fix: reset readErrCount on success and lower panic threshold to 2

conn.go

@@ -1012,18 +1012,16 @@ func (c *Conn) NextReader() (messageType int, r io.Reader, err error) {
 		c.reader.Close()
 		c.reader = nil
 	}
-
 	c.messageReader = nil
 	c.readLength = 0
-
 	for c.readErr == nil {
 		frameType, err := c.advanceFrame()
 		if err != nil {
 			c.readErr = err
 			break
 		}
-
 		if frameType == TextMessage || frameType == BinaryMessage {
+			c.readErrCount = 0 // resets on success
 			c.messageReader = &messageReader{c}
 			c.reader = c.messageReader
 			if c.readDecompress {
@@ -1032,15 +1030,14 @@ func (c *Conn) NextReader() (messageType int, r io.Reader, err error) {
 			return frameType, c.reader, nil
 		}
 	}
-
 	// Applications that do handle the error returned from this method spin in
 	// tight loop on connection failure. To help application developers detect
 	// this error, panic on repeated reads to the failed connection.
 	c.readErrCount++
-	if c.readErrCount >= 1000 {
-		panic("repeated read on failed websocket connection")
+	if c.readErrCount >= 2 {
+		panic("gorilla/websocket: application did not handle error from NextReader, error: " +
+			c.readErr.Error())
 	}
-
 	return noFrame, nil, c.readErr
 }
 

conn_test.go

@@ -744,3 +744,45 @@ func TestFailedConnectionReadPanic(t *testing.T) {
 	}
 	t.Fatal("should not get here")
 }
+
+func TestNextReadErrCountResetOnSuccess(t *testing.T) {
+	// setup a pipe to write a real websocket frame
+	r, w := io.Pipe()
+	conn := newTestConn(r, w, false) // client connection
+
+	// simulate accumulated errors from previous failures
+	conn.readErrCount = 1
+
+	// write a valid text frame from another goroutine
+	go func() {
+		serverConn := newTestConn(r, w, true) // server connection
+		serverConn.WriteMessage(TextMessage, []byte("Test"))
+	}()
+
+	// successful read should reset the counter
+	_, _, err := conn.NextReader()
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if conn.readErrCount != 0 {
+		t.Errorf("expected readErrCount to be 0 after success, got %d", conn.readErrCount)
+	}
+}
+
+func TestNextReaderPanicsOnSecondFailedRead(t *testing.T) {
+	r, w := io.Pipe()
+	conn := newTestConn(r, w, false) // client connection
+
+	// force the connection into a permanently failed state
+	conn.readErr = errors.New("simulated failure")
+	conn.readErrCount = 1 // already had 1 failed read
+
+	defer func() {
+		r := recover()
+		if r == nil {
+			t.Fatal("expected panic on second read of failed connection, got none")
+		}
+	}()
+
+	conn.NextReader()
+}