Resend Close Frames

src/core/connection.c

@@ -4411,6 +4411,19 @@ QuicConnRecvFrames(
     uint16_t PayloadLength = Packet->PayloadLength;
     uint64_t RecvTime = CxPlatTimeUs64();
 
+    //
+    // In closing state, respond to any packet with a new close frame (rate-limited).
+    //
+    if (Closed && !Connection->State.ShutdownComplete) {
+        if (RecvTime - Connection->LastCloseResponseTimeUs >= QUIC_CLOSING_RESPONSE_MIN_INTERVAL_US) {
+            QuicSendSetSendFlag(
+                &Connection->Send,
+                Connection->State.AppClosed ?
+                    QUIC_CONN_SEND_FLAG_APPLICATION_CLOSE :
+                    QUIC_CONN_SEND_FLAG_CONNECTION_CLOSE);
+        }
+    }
+
     if (QuicConnIsClient(Connection) &&
         !Connection->State.GotFirstServerResponse) {
         Connection->State.GotFirstServerResponse = TRUE;

src/core/connection.h

@@ -536,6 +536,12 @@ typedef struct QUIC_CONNECTION {
     //
     uint64_t EarliestExpirationTime;
 
+    //
+    // Timestamp (us) of when we last queued up a connection close (or
+    // application close) response to be sent.
+    //
+    uint64_t LastCloseResponseTimeUs;
+
     //
     // Receive packet queue.
     //

src/core/quicdef.h

@@ -318,6 +318,12 @@ CXPLAT_STATIC_ASSERT(
 //
 #define QUIC_DEFAULT_HANDSHAKE_IDLE_TIMEOUT     10000
 
+//
+// Minimum interval (in microseconds) between CONNECTION_CLOSE responses in
+// closing state.
+//
+#define QUIC_CLOSING_RESPONSE_MIN_INTERVAL_US   5000
+
 //
 // The default value for keep alives being enabled or not.
 //

src/core/send.c

@@ -307,6 +307,7 @@ QuicSendSetSendFlag(
     }
 
     if (IsCloseFrame) {
+        Connection->LastCloseResponseTimeUs = CxPlatTimeUs64();
         QuicSendClear(Send);
     }