From a53569839cb79fd654ae44e27949d348ec3d4c36 Mon Sep 17 00:00:00 2001
From: Marten Seemann <martenseemann@gmail.com>
Date: Sun, 24 Nov 2019 09:35:14 +0700
Subject: [PATCH] don't queue the currently active conn ID when receiving a
 duplicate

---
 conn_id_manager.go      |  4 ++++
 conn_id_manager_test.go | 16 ++++++++++++++++
 2 files changed, 20 insertions(+)

diff --git a/conn_id_manager.go b/conn_id_manager.go
index d761897d..a2b268df 100644
--- a/conn_id_manager.go
+++ b/conn_id_manager.go
@@ -89,6 +89,10 @@ func (h *connIDManager) add(f *wire.NewConnectionIDFrame) error {
 		h.retiredPriorTo = f.RetirePriorTo
 	}
 
+	if f.SequenceNumber == h.activeSequenceNumber {
+		return nil
+	}
+
 	// insert a new element at the end
 	if h.queue.Len() == 0 || h.queue.Back().Value.SequenceNumber < f.SequenceNumber {
 		h.queue.PushBack(utils.NewConnectionID{
diff --git a/conn_id_manager_test.go b/conn_id_manager_test.go
index b5fc211b..49af58d0 100644
--- a/conn_id_manager_test.go
+++ b/conn_id_manager_test.go
@@ -95,6 +95,22 @@ var _ = Describe("Connection ID Manager", func() {
 		Expect(rt2).To(BeNil())
 	})
 
+	It("ignores duplicates for the currently used connection ID", func() {
+		f := &wire.NewConnectionIDFrame{
+			SequenceNumber:      1,
+			ConnectionID:        protocol.ConnectionID{1, 2, 3, 4},
+			StatelessResetToken: [16]byte{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0xa, 0xb, 0xc, 0xd, 0xe},
+		}
+		Expect(m.Add(f)).To(Succeed())
+		Expect(m.Get()).To(Equal(protocol.ConnectionID{1, 2, 3, 4}))
+		c, _ := get()
+		Expect(c).To(BeNil())
+		// Now send the same connection ID again. It should not be queued.
+		Expect(m.Add(f)).To(Succeed())
+		c, _ = get()
+		Expect(c).To(BeNil())
+	})
+
 	It("rejects duplicates with different connection IDs", func() {
 		Expect(m.Add(&wire.NewConnectionIDFrame{
 			SequenceNumber: 42,