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// 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)
// 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, msg api.Message) (context uint32, err error) {
if msg == nil {
return 0, errors.New("nil message passed in")
}
switch msg.GetMessageType() {
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
}
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