLAIMED. IN NO EVENT SHALL Berkeley Software Design, Inc. BE LIABLE 17.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 18.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 19.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 20.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 21.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 22.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 23.\" SUCH DAMAGE. 24.\" 25.\" $FreeBSD$ 26.\" 27.Dd May 21, 2013 28.Dt GETIFADDRS 3 29.Os 30.Sh NAME 31.Nm getifaddrs 32.Nd get interface addresses 33.Sh SYNOPSIS 34.In ifaddrs.h 35.Ft int 36.Fn getifaddrs "struct ifaddrs **ifap" 37.Ft void 38.Fn freeifaddrs "struct ifaddrs *ifp" 39.Sh DESCRIPTION 40The 41.Fn getifaddrs 42function stores a reference to a linked list of the network interfaces 43on the local machine in the memory referenced by 44.Fa ifap . 45The list consists of 46.Nm ifaddrs 47structures, as defined in the include file 48.In ifaddrs.h . 49The 50.Nm ifaddrs 51structure contains at least the following entries: 52.Bd -literal 53 struct ifaddrs *ifa_next; /* Pointer to next struct */ 54 char *ifa_name; /* Interface name */ 55 u_int ifa_flags; /* Interface flags */ 56 struct sockaddr *ifa_addr; /* Interface address */ 57 struct sockaddr *ifa_netmask; /* Interface netmask */ 58 struct sockaddr *ifa_broadaddr; /* Interface broadcast address */ 59 struct sockaddr *ifa_dstaddr; /* P2P interface destination */ 60 void *ifa_data; /* Address specific data */ 61.Ed 62.Pp 63The 64.Li ifa_next 65field contains a pointer to the next structure on the list. 66This field is 67.Dv NULL 68in last structure on the list. 69.Pp 70The 71.Li ifa_name 72field contains the interface name. 73.Pp 74The 75.Li ifa_flags 76field contains the interface flags, as set by 77.Xr ifconfig 8 78utility. 79.Pp 80The 81.Li ifa_addr 82field references either the address of the interface or the link level 83address of the interface, if one exists, otherwise it is NULL. 84(The 85.Li sa_family 86field of the 87.Li ifa_addr 88field should be consulted to determine the format of the 89.Li ifa_addr 90address.) 91.Pp 92The 93.Li ifa_netmask 94field references the netmask associated with 95.Li ifa_addr , 96if one is set, otherwise it is NULL. 97.Pp 98The 99.Li ifa_broadaddr 100field, 101which should only be referenced for non-P2P interfaces, 102references the broadcast address associated with 103.Li ifa_addr , 104if one exists, otherwise it is NULL. 105.Pp 106The 107.Li ifa_dstaddr 108field references the destination address on a P2P interface, 109if one exists, otherwise it is NULL. 110.Pp 111The 112.Li ifa_data 113field references address family specific data. 114For 115.Dv AF_LINK 116addresses it contains a pointer to the 117.Fa struct if_data 118(as defined in include file 119.In net/if.h ) 120which contains various interface attributes and statistics. 121For all other address families, it contains a pointer to the 122.Fa struct ifa_data 123(as defined in include file 124.In net/if.h ) 125which contains per-address interface statistics. 126.Pp 127The data returned by 128.Fn getifaddrs 129is dynamically allocated and should be freed using 130.Fn freeifaddrs 131when no longer needed. 132.Sh RETURN VALUES 133.Rv -std getifaddrs 134.Sh ERRORS 135The 136.Fn getifaddrs 137may fail and set 138.Va errno 139for any of the errors specified for the library routines 140.Xr ioctl 2 , 141.Xr socket 2 , 142.Xr malloc 3 143or 144.Xr sysctl 3 . 145.Sh SEE ALSO 146.Xr ioctl 2 , 147.Xr socket 2 , 148.Xr sysctl 3 , 149.Xr networking 4 , 150.Xr ifconfig 8 151.Sh HISTORY 152The 153.Nm 154implementation first appeared in BSDi 155.Bsx . 156.Sh BUGS 157If both 158.In net/if.h 159and 160.In ifaddrs.h 161are being included, 162.In net/if.h 163.Em must 164be included before 165.In ifaddrs.h . 166