[Emu] [ONOS-2599] Implement BGP Notification protocol Messgae parsing, Decode and encoding

Change-Id: I93c2e0787a4f16810a9fec655b33ebef73e001e0

+/*
+ * Copyright 2015 Open Networking Laboratory
+ *
+ * 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 org.onosproject.bgpio.protocol;
+
+import org.onosproject.bgpio.exceptions.BGPParseException;
+import org.onosproject.bgpio.types.BGPHeader;
+
+/**
+ * Abstraction of an entity providing BGP Notification Message.
+ */
+public interface BGPNotificationMsg extends BGPMessage {
+    /**
+     * Returns errorCode in Notification message.
+     *
+     * @return errorCode in Notification message
+     */
+    byte getErrorCode();
+
+    /**
+     * Returns error SubCode in Notification message.
+     *
+     * @return error SubCode in Notification message
+     */
+    byte getErrorSubCode();
+
+    /**
+     * Returns error data in Notification message.
+     *
+     * @return error data in Notification message
+     */
+    byte[] getData();
+
+    /**
+     * Builder interface with get and set functions to build Notification
+     * message.
+     */
+    public interface Builder extends BGPMessage.Builder {
+
+        @Override
+        BGPNotificationMsg build() throws BGPParseException;
+
+        /**
+         * Sets notification message header and returns its builder.
+         *
+         * @param header of notification message
+         * @return Builder by setting notification message header
+         */
+        Builder setNotificationMsgHeader(BGPHeader header);
+
+        /**
+         * Sets errorCode in notification message and return its builder.
+         *
+         * @param errorCode in notification message
+         * @return builder by setting ErrorCode in notification message
+         */
+        Builder setErrorCode(byte errorCode);
+
+        /**
+         * Sets error SubCode in notification message and return its builder.
+         *
+         * @param errorSubCode in notification Message
+         * @return builder by setting ErrorSubCode in notification Message
+         */
+        Builder setErrorSubCode(byte errorSubCode);
+
+        /**
+         * Sets error data in notification message and return its builder.
+         *
+         * @param data in notification message
+         * @return builder by setting Data in notification message
+         */
+        Builder setData(byte[] data);
+    }
+}
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+/*
+ * Copyright 2015 Open Networking Laboratory
+ *
+ * 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 org.onosproject.bgpio.protocol.ver4;
+
+import org.jboss.netty.buffer.ChannelBuffer;
+import org.onosproject.bgpio.exceptions.BGPParseException;
+import org.onosproject.bgpio.protocol.BGPMessageReader;
+import org.onosproject.bgpio.protocol.BGPMessageWriter;
+import org.onosproject.bgpio.protocol.BGPNotificationMsg;
+import org.onosproject.bgpio.protocol.BGPType;
+import org.onosproject.bgpio.protocol.BGPVersion;
+import org.onosproject.bgpio.types.BGPErrorType;
+import org.onosproject.bgpio.types.BGPHeader;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import com.google.common.base.MoreObjects;
+
+/**
+ * A NOTIFICATION message is sent when an error condition is detected. The BGP connection is closed immediately after it
+ * is sent.
+ */
+class BGPNotificationMsgVer4 implements BGPNotificationMsg {
+
+    /*
+          0                   1                   2                   3
+          0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+          | Error code    | Error subcode |   Data (variable)             |
+          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+              REFERENCE : RFC 4271
+    */
+
+    protected static final Logger log = LoggerFactory.getLogger(BGPNotificationMsgVer4.class);
+
+    static final byte PACKET_VERSION = 4;
+    //BGPHeader(19) + Error code(1) + Error subcode(1)
+    static final int TOTAL_MESSAGE_MIN_LENGTH = 21;
+    static final int PACKET_MINIMUM_LENGTH = 2;
+    static final BGPType MSG_TYPE = BGPType.NOTIFICATION;
+    static final byte DEFAULT_ERRORSUBCODE = 0;
+    static final byte[] MARKER = {0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
+            0x01, 0x01};
+    static final byte MESSAGE_TYPE = 3;
+    static final BGPHeader DEFAULT_MESSAGE_HEADER = new BGPHeader(MARKER, BGPHeader.DEFAULT_HEADER_LENGTH,
+                                                                  MESSAGE_TYPE);
+
+    private byte errorCode;
+    private byte errorSubCode;
+    private byte[] data;
+    private BGPHeader bgpHeader;
+    public static final BGPNotificationMsgVer4.Reader READER = new Reader();
+
+    /**
+     * Resets fields.
+     */
+    public BGPNotificationMsgVer4() {
+        this.bgpHeader = null;
+        this.data = null;
+        this.errorCode = 0;
+        this.errorSubCode = 0;
+    }
+
+    /**
+     * Constructor to initialize parameters.
+     *
+     * @param bgpHeader BGP Header in notification message
+     * @param errorCode error code
+     * @param errorSubCode error subcode
+     * @param data field
+     */
+    public BGPNotificationMsgVer4(BGPHeader bgpHeader, byte errorCode, byte errorSubCode, byte[] data) {
+        this.bgpHeader = bgpHeader;
+        this.data = data;
+        this.errorCode = errorCode;
+        this.errorSubCode = errorSubCode;
+    }
+
+    /**
+     * Reader reads BGP Notification Message from the channel buffer.
+     */
+    static class Reader implements BGPMessageReader<BGPNotificationMsg> {
+        @Override
+        public BGPNotificationMsg readFrom(ChannelBuffer cb, BGPHeader bgpHeader) throws BGPParseException {
+            byte errorCode;
+            byte errorSubCode;
+            if (cb.readableBytes() < PACKET_MINIMUM_LENGTH) {
+                throw new BGPParseException("Not enough readable bytes");
+            }
+            errorCode = cb.readByte();
+            errorSubCode = cb.readByte();
+            //Message Length = 21 + Data Length
+            int dataLength = bgpHeader.getLength() - TOTAL_MESSAGE_MIN_LENGTH;
+            byte[] data = new byte[dataLength];
+            cb.readBytes(data, 0, dataLength);
+            return new BGPNotificationMsgVer4(bgpHeader, errorCode, errorSubCode, data);
+        }
+    }
+
+    /**
+     * Builder class for BGP notification message.
+     */
+    static class Builder implements BGPNotificationMsg.Builder {
+        private byte errorCode;
+        private byte errorSubCode;
+        private byte[] data;
+        private BGPHeader bgpHeader;
+        private boolean isErrorCodeSet = false;
+        private boolean isErrorSubCodeSet = false;
+        private boolean isBGPHeaderSet = false;
+
+        @Override
+        public BGPVersion getVersion() {
+            return BGPVersion.BGP_4;
+        }
+
+        @Override
+        public BGPType getType() {
+            return BGPType.NOTIFICATION;
+        }
+
+        @Override
+        public BGPNotificationMsg build() throws BGPParseException {
+            BGPHeader bgpHeader = this.isBGPHeaderSet ? this.bgpHeader : DEFAULT_MESSAGE_HEADER;
+            if (!this.isErrorCodeSet) {
+                throw new BGPParseException("Error code must be present");
+            }
+
+            byte errorSubCode = this.isErrorSubCodeSet ? this.errorSubCode : DEFAULT_ERRORSUBCODE;
+            return new BGPNotificationMsgVer4(bgpHeader, this.errorCode, errorSubCode, this.data);
+        }
+
+        @Override
+        public Builder setErrorCode(byte errorCode) {
+            this.errorCode = errorCode;
+            this.isErrorCodeSet = true;
+            return this;
+        }
+
+        @Override
+        public Builder setErrorSubCode(byte errorSubCode) {
+            this.errorSubCode = errorSubCode;
+            this.isErrorSubCodeSet = true;
+            return this;
+        }
+
+        @Override
+        public Builder setData(byte[] data) {
+            this.data = data;
+            return this;
+        }
+
+        @Override
+        public Builder setNotificationMsgHeader(BGPHeader header) {
+            this.bgpHeader = header;
+            this.isBGPHeaderSet = true;
+            return this;
+        }
+
+        @Override
+        public BGPHeader getHeader() {
+            return this.bgpHeader;
+        }
+
+        @Override
+        public Builder setHeader(BGPHeader bgpMsgHeader) {
+            this.bgpHeader = bgpMsgHeader;
+            return this;
+        }
+    }
+
+    @Override
+    public BGPVersion getVersion() {
+        return BGPVersion.BGP_4;
+    }
+
+    @Override
+    public BGPType getType() {
+        return BGPType.NOTIFICATION;
+    }
+
+    @Override
+    public void writeTo(ChannelBuffer cb) throws BGPParseException {
+        WRITER.write(cb, this);
+    }
+
+    static final Writer WRITER = new Writer();
+
+    /**
+     * Writer writes BGP notification message to channel buffer.
+     */
+    static class Writer implements BGPMessageWriter<BGPNotificationMsgVer4> {
+        @Override
+        public void write(ChannelBuffer cb, BGPNotificationMsgVer4 message) throws BGPParseException {
+            int msgStartIndex = cb.writerIndex();
+            int headerLenIndex = message.bgpHeader.write(cb);
+            if (headerLenIndex <= 0) {
+                throw new BGPParseException(BGPErrorType.MESSAGE_HEADER_ERROR, (byte) 0, null);
+            }
+            cb.writeByte(message.errorCode);
+            cb.writeByte(message.errorSubCode);
+            cb.writeBytes(message.data);
+
+            //Update message length field in notification message
+            int length = cb.writerIndex() - msgStartIndex;
+            cb.setShort(headerLenIndex, (short) length);
+            message.bgpHeader.setLength((short) length);
+        }
+    }
+
+    @Override
+    public byte getErrorCode() {
+        return this.errorCode;
+    }
+
+    /**
+     * Sets errorcode with specified errorcode.
+     *
+     * @param errorCode field
+     */
+    public void setErrorCode(byte errorCode) {
+        this.errorCode = errorCode;
+    }
+
+    @Override
+    public byte getErrorSubCode() {
+        return this.errorSubCode;
+    }
+
+    /**
+     * Sets error subcode with specified errorSubCode.
+     *
+     * @param errorSubCode field
+     */
+    public void setErrorSubCode(byte errorSubCode) {
+        this.errorSubCode = errorSubCode;
+    }
+
+    @Override
+    public byte[] getData() {
+        return this.data;
+    }
+
+    /**
+     * Sets error data with specified data.
+     *
+     * @param data field
+     */
+    public void setData(byte[] data) {
+        this.data = data;
+    }
+
+    @Override
+    public BGPHeader getHeader() {
+        return this.bgpHeader;
+    }
+
+    @Override
+    public String toString() {
+        return MoreObjects.toStringHelper(getClass())
+                .omitNullValues()
+                .add("bgpHeader", bgpHeader)
+                .add("data", data)
+                .add("errorCode", errorCode)
+                .add("errorSubCode", errorSubCode)
+                .toString();
+    }
+}
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