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, 1 insertions, 164 deletions

diff --git a/sys/netinet/in.c b/sys/netinet/in.c
index dd20e00..d0c36fa 100644
--- a/sys/netinet/in.c
+++ b/sys/netinet/in.c
@@ -49,10 +49,7 @@
 #include <netinet/in.h>
 #include <netinet/in_var.h>
 #include <netinet/in_pcb.h>
-
-#include <netinet/igmp_var.h>
-
-static MALLOC_DEFINE(M_IPMADDR, "in_multi", "internet multicast address");
+#include <netinet/ip_var.h>
 
 static int in_mask2len(struct in_addr *);
 static void in_len2mask(struct in_addr *, int);
@@ -74,17 +71,6 @@ SYSCTL_INT(_net_inet_ip, OID_AUTO, same_prefix_carp_only, CTLFLAG_RW,
 	&sameprefixcarponly, 0,
 	"Refuse to create same prefixes on different interfaces");
 
-/*
- * The IPv4 multicast list (in_multihead and associated structures) are
- * protected by the global in_multi_mtx.  See in_var.h for more details.  For
- * now, in_multi_mtx is marked as recursible due to IGMP's calling back into
- * ip_output() to send IGMP packets while holding the lock; this probably is
- * not quite desirable.
- */
-struct in_multihead in_multihead; /* XXX BSS initialization */
-struct mtx in_multi_mtx;
-MTX_SYSINIT(in_multi_mtx, &in_multi_mtx, "in_multi_mtx", MTX_DEF | MTX_RECURSE);
-
 extern struct inpcbinfo ripcbinfo;
 extern struct inpcbinfo udbinfo;
 
@@ -977,155 +963,6 @@ in_broadcast(struct in_addr in, struct ifnet *ifp)
 }
 
 /*
- * Add an address to the list of IP multicast addresses for a given interface.
- */
-struct in_multi *
-in_addmulti(struct in_addr *ap, struct ifnet *ifp)
-{
-	struct in_multi *inm;
-
-	inm = NULL;
-
-	IFF_LOCKGIANT(ifp);
-	IN_MULTI_LOCK();
-
-	IN_LOOKUP_MULTI(*ap, ifp, inm);
-	if (inm != NULL) {
-		/*
-		 * If we already joined this group, just bump the
-		 * refcount and return it.
-		 */
-		KASSERT(inm->inm_refcount >= 1,
-		    ("%s: bad refcount %d", __func__, inm->inm_refcount));
-		++inm->inm_refcount;
-	} else do {
-		struct sockaddr_in sin;
-		struct ifmultiaddr *ifma;
-		struct in_multi *ninm;
-		int error;
-
-		bzero(&sin, sizeof sin);
-		sin.sin_family = AF_INET;
-		sin.sin_len = sizeof(struct sockaddr_in);
-		sin.sin_addr = *ap;
-
-		/*
-		 * Check if a link-layer group is already associated
-		 * with this network-layer group on the given ifnet.
-		 * If so, bump the refcount on the existing network-layer
-		 * group association and return it.
-		 */
-		error = if_addmulti(ifp, (struct sockaddr *)&sin, &ifma);
-		if (error)
-			break;
-		if (ifma->ifma_protospec != NULL) {
-			inm = (struct in_multi *)ifma->ifma_protospec;
-#ifdef INVARIANTS
-			if (inm->inm_ifma != ifma || inm->inm_ifp != ifp ||
-			    inm->inm_addr.s_addr != ap->s_addr)
-				panic("%s: ifma is inconsistent", __func__);
-#endif
-			++inm->inm_refcount;
-			break;
-		}
-
-		/*
-		 * A new membership is needed; construct it and
-		 * perform the IGMP join.
-		 */
-		ninm = malloc(sizeof(*ninm), M_IPMADDR, M_NOWAIT | M_ZERO);
-		if (ninm == NULL) {
-			if_delmulti_ifma(ifma);
-			break;
-		}
-		ninm->inm_addr = *ap;
-		ninm->inm_ifp = ifp;
-		ninm->inm_ifma = ifma;
-		ninm->inm_refcount = 1;
-		ifma->ifma_protospec = ninm;
-		LIST_INSERT_HEAD(&in_multihead, ninm, inm_link);
-
-		igmp_joingroup(ninm);
-
-		inm = ninm;
-	} while (0);
-
-	IN_MULTI_UNLOCK();
-	IFF_UNLOCKGIANT(ifp);
-
-	return (inm);
-}
-
-/*
- * Delete a multicast address record.
- * It is OK to call this routine if the underlying ifnet went away.
- *
- * XXX: To deal with the ifp going away, we cheat; the link-layer code in net
- * will set ifma_ifp to NULL when the associated ifnet instance is detached
- * from the system.
- * The only reason we need to violate layers and check ifma_ifp here at all
- * is because certain hardware drivers still require Giant to be held,
- * and it must always be taken before other locks.
- */
-void
-in_delmulti(struct in_multi *inm)
-{
-	struct ifnet *ifp;
-
-	KASSERT(inm->inm_ifma != NULL, ("%s: no ifma", __func__));
-	ifp = inm->inm_ifma->ifma_ifp;
-
-	if (ifp != NULL) {
-		/*
-		 * Sanity check that netinet's notion of ifp is the
-		 * same as net's.
-		 */
-		KASSERT(inm->inm_ifp == ifp, ("%s: bad ifp", __func__));
-		IFF_LOCKGIANT(ifp);
-	}
-
-	IN_MULTI_LOCK();
-	in_delmulti_locked(inm);
-	IN_MULTI_UNLOCK();
-
-	if (ifp != NULL)
-		IFF_UNLOCKGIANT(ifp);
-}
-
-/*
- * Delete a multicast address record, with locks held.
- *
- * It is OK to call this routine if the ifp went away.
- * Assumes that caller holds the IN_MULTI lock, and that
- * Giant was taken before other locks if required by the hardware.
- */
-void
-in_delmulti_locked(struct in_multi *inm)
-{
-	struct ifmultiaddr *ifma;
-
-	IN_MULTI_LOCK_ASSERT();
-	KASSERT(inm->inm_refcount >= 1, ("%s: freeing freed inm", __func__));
-
-	if (--inm->inm_refcount == 0) {
-		igmp_leavegroup(inm);
-
-		ifma = inm->inm_ifma;
-#ifdef DIAGNOSTIC
-		printf("%s: purging ifma %p\n", __func__, ifma);
-#endif
-		KASSERT(ifma->ifma_protospec == inm,
-		    ("%s: ifma_protospec != inm", __func__));
-		ifma->ifma_protospec = NULL;
-
-		LIST_REMOVE(inm, inm_link);
-		free(inm, M_IPMADDR);
-
-		if_delmulti_ifma(ifma);
-	}
-}
-
-/*
  * Delete all IPv4 multicast address records, and associated link-layer
  * multicast address records, associated with ifp.
  */