VOL-4337: Code upgrade for 3/2020 G.988 support and remaining Extended Message Set support

Change-Id: I6c5e1a167216ad9b51e9da89460e9909465ae1bc
diff --git a/avc.go b/avc.go
new file mode 100644
index 0000000..5242e3b
--- /dev/null
+++ b/avc.go
@@ -0,0 +1,160 @@
+/*
+ * Copyright (c) 2018 - present.  Boling Consulting Solutions (bcsw.net)
+ * Copyright 2020-present Open Networking Foundation
+
+ * 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 omci
+
+import (
+	"encoding/binary"
+	"fmt"
+	"github.com/google/gopacket"
+	me "github.com/opencord/omci-lib-go/generated"
+)
+
+type AttributeValueChangeMsg struct {
+	MeBasePacket
+	AttributeMask uint16
+	Attributes    me.AttributeValueMap
+}
+
+func (omci *AttributeValueChangeMsg) String() string {
+	return fmt.Sprintf("%v, Mask: %#x, attributes: %v",
+		omci.MeBasePacket.String(), omci.AttributeMask, omci.Attributes)
+}
+
+// LayerType returns LayerTypeAttributeValueChange
+func (omci *AttributeValueChangeMsg) LayerType() gopacket.LayerType {
+	return LayerTypeAttributeValueChange
+}
+
+// CanDecode returns the set of layer types that this DecodingLayer can decode
+func (omci *AttributeValueChangeMsg) CanDecode() gopacket.LayerClass {
+	return LayerTypeAttributeValueChange
+}
+
+// NextLayerType returns the layer type contained by this DecodingLayer.
+func (omci *AttributeValueChangeMsg) NextLayerType() gopacket.LayerType {
+	return gopacket.LayerTypePayload
+}
+
+// DecodeFromBytes decodes the given bytes of an Attribute Value Change notification into this layer
+func (omci *AttributeValueChangeMsg) DecodeFromBytes(data []byte, p gopacket.PacketBuilder) error {
+	// Common ClassID/EntityID decode in msgBase
+	err := omci.MeBasePacket.DecodeFromBytes(data, p, 4+2)
+	if err != nil {
+		return err
+	}
+	meDefinition, omciErr := me.LoadManagedEntityDefinition(omci.EntityClass,
+		me.ParamData{EntityID: omci.EntityInstance})
+	if omciErr.StatusCode() != me.Success {
+		return omciErr.GetError()
+	}
+	// TODO: Support for encoding AVC into message type support not yet supported
+	//if !me.SupportsMsgType(meDefinition, me.AlarmNotification) {
+	//	return me.NewProcessingError("managed entity does not support Alarm Notification Message-Type")
+	//}
+	maskOffset := 4
+	if omci.Extended {
+		maskOffset = 6
+	}
+	omci.AttributeMask = binary.BigEndian.Uint16(data[maskOffset:])
+	// Attribute decode
+	omci.Attributes, err = meDefinition.DecodeAttributes(omci.AttributeMask, data[maskOffset+2:],
+		p, byte(AttributeValueChangeType))
+	// TODO: Add support for attributes that can have an AVC associated with them and then add a check here
+	// Validate all attributes support AVC
+	//for attrName := range omci.attributes {
+	//	attr, err := me.GetAttributeDefinitionByName(meDefinition.GetAttributeDefinitions(), attrName)
+	//	if err != nil {
+	//		return err
+	//	}
+	//	if attr.Index != 0 && !me.SupportsAttributeAVC(attr) {
+	//		msg := fmt.Sprintf("attribute '%v' does not support AVC notifications", attrName)
+	//		return me.NewProcessingError(msg)
+	//	}
+	//}
+	return err
+}
+
+func decodeAttributeValueChange(data []byte, p gopacket.PacketBuilder) error {
+	omci := &AttributeValueChangeMsg{}
+	omci.MsgLayerType = LayerTypeAttributeValueChange
+	return decodingLayerDecoder(omci, data, p)
+}
+
+func decodeAttributeValueChangeExtended(data []byte, p gopacket.PacketBuilder) error {
+	omci := &AttributeValueChangeMsg{}
+	omci.MsgLayerType = LayerTypeAttributeValueChange
+	omci.Extended = true
+	return decodingLayerDecoder(omci, data, p)
+}
+
+// SerializeTo provides serialization of an Attribute Value Change Notification message
+func (omci *AttributeValueChangeMsg) SerializeTo(b gopacket.SerializeBuffer, _ gopacket.SerializeOptions) error {
+	// Basic (common) OMCI Header is 8 octets, 10
+	err := omci.MeBasePacket.SerializeTo(b)
+	if err != nil {
+		return err
+	}
+	meDefinition, omciErr := me.LoadManagedEntityDefinition(omci.EntityClass,
+		me.ParamData{EntityID: omci.EntityInstance})
+	if omciErr.StatusCode() != me.Success {
+		return omciErr.GetError()
+	}
+	// TODO: Add support for attributes that can have an AVC associated with them and then add a check here
+	// Validate all attributes support AVC
+	//for attrName := range omci.attributes {
+	//	attr, err := me.GetAttributeDefinitionByName(meDefinition.GetAttributeDefinitions(), attrName)
+	//	if err != nil {
+	//		return err
+	//	}
+	//	if attr.Index != 0 && !me.SupportsAttributeAVC(attr) {
+	//		msg := fmt.Sprintf("attribute '%v' does not support AVC notifications", attrName)
+	//		return me.NewProcessingError(msg)
+	//	}
+	//}
+	var maskOffset int
+	var bytesAvailable int
+	if omci.Extended {
+		maskOffset = 2
+		bytesAvailable = MaxExtendedLength - 12 - 4
+	} else {
+		maskOffset = 0
+		bytesAvailable = MaxBaselineLength - 10 - 8
+	}
+	bytes, err := b.AppendBytes(maskOffset + 2)
+	if err != nil {
+		return err
+	}
+	binary.BigEndian.PutUint16(bytes[maskOffset:], omci.AttributeMask)
+
+	// Attribute serialization
+	attributeBuffer := gopacket.NewSerializeBuffer()
+	if err, _ = meDefinition.SerializeAttributes(omci.Attributes, omci.AttributeMask,
+		attributeBuffer, byte(GetResponseType), bytesAvailable, false); err != nil {
+		return err
+	}
+
+	if omci.Extended {
+		binary.BigEndian.PutUint16(bytes, uint16(len(attributeBuffer.Bytes())+2))
+	}
+	bytes, err = b.AppendBytes(len(attributeBuffer.Bytes()))
+	if err != nil {
+		return err
+	}
+	copy(bytes, attributeBuffer.Bytes())
+	return nil
+}