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sourcefilter(3)          BSD Library Functions Manual          sourcefilter(3)


NAME

     sourcefilter -- advanced multicast group membership API


SYNOPSIS

     #include <sys/socket.h>
     #include <netinet/in.h>

     int
     getipv4sourcefilter(int s, struct in_addr interface,
         struct in_addr group, uint32_t *fmode, uint32_t *numsrc,
         struct in_addr *slist);

     int
     getsourcefilter(int s, uint32_t interface, struct sockaddr *group,
         socklen_t grouplen, uint32_t *fmode, uint32_t *numsrc,
         struct sockaddr_storage *slist);

     int
     setipv4sourcefilter(int s, struct in_addr interface,
         struct in_addr group, uint32_t fmode, uint32_t numsrc,
         struct in_addr *slist);

     int
     setsourcefilter(int s, uint32_t interface, struct sockaddr *group,
         socklen_t grouplen, uint32_t fmode, uint32_t numsrc,
         struct sockaddr_storage *slist);


DESCRIPTION

     The sourcefilter functions implement the advanced, full-state multicast
     API defined in RFC 3678.  An application may use these functions to atom-
     ically set and retrieve the multicast source address filters associated
     with a socket s and a multicast group.

     The functions getipv4sourcefilter() and getsourcefilter() allow an appli-
     cation to discover the filter mode, and source filter entries, for an
     existing group membership.

     The kernel will always return the number of source filter entries on the
     socket for that group in *numsrc.  If the *numsrc argument is non-zero,
     the kernel will attempt to return up to *numsrc filter entries in the
     array pointed to by slist.  The *numsrc argument may be set to 0, in
     which case the slist argument will be ignored.

     For the setipv4sourcefilter() and setsourcefilter() functions, the fmode
     argument may be used to place the socket into inclusive or exclusive
     group membership modes, by using the MCAST_INCLUDE or MCAST_EXCLUDE con-
     stants respectively.  The numsrc argument specifies the number of source
     entries in the slist array.  If the numsrc argument has a value of 0, all
     source filters will be removed from the socket.  Removing all source fil-
     ters from a membership which is in the MCAST_INCLUDE filter mode will
     cause the group to be left on that socket.

     The protocol-independent function setsourcefilter() allows an application
     to join a multicast group on an interface which may not have an assigned
     protocol address, by passing its index for the interface argument.

     Any changes made by these functions will be communicated to IGMPv3 and/or
     MLDv2 routers on the local network as appropriate.  If no IGMPv3 or MLDv2
     routers are present, changes in the source filter lists made by these
     functions will not cause state changes to be transmitted, with the excep-
     tion of any change which causes a group to be joined or left.  The kernel
     will continue to maintain the source filter state regardless of the IGMP
     or MLD version in use on the link.


IMPLEMENTATION NOTES

     The IPv4 specific versions of these functions are implemented in terms of
     the protocol-independent functions.  Application writers are encouraged
     to use the protocol-independent functions for efficiency, and forwards
     compatibility with IPv6 networks.

     For the protocol-independent functions getsourcefilter() and
     setsourcefilter(), the argument grouplen argument specifies the size of
     the structure pointed to by group.  This is required in order to differ-
     entiate between different address families.

     Currently FreeBSD does not support source address selection for the IPv4
     protocol family, therefore the use of multicast APIs with an unnumbered
     IPv4 interface is not recommended. In all cases, the first assigned IPv4
     address on the interface will be used as the source address of IGMP con-
     trol traffic.  If this address is removed or changed, the results are
     undefined.


RETURN VALUES

     The getsourcefilter(), getipv4sourcefilter(), setsourcefilter(), and
     setipv4sourcefilter() functions return the value 0 if successful; other-
     wise the value -1 is returned and the global variable errno is set to
     indicate the error.


ERRORS

     The sourcefilter functions may fail because of:

     [EADDRNOTAVAIL]    The network interface which the interface argument
                        refers to was not configured in the system, or the
                        system is not a member of the group.

     [EAFNOSUPPORT]     The group and/or one or more of the slist arguments
                        were of an address family unsupported by the system,
                        or the address family of the group and slist arguments
                        were not identical.

     [EINVAL]           The group argument does not contain a multicast
                        address.  The fmode argument is invalid; it must be
                        set to either MCAST_INCLUDE or MCAST_EXCLUDE.  The
                        numsrc or slist arguments do not specify a source
                        list.

     [ENOMEM]           Insufficient memory was available to carry out the
                        requested operation.


SEE ALSO

     ip(4), ip6(4)

     D. Thaler, B. Fenner, and B. Quinn, Socket Interface Extensions for
     Multicast Source Filters, RFC 3678, Jan 2004.


HISTORY

     The sourcefilter functions first appeared in FreeBSD 7.0.


AUTHORS

     Bruce M. Simpson <bms@FreeBSD.org>

BSD                            February 13, 2009                           BSD

Mac OS X 10.8 - Generated Fri Aug 31 05:32:06 CDT 2012
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