1.\" $OpenBSD: getifaddrs.3,v 1.14 2007/05/31 19:19:30 jmc 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: May 31 2007 $ 25.Dt GETIFADDRS 3 26.Os 27.Sh NAME 28.Nm getifaddrs 29.Nd get interface addresses 30.Sh SYNOPSIS 31.Fd #include <sys/types.h> 32.Fd #include <sys/socket.h> 33.Fd #include <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.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.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 95References the destination address on a P2P interface, 96if one exists, otherwise it is 97.Dv NULL . 98.It Fa ifa_data 99References address family specific data. 100For 101.Dv AF_LINK 102addresses it contains a pointer to the 103.Li struct if_data 104(as defined in include file 105.Aq Pa net/if.h ) 106which contains various interface attributes and statistics. 107For all other address families, 108.Fa ifa_data 109is 110.Dv NULL . 111.El 112.Pp 113The data returned by 114.Fn getifaddrs 115is dynamically allocated and should be freed using 116.Fn freeifaddrs 117when no longer needed. 118.Sh RETURN VALUES 119Upon successful completion, a value of 0 is returned. 120Otherwise, a value of \-1 is returned and 121.Va errno 122is set to indicate the error. 123.Sh ERRORS 124The 125.Fn getifaddrs 126may fail and set 127.Va errno 128for any of the errors specified for the library routines 129.Xr ioctl 2 , 130.Xr socket 2 , 131.Xr malloc 3 , 132or 133.Xr sysctl 3 . 134.Sh SEE ALSO 135.Xr ioctl 2 , 136.Xr socket 2 , 137.Xr sysctl 3 , 138.Xr networking 4 , 139.Xr ifconfig 8 140.Sh HISTORY 141The 142.Fn getifaddrs 143function first appeared in BSDI BSD/OS. 144The function has been available on 145.Ox 146since 147.Ox 2.7 . 148.Sh BUGS 149If both 150.Aq Pa net/if.h 151and 152.Aq Pa ifaddrs.h 153are being included, 154.Aq Pa net/if.h 155.Em must 156be included before 157.Aq Pa ifaddrs.h . 158