getifmaddrs(3)

NAME

getifmaddrs - get multicast group memberships

SYNOPSIS

#include <sys/types.h>
#include <sys/socket.h>
#include <ifaddrs.h>
int
getifmaddrs(struct ifmaddrs **ifmap);
void
freeifmaddrs(struct ifmaddrs *ifmp);

DESCRIPTION

The getifmaddrs() function stores a reference to a linked

list of the
multicast memberships on the local machine in the memory

referenced by
ifmap. The list consists of ifmaddrs structures, as defined

in the
include file The ifmaddrs structure contains at least the

following
entries:

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 transla

tion, if any */

The ifma_next field contains a pointer to the next structure

on the list.
This field is NULL in last structure on the list.

The ifma_name field references an AF_LINK address structure,

containing
the name of the interface where the membership exists.

The ifma_addr references the address that this membership is

for.

The ifma_lladdr field references a link-layer translation

for the protocol-level address in ifma_addr, if one is set, otherwise it

is NULL.

The data returned by getifmaddrs() is dynamically allocated

and should be
freed using freeifmaddrs() when no longer needed.

RETURN VALUES

The getifmaddrs() function returns the value 0 if success

ful; otherwise
the value -1 is returned and the global variable errno is

set to indicate
the error.

ERRORS

The getifmaddrs() may fail and set errno for any of the er

rors specified
for the library routines malloc(3) or sysctl(3).

SEE ALSO

sysctl(3), networking(4), ifconfig(8)

HISTORY

The getifmaddrs() function first appeared in FreeBSD 5.2.

BUGS

If both #include <net/if.h>
and #include <ifaddrs.h>
are being included, #include <net/if.h> must be included before

BSD November 14, 2003

BSD