SCTP uses CRC32C and not Adler anymore. While there change the reference

to RFC 4960.
This does not change any code, just comments.

MFC after: 3 days

sys/netinet/sctp.h

@@ -43,13 +43,13 @@ __FBSDID("$FreeBSD$");
 #define SCTP_PACKED __attribute__((packed))
 
 /*
- * SCTP protocol - RFC2960.
+ * SCTP protocol - RFC4960.
  */
 struct sctphdr {
 	uint16_t src_port;	/* source port */
 	uint16_t dest_port;	/* destination port */
 	uint32_t v_tag;		/* verification tag of packet */
-	uint32_t checksum;	/* Adler32 C-Sum */
+	uint32_t checksum;	/* CRC32C checksum */
 	/* chunks follow... */
 }       SCTP_PACKED;