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SOURCEFILTER(3) FreeBSD 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
atomically set and retrieve the multicast source address filters
associated with a socket s and a multicast group.
The functions getipv4sourcefilter() and getsourcefilter() allow an
application 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
constants 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 filters 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
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 grouplen argument specifies the size of the
structure pointed to by group. This is required in order to
differentiate 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
control 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;
otherwise 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), multicast(4), ifmcstat(8)
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>
FreeBSD 14.0-RELEASE-p11 February 13, 2009 FreeBSD 14.0-RELEASE-p11