MFC r280714:

Improve the selection of the destination address of SACK chunks.
This fixes
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=196755
and is joint work with rrs@.

2 files changed, 4 insertions, 20 deletions

diff --git a/sys/netinet/sctp_output.c b/sys/netinet/sctp_output.c
index 347b269..251d1ff 100644
--- a/sys/netinet/sctp_output.c
+++ b/sys/netinet/sctp_output.c
@@ -10425,32 +10425,17 @@ sctp_send_sack(struct sctp_tcb *stcb, int so_locked
 	a_chk->sent = SCTP_DATAGRAM_UNSENT;
 	a_chk->whoTo = NULL;
 
-	if ((asoc->numduptsns) ||
-	    (!(asoc->last_data_chunk_from->dest_state & SCTP_ADDR_REACHABLE))) {
+	if (!(asoc->last_data_chunk_from->dest_state & SCTP_ADDR_REACHABLE)) {
 		/*-
-		 * Ok, we have some duplicates or the destination for the
-		 * sack is unreachable, lets see if we can select an
-		 * alternate than asoc->last_data_chunk_from
+		 * Ok, the destination for the SACK is unreachable, lets see if
+		 * we can select an alternate to asoc->last_data_chunk_from
 		 */
-		if ((asoc->last_data_chunk_from->dest_state & SCTP_ADDR_REACHABLE) &&
-		    (asoc->used_alt_onsack > asoc->numnets)) {
-			/* We used an alt last time, don't this time */
-			a_chk->whoTo = NULL;
-		} else {
-			asoc->used_alt_onsack++;
-			a_chk->whoTo = sctp_find_alternate_net(stcb, asoc->last_data_chunk_from, 0);
-		}
+		a_chk->whoTo = sctp_find_alternate_net(stcb, asoc->last_data_chunk_from, 0);
 		if (a_chk->whoTo == NULL) {
 			/* Nope, no alternate */
 			a_chk->whoTo = asoc->last_data_chunk_from;
-			asoc->used_alt_onsack = 0;
 		}
 	} else {
-		/*
-		 * No duplicates so we use the last place we received data
-		 * from.
-		 */
-		asoc->used_alt_onsack = 0;
 		a_chk->whoTo = asoc->last_data_chunk_from;
 	}
 	if (a_chk->whoTo) {
diff --git a/sys/netinet/sctp_structs.h b/sys/netinet/sctp_structs.h
index b1df17d..8f61cd7 100644
--- a/sys/netinet/sctp_structs.h
+++ b/sys/netinet/sctp_structs.h
@@ -1174,7 +1174,6 @@ struct sctp_association {
 
 	struct sctp_scoping scope;
 	/* flags to handle send alternate net tracking */
-	uint8_t used_alt_onsack;
 	uint8_t used_alt_asconfack;
 	uint8_t fast_retran_loss_recovery;
 	uint8_t sat_t3_loss_recovery;