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: src/lib/libc/net/getifaddrs.3,v 1.10 2005/02/09 18:03:13 ru Exp $ 26.\" $DragonFly: src/lib/libc/net/getifaddrs.3,v 1.5 2007/08/18 20:48:47 swildner Exp $ 27.\" 28.Dd October 12, 1995 29.Dt GETIFADDRS 3 30.Os 31.Sh NAME 32.Nm getifaddrs 33.Nd get interface addresses 34.Sh LIBRARY 35.Lb libc 36.Sh SYNOPSIS 37.In sys/types.h 38.In sys/socket.h 39.In ifaddrs.h 40.Ft int 41.Fn getifaddrs "struct ifaddrs **ifap" 42.Ft void 43.Fn freeifaddrs "struct ifaddrs *ifp" 44.Sh DESCRIPTION 45The 46.Fn getifaddrs 47function stores a reference to a linked list of the network interfaces 48on the local machine in the memory referenced by 49.Fa ifap . 50The list consists of 51.Nm ifaddrs 52structures, as defined in the include file 53.In ifaddrs.h . 54The 55.Nm ifaddrs 56structure contains at least the following entries: 57.Bd -literal 58 struct ifaddrs *ifa_next; /* Pointer to next struct */ 59 char *ifa_name; /* Interface name */ 60 u_int ifa_flags; /* Interface flags */ 61 struct sockaddr *ifa_addr; /* Interface address */ 62 struct sockaddr *ifa_netmask; /* Interface netmask */ 63 struct sockaddr *ifa_broadaddr; /* Interface broadcast address */ 64 struct sockaddr *ifa_dstaddr; /* P2P interface destination */ 65 void *ifa_data; /* Address specific data */ 66.Ed 67.Pp 68The 69.Li ifa_next 70field contains a pointer to the next structure on the list. 71This field is 72.Dv NULL 73in last structure on the list. 74.Pp 75The 76.Li ifa_name 77field contains the interface name. 78.Pp 79The 80.Li ifa_flags 81field contains the interface flags, as set by 82.Xr ifconfig 8 83utility. 84.Pp 85The 86.Li ifa_addr 87field references either the address of the interface or the link level 88address of the interface, if one exists, otherwise it is NULL. 89(The 90.Li sa_family 91field of the 92.Li ifa_addr 93field should be consulted to determine the format of the 94.Li ifa_addr 95address.) 96.Pp 97The 98.Li ifa_netmask 99field references the netmask associated with 100.Li ifa_addr , 101if one is set, otherwise it is NULL. 102.Pp 103The 104.Li ifa_broadaddr 105field, 106which should only be referenced for non-P2P interfaces, 107references the broadcast address associated with 108.Li ifa_addr , 109if one exists, otherwise it is NULL. 110.Pp 111The 112.Li ifa_dstaddr 113field references the destination address on a P2P interface, 114if one exists, otherwise it is NULL. 115.Pp 116The 117.Li ifa_data 118field references address family specific data. 119For 120.Dv AF_LINK 121addresses it contains a pointer to the 122.Fa struct if_data 123(as defined in include file 124.In net/if.h ) 125which contains various interface attributes and statistics. 126For all other address families, it contains a pointer to the 127.Fa struct ifa_data 128(as defined in include file 129.In net/if.h ) 130which contains per-address interface statistics. 131.Pp 132The data returned by 133.Fn getifaddrs 134is dynamically allocated and should be freed using 135.Fn freeifaddrs 136when no longer needed. 137.Sh RETURN VALUES 138.Rv -std getifaddrs 139.Sh ERRORS 140The 141.Fn getifaddrs 142may fail and set 143.Va errno 144for any of the errors specified for the library routines 145.Xr ioctl 2 , 146.Xr socket 2 , 147.Xr malloc 3 148or 149.Xr sysctl 3 . 150.Sh SEE ALSO 151.Xr ioctl 2 , 152.Xr socket 2 , 153.Xr sysctl 3 , 154.Xr networking 4 , 155.Xr ifconfig 8 156.Sh HISTORY 157The 158.Nm 159implementation first appeared in BSDi 160.Bsx . 161.Sh BUGS 162If both 163.In net/if.h 164and 165.In ifaddrs.h 166are being included, 167.In net/if.h 168.Em must 169be included before 170.In ifaddrs.h . 171