1.\" $OpenBSD: getifaddrs.3,v 1.6 2000/04/18 03:01:31 aaron 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 <sys/types.h> 31.Fd #include <sys/socket.h> 32.Fd #include <ifaddrs.h> 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 61.Bl -tag -width Ds 62.It Fa ifa_next 63Contains a pointer to the next structure on the list. 64This field is set to 65.Dv NULL 66in 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, it contains a pointer to the 108.Li struct ifa_data 109(as defined in include file 110.Aq Pa net/if.h ) 111which contains per-address interface statistics. 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 BUGS 136If both 137.Aq Pa net/if.h 138and 139.Aq Pa ifaddrs.h 140are being included, 141.Aq Pa net/if.h 142.Em must 143be included before 144.Aq Pa ifaddrs.h . 145.Sh SEE ALSO 146.Xr ioctl 2 , 147.Xr socket 2 , 148.Xr sysctl 3 , 149.Xr networking 4 , 150.Xr ifconfig 8 151.Sh HISTORY 152The 153.Fn getifaddrs 154function first appeared in BSDI BSD/OS. 155The function is supplied on 156.Ox 157since 158.Ox 2.7 . 159