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, 30 insertions, 7 deletions

diff --git a/sys/netinet/ip_var.h b/sys/netinet/ip_var.h
index 1ad36bb..eef4e1f 100644
--- a/sys/netinet/ip_var.h
+++ b/sys/netinet/ip_var.h
@@ -79,8 +79,28 @@ struct ipoption {
 };
 
 /*
+ * Multicast source list entry.
+ */
+struct in_msource {
+	TAILQ_ENTRY(in_msource) ims_next;	/* next source */
+	struct sockaddr_storage ims_addr;	/* address of this source */
+};
+
+/*
+ * Multicast filter descriptor; there is one instance per group membership
+ * on a socket, allocated as an expandable vector hung off ip_moptions.
+ * struct in_multi contains separate IPv4-stack-wide state for IGMPv3.
+ */
+struct in_mfilter {
+	uint16_t	imf_fmode;	/* filter mode for this socket/group */
+	uint16_t	imf_nsources;	/* # of sources for this socket/group */
+	TAILQ_HEAD(, in_msource) imf_sources;	/* source list */
+};
+
+/*
  * Structure attached to inpcb.ip_moptions and
  * passed to ip_output when IP multicast options are in use.
+ * This structure is lazy-allocated.
  */
 struct ip_moptions {
 	struct	ifnet *imo_multicast_ifp; /* ifp for outgoing multicasts */
@@ -91,6 +111,7 @@ struct ip_moptions {
 	u_short	imo_num_memberships;	/* no. memberships this socket */
 	u_short	imo_max_memberships;	/* max memberships this socket */
 	struct	in_multi **imo_membership;	/* group memberships */
+	struct	in_mfilter *imo_mfilters;	/* source filters */
 };
 
 struct	ipstat {
@@ -127,12 +148,11 @@ struct	ipstat {
 
 #ifdef _KERNEL
 
-/*
- * Flags passed to ip_output as last parameter.
- */
-#define IP_FORWARDING		0x01		/* most of ip header exists */
-#define IP_RAWOUTPUT		0x02		/* raw ip header exists */
-#define IP_SENDONES		0x04		/* send all-ones broadcast */
+/* flags passed to ip_output as last parameter */
+#define	IP_FORWARDING		0x1		/* most of ip header exists */
+#define	IP_RAWOUTPUT		0x2		/* raw ip header exists */
+#define	IP_SENDONES		0x4		/* send all-ones broadcast */
+#define	IP_SENDTOIF		0x8		/* send on specific ifnet */
 #define IP_ROUTETOIF		SO_DONTROUTE	/* 0x10 bypass routing tables */
 #define IP_ALLOWBROADCAST	SO_BROADCAST	/* 0x20 can send broadcast packets */
 
@@ -167,12 +187,15 @@ extern u_long	(*ip_mcast_src)(int);
 extern int rsvp_on;
 extern struct	pr_usrreqs rip_usrreqs;
 
+void	inp_freemoptions(struct ip_moptions *);
+int	inp_getmoptions(struct inpcb *, struct sockopt *);
+int	inp_setmoptions(struct inpcb *, struct sockopt *);
+
 int	ip_ctloutput(struct socket *, struct sockopt *sopt);
 void	ip_drain(void);
 void	ip_fini(void *xtp);
 int	ip_fragment(struct ip *ip, struct mbuf **m_frag, int mtu,
 	    u_long if_hwassist_flags, int sw_csum);
-void	ip_freemoptions(struct ip_moptions *);
 void	ip_forward(struct mbuf *m, int srcrt);
 void	ip_init(void);
 extern int