[SCTP]: Initial souce address selection support.

include/net/sctp/structs.h

@@ -246,7 +246,10 @@ typedef struct sctp_func {
 					 int optname,
 					 char *optval,
 					 int *optlen);
-	int		(*get_dst_mtu)	(const sockaddr_storage_t *address);
+	struct dst_entry *(*get_dst)	(sockaddr_storage_t *daddr,
+					 sockaddr_storage_t *saddr);
+	int		(*cmp_saddr)	(struct dst_entry *dst,
+					 sockaddr_storage_t *saddr);
 	__u16		net_header_len;	
 	int		sockaddr_len;
 	sa_family_t	sa_family;
@@ -476,6 +479,8 @@ struct SCTP_chunk {
 
 	/* What is the origin IP address for this chunk?  */
 	sockaddr_storage_t source;
+	/* Destination address for this chunk. */
+	sockaddr_storage_t dest;
 
 	/* For an inbound chunk, this tells us where it came from.
 	 * For an outbound chunk, it tells us where we'd like it to
@@ -492,7 +497,7 @@ void  *sctp_addto_chunk(sctp_chunk_t *chunk, int len, const void *data);
 int sctp_user_addto_chunk(sctp_chunk_t *chunk, int len, struct iovec *data);
 sctp_chunk_t *sctp_chunkify(struct sk_buff *, const sctp_association_t *,
 			    struct sock *);
-void sctp_init_source(sctp_chunk_t *chunk);
+void sctp_init_addrs(sctp_chunk_t *chunk);
 const sockaddr_storage_t *sctp_source(const sctp_chunk_t *chunk);
 
 /* This is a structure for holding either an IPv6 or an IPv4 address.  */
@@ -655,6 +660,9 @@ struct SCTP_transport {
 	/* PMTU       : The current known path MTU.  */
 	__u32 pmtu;
 
+	/* Destination */
+	struct dst_entry *dst;
+
 	/* When was the last time(in jiffies) that a data packet was sent on
 	 * this transport?  This is used to adjust the cwnd when the transport
 	 * becomes inactive.
@@ -735,6 +743,7 @@ extern sctp_transport_t *sctp_transport_new(const sockaddr_storage_t *, int);
 extern sctp_transport_t *sctp_transport_init(sctp_transport_t *,
 					     const sockaddr_storage_t *, int);
 extern void sctp_transport_set_owner(sctp_transport_t *, sctp_association_t *);
+extern void sctp_transport_route(sctp_transport_t *, sockaddr_storage_t *);
 extern void sctp_transport_free(sctp_transport_t *);
 extern void sctp_transport_destroy(sctp_transport_t *);
 extern void sctp_transport_reset_timers(sctp_transport_t *);

net/sctp/associola.c

@@ -404,6 +404,9 @@ sctp_transport_t *sctp_assoc_add_peer(sctp_association_t *asoc,
 
 	sctp_transport_set_owner(peer, asoc);
 
+	/* Cache a route for the transport. */
+	sctp_transport_route(peer, NULL);
+
 	/* If this is the first transport addr on this association,
 	 * initialize the association PMTU to the peer's PMTU.
 	 * If not and the current association PMTU is higher than the new

net/sctp/input.c

@@ -41,6 +41,7 @@
  *    Jon Grimm <jgrimm@us.ibm.com>
  *    Hui Huang <hui.huang@nokia.com>
  *    Daisy Chang <daisyc@us.ibm.com>
+ *    Sridhar Samudrala <sri@us.ibm.com>
  *
  * Any bugs reported given to us we will try to fix... any fixes shared will
  * be incorporated into the next SCTP release.
@@ -217,8 +218,8 @@ int sctp_rcv(struct sk_buff *skb)
 	/* Remember the SCTP header. */
 	chunk->sctp_hdr = sh;
 
-	/* Set the source address.  */
-	sctp_init_source(chunk);
+	/* Set the source and destination addresses of the incoming chunk.  */
+	sctp_init_addrs(chunk);
 
 	/* Remember where we came from.  */
 	chunk->transport = transport;

net/sctp/ipv6.c

@@ -158,35 +158,61 @@ static inline int sctp_v6_xmit(struct sk_buff *skb)
 }
 #endif /* TEST_FRAME */
 
-/* Returns the mtu for the given v6 destination address. */
-int sctp_v6_get_dst_mtu(const sockaddr_storage_t *address)
+/* FIXME: This macro needs to be moved to a common header file. */
+#define NIP6(addr) \
+        ntohs((addr)->s6_addr16[0]), \
+        ntohs((addr)->s6_addr16[1]), \
+        ntohs((addr)->s6_addr16[2]), \
+        ntohs((addr)->s6_addr16[3]), \
+        ntohs((addr)->s6_addr16[4]), \
+        ntohs((addr)->s6_addr16[5]), \
+        ntohs((addr)->s6_addr16[6]), \
+        ntohs((addr)->s6_addr16[7])
+
+/* Returns the dst cache entry for the given source and destination ip
+ * addresses.
+ */
+struct dst_entry *sctp_v6_get_dst(sockaddr_storage_t *daddr,
+				  sockaddr_storage_t *saddr)
 {
 	struct dst_entry *dst;
-	struct flowi fl;
-	int dst_mtu = SCTP_DEFAULT_MAXSEGMENT;
+	struct flowi fl = { .nl_u = { .ip6_u = { .daddr = &daddr->v6.sin6_addr,
+					       } } };
 
-	fl.proto = 0;
-	fl.fl6_dst = (struct in6_addr *)&address->v6.sin6_addr;
-	fl.fl6_src = NULL;
-	fl.fl6_flowlabel = 0;
-	fl.oif = 0;
-	fl.uli_u.ports.sport = 0;
-	fl.uli_u.ports.dport = 0;
+
+	SCTP_DEBUG_PRINTK("%s: DST=%04x:%04x:%04x:%04x:%04x:%04x:%04x:%04x ",
+			  __FUNCTION__, NIP6(fl.fl6_dst)); 
+
+	if (saddr) {
+		fl.fl6_src = &saddr->v6.sin6_addr;
+		SCTP_DEBUG_PRINTK(
+			"SRC=%04x:%04x:%04x:%04x:%04x:%04x:%04x:%04x - ",
+			NIP6(fl.fl6_src));
+	}
 
 	dst = ip6_route_output(NULL, &fl);
 	if (dst) {
-		dst_mtu = dst->pmtu;
-		SCTP_DEBUG_PRINTK("sctp_v6_get_dst_mtu: "
-				  "ip6_route_output: dev:%s pmtu:%d\n",
-				  dst->dev->name, dst_mtu);
-		dst_release(dst);
+		struct rt6_info *rt;
+		rt = (struct rt6_info *)dst;
+		SCTP_DEBUG_PRINTK(
+			"rt6_dst:%04x:%04x:%04x:%04x:%04x:%04x:%04x:%04x "
+			"rt6_src:%04x:%04x:%04x:%04x:%04x:%04x:%04x:%04x\n",
+			NIP6(&rt->rt6i_dst.addr), NIP6(&rt->rt6i_src.addr));
+
 	} else {
-		SCTP_DEBUG_PRINTK("sctp_v6_get_dst_mtu: "
-				  "ip6_route_output failed, returning "
-				  "%d as dst_mtu\n", dst_mtu);
+		SCTP_DEBUG_PRINTK("NO ROUTE\n");
+		return NULL;
 	}
 
-	return dst_mtu;
+	return dst;
+}
+
+/* Check if the dst entry's source addr matches the given source addr. */
+int sctp_v6_cmp_saddr(struct dst_entry *dst, sockaddr_storage_t *saddr)
+{
+	struct rt6_info *rt = (struct rt6_info *)dst;
+
+	return ipv6_addr_cmp(&rt->rt6i_src.addr, &saddr->v6.sin6_addr); 
 }
 
 /* Initialize a PF_INET6 socket msg_name. */
@@ -301,7 +327,8 @@ static sctp_func_t sctp_ipv6_specific = {
 	.queue_xmit      = sctp_v6_xmit,
 	.setsockopt      = ipv6_setsockopt,
 	.getsockopt      = ipv6_getsockopt,
-	.get_dst_mtu     = sctp_v6_get_dst_mtu,
+	.get_dst	 = sctp_v6_get_dst,
+	.cmp_saddr	 = sctp_v6_cmp_saddr,
 	.net_header_len  = sizeof(struct ipv6hdr),
 	.sockaddr_len    = sizeof(struct sockaddr_in6),
 	.sa_family       = AF_INET6,

net/sctp/output.c

@@ -245,6 +245,7 @@ int sctp_packet_transmit(sctp_packet_t *packet)
 	int err = 0;
 	int padding;		/* How much padding do we need?  */
 	__u8 packet_has_data = 0;
+	struct dst_entry *dst;
 
 	/* Do NOT generate a chunkless packet... */
 	if (skb_queue_empty(&packet->chunks))
@@ -410,13 +411,6 @@ int sctp_packet_transmit(sctp_packet_t *packet)
 		asoc->peer.last_sent_to = transport;
 	}
 
-	/* Hey, before Linux changes, here's what we have to
-	 * do to force IP routing to recognize the change of
-	 * dest addr.				--xguo
-	 */
-	if (sk->dst_cache)
-		sk->dst_cache->obsolete = 1;
-
 	if (packet_has_data) {
 		struct timer_list *timer;
 		unsigned long timeout;
@@ -434,6 +428,13 @@ int sctp_packet_transmit(sctp_packet_t *packet)
 		}
 	}
 
+	dst = transport->dst;
+	if (!dst || dst->obsolete) {
+		sctp_transport_route(transport, NULL);
+	}
+
+	nskb->dst = dst_clone(transport->dst);
+
 	SCTP_DEBUG_PRINTK("***sctp_transmit_packet*** skb length %d\n",
 			  nskb->len);
 	(*transport->af_specific->queue_xmit)(nskb);

net/sctp/protocol.c

@@ -256,27 +256,41 @@ int sctp_copy_local_addr_list(sctp_protocol_t *proto, sctp_bind_addr_t *bp,
 	return error;
 }
 
-/* Returns the mtu for the given v4 destination address.  */
-int sctp_v4_get_dst_mtu(const sockaddr_storage_t *address)
+/* Returns the dst cache entry for the given source and destination ip
+ * addresses.
+ */
+struct dst_entry *sctp_v4_get_dst(sockaddr_storage_t *daddr,
+				  sockaddr_storage_t *saddr)
 {
-	int dst_mtu = SCTP_DEFAULT_MAXSEGMENT;
 	struct rtable *rt;
-	struct flowi fl = { .nl_u = { .ip4_u =
-				      { .daddr = address->v4.sin_addr.s_addr } } };
+	struct flowi fl = { .nl_u = { .ip4_u = { .daddr =
+						    daddr->v4.sin_addr.s_addr,
+					       } } };
+
+	if (saddr)
+		fl.fl4_src = saddr->v4.sin_addr.s_addr;
+
+	SCTP_DEBUG_PRINTK("%s: DST:%u.%u.%u.%u, SRC:%u.%u.%u.%u - ",
+			  __FUNCTION__, NIPQUAD(fl.fl4_dst),
+			  NIPQUAD(fl.fl4_src));
 
 	if (ip_route_output_key(&rt, &fl)) {
-		SCTP_DEBUG_PRINTK("sctp_v4_get_dst_mtu:ip_route_output_key"
-				  " failed, returning %d as dst_mtu\n",
-				  dst_mtu);
-	} else {
-		dst_mtu = rt->u.dst.pmtu;
-		SCTP_DEBUG_PRINTK("sctp_v4_get_dst_mtu: "
-				  "ip_route_output_key: dev:%s pmtu:%d\n",
-				  rt->u.dst.dev->name, dst_mtu);
-		ip_rt_put(rt);
+		SCTP_DEBUG_PRINTK("NO ROUTE\n");
+		return NULL;
 	}
 
-	return dst_mtu;
+	SCTP_DEBUG_PRINTK("rt_dst:%u.%u.%u.%u, rt_src:%u.%u.%u.%u\n",
+			  NIPQUAD(rt->rt_src), NIPQUAD(rt->rt_dst));
+
+	return &rt->u.dst;
+}
+
+/* Check if the dst entry's source addr matches the given source addr. */
+int sctp_v4_cmp_saddr(struct dst_entry *dst, sockaddr_storage_t *saddr)
+{
+	struct rtable *rt = (struct rtable *)dst;
+
+	return (rt->rt_src == saddr->v4.sin_addr.s_addr); 
 }
 
 /* Event handler for inet device events.
@@ -438,7 +452,8 @@ sctp_func_t sctp_ipv4_specific = {
 	.queue_xmit     = ip_queue_xmit,
 	.setsockopt     = ip_setsockopt,
 	.getsockopt     = ip_getsockopt,
-	.get_dst_mtu    = sctp_v4_get_dst_mtu,
+	.get_dst	= sctp_v4_get_dst,
+	.cmp_saddr	= sctp_v4_cmp_saddr,
 	.net_header_len = sizeof(struct iphdr),
 	.sockaddr_len   = sizeof(struct sockaddr_in),
 	.sa_family      = AF_INET,

net/sctp/sm_make_chunk.c

@@ -1030,16 +1030,17 @@ sctp_chunk_t *sctp_chunkify(struct sk_buff *skb, const sctp_association_t *asoc,
 	return retval;
 }
 
-/* Set chunk->source based on the IP header in chunk->skb.  */
-void sctp_init_source(sctp_chunk_t *chunk)
+/* Set chunk->source and dest based on the IP header in chunk->skb.  */
+void sctp_init_addrs(sctp_chunk_t *chunk)
 {
-	sockaddr_storage_t *source;
+	sockaddr_storage_t *source, *dest;
 	struct sk_buff *skb;
 	struct sctphdr *sh;
 	struct iphdr *ih4;
 	struct ipv6hdr *ih6;
 
 	source = &chunk->source;
+	dest = &chunk->dest;
 	skb = chunk->skb;
 	ih4 = skb->nh.iph;
 	ih6 = skb->nh.ipv6h;
@@ -1050,6 +1051,9 @@ void sctp_init_source(sctp_chunk_t *chunk)
 		source->v4.sin_family = AF_INET;
 		source->v4.sin_port = ntohs(sh->source);
 		source->v4.sin_addr.s_addr = ih4->saddr;
+		dest->v4.sin_family = AF_INET;
+		dest->v4.sin_port = ntohs(sh->dest);
+		dest->v4.sin_addr.s_addr = ih4->daddr;
 		break;
 
 	case 6:
@@ -1057,6 +1061,9 @@ void sctp_init_source(sctp_chunk_t *chunk)
 			source->v6.sin6_family = AF_INET6;
 			source->v6.sin6_port = ntohs(sh->source);
 			source->v6.sin6_addr = ih6->saddr;
+			dest->v6.sin6_family = AF_INET6;
+			dest->v6.sin6_port = ntohs(sh->dest);
+			dest->v6.sin6_addr = ih6->daddr;
 			/* FIXME:  What do we do with scope, etc. ? */
 			break;
 		)

net/sctp/sm_statefuns.c

@@ -4261,6 +4261,11 @@ sctp_packet_t *sctp_ootb_pkt_new(const sctp_association_t *asoc,
 	if (!packet)
 		goto nomem_packet;
 
+	/* Cache a route for the transport with the chunk's destination as
+	 * the source address.
+	 */
+	sctp_transport_route(transport, (sockaddr_storage_t *)&chunk->dest);
+
 	packet = sctp_packet_init(packet, transport, sport, dport);
 	packet = sctp_packet_config(packet, vtag, 0, NULL);
 

net/sctp/transport.c

@@ -87,7 +87,6 @@ sctp_transport_t *sctp_transport_init(sctp_transport_t *peer,
 	peer->ipaddr = *addr;
 	peer->af_specific = sctp_get_af_specific(addr);
 	peer->asoc = NULL;
-	peer->pmtu = peer->af_specific->get_dst_mtu(addr);
 
 	/* From 6.3.1 RTO Calculation:
 	 *
@@ -161,6 +160,7 @@ void sctp_transport_destroy(sctp_transport_t *transport)
 	if (transport->asoc)
 		sctp_association_put(transport->asoc);
 
+	dst_release(transport->dst);
 	kfree(transport);
 	SCTP_DBG_OBJCNT_DEC(transport);
 }
@@ -200,6 +200,78 @@ void sctp_transport_set_owner(sctp_transport_t *transport,
 	sctp_association_hold(asoc);
 }
 
+/* Caches the dst entry for a transport's destination address and an optional
+ * souce address.
+ */ 
+void sctp_transport_route(sctp_transport_t *transport,
+			  sockaddr_storage_t *saddr)
+{
+	sctp_association_t *asoc = transport->asoc;
+	sctp_func_t *af = transport->af_specific;
+	sockaddr_storage_t *daddr = &transport->ipaddr;
+	sctp_bind_addr_t *bp;
+	rwlock_t *addr_lock;
+	struct sockaddr_storage_list *laddr;
+	struct list_head *pos;
+	struct dst_entry *dst;
+
+	dst = af->get_dst(daddr, saddr);
+
+	/* If there is no association or if a source address is passed,
+	 * no more validation is required.
+	 */
+	if (!asoc || saddr)
+		goto out;
+
+	if (SCTP_STATE_ESTABLISHED == asoc->state) {
+		bp = &asoc->base.bind_addr;
+		addr_lock = &asoc->base.addr_lock;
+	} else {
+		bp = &asoc->ep->base.bind_addr;
+		addr_lock = &asoc->ep->base.addr_lock;
+	}
+
+	if (dst) {
+		/* Walk through the bind address list and look for a bind
+		 * address that matches the source address of the returned dst.
+		 */
+		sctp_read_lock(addr_lock);
+		list_for_each(pos, &bp->address_list) {
+			laddr = list_entry(pos, struct sockaddr_storage_list,
+					   list);
+			if (af->cmp_saddr(dst, &laddr->a))
+				goto out_unlock;
+		}
+		sctp_read_unlock(addr_lock);
+	
+		/* None of the bound addresses match the source address of the
+		 * dst. So release it.
+		 */	
+		dst_release(dst);
+	}
+
+	/* Walk through the bind address list and try to get a dst that
+	 * matches a bind address as the source address.
+	 */
+	sctp_read_lock(addr_lock);
+	list_for_each(pos, &bp->address_list) {
+		laddr = list_entry(pos, struct sockaddr_storage_list, list);
+
+		dst = af->get_dst(daddr, &laddr->a);
+		if (dst)
+			goto out_unlock;
+	}
+
+out_unlock:
+	sctp_read_unlock(addr_lock);
+out:
+	transport->dst = dst;
+	if (dst)
+		transport->pmtu = dst->pmtu;
+	else
+		transport->pmtu = SCTP_DEFAULT_MAXSEGMENT;
+}
+
 /* Hold a reference to a transport.  */
 void sctp_transport_hold(sctp_transport_t *transport)
 {