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$FreeBSD: src/lib/libc/net/getifmaddrs.3,v 1.3.22.1.4.1 2010/06/14 02:09:06 kensmith Exp $
.Dd November 14, 2003 .Dt GETIFMADDRS 3 .Os .Sh NAME .Nm getifmaddrs .Nd get multicast group memberships .Sh SYNOPSIS n sys/types.h n sys/socket.h n ifaddrs.h .Ft int .Fn getifmaddrs "struct ifmaddrs **ifmap" .Ft void .Fn freeifmaddrs "struct ifmaddrs *ifmp" .Sh DESCRIPTION The .Fn getifmaddrs function stores a reference to a linked list of the multicast memberships on the local machine in the memory referenced by .Fa ifmap . The list consists of .Vt ifmaddrs structures, as defined in the include file n ifaddrs.h . The .Vt ifmaddrs structure contains at least the following entries: d -literal struct ifmaddrs *ifma_next; /* Pointer to next struct */ struct sockaddr *ifma_name; /* Interface name (AF_LINK) */ struct sockaddr *ifma_addr; /* Multicast address */ struct sockaddr *ifma_lladdr; /* Link-layer translation, if any */ .Ed
p The .Va ifma_next field contains a pointer to the next structure on the list. This field is .Dv NULL in last structure on the list.
p The .Va ifma_name field references an .Dv AF_LINK address structure, containing the name of the interface where the membership exists.
p The .Va ifma_addr references the address that this membership is for.
p The .Va ifma_lladdr field references a link-layer translation for the protocol-level address in .Va ifma_addr , if one is set, otherwise it is .Dv NULL .
p The data returned by .Fn getifmaddrs is dynamically allocated and should be freed using .Fn freeifmaddrs when no longer needed. .Sh RETURN VALUES .Rv -std getifmaddrs .Sh ERRORS The .Fn getifmaddrs may fail and set .Va errno for any of the errors specified for the library routines .Xr malloc 3 or .Xr sysctl 3 . .Sh SEE ALSO .Xr sysctl 3 , .Xr networking 4 , .Xr ifconfig 8 .Sh HISTORY The .Fn getifmaddrs function first appeared in .Fx 5.2 . .Sh BUGS If both n net/if.h and n ifaddrs.h are being included, n net/if.h .Em must be included before n ifaddrs.h .