Import rewrite of IPv4 socket multicast layer to support source-specific

and protocol-independent host mode multicast. The code is written to
accomodate IPv6, IGMPv3 and MLDv2 with only a little additional work.

This change only pertains to FreeBSD's use as a multicast end-station and
does not concern multicast routing; for an IGMPv3/MLDv2 router
implementation, consider the XORP project.

The work is based on Wilbert de Graaf's IGMPv3 code drop for FreeBSD 4.6,
which is available at: http://www.kloosterhof.com/wilbert/igmpv3.html

Summary
 * IPv4 multicast socket processing is now moved out of ip_output.c
   into a new module, in_mcast.c.
 * The in_mcast.c module implements the IPv4 legacy any-source API in
   terms of the protocol-independent source-specific API.
 * Source filters are lazy allocated as the common case does not use them.
   They are part of per inpcb state and are covered by the inpcb lock.
 * struct ip_mreqn is now supported to allow applications to specify
   multicast joins by interface index in the legacy IPv4 any-source API.
 * In UDP, an incoming multicast datagram only requires that the source
   port matches the 4-tuple if the socket was already bound by source port.
   An unbound socket SHOULD be able to receive multicasts sent from an
   ephemeral source port.
 * The UDP socket multicast filter mode defaults to exclusive, that is,
   sources present in the per-socket list will be blocked from delivery.
 * The RFC 3678 userland functions have been added to libc: setsourcefilter,
   getsourcefilter, setipv4sourcefilter, getipv4sourcefilter.
 * Definitions for IGMPv3 are merged but not yet used.
 * struct sockaddr_storage is now referenced from <netinet/in.h>. It
   is therefore defined there if not already declared in the same way
   as for the C99 types.
 * The RFC 1724 hack (specify 0.0.0.0/8 addresses to IP_MULTICAST_IF
   which are then interpreted as interface indexes) is now deprecated.
 * A patch for the Rhyolite.com routed in the FreeBSD base system
   is available in the -net archives. This only affects individuals
   running RIPv1 or RIPv2 via point-to-point and/or unnumbered interfaces.
 * Make IPv6 detach path similar to IPv4's in code flow; functionally same.
 * Bump __FreeBSD_version to 700048; see UPDATING.

This work was financially supported by another FreeBSD committer.

Obtained from:  p4://bms_netdev
Submitted by:   Wilbert de Graaf (original work)
Reviewed by:    rwatson (locking), silence from fenner,
		net@ (but with encouragement)

1 files changed, 19 insertions, 0 deletions

diff --git a/UPDATING b/UPDATING
index d509867..a6cfbe2 100644
--- a/UPDATING
+++ b/UPDATING
@@ -21,6 +21,25 @@ NOTE TO PEOPLE WHO THINK THAT FreeBSD 7.x IS SLOW:
 	developers choose to disable these features on build machines
 	to maximize performance.
 
+20070612:
+	The IPv4 multicast socket code has been considerably modified, and
+	moved to the file sys/netinet/in_mcast.c. Initial support for the
+	RFC 3678 Source-Specific Multicast Socket API has been added to
+	the IPv4 network stack.
+
+	Strict multicast and broadcast reception is now the default for
+	UDP/IPv4 sockets; the net.inet.udp.strict_mcast_mship sysctl variable
+	has now been removed.
+
+	The RFC 1724 hack for interface selection has been removed; the use
+	of the Linux-derived ip_mreqn structure with IP_MULTICAST_IF has
+	been added to replace it. Consumers such as routed will soon be
+	updated to reflect this.
+
+	These changes affect users who are running routed(8) or rdisc(8)
+	from the FreeBSD base system on point-to-point or unnumbered
+	interfaces.
+
 20070610:
 	The net80211 layer has changed significantly and all wireless
 	drivers that depend on it need to be recompiled.  Further these