tipc: improve sequence number checking

[cascardo/linux.git] / net / tipc / link.c

diff --git a/net/tipc/link.c b/net/tipc/link.c
index 8e23ab5..2b549f6 100644 (file)
--- a/net/tipc/link.c
+++ b/net/tipc/link.c
@@ -1077,13 +1077,14 @@ int tipc_link_rcv(struct tipc_link *l, struct sk_buff *skb,
 {
        struct sk_buff_head *defq = &l->deferdq;
        struct tipc_msg *hdr;
-       u16 seqno, rcv_nxt;
+       u16 seqno, rcv_nxt, win_lim;
        int rc = 0;
 
        do {
                hdr = buf_msg(skb);
                seqno = msg_seqno(hdr);
                rcv_nxt = l->rcv_nxt;
+               win_lim = rcv_nxt + TIPC_MAX_LINK_WIN;
 
                /* Verify and update link state */
                if (unlikely(msg_user(hdr) == LINK_PROTOCOL))
@@ -1098,6 +1099,12 @@ int tipc_link_rcv(struct tipc_link *l, struct sk_buff *skb,
                /* Don't send probe at next timeout expiration */
                l->silent_intv_cnt = 0;
 
+               /* Drop if outside receive window */
+               if (unlikely(less(seqno, rcv_nxt) || more(seqno, win_lim))) {
+                       l->stats.duplicates++;
+                       goto drop;
+               }
+
                /* Forward queues and wake up waiting users */
                if (likely(tipc_link_release_pkts(l, msg_ack(hdr)))) {
                        tipc_link_advance_backlog(l, xmitq);
@@ -1105,29 +1112,20 @@ int tipc_link_rcv(struct tipc_link *l, struct sk_buff *skb,
                                link_prepare_wakeup(l);
                }
 
-               /* Defer reception if there is a gap in the sequence */
-               if (unlikely(less(rcv_nxt, seqno))) {
+               /* Defer delivery if sequence gap */
+               if (unlikely(seqno != rcv_nxt)) {
                        __tipc_skb_queue_sorted(defq, skb);
                        tipc_link_build_nack_msg(l, xmitq);
                        break;
                }
 
-               /* Drop if packet already received */
-               if (unlikely(more(rcv_nxt, seqno))) {
-                       l->stats.duplicates++;
-                       goto drop;
-               }
-
-               /* Packet can be delivered */
+               /* Deliver packet */
                l->rcv_nxt++;
                l->stats.recv_info++;
-
                if (!tipc_data_input(l, skb, l->inputq))
                        rc = tipc_link_input(l, skb, l->inputq);
-               if (rc)
+               if (unlikely(rc))
                        break;
-
-               /* Ack at regular intervals */
                if (unlikely(++l->rcv_unacked >= TIPC_MIN_LINK_WIN))
                        tipc_link_build_ack_msg(l, xmitq);