sctp: fix mapping of interface address flags

Do not clear the SCTP_ADDR_IFA_UNUSEABLE flag, if it was set due
to the address being deprecated. Also don't declare tentative
addresses as unusable.
While there, cleanup the code.

PR:		230242
MFC after:	3 days

Author: tuexen

sys/netinet/sctp_bsd_addr.c

@@ -119,23 +119,21 @@ sctp_gather_internal_ifa_flags(struct sctp_ifa *ifa)
 
 	ifa6 = (struct in6_ifaddr *)ifa->ifa;
 	ifa->flags = ifa6->ia6_flags;
-	if (!MODULE_GLOBAL(ip6_use_deprecated)) {
-		if (ifa->flags &
-		    IN6_IFF_DEPRECATED) {
+	if (MODULE_GLOBAL(ip6_use_deprecated)) {
+		ifa->localifa_flags &= ~SCTP_ADDR_IFA_UNUSEABLE;
+	} else {
+		if (ifa->flags & IN6_IFF_DEPRECATED) {
 			ifa->localifa_flags |= SCTP_ADDR_IFA_UNUSEABLE;
 		} else {
 			ifa->localifa_flags &= ~SCTP_ADDR_IFA_UNUSEABLE;
 		}
-	} else {
-		ifa->localifa_flags &= ~SCTP_ADDR_IFA_UNUSEABLE;
 	}
-	if (ifa->flags &
-	    (IN6_IFF_DETACHED |
-	    IN6_IFF_ANYCAST |
-	    IN6_IFF_NOTREADY)) {
+	if (ifa->flags & (IN6_IFF_DETACHED | IN6_IFF_DUPLICATED)) {
+		ifa->localifa_flags |= SCTP_ADDR_IFA_UNUSEABLE;
+	}
+	/* Right now, do not support IPv6 anycast addresses */
+	if (ifa->flags & IN6_IFF_ANYCAST) {
 		ifa->localifa_flags |= SCTP_ADDR_IFA_UNUSEABLE;
-	} else {
-		ifa->localifa_flags &= ~SCTP_ADDR_IFA_UNUSEABLE;
 	}
 }
 #endif				/* INET6 */