Initialize Path Smoothed RTT Field (#169)

src/core/connection.c

@@ -653,6 +653,13 @@ QuicConnUpdateRtt(
     BOOLEAN RttUpdated;
     UNREFERENCED_PARAMETER(Connection);
 
+    if (LatestRtt == 0) {
+        //
+        // RTT cannot be zero or several loss recovery algorithms break down.
+        //
+        LatestRtt = 1;
+    }
+
     Path->LatestRttSample = LatestRtt;
     if (LatestRtt < Path->MinRtt) {
         Path->MinRtt = LatestRtt;
@@ -680,6 +687,7 @@ QuicConnUpdateRtt(
     }
 
     if (RttUpdated) {
+        QUIC_DBG_ASSERT(Path->SmoothedRtt != 0);
         QuicTraceLogConnVerbose(RttUpdated, Connection, "Updated Rtt=%u.%u ms, Var=%u.%u",
             Path->SmoothedRtt / 1000, Path->SmoothedRtt % 1000,
             Path->RttVariance / 1000, Path->RttVariance % 1000);

src/core/loss_detection.c

@@ -174,6 +174,8 @@ QuicLossDetectionComputeProbeTimeout(
 {
     QUIC_CONNECTION* Connection = QuicLossDetectionGetConnection(LossDetection);
 
+    QUIC_DBG_ASSERT(Path->SmoothedRtt != 0);
+
     //
     // Microseconds.
     //
@@ -242,6 +244,8 @@ QuicLossDetectionUpdateTimer(
 
     uint32_t TimeNow = QuicTimeUs32();
 
+    QUIC_DBG_ASSERT(Path->SmoothedRtt != 0);
+
     uint32_t TimeFires;
     QUIC_LOSS_TIMER_TYPE TimeoutType;
     if (OldestPacket != NULL &&

src/core/path.c

@@ -30,6 +30,11 @@ QuicPathInitialize(
     Path->ID = Connection->NextPathId++; // TODO - Check for duplicates after wrap around?
     Path->MinRtt = UINT32_MAX;
     Path->Mtu = QUIC_DEFAULT_PATH_MTU;
+    if (Connection->Session != NULL) {
+        Path->SmoothedRtt = MS_TO_US(Connection->Session->Settings.InitialRttMs);
+    } else {
+        Path->SmoothedRtt = MS_TO_US(QUIC_INITIAL_RTT);
+    }
 
     QuicTraceLogConnInfo(PathInitialized, Connection, "Path[%u] Initialized", Path->ID);
 }