1.\" $OpenBSD: getifaddrs.3,v 1.18 2014/01/21 03:15:45 schwarze 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 $Mdocdate: January 21 2014 $ 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 *ifap" 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.In 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.Bl -tag -width ifa_broadaddr 62.It Fa ifa_next 63Contains a pointer to the next structure on the list. 64This field is set to 65.Dv NULL 66in the last structure on the list. 67.It Fa ifa_name 68Contains the interface name. 69.It Fa ifa_flags 70Contains the interface flags, as set by 71.Xr ifconfig 8 . 72.It Fa ifa_addr 73References either the address of the interface or the link level 74address of the interface, if one exists, otherwise it is 75.Dv NULL . 76(The 77.Fa sa_family 78field of the 79.Fa ifa_addr 80field should be consulted to determine the format of the 81.Fa ifa_addr 82address.) 83.It Fa ifa_netmask 84References the netmask associated with 85.Fa ifa_addr , 86if one is set, otherwise it is 87.Dv NULL . 88.It Fa ifa_broadaddr 89This field, which should only be referenced for non-P2P interfaces, 90references the broadcast address associated with 91.Fa ifa_addr , 92if one exists, otherwise it is 93.Dv NULL . 94.It Fa ifa_dstaddr 95This field, which should only be referenced for P2P interfaces, 96references the destination address on a P2P interface, 97if one exists, otherwise it is 98.Dv NULL . 99.It Fa ifa_data 100References address family specific data. 101For 102.Dv AF_LINK 103addresses it contains a pointer to the 104.Li struct if_data 105(as defined in include file 106.In net/if.h ) 107which contains various interface attributes and statistics. 108For all other address families, 109.Fa ifa_data 110is 111.Dv NULL . 112.El 113.Pp 114The data returned by 115.Fn getifaddrs 116is dynamically allocated and should be freed using 117.Fn freeifaddrs 118when no longer needed. 119.Sh RETURN VALUES 120Upon successful completion, a value of 0 is returned. 121Otherwise, a value of \-1 is returned and 122.Va errno 123is set to indicate the error. 124.Sh ERRORS 125The 126.Fn getifaddrs 127may fail and set 128.Va errno 129for any of the errors specified for the library routines 130.Xr ioctl 2 , 131.Xr socket 2 , 132.Xr malloc 3 , 133or 134.Xr sysctl 3 . 135.Sh SEE ALSO 136.Xr ioctl 2 , 137.Xr socket 2 , 138.Xr sysctl 3 , 139.Xr networking 4 , 140.Xr ifconfig 8 141.Sh HISTORY 142The 143.Fn getifaddrs 144function first appeared in BSDI 145.Bsx . 146The function has been available on 147.Ox 148since 149.Ox 2.7 . 150.Sh BUGS 151If both 152.In net/if.h 153and 154.In ifaddrs.h 155are being included, 156.In net/if.h 157.Em must 158be included before 159.In ifaddrs.h . 160