feat: Supports callbacks when reading a message fails

server/serverimpl.go

@@ -5,6 +5,7 @@ import (
 	"compress/gzip"
 	"context"
 	"errors"
+	"fmt"
 	"io"
 	"net"
 	"net/http"
@@ -226,27 +227,39 @@ func (s *server) handleWSConnection(reqCtx context.Context, wsConn *websocket.Co
 	// Loop until fail to read from the WebSocket connection.
 	for {
 		msgContext := context.Background()
+		request := protobufs.AgentToServer{}
+
 		// Block until the next message can be read.
 		mt, msgBytes, err := wsConn.ReadMessage()
-		if err != nil {
-			if !websocket.IsUnexpectedCloseError(err) {
-				s.logger.Errorf(msgContext, "Cannot read a message from WebSocket: %v", err)
-				break
+		isBreak, err := func() (bool, error) {
+			if err != nil {
+				if !websocket.IsUnexpectedCloseError(err) {
+					s.logger.Errorf(msgContext, "Cannot read a message from WebSocket: %v", err)
+					return true, err
+				}
+				// This is a normal closing of the WebSocket connection.
+				s.logger.Debugf(msgContext, "Agent disconnected: %v", err)
+				return true, err
+			}
+			if mt != websocket.BinaryMessage {
+				err = fmt.Errorf("Received unexpected message type from WebSocket: %v", mt)
+				s.logger.Errorf(msgContext, err.Error())
+				return false, err
 			}
-			// This is a normal closing of the WebSocket connection.
-			s.logger.Debugf(msgContext, "Agent disconnected: %v", err)
-			break
-		}
-		if mt != websocket.BinaryMessage {
-			s.logger.Errorf(msgContext, "Received unexpected message type from WebSocket: %v", mt)
-			continue
-		}
 
-		// Decode WebSocket message as a Protobuf message.
-		var request protobufs.AgentToServer
-		err = internal.DecodeWSMessage(msgBytes, &request)
+			// Decode WebSocket message as a Protobuf message.
+			err = internal.DecodeWSMessage(msgBytes, &request)
+			if err != nil {
+				s.logger.Errorf(msgContext, "Cannot decode message from WebSocket: %v", err)
+				return false, err
+			}
+			return false, nil
+		}()
 		if err != nil {
-			s.logger.Errorf(msgContext, "Cannot decode message from WebSocket: %v", err)
+			connectionCallbacks.OnReadMessageError(agentConn, mt, msgBytes, err)
+			if isBreak {
+				break
+			}
 			continue
 		}
 
@@ -366,7 +379,6 @@ func (s *server) handlePlainHTTPRequest(req *http.Request, w http.ResponseWriter
 		w.Header().Set(headerContentEncoding, contentEncodingGzip)
 	}
 	_, err = w.Write(bodyBytes)
-
 	if err != nil {
 		s.logger.Debugf(req.Context(), "Cannot send HTTP response: %v", err)
 	}

server/serverimpl_test.go

@@ -315,6 +315,52 @@ func TestServerReceiveSendMessage(t *testing.T) {
 	assert.EqualValues(t, settings.CustomCapabilities, response.CustomCapabilities.Capabilities)
 }
 
+func TestServerReceiveSendErrorMessage(t *testing.T) {
+	var rcvMsg atomic.Value
+	type ErrorInfo struct {
+		mt      int
+		msgByte []byte
+		err     error
+	}
+	callbacks := types.Callbacks{
+		OnConnecting: func(request *http.Request) types.ConnectionResponse {
+			return types.ConnectionResponse{Accept: true, ConnectionCallbacks: types.ConnectionCallbacks{
+				OnReadMessageError: func(conn types.Connection, mt int, msgByte []byte, err error) {
+					rcvMsg.Store(ErrorInfo{
+						mt:      mt,
+						msgByte: msgByte,
+						err:     err,
+					})
+				},
+			}}
+		},
+	}
+
+	// Start a Server.
+	settings := &StartSettings{Settings: Settings{
+		Callbacks:          callbacks,
+		CustomCapabilities: []string{"local.test.capability"},
+	}}
+	srv := startServer(t, settings)
+	defer srv.Stop(context.Background())
+
+	// Connect using a WebSocket client.
+	conn, _, _ := dialClient(settings)
+	require.NotNil(t, conn)
+	defer conn.Close()
+
+	// Send a message to the Server.
+	err := conn.WriteMessage(websocket.TextMessage, []byte("abc"))
+	require.NoError(t, err)
+
+	// Wait until Server receives the message.
+	eventually(t, func() bool { return rcvMsg.Load() != nil })
+	errInfo := rcvMsg.Load().(ErrorInfo)
+	assert.EqualValues(t, websocket.TextMessage, errInfo.mt)
+	assert.EqualValues(t, []byte("abc"), errInfo.msgByte)
+	assert.NotNil(t, errInfo.err)
+}
+
 func TestServerReceiveSendMessageWithCompression(t *testing.T) {
 	// Use highly compressible config body.
 	uncompressedCfg := []byte(strings.Repeat("test", 10000))
@@ -620,7 +666,6 @@ func TestServerAttachSendMessagePlainHTTP(t *testing.T) {
 }
 
 func TestServerHonoursClientRequestContentEncoding(t *testing.T) {
-
 	hc := http.Client{}
 	var rcvMsg atomic.Value
 	var onConnectedCalled, onCloseCalled int32
@@ -698,7 +743,6 @@ func TestServerHonoursClientRequestContentEncoding(t *testing.T) {
 }
 
 func TestServerHonoursAcceptEncoding(t *testing.T) {
-
 	hc := http.Client{}
 	var rcvMsg atomic.Value
 	var onConnectedCalled, onCloseCalled int32
@@ -985,7 +1029,6 @@ func BenchmarkSendToClient(b *testing.B) {
 	}
 	srv := New(&sharedinternal.NopLogger{})
 	err := srv.Start(*settings)
-
 	if err != nil {
 		b.Error(err)
 	}
@@ -1017,7 +1060,6 @@ func BenchmarkSendToClient(b *testing.B) {
 
 	for _, conn := range serverConnections {
 		err := conn.Send(context.Background(), &protobufs.ServerToAgent{})
-
 		if err != nil {
 			b.Error(err)
 		}
@@ -1026,5 +1068,4 @@ func BenchmarkSendToClient(b *testing.B) {
 	for _, conn := range clientConnections {
 		conn.Close()
 	}
-
 }

server/types/callbacks.go

@@ -62,6 +62,9 @@ type ConnectionCallbacks struct {
 
 	// OnConnectionClose is called when the OpAMP connection is closed.
 	OnConnectionClose func(conn Connection)
+
+	// OnReadMessageError is called when an error occurs while reading or deserializing a message.
+	OnReadMessageError func(conn Connection, mt int, msgByte []byte, err error)
 }
 
 func defaultOnConnected(ctx context.Context, conn Connection) {}
@@ -77,6 +80,8 @@ func defaultOnMessage(
 
 func defaultOnConnectionClose(conn Connection) {}
 
+func defaultOnReadMessageError(conn Connection, mt int, msgByte []byte, err error) {}
+
 func (c *ConnectionCallbacks) SetDefaults() {
 	if c.OnConnected == nil {
 		c.OnConnected = defaultOnConnected
@@ -89,4 +94,8 @@ func (c *ConnectionCallbacks) SetDefaults() {
 	if c.OnConnectionClose == nil {
 		c.OnConnectionClose = defaultOnConnectionClose
 	}
+
+	if c.OnReadMessageError == nil {
+		c.OnReadMessageError = defaultOnReadMessageError
+	}
 }