[SCTP]: Verify all the paths to a peer via heartbeat before using them.

This patch implements Path Initialization procedure as described in
Sec 2.36 of RFC4460.

Signed-off-by: Sridhar Samudrala <sri@us.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/sctp/structs.h

@@ -445,6 +445,7 @@ typedef struct sctp_sender_hb_info {
 	struct sctp_paramhdr param_hdr;
 	union sctp_addr daddr;
 	unsigned long sent_at;
+	__u64 hb_nonce;
 } __attribute__((packed)) sctp_sender_hb_info_t;
 
 /*
@@ -984,6 +985,9 @@ struct sctp_transport {
 		 */
 		char cacc_saw_newack;
 	} cacc;
+
+	/* 64-bit random number sent with heartbeat. */
+	__u64 hb_nonce;
 };
 
 struct sctp_transport *sctp_transport_new(const union sctp_addr *,

include/net/sctp/user.h

@@ -560,9 +560,18 @@ struct sctp_paddrinfo {
 } __attribute__((packed, aligned(4)));
 
 /* Peer addresses's state. */
+/* UNKNOWN: Peer address passed by the upper layer in sendmsg or connect[x]
+ * calls.
+ * UNCONFIRMED: Peer address received in INIT/INIT-ACK address parameters.
+ *              Not yet confirmed by a heartbeat and not available for data
+ *		transfers.
+ * ACTIVE : Peer address confirmed, active and available for data transfers.
+ * INACTIVE: Peer address inactive and not available for data transfers.
+ */
 enum sctp_spinfo_state {
 	SCTP_INACTIVE,
 	SCTP_ACTIVE,
+	SCTP_UNCONFIRMED,
 	SCTP_UNKNOWN = 0xffff  /* Value used for transport state unknown */
 };