initial commit

Signed-off-by: Rastislav Szabo <raszabo@cisco.com>

1 files changed, 146 insertions, 0 deletions

diff --git a/core/msg_codec.go b/core/msg_codec.go
new file mode 100644
index 0000000..1543f3d
--- /dev/null
+++ b/core/msg_codec.go
@@ -0,0 +1,146 @@
+// 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 core
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"reflect"
+
+	logger "github.com/Sirupsen/logrus"
+	"github.com/lunixbochs/struc"
+
+	"gerrit.fd.io/r/govpp/api"
+)
+
+// MsgCodec provides encoding and decoding functionality of `api.Message` structs into/from
+// binary format as accepted by VPP.
+type MsgCodec struct{}
+
+// vppRequestHeader struct contains header fields implemented by all VPP requests.
+type vppRequestHeader struct {
+	VlMsgID     uint16
+	ClientIndex uint32
+	Context     uint32
+}
+
+// vppReplyHeader struct contains header fields implemented by all VPP replies.
+type vppReplyHeader struct {
+	VlMsgID uint16
+	Context uint32
+}
+
+// vppOtherHeader struct contains header fields implemented by other VPP messages (not requests nor replies).
+type vppOtherHeader struct {
+	VlMsgID uint16
+}
+
+const (
+	vppRequestHeaderSize = 10 // size of a VPP request header
+	vppReplyHeaderSize   = 6  // size of a VPP reply header
+	vppOtherHeaderSize   = 2  // size of the header of other VPP messages
+)
+
+// EncodeMsg encodes provided `Message` structure into its binary-encoded data representation.
+func (*MsgCodec) EncodeMsg(msg api.Message, msgID uint16) ([]byte, error) {
+	if msg == nil {
+		return nil, errors.New("nil message passed in")
+	}
+
+	buf := new(bytes.Buffer)
+
+	// encode message header
+	var header interface{}
+	if msg.GetMessageType() == api.RequestMessage {
+		header = &vppRequestHeader{VlMsgID: msgID}
+	} else if msg.GetMessageType() == api.ReplyMessage {
+		header = &vppReplyHeader{VlMsgID: msgID}
+	} else {
+		header = &vppOtherHeader{VlMsgID: msgID}
+	}
+	err := struc.Pack(buf, header)
+	if err != nil {
+		log.WithFields(logger.Fields{
+			"error":  err,
+			"header": header,
+		}).Error("Unable to encode the message header: ", err)
+		return nil, fmt.Errorf("unable to encode the message header: %v", err)
+	}
+
+	// encode message content
+	if reflect.Indirect(reflect.ValueOf(msg)).NumField() > 0 {
+		err := struc.Pack(buf, msg)
+		if err != nil {
+			log.WithFields(logger.Fields{
+				"error":   err,
+				"message": msg,
+			}).Error("Unable to encode the message: ", err)
+			return nil, fmt.Errorf("unable to encode the message: %v", err)
+		}
+	}
+
+	return buf.Bytes(), nil
+}
+
+// DecodeMsg decodes binary-encoded data of a message into provided `Message` structure.
+func (*MsgCodec) DecodeMsg(data []byte, msg api.Message) error {
+	if msg == nil {
+		return errors.New("nil message passed in")
+	}
+
+	buf := bytes.NewReader(data)
+
+	// check which header is expected
+	var header interface{}
+	if msg.GetMessageType() == api.RequestMessage {
+		header = &vppRequestHeader{}
+	} else if msg.GetMessageType() == api.ReplyMessage {
+		header = &vppReplyHeader{}
+	} else {
+		header = &vppOtherHeader{}
+	}
+
+	// decode message header
+	err := struc.Unpack(buf, header)
+	if err != nil {
+		log.WithFields(logger.Fields{
+			"error": err,
+			"data":  data,
+		}).Error("Unable to decode header of the message.")
+		return fmt.Errorf("unable to decode the message header: %v", err)
+	}
+
+	// get rid of the message header
+	if msg.GetMessageType() == api.RequestMessage {
+		buf = bytes.NewReader(data[vppRequestHeaderSize:])
+	} else if msg.GetMessageType() == api.ReplyMessage {
+		buf = bytes.NewReader(data[vppReplyHeaderSize:])
+	} else {
+		buf = bytes.NewReader(data[vppOtherHeaderSize:])
+	}
+
+	// decode message content
+	err = struc.Unpack(buf, msg)
+	if err != nil {
+		log.WithFields(logger.Fields{
+			"error": err,
+			"data":  buf,
+		}).Error("Unable to decode the message.")
+		return fmt.Errorf("unable to decode the message: %v", err)
+	}
+
+	return nil
+}