GETIFMADDRS(3)         FreeBSD Library Functions Manual         GETIFMADDRS(3)

NAME
     getifmaddrs - get multicast group memberships

SYNOPSIS
     #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 <ifaddrs.h>.  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 translation, 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 successful; 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 errors 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 <net/if.h> and <ifaddrs.h> are being included, <net/if.h> must be
     included before <ifaddrs.h>.

FreeBSD 13.1-RELEASE-p6          May 21, 2013          FreeBSD 13.1-RELEASE-p6