1.\" $NetBSD: getifaddrs.3,v 1.7 2002/02/07 07:00:20 ross 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.Sh NAME 27.Nm getifaddrs 28.Nd get interface addresses 29.Sh SYNOPSIS 30.Fd #include \*[Lt]sys/types.h\*[Gt] 31.Fd #include \*[Lt]sys/socket.h\*[Gt] 32.Fd #include \*[Lt]ifaddrs.h\*[Gt] 33.Ft int 34.Fn getifaddrs "struct ifaddrs **ifap" 35.Ft void 36.Fn freeifaddrs "struct ifaddrs *ifp" 37.Sh DESCRIPTION 38The 39.Fn getifaddrs 40function stores a reference to a linked list of the network interfaces 41on the local machine in the memory referenced by 42.Fa ifap . 43The list consists of 44.Nm ifaddrs 45structures, as defined in the include file 46.Aq Pa ifaddrs.h . 47The 48.Nm ifaddrs 49structure contains at least the following entries: 50.Bd -literal 51 struct ifaddrs *ifa_next; /* Pointer to next struct */ 52 char *ifa_name; /* Interface name */ 53 u_int ifa_flags; /* Interface flags */ 54 struct sockaddr *ifa_addr; /* Interface address */ 55 struct sockaddr *ifa_netmask; /* Interface netmask */ 56 struct sockaddr *ifa_broadaddr; /* Interface broadcast address */ 57 struct sockaddr *ifa_dstaddr; /* P2P interface destination */ 58 void *ifa_data; /* Address specific data */ 59.Ed 60.Pp 61The 62.Li ifa_next 63field contains a pointer to the next structure on the list. 64This field is 65.Dv NULL 66in last structure on the list. 67.Pp 68The 69.Li ifa_name 70field contains the interface name. 71.Pp 72The 73.Li ifa_flags 74field contains the interface flags, as set by 75.Xr ifconfig 8 76utility. 77.Pp 78The 79.Li ifa_addr 80field references either the address of the interface or the link level 81address of the interface, if one exists, otherwise it is NULL. 82(The 83.Li sa_family 84field of the 85.Li ifa_addr 86field should be consulted to determine the format of the 87.Li ifa_addr 88address.) 89.Pp 90The 91.Li ifa_netmask 92field references the netmask associated with 93.Li ifa_addr , 94if one is set, otherwise it is NULL. 95.Pp 96The 97.Li ifa_broadaddr 98field, 99which should only be referenced for non-P2P interfaces, 100references the broadcast address associated with 101.Li ifa_addr , 102if one exists, otherwise it is NULL. 103.Pp 104The 105.Li ifa_dstaddr 106field references the destination address on a P2P interface, 107if one exists, otherwise it is NULL. 108.Pp 109The 110.Li ifa_data 111field references address family specific data. For 112.Dv AF_LINK 113addresses it contains a pointer to the 114.Fa struct if_data 115.Pq as defined in include file Aq Pa net/if.h 116which contains various interface attributes and statistics. 117For all other address families, it contains a pointer to the 118.Fa struct ifa_data 119.Pq as defined in include file Aq Pa net/if.h 120which contains per-address interface statistics. 121.Pp 122The data returned by 123.Fn getifaddrs 124is dynamically allocated and should be freed using 125.Fn freeifaddrs 126when no longer needed. 127.Sh RETURN VALUES 128Upon successful completion, a value of 0 is returned. 129Otherwise, a value of -1 is returned and 130.Va errno 131is set to indicate the error. 132.Sh ERRORS 133The 134.Fn getifaddrs 135may fail and set 136.Va errno 137for any of the errors specified for the library routines 138.Xr ioctl 2 , 139.Xr socket 2 , 140.Xr malloc 3 141or 142.Xr sysctl 3 . 143.Sh SEE ALSO 144.Xr ioctl 2 , 145.Xr socket 2 , 146.Xr sysctl 3 , 147.Xr networking 4 , 148.Xr ifconfig 8 149.Sh HISTORY 150The 151.Nm 152implementation first appeared in 153.Bsx . 154.Sh BUGS 155If both 156.Aq Pa net/if.h 157and 158.Aq Pa ifaddrs.h 159are being included, 160.Aq Pa net/if.h 161.Em must 162be included before 163.Aq Pa ifaddrs.h . 164