summaryrefslogtreecommitdiffstats
path: root/codec/msg_codec.go
blob: 227764d0eb7760dddf748066a022c6d1517b3d23 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
// Copyright (c) 2017 Cisco and/or its affiliates.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at:
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package codec

import (
	"encoding/binary"
	"errors"
	"fmt"

	"git.fd.io/govpp.git/api"
)

var DefaultCodec = new(MsgCodec)

func EncodeMsg(msg api.Message, msgID uint16) (data []byte, err error) {
	return DefaultCodec.EncodeMsg(msg, msgID)
}
func DecodeMsg(data []byte, msg api.Message) (err error) {
	return DefaultCodec.DecodeMsg(data, msg)
}
func DecodeMsgContext(data []byte, msgType api.MessageType) (context uint32, err error) {
	return DefaultCodec.DecodeMsgContext(data, msgType)
}

// MsgCodec provides encoding and decoding functionality of `api.Message` structs into/from
// binary format as accepted by VPP.
type MsgCodec struct{}

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
	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 during encoding message %s: %v", msg.GetMessageName(), err)
		}
	}()

	marshaller, ok := msg.(Marshaler)
	if !ok {
		marshaller = Wrapper{msg}
	}

	size := marshaller.Size()
	offset := getOffset(msg)

	// encode msg ID
	b := make([]byte, size+offset)
	b[0] = byte(msgID >> 8)
	b[1] = byte(msgID)

	data, err = marshaller.Marshal(b[offset:])
	if err != nil {
		return nil, err
	}

	return b[0:len(b):len(b)], nil
}

func (*MsgCodec) DecodeMsg(data []byte, msg api.Message) (err error) {
	if msg == nil {
		return errors.New("nil message passed in")
	}

	// try to recover panic which might possibly occur
	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 during decoding message %s: %v", msg.GetMessageName(), err)
		}
	}()

	marshaller, ok := msg.(Unmarshaler)
	if !ok {
		marshaller = Wrapper{msg}
	}

	offset := getOffset(msg)

	err = marshaller.Unmarshal(data[offset:len(data)])
	if err != nil {
		return err
	}

	return nil
}

func (*MsgCodec) DecodeMsgContext(data []byte, msgType api.MessageType) (context uint32, err error) {
	switch msgType {
	case api.RequestMessage:
		return binary.BigEndian.Uint32(data[6:10]), nil
	case api.ReplyMessage:
		return binary.BigEndian.Uint32(data[2:6]), nil
	}

	return 0, nil
}

func getOffset(msg api.Message) (offset int) {
	switch msg.GetMessageType() {
	case api.RequestMessage:
		return 10
	case api.ReplyMessage:
		return 6
	case api.EventMessage:
		return 6
	}
	return 2
}