Recover possible panic in EncodeMsg and improve debug logs

Change-Id: I771c171ae30a957f4436e7f4ba834d8a38d02f80
Signed-off-by: Ondrej Fabry <ofabry@cisco.com>

2 files changed, 79 insertions, 11 deletions

diff --git a/codec/msg_codec.go b/codec/msg_codec.go
index 9d3f614..67628a4 100644
--- a/codec/msg_codec.go
+++ b/codec/msg_codec.go
@@ -53,24 +53,32 @@ type VppOtherHeader struct {
 }
 
 // EncodeMsg encodes provided `Message` structure into its binary-encoded data representation.
-func (*MsgCodec) EncodeMsg(msg api.Message, msgID uint16) ([]byte, error) {
+func (*MsgCodec) EncodeMsg(msg api.Message, msgID uint16) (data []byte, err error) {
 	if msg == nil {
 		return nil, errors.New("nil message passed in")
 	}
 
+	// try to recover panic which might possibly occur in struc.Pack call
+	defer func() {
+		if r := recover(); r != nil {
+			var ok bool
+			if err, ok = r.(error); !ok {
+				err = fmt.Errorf("%v", r)
+			}
+			err = fmt.Errorf("panic occurred: %v", err)
+		}
+	}()
+
 	var header interface{}
 
 	// encode message header
 	switch msg.GetMessageType() {
 	case api.RequestMessage:
 		header = &VppRequestHeader{VlMsgID: msgID}
-
 	case api.ReplyMessage:
 		header = &VppReplyHeader{VlMsgID: msgID}
-
 	case api.EventMessage:
 		header = &VppEventHeader{VlMsgID: msgID}
-
 	default:
 		header = &VppOtherHeader{VlMsgID: msgID}
 	}
@@ -79,13 +87,13 @@ func (*MsgCodec) EncodeMsg(msg api.Message, msgID uint16) ([]byte, error) {
 
 	// encode message header
 	if err := struc.Pack(buf, header); err != nil {
-		return nil, fmt.Errorf("unable to encode message header: %v, error %v", header, err)
+		return nil, fmt.Errorf("failed to encode message header: %+v, error: %v", header, err)
 	}
 
 	// encode message content
 	if reflect.TypeOf(msg).Elem().NumField() > 0 {
 		if err := struc.Pack(buf, msg); err != nil {
-			return nil, fmt.Errorf("unable to encode message data: %v, error %v", header, err)
+			return nil, fmt.Errorf("failed to encode message data: %+v, error: %v", data, err)
 		}
 	}
 
@@ -104,13 +112,10 @@ func (*MsgCodec) DecodeMsg(data []byte, msg api.Message) error {
 	switch msg.GetMessageType() {
 	case api.RequestMessage:
 		header = new(VppRequestHeader)
-
 	case api.ReplyMessage:
 		header = new(VppReplyHeader)
-
 	case api.EventMessage:
 		header = new(VppEventHeader)
-
 	default:
 		header = new(VppOtherHeader)
 	}
@@ -119,12 +124,12 @@ func (*MsgCodec) DecodeMsg(data []byte, msg api.Message) error {
 
 	// decode message header
 	if err := struc.Unpack(buf, header); err != nil {
-		return fmt.Errorf("unable to decode message header: %+v, error %v", data, err)
+		return fmt.Errorf("failed to decode message header: %+v, error: %v", header, err)
 	}
 
 	// decode message content
 	if err := struc.Unpack(buf, msg); err != nil {
-		return fmt.Errorf("unable to decode message data: %+v, error %v", data, err)
+		return fmt.Errorf("failed to decode message data: %+v, error: %v", data, err)
 	}
 
 	return nil
diff --git a/codec/msg_codec_test.go b/codec/msg_codec_test.go
new file mode 100644
index 0000000..cd1240e
--- /dev/null
+++ b/codec/msg_codec_test.go
@@ -0,0 +1,63 @@
+package codec
+
+import (
+	"bytes"
+	"testing"
+
+	"git.fd.io/govpp.git/api"
+)
+
+type MyMsg struct {
+	Index uint16
+	Label []byte `struc:"[16]byte"`
+	Port  uint16
+}
+
+func (*MyMsg) GetMessageName() string {
+	return "my_msg"
+}
+func (*MyMsg) GetCrcString() string {
+	return "xxxxx"
+}
+func (*MyMsg) GetMessageType() api.MessageType {
+	return api.OtherMessage
+}
+
+func TestEncode(t *testing.T) {
+	tests := []struct {
+		name    string
+		msg     api.Message
+		msgID   uint16
+		expData []byte
+	}{
+		{name: "basic",
+			msg:     &MyMsg{Index: 1, Label: []byte("Abcdef"), Port: 1000},
+			msgID:   100,
+			expData: []byte{0x00, 0x64, 0x00, 0x01, 0x41, 0x62, 0x63, 0x64, 0x65, 0x66, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x03, 0xE8},
+		},
+	}
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			c := &MsgCodec{}
+
+			data, err := c.EncodeMsg(test.msg, test.msgID)
+			if err != nil {
+				t.Fatalf("expected nil error, got: %v", err)
+			}
+			if !bytes.Equal(data, test.expData) {
+				t.Fatalf("expected data: % 0X, got: % 0X", test.expData, data)
+			}
+		})
+	}
+}
+
+func TestEncodePanic(t *testing.T) {
+	c := &MsgCodec{}
+
+	msg := &MyMsg{Index: 1, Label: []byte("thisIsLongerThan16Bytes"), Port: 1000}
+
+	_, err := c.EncodeMsg(msg, 100)
+	if err == nil {
+		t.Fatalf("expected non-nil error, got: %v", err)
+	}
+}