.\" $KAME: getifaddrs.3,v 1.4 2000/05/17 14:13:14 itojun Exp $ .\" BSDI getifaddrs.3,v 2.5 2000/02/23 14:51:59 dab Exp .\" .\" Copyright (c) 1995, 1999 .\" Berkeley Software Design, Inc. All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" .\" THIS SOFTWARE IS PROVIDED BY Berkeley Software Design, Inc. ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL Berkeley Software Design, Inc. BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .\" $FreeBSD: src/lib/libc/net/getifaddrs.3,v 1.10 2005/02/09 18:03:13 ru Exp $ .\" .Dd October 12, 1995 .Dt GETIFADDRS 3 .Os .Sh NAME .Nm getifaddrs .Nd get interface addresses .Sh SYNOPSIS .In sys/types.h .In sys/socket.h .In ifaddrs.h .Ft int .Fn getifaddrs "struct ifaddrs **ifap" .Ft void .Fn freeifaddrs "struct ifaddrs *ifp" .Sh DESCRIPTION The .Fn getifaddrs function stores a reference to a linked list of the network interfaces on the local machine in the memory referenced by .Fa ifap . The list consists of .Nm ifaddrs structures, as defined in the include file .In ifaddrs.h . The .Nm ifaddrs structure contains at least the following entries: .Bd -literal struct ifaddrs *ifa_next; /* Pointer to next struct */ char *ifa_name; /* Interface name */ u_int ifa_flags; /* Interface flags */ struct sockaddr *ifa_addr; /* Interface address */ struct sockaddr *ifa_netmask; /* Interface netmask */ .\" struct sockaddr *ifa_broadaddr; /* Interface broadcast address */ struct sockaddr *ifa_dstaddr; /* P2P interface destination */ void *ifa_data; /* Address specific data */ .Ed .Pp The .Li ifa_next field contains a pointer to the next structure on the list. This field is .Dv NULL in last structure on the list. .Pp The .Li ifa_name field contains the interface name. .Pp The .Li ifa_flags field contains the interface flags, as set by .Xr ifconfig 8 utility. .Pp The .Li ifa_addr field references either the address of the interface or the link level address of the interface, if one exists, otherwise it is NULL. (The .Li sa_family field of the .Li ifa_addr field should be consulted to determine the format of the .Li ifa_addr address.) .Pp The .Li ifa_netmask field references the netmask associated with .Li ifa_addr , if one is set, otherwise it is NULL. .Pp The .Li ifa_dstaddr field references the destination address on a P2P interface, if one exists, otherwise it contains the broadcast address. .Pp Note that as a convenience, .Li ifa_broadaddr is defined by a compiler .Li #define directive to be the same as .Li ifa_dstaddr . .Pp The .Li ifa_data field references address family specific data. For .Dv AF_LINK addresses it contains a pointer to the .Fa struct if_data (as defined in include file .In net/if.h ) which contains various interface attributes and statistics. For all other address families, it contains a pointer to the .Fa struct ifa_data (as defined in include file .In net/if.h ) which contains per-address interface statistics. .Pp The data returned by .Fn getifaddrs is dynamically allocated and should be freed using .Fn freeifaddrs when no longer needed. .Sh RETURN VALUES .Rv -std getifaddrs .Sh ERRORS The .Fn getifaddrs may fail and set .Va errno for any of the errors specified for the library routines .Xr ioctl 2 , .Xr socket 2 , .Xr malloc 3 or .Xr sysctl 3 . .Sh SEE ALSO .Xr ioctl 2 , .Xr socket 2 , .Xr sysctl 3 , .Xr networking 4 , .Xr ifconfig 8 .Sh HISTORY The .Nm implementation first appeared in BSDi .Bsx . .Sh BUGS If both .In net/if.h and .In ifaddrs.h are being included, .In net/if.h .Em must be included before .In ifaddrs.h .