Reset the retransmission timer when receiving duplicate ACKs.

[utcp] / utcp.c

diff --git a/utcp.c b/utcp.c
index 67d4be3a7a632d4cdafd004b217ad01976092caa..ac598ddae28667fd9a40c28ace29255b7dd22f66 100644 (file)
--- a/utcp.c
+++ b/utcp.c
@@ -848,6 +848,7 @@ static void retransmit(struct utcp_connection *c) {
        }
 
        c->rtt_start.tv_sec = 0; // invalidate RTT timer
+       c->dupack = 0; // cancel any ongoing fast recovery
 
 cleanup:
        free(pkt);
@@ -1457,7 +1458,7 @@ synack:
                        break;
                }
        } else {
-               if(!len && is_reliable(c)) {
+               if(!len && is_reliable(c) && c->snd.una != c->snd.last) {
                        c->dupack++;
                        debug(c, "duplicate ACK %d\n", c->dupack);
 
@@ -1484,6 +1485,11 @@ synack:
 
                                debug_cwnd(c);
                        }
+
+                       // We got an ACK which indicates the other side did get one of our packets.
+                       // Reset the retransmission timer to avoid going to slow start,
+                       // but don't touch the connection timeout.
+                       start_retransmit_timer(c);
                }
        }