From 4e15fac25066d29a95b72ada046c2f0865cddce2 Mon Sep 17 00:00:00 2001
From: Joe Turki <git@joeturki.com>
Date: Sun, 5 Jan 2025 22:41:58 -0600
Subject: [PATCH] Gracefully close connecting channels

---
 datachannel.go      | 10 +++++-
 datachannel_test.go | 75 +++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 84 insertions(+), 1 deletion(-)

diff --git a/datachannel.go b/datachannel.go
index 5fef7900174..053b3e0e51a 100644
--- a/datachannel.go
+++ b/datachannel.go
@@ -322,6 +322,9 @@ func (d *DataChannel) handleOpen(dc *datachannel.DataChannel, isRemote, isAlread
 	d.mu.Lock()
 	if d.isGracefulClosed {
 		d.mu.Unlock()
+		dc.Close() // nolint:errcheck,gosec
+		d.onClose()
+
 		return
 	}
 	d.dataChannel = dc
@@ -346,9 +349,12 @@ func (d *DataChannel) handleOpen(dc *datachannel.DataChannel, isRemote, isAlread
 	}
 
 	d.mu.Lock()
-	defer d.mu.Unlock()
 
 	if d.isGracefulClosed {
+		d.mu.Unlock() // we unlock before we call d.onClose to avoid side effects
+		dc.Close()    // nolint:errcheck,gosec
+		d.onClose()
+
 		return
 	}
 
@@ -356,6 +362,8 @@ func (d *DataChannel) handleOpen(dc *datachannel.DataChannel, isRemote, isAlread
 		d.readLoopActive = make(chan struct{})
 		go d.readLoop()
 	}
+
+	d.mu.Unlock()
 }
 
 // OnError sets an event handler which is invoked when
diff --git a/datachannel_test.go b/datachannel_test.go
index 5969da815d4..8932e9c928c 100644
--- a/datachannel_test.go
+++ b/datachannel_test.go
@@ -455,6 +455,81 @@ func TestDataChannelParameters(t *testing.T) {
 		closeReliabilityParamTest(t, offerPC, answerPC, done)
 	})
 
+	// Test if onClose is fired for self and remote after Close is called
+	t.Run("close open channels", func(t *testing.T) {
+		options := &DataChannelInit{}
+
+		offerPC, answerPC, dc, done := setUpDataChannelParametersTest(t, options)
+
+		answerPC.OnDataChannel(func(dataChannel *DataChannel) {
+			// Make sure this is the data channel we were looking for. (Not the one
+			// created in signalPair).
+			if dataChannel.Label() != expectedLabel {
+				return
+			}
+
+			dataChannel.OnOpen(func() {
+				assert.NoError(t, dataChannel.Close())
+			})
+
+			dataChannel.OnClose(func() {
+				done <- true
+			})
+		})
+
+		dc.OnClose(func() {
+			done <- true
+		})
+
+		assert.NoError(t, signalPair(offerPC, answerPC))
+
+		// Offer and Answer OnClose
+		<-done
+		<-done
+
+		assert.NoError(t, offerPC.Close())
+		assert.NoError(t, answerPC.Close())
+	})
+
+	// Test if OnClose is fired for self and remote after Close is called on non-established channel
+	// https://github.com/pion/webrtc/issues/2659
+	t.Run("Close connecting channels", func(t *testing.T) {
+		options := &DataChannelInit{}
+
+		offerPC, answerPC, dc, done := setUpDataChannelParametersTest(t, options)
+
+		answerPC.OnDataChannel(func(dataChannel *DataChannel) {
+			// Make sure this is the data channel we were looking for. (Not the one
+			// created in signalPair).
+			if dataChannel.Label() != expectedLabel {
+				return
+			}
+
+			dataChannel.OnOpen(func() {
+				t.Fatal("OnOpen must not be fired after we call Close")
+			})
+
+			dataChannel.OnClose(func() {
+				done <- true
+			})
+
+			assert.NoError(t, dataChannel.Close())
+		})
+
+		dc.OnClose(func() {
+			done <- true
+		})
+
+		assert.NoError(t, signalPair(offerPC, answerPC))
+
+		// Offer and Answer OnClose
+		<-done
+		<-done
+
+		assert.NoError(t, offerPC.Close())
+		assert.NoError(t, answerPC.Close())
+	})
+
 	t.Run("Negotiated exchange", func(t *testing.T) {
 		const expectedMessage = "Hello World"