From 4ae549a8e2037826845f096cd2a702f6ffd412d4 Mon Sep 17 00:00:00 2001
From: Sukun <sukunrt@gmail.com>
Date: Thu, 21 Sep 2023 18:04:16 +0530
Subject: [PATCH] webrtc: fail Write early if deadline has exceeded before the
 call (#2578)

---
 p2p/transport/webrtc/stream_write.go   | 4 ++++
 p2p/transport/webrtc/transport_test.go | 8 +++++++-
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/p2p/transport/webrtc/stream_write.go b/p2p/transport/webrtc/stream_write.go
index c7eb3bf7a4..698af9c4d6 100644
--- a/p2p/transport/webrtc/stream_write.go
+++ b/p2p/transport/webrtc/stream_write.go
@@ -35,6 +35,10 @@ func (s *stream) Write(b []byte) (int, error) {
 		s.readLoopOnce.Do(s.spawnControlMessageReader)
 	}
 
+	if !s.writeDeadline.IsZero() && time.Now().After(s.writeDeadline) {
+		return 0, os.ErrDeadlineExceeded
+	}
+
 	var writeDeadlineTimer *time.Timer
 	defer func() {
 		if writeDeadlineTimer != nil {
diff --git a/p2p/transport/webrtc/transport_test.go b/p2p/transport/webrtc/transport_test.go
index 19d39ba282..7f4df94fc1 100644
--- a/p2p/transport/webrtc/transport_test.go
+++ b/p2p/transport/webrtc/transport_test.go
@@ -402,10 +402,16 @@ func TestTransportWebRTC_Deadline(t *testing.T) {
 		stream, err := conn.OpenStream(context.Background())
 		require.NoError(t, err)
 
-		stream.SetWriteDeadline(time.Now().Add(200 * time.Millisecond))
+		stream.SetWriteDeadline(time.Now().Add(100 * time.Millisecond))
 		largeBuffer := make([]byte, 2*1024*1024)
 		_, err = stream.Write(largeBuffer)
 		require.ErrorIs(t, err, os.ErrDeadlineExceeded)
+
+		stream.SetWriteDeadline(time.Now().Add(-200 * time.Millisecond))
+		smallBuffer := make([]byte, 1024)
+		_, err = stream.Write(smallBuffer)
+		require.ErrorIs(t, err, os.ErrDeadlineExceeded)
+
 	})
 }