[SCTP] Support SCTP ECN on ipv6.

include/net/sctp/structs.h

@@ -239,6 +239,7 @@ struct sctp_af {
 	int             (*is_any)       (const union sctp_addr *);
 	int             (*available)    (const union sctp_addr *);
 	int             (*skb_iif)      (const struct sk_buff *sk);
+	int             (*is_ce)        (const struct sk_buff *sk); 
 	__u16		net_header_len;
 	int		sockaddr_len;
 	sa_family_t	sa_family;

net/sctp/ipv6.c

@@ -572,6 +572,12 @@ static int sctp_v6_skb_iif(const struct sk_buff *skb)
 	return opt->iif;
 }
 
+/* Was this packet marked by Explicit Congestion Notification? */
+static int sctp_v6_is_ce(const struct sk_buff *skb)
+{
+	return *((__u32 *)(skb->nh.ipv6h)) & htonl(1<<20);
+}
+
 /* Initialize a PF_INET6 socket msg_name. */
 static void sctp_inet6_msgname(char *msgname, int *addr_len)
 {
@@ -832,6 +838,7 @@ static struct sctp_af sctp_ipv6_specific = {
 	.is_any          = sctp_v6_is_any,
 	.available       = sctp_v6_available,
 	.skb_iif         = sctp_v6_skb_iif,
+	.is_ce           = sctp_v6_is_ce,
 	.net_header_len  = sizeof(struct ipv6hdr),
 	.sockaddr_len    = sizeof(struct sockaddr_in6),
 	.sa_family       = AF_INET6,

net/sctp/output.c

@@ -221,8 +221,8 @@ sctp_xmit_t sctp_packet_append_chunk(struct sctp_packet *packet,
 		 */
 		if (packet_empty) {
 
-			/* We no longer do refragmentation at all.  
-			 * Just fragment at the IP layer, if we 
+			/* We no longer do refragmentation at all.
+			 * Just fragment at the IP layer, if we
 			 * actually hit this condition
 			 */
 
@@ -419,17 +419,13 @@ int sctp_packet_transmit(struct sctp_packet *packet)
 	 *   data sender to indicate that the end-points of the
 	 *   transport protocol are ECN-capable."
 	 *
-	 * If ECN capable && negotiated && it makes sense for
-	 * this packet to support it (e.g. post ECN negotiation)
-	 * then lets set the ECT bit
+	 * Now setting the ECT bit all the time, as it should not cause
+	 * any problems protocol-wise even if our peer ignores it.
 	 *
-	 * FIXME:  Need to do something else for IPv6
+	 * Note: The works for IPv6 layer checks this bit too later
+	 * in transmission.  See IP6_ECN_flow_xmit().
 	 */
-	if (packet->ecn_capable) {
-		INET_ECN_xmit(nskb->sk);
-	} else {
-		INET_ECN_dontxmit(nskb->sk);
-	}
+	INET_ECN_xmit(nskb->sk);
 
 	/* Set up the IP options.  */
 	/* BUG: not implemented

net/sctp/protocol.c

@@ -56,6 +56,7 @@
 #include <net/sctp/sctp.h>
 #include <net/addrconf.h>
 #include <net/inet_common.h>
+#include <net/inet_ecn.h>
 
 /* Global data structures. */
 struct sctp_protocol sctp_proto;
@@ -491,11 +492,17 @@ void sctp_v4_get_saddr(struct sctp_association *asoc,
 }
 
 /* What interface did this skb arrive on? */
-int sctp_v4_skb_iif(const struct sk_buff *skb)
+static int sctp_v4_skb_iif(const struct sk_buff *skb)
 {
      	return ((struct rtable *)skb->dst)->rt_iif;
 }
 
+/* Was this packet marked by Explicit Congestion Notification? */
+static int sctp_v4_is_ce(const struct sk_buff *skb)
+{
+	return INET_ECN_is_ce(skb->nh.iph->tos);
+}
+
 /* Create and initialize a new sk for the socket returned by accept(). */
 struct sock *sctp_v4_create_accept_sk(struct sock *sk,
 				      struct sctp_association *asoc)
@@ -829,6 +836,7 @@ struct sctp_af sctp_ipv4_specific = {
 	.available      = sctp_v4_available,
 	.scope          = sctp_v4_scope,
 	.skb_iif        = sctp_v4_skb_iif,
+	.is_ce          = sctp_v4_is_ce,
 	.net_header_len = sizeof(struct iphdr),
 	.sockaddr_len   = sizeof(struct sockaddr_in),
 	.sa_family      = AF_INET,

net/sctp/sm_statefuns.c

@@ -2310,9 +2310,7 @@ sctp_disposition_t sctp_sf_eat_data_6_2(const struct sctp_endpoint *ep,
 	skb_pull(chunk->skb, sizeof(sctp_datahdr_t));
 
 	tsn = ntohl(data_hdr->tsn);
-
 	SCTP_DEBUG_PRINTK("eat_data: TSN 0x%x.\n", tsn);
-	SCTP_DEBUG_PRINTK("eat_data: skb->head %p.\n", chunk->skb->head);
 
 	/* ASSERT:  Now skb->data is really the user data.  */
 
@@ -2327,11 +2325,15 @@ sctp_disposition_t sctp_sf_eat_data_6_2(const struct sctp_endpoint *ep,
 	 */
 
 	if (!chunk->ecn_ce_done) {
+		struct sctp_af *af;
 		chunk->ecn_ce_done = 1;
-		if (INET_ECN_is_ce(chunk->skb->nh.iph->tos) &&
-		    asoc->peer.ecn_capable) {
+
+		af = sctp_get_af_specific(
+			ipver2af(chunk->skb->nh.iph->version));
+
+		if (af && af->is_ce(chunk->skb) && asoc->peer.ecn_capable) {
 			/* Do real work as sideffect. */
-			sctp_add_cmd_sf(commands, SCTP_CMD_ECN_CE,
+			sctp_add_cmd_sf(commands, SCTP_CMD_ECN_CE, 
 					SCTP_U32(tsn));
 		}
 	}
@@ -2583,11 +2585,15 @@ sctp_disposition_t sctp_sf_eat_data_fast_4_4(const struct sctp_endpoint *ep,
 	 * chunk later.
 	 */
 	if (!chunk->ecn_ce_done) {
+		struct sctp_af *af;
 		chunk->ecn_ce_done = 1;
-		if (INET_ECN_is_ce(chunk->skb->nh.iph->tos) &&
-		    asoc->peer.ecn_capable) {
+
+		af = sctp_get_af_specific(
+			ipver2af(chunk->skb->nh.iph->version));
+
+		if (af && af->is_ce(chunk->skb) && asoc->peer.ecn_capable) {
 			/* Do real work as sideffect. */
-			sctp_add_cmd_sf(commands, SCTP_CMD_ECN_CE,
+			sctp_add_cmd_sf(commands, SCTP_CMD_ECN_CE, 
 					SCTP_U32(tsn));
 		}
 	}