1.\" $FreeBSD$ 2.\" $KAME: getifaddrs.3,v 1.4 2000/05/17 14:13:14 itojun Exp $ 3.\" BSDI getifaddrs.3,v 2.5 2000/02/23 14:51:59 dab Exp 4.\" 5.\" Copyright (c) 1995, 1999 6.\" Berkeley Software Design, Inc. All rights reserved. 7.\" 8.\" Redistribution and use in source and binary forms, with or without 9.\" modification, are permitted provided that the following conditions 10.\" are met: 11.\" 1. Redistributions of source code must retain the above copyright 12.\" notice, this list of conditions and the following disclaimer. 13.\" 14.\" THIS SOFTWARE IS PROVIDED BY Berkeley Software Design, Inc. ``AS IS'' AND 15.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17.\" ARE DISCLAIMED. IN NO EVENT SHALL Berkeley Software Design, Inc. BE LIABLE 18.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24.\" SUCH DAMAGE. 25.Dd October 12, 1995 26.Dt GETIFADDRS 3 27.Os 28.Sh NAME 29.Nm getifaddrs 30.Nd get interface addresses 31.Sh SYNOPSIS 32.In sys/types.h 33.In sys/socket.h 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. For 114.Dv AF_LINK 115addresses it contains a pointer to the 116.Fa struct if_data 117(as defined in include file 118.In net/if.h ) 119which contains various interface attributes and statistics. 120For all other address families, it contains a pointer to the 121.Fa struct ifa_data 122(as defined in include file 123.In net/if.h ) 124which contains per-address interface statistics. 125.Pp 126The data returned by 127.Fn getifaddrs 128is dynamically allocated and should be freed using 129.Fn freeifaddrs 130when no longer needed. 131.Sh RETURN VALUES 132.Rv -std getifaddrs 133.Sh ERRORS 134The 135.Fn getifaddrs 136may fail and set 137.Va errno 138for any of the errors specified for the library routines 139.Xr ioctl 2 , 140.Xr socket 2 , 141.Xr malloc 3 142or 143.Xr sysctl 3 . 144.Sh BUGS 145If both 146.In net/if.h 147and 148.In ifaddrs.h 149are being included, 150.In net/if.h 151.Em must 152be included before 153.In ifaddrs.h . 154.Sh SEE ALSO 155.Xr ioctl 2 , 156.Xr socket 2 , 157.Xr sysctl 3 , 158.Xr networking 4 , 159.Xr ifconfig 8 160.Sh HISTORY 161The 162.Nm 163implementation first appeared in BSDi 164.Bsx . 165