[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>
diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h
index 5f69158..268f2e1 100644
--- a/include/net/sctp/structs.h
+++ b/include/net/sctp/structs.h
@@ -445,6 +445,7 @@
 	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 @@
 		 */
 		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 *,