1.\" $NetBSD: getifaddrs.3,v 1.9 2009/03/11 13:35:42 joerg 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.Dd October 12, 1995 25.Dt GETIFADDRS 3 26.Os 27.Sh NAME 28.Nm getifaddrs 29.Nd get interface addresses 30.Sh SYNOPSIS 31.In sys/types.h 32.In sys/socket.h 33.In ifaddrs.h 34.Ft int 35.Fn getifaddrs "struct ifaddrs **ifap" 36.Ft void 37.Fn freeifaddrs "struct ifaddrs *ifp" 38.Sh DESCRIPTION 39The 40.Fn getifaddrs 41function stores a reference to a linked list of the network interfaces 42on the local machine in the memory referenced by 43.Fa ifap . 44The list consists of 45.Nm ifaddrs 46structures, as defined in the include file 47.Aq Pa ifaddrs.h . 48The 49.Nm ifaddrs 50structure contains at least the following entries: 51.Bd -literal 52 struct ifaddrs *ifa_next; /* Pointer to next struct */ 53 char *ifa_name; /* Interface name */ 54 u_int ifa_flags; /* Interface flags */ 55 struct sockaddr *ifa_addr; /* Interface address */ 56 struct sockaddr *ifa_netmask; /* Interface netmask */ 57 struct sockaddr *ifa_broadaddr; /* Interface broadcast address */ 58 struct sockaddr *ifa_dstaddr; /* P2P interface destination */ 59 void *ifa_data; /* Address specific data */ 60.Ed 61.Pp 62The 63.Li ifa_next 64field contains a pointer to the next structure on the list. 65This field is 66.Dv NULL 67in last structure on the list. 68.Pp 69The 70.Li ifa_name 71field contains the interface name. 72.Pp 73The 74.Li ifa_flags 75field contains the interface flags, as set by 76.Xr ifconfig 8 77utility. 78.Pp 79The 80.Li ifa_addr 81field references either the address of the interface or the link level 82address of the interface, if one exists, otherwise it is NULL. 83(The 84.Li sa_family 85field of the 86.Li ifa_addr 87field should be consulted to determine the format of the 88.Li ifa_addr 89address.) 90.Pp 91The 92.Li ifa_netmask 93field references the netmask associated with 94.Li ifa_addr , 95if one is set, otherwise it is NULL. 96.Pp 97The 98.Li ifa_broadaddr 99field, 100which should only be referenced for non-P2P interfaces, 101references the broadcast address associated with 102.Li ifa_addr , 103if one exists, otherwise it is NULL. 104.Pp 105The 106.Li ifa_dstaddr 107field references the destination address on a P2P interface, 108if one exists, otherwise it is NULL. 109.Pp 110The 111.Li ifa_data 112field references address family specific data. For 113.Dv AF_LINK 114addresses it contains a pointer to the 115.Fa struct if_data 116.Pq as defined in include file Aq Pa net/if.h 117which contains various interface attributes and statistics. 118For all other address families, it contains a pointer to the 119.Fa struct ifa_data 120.Pq as defined in include file Aq Pa net/if.h 121which contains per-address interface statistics. 122.Pp 123The data returned by 124.Fn getifaddrs 125is dynamically allocated and should be freed using 126.Fn freeifaddrs 127when no longer needed. 128.Sh RETURN VALUES 129Upon successful completion, a value of 0 is returned. 130Otherwise, a value of -1 is returned and 131.Va errno 132is set to indicate the error. 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 SEE ALSO 145.Xr ioctl 2 , 146.Xr socket 2 , 147.Xr sysctl 3 , 148.Xr networking 4 , 149.Xr ifconfig 8 150.Sh HISTORY 151The 152.Nm 153implementation first appeared in 154.Bsx . 155.Sh BUGS 156If both 157.Aq Pa net/if.h 158and 159.Aq Pa ifaddrs.h 160are being included, 161.Aq Pa net/if.h 162.Em must 163be included before 164.Aq Pa ifaddrs.h . 165