From 4a6e72637b1fbac6a49d566156ce2d32024958d9 Mon Sep 17 00:00:00 2001
From: Marten Seemann <martenseemann@gmail.com>
Date: Tue, 12 Sep 2023 12:47:27 +0700
Subject: [PATCH] webrtc: don't close stream, but limit to 512 streams per
 direction

---
 p2p/test/transport/transport_test.go |  2 +-
 p2p/transport/webrtc/connection.go   | 15 +++++++++++++++
 p2p/transport/webrtc/stream.go       |  4 +++-
 3 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/p2p/test/transport/transport_test.go b/p2p/test/transport/transport_test.go
index 75bf306d13..a7e98a0d85 100644
--- a/p2p/test/transport/transport_test.go
+++ b/p2p/test/transport/transport_test.go
@@ -247,7 +247,7 @@ func TestLotsOfDataManyStreams(t *testing.T) {
 	// 64k buffer
 	const bufSize = 64 << 10
 	sendBuf := [bufSize]byte{}
-	const totalStreams = 512
+	const totalStreams = 500
 	const parallel = 8
 	// Total sends are > 20MiB
 	require.Greater(t, len(sendBuf)*totalStreams, 20<<20)
diff --git a/p2p/transport/webrtc/connection.go b/p2p/transport/webrtc/connection.go
index 550c6a8cdc..fd31f8351a 100644
--- a/p2p/transport/webrtc/connection.go
+++ b/p2p/transport/webrtc/connection.go
@@ -27,6 +27,8 @@ var _ tpt.CapableConn = &connection{}
 
 const maxAcceptQueueLen = 10
 
+const maxDataChannelID = 1 << 10
+
 type errConnectionTimeout struct{}
 
 var _ net.Error = &errConnectionTimeout{}
@@ -108,6 +110,12 @@ func newConnection(
 		if c.IsClosed() {
 			return
 		}
+		// Limit the number of streams, since we're not able to actually properly close them.
+		// See https://github.com/libp2p/specs/issues/575 for details.
+		if *dc.ID() > maxDataChannelID {
+			c.Close()
+			return
+		}
 		dc.OnOpen(func() {
 			rwc, err := dc.Detach()
 			if err != nil {
@@ -166,6 +174,13 @@ func (c *connection) OpenStream(ctx context.Context) (network.MuxedStream, error
 	if id > math.MaxUint16 {
 		return nil, errors.New("exhausted stream ID space")
 	}
+	// Limit the number of streams, since we're not able to actually properly close them.
+	// See https://github.com/libp2p/specs/issues/575 for details.
+	if id > maxDataChannelID {
+		c.Close()
+		return c.OpenStream(ctx)
+	}
+
 	streamID := uint16(id)
 	dc, err := c.pc.CreateDataChannel("", &webrtc.DataChannelInit{ID: &streamID})
 	if err != nil {
diff --git a/p2p/transport/webrtc/stream.go b/p2p/transport/webrtc/stream.go
index b86128dc31..7e873f5634 100644
--- a/p2p/transport/webrtc/stream.go
+++ b/p2p/transport/webrtc/stream.go
@@ -192,7 +192,9 @@ func (s *stream) maybeDeclareStreamDone() {
 		(s.receiveState == receiveStateReset || s.receiveState == receiveStateDataRead) &&
 		len(s.controlMsgQueue) == 0 {
 		_ = s.SetReadDeadline(time.Now().Add(-1 * time.Hour)) // pion ignores zero times
-		_ = s.dataChannel.Close()
+		// TODO: we should be closing the underlying datachannel, but this resets the stream
+		// See https://github.com/libp2p/specs/issues/575 for details.
+		// _ = s.dataChannel.Close()
 		// TODO: write for the spawned reader to return
 		s.onDone()
 	}