[Emu] [ONOS-2596] BGP Open message parsing, encoding and decoding

Change-Id: I2847849aef78314dfa8f3be0c8f34715719a15f2

+/*
+ * 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 java.util.LinkedList;
+
+import org.onosproject.bgpio.exceptions.BGPParseException;
+import org.onosproject.bgpio.types.BGPHeader;
+import org.onosproject.bgpio.types.BGPValueType;
+
+/**
+ * Abstraction of an entity providing BGP Open Message.
+ */
+public interface BGPOpenMsg extends BGPMessage {
+
+    @Override
+    BGPHeader getHeader();
+
+    @Override
+    BGPVersion getVersion();
+
+    @Override
+    BGPType getType();
+
+    /**
+     * Returns hold time of Open Message.
+     *
+     * @return hold time of Open Message
+     */
+    short getHoldTime();
+
+    /**
+     * Returns AS Number of Open Message.
+     *
+     * @return AS Number of Open Message
+     */
+    short getAsNumber();
+
+    /**
+     * Returns BGP Identifier of Open Message.
+     *
+     * @return BGP Identifier of Open Message
+     */
+    int getBgpId();
+
+    /**
+     * Returns capabilities of Open Message.
+     *
+     * @return capabilities of Open Message
+     */
+    LinkedList<BGPValueType> getCapabilityTlv();
+
+    /**
+     * Builder interface with get and set functions to build Open message.
+     */
+    interface Builder extends BGPMessage.Builder {
+
+        @Override
+        BGPOpenMsg build() throws BGPParseException;
+
+        @Override
+        BGPHeader getHeader();
+
+        @Override
+        BGPVersion getVersion();
+
+        @Override
+        BGPType getType();
+
+        /**
+         * Returns hold time of Open Message.
+         *
+         * @return hold time of Open Message
+         */
+        short getHoldTime();
+
+        /**
+         * Sets hold time in Open Message and return its builder.
+         *
+         * @param holdtime
+         *           hold timer value in open message
+         * @return builder by setting hold time
+         */
+        Builder setHoldTime(short holdtime);
+
+        /**
+         * Returns as number of Open Message.
+         *
+         * @return as number of Open Message
+         */
+        short getAsNumber();
+
+        /**
+         * Sets AS number in Open Message and return its builder.
+         *
+         * @param asNumber
+         *           as number in open message
+         * @return builder by setting asNumber
+         */
+        Builder setAsNumber(short asNumber);
+
+        /**
+         * Returns BGP Identifier of Open Message.
+         *
+         * @return BGP Identifier of Open Message
+         */
+        int getBgpId();
+
+        /**
+         * Sets BGP Identifier in Open Message and return its builder.
+         *
+         * @param bgpId
+         *           BGP Identifier in open message
+         * @return builder by setting BGP Identifier
+         */
+        Builder setBgpId(int bgpId);
+
+        /**
+         * Returns capabilities of Open Message.
+         *
+         * @return capabilities of Open Message
+         */
+        LinkedList<BGPValueType> getCapabilityTlv();
+
+        /**
+         * Sets capabilities in Open Message and return its builder.
+         *
+         * @param capabilityTlv
+         *           capabilities in open message
+         * @return builder by setting capabilities
+         */
+        Builder setCapabilityTlv(LinkedList<BGPValueType> capabilityTlv);
+
+        @Override
+        Builder setHeader(BGPHeader bgpMsgHeader);
+    }
+}

+/*
+ * 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 java.util.LinkedList;
+import java.util.ListIterator;
+
+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.BGPOpenMsg;
+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.onosproject.bgpio.types.BGPValueType;
+import org.onosproject.bgpio.util.Validation;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import com.google.common.base.MoreObjects;
+
+/**
+ * Provides BGP open message.
+ */
+public class BGPOpenMsgVer4 implements BGPOpenMsg {
+
+    /*
+       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
+       +-+-+-+-+-+-+-+-+
+       |    Version    |
+       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+       |    My Autonomous System       |
+       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+       |         Hold Time             |
+       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+       |                  BGP Identifier                             |
+       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+       | Opt Parm Len  |
+       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+       |             Optional Parameters (variable)                  |
+       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+       OPEN Message Format
+       REFERENCE : RFC 4271
+    */
+
+    protected static final Logger log = LoggerFactory.getLogger(BGPOpenMsgVer4.class);
+
+    public static final byte PACKET_VERSION = 4;
+    public static final int OPEN_MSG_MINIMUM_LENGTH = 10;
+    public static final int MSG_HEADER_LENGTH = 19;
+    public static final int MARKER_LENGTH  = 16;
+    public static final int DEFAULT_HOLD_TIME = 120;
+    public static final int OPT_PARA_TYPE_CAPABILITY = 2;
+    public static final BGPType MSG_TYPE = BGPType.OPEN;
+    public static final byte[] MARKER = new byte[]{(byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff,
+        (byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff,
+        (byte) 0xff, (byte) 0xff, (byte) 0xff, (byte) 0xff};
+    public static final BGPHeader DEFAULT_OPEN_HEADER = new BGPHeader(MARKER,
+        (short) OPEN_MSG_MINIMUM_LENGTH, (byte) 0X01);
+    private BGPHeader bgpMsgHeader;
+    private byte version;
+    private short asNumber;
+    private short holdTime;
+    private int bgpId;
+    private LinkedList<BGPValueType> capabilityTlv;
+
+    public static final BGPOpenMsgVer4.Reader READER = new Reader();
+
+    /**
+     * reset variables.
+     */
+    public BGPOpenMsgVer4() {
+        this.bgpMsgHeader = null;
+        this.version = 0;
+        this.holdTime = 0;
+        this.asNumber = 0;
+        this.bgpId = 0;
+        this.capabilityTlv = null;
+    }
+
+    /**
+     * Constructor to initialize all variables of BGP Open message.
+     *
+     * @param bgpMsgHeader
+     *           BGP Header in open message
+     * @param version
+     *           BGP version in open message
+     * @param holdTime
+     *           hold time in open message
+     * @param asNumber
+     *           AS number in open message
+     * @param bgpId
+     *           BGP identifier in open message
+     * @param capabilityTlv
+     *           capabilities in open message
+     */
+    public BGPOpenMsgVer4(BGPHeader bgpMsgHeader, byte version, short asNumber, short holdTime,
+             int bgpId, LinkedList<BGPValueType> capabilityTlv) {
+        this.bgpMsgHeader = bgpMsgHeader;
+        this.version = version;
+        this.asNumber = asNumber;
+        this.holdTime = holdTime;
+        this.bgpId = bgpId;
+        this.capabilityTlv = capabilityTlv;
+    }
+
+    @Override
+    public BGPHeader getHeader() {
+        return this.bgpMsgHeader;
+    }
+
+    @Override
+    public BGPVersion getVersion() {
+        return BGPVersion.BGP_4;
+    }
+
+    @Override
+    public BGPType getType() {
+        return MSG_TYPE;
+    }
+
+    @Override
+    public short getHoldTime() {
+        return this.holdTime;
+    }
+
+    @Override
+    public short getAsNumber() {
+        return this.asNumber;
+    }
+
+    @Override
+    public int getBgpId() {
+        return this.bgpId;
+    }
+
+    @Override
+    public LinkedList<BGPValueType> getCapabilityTlv() {
+        return this.capabilityTlv;
+    }
+
+    /**
+     * Reader class for reading BGP open message from channel buffer.
+     */
+    public static class Reader implements BGPMessageReader<BGPOpenMsg> {
+
+        @Override
+        public BGPOpenMsg readFrom(ChannelBuffer cb, BGPHeader bgpHeader) throws BGPParseException {
+
+            byte version;
+            short holdTime;
+            short asNumber;
+            int bgpId;
+            byte optParaLen = 0;
+            byte optParaType;
+            byte capParaLen = 0;
+            LinkedList<BGPValueType> capabilityTlv = new LinkedList<>();
+
+            if (cb.readableBytes() < OPEN_MSG_MINIMUM_LENGTH) {
+                log.error("[readFrom] Invalid length: Packet size is less than the minimum length ");
+                Validation.validateLen(BGPErrorType.OPEN_MESSAGE_ERROR, BGPErrorType.BAD_MESSAGE_LENGTH,
+                        cb.readableBytes());
+            }
+
+            // Read version
+            version = cb.readByte();
+            if (version != PACKET_VERSION) {
+                log.error("[readFrom] Invalid version: " + version);
+                throw new BGPParseException(BGPErrorType.OPEN_MESSAGE_ERROR,
+                        BGPErrorType.UNSUPPORTED_VERSION_NUMBER, null);
+            }
+
+            // Read AS number
+            asNumber = cb.readShort();
+
+            // Read Hold timer
+            holdTime = cb.readShort();
+
+            // Read BGP Identifier
+            bgpId = cb.readInt();
+
+            // Read optional parameter length
+            optParaLen = cb.readByte();
+
+            // Read Capabilities if optional parameter length is greater than 0
+            if (optParaLen != 0) {
+                // Read optional parameter type
+                optParaType = cb.readByte();
+
+                // Read optional parameter length
+                capParaLen = cb.readByte();
+
+                if (cb.readableBytes() < capParaLen) {
+                    throw new BGPParseException(BGPErrorType.OPEN_MESSAGE_ERROR, (byte) 0, null);
+                }
+
+                ChannelBuffer capaCb = cb.readBytes(capParaLen);
+
+                // Parse capabilities only if optional parameter type is 2
+                if ((optParaType == OPT_PARA_TYPE_CAPABILITY) && (capParaLen != 0)) {
+                    capabilityTlv = parseCapabilityTlv(capaCb);
+                } else {
+                    throw new BGPParseException(BGPErrorType.OPEN_MESSAGE_ERROR,
+                        BGPErrorType.UNSUPPORTED_OPTIONAL_PARAMETER, null);
+                }
+            }
+            return new BGPOpenMsgVer4(bgpHeader, version, asNumber, holdTime, bgpId, capabilityTlv);
+        }
+    }
+
+    /**
+     * Parsing capabilities.
+     *
+     * @param cb of type channel buffer
+     * @return capabilityTlv of open message
+     * @throws BGPParseException while parsing capabilities
+     */
+    protected static LinkedList<BGPValueType> parseCapabilityTlv(ChannelBuffer cb) throws BGPParseException {
+
+        LinkedList<BGPValueType> capabilityTlv = new LinkedList<>();
+
+        // TODO: Capability parsing
+        return capabilityTlv;
+    }
+
+    /**
+     * Builder class for BGP open message.
+     */
+    static class Builder implements BGPOpenMsg.Builder {
+
+        private boolean isHeaderSet = false;
+        private BGPHeader bgpMsgHeader;
+        private boolean isHoldTimeSet = false;
+        private short  holdTime;
+        private boolean isAsNumSet = false;
+        private short asNumber;
+        private boolean isBgpIdSet = false;
+        private int bgpId;
+
+        LinkedList<BGPValueType> capabilityTlv = new LinkedList<>();
+
+        @Override
+        public BGPOpenMsg build() throws BGPParseException {
+            BGPHeader bgpMsgHeader = this.isHeaderSet ? this.bgpMsgHeader : DEFAULT_OPEN_HEADER;
+            short holdTime = this.isHoldTimeSet ? this.holdTime : DEFAULT_HOLD_TIME;
+
+            if (!this.isAsNumSet) {
+                throw new BGPParseException("BGP AS number is not set (mandatory)");
+            }
+
+            if (!this.isBgpIdSet) {
+                throw new BGPParseException("BGPID  is not set (mandatory)");
+            }
+
+            // TODO: capabilities build
+
+            return new BGPOpenMsgVer4(bgpMsgHeader, PACKET_VERSION, this.asNumber, holdTime, this.bgpId,
+                       this.capabilityTlv);
+        }
+
+        @Override
+        public BGPHeader getHeader() {
+            return this.bgpMsgHeader;
+        }
+
+        @Override
+        public Builder setHeader(BGPHeader bgpMsgHeader) {
+            this.bgpMsgHeader = bgpMsgHeader;
+            return this;
+        }
+
+        @Override
+        public BGPVersion getVersion() {
+            return BGPVersion.BGP_4;
+        }
+
+        @Override
+        public BGPType getType() {
+            return MSG_TYPE;
+        }
+
+        @Override
+        public short getHoldTime() {
+            return this.holdTime;
+        }
+
+        @Override
+        public short getAsNumber() {
+            return this.asNumber;
+        }
+
+        @Override
+        public int getBgpId() {
+            return this.bgpId;
+        }
+
+        @Override
+        public LinkedList<BGPValueType> getCapabilityTlv() {
+            return this.capabilityTlv;
+        }
+
+        @Override
+        public Builder setHoldTime(short holdTime) {
+            this.holdTime = holdTime;
+            this.isHoldTimeSet = true;
+            return this;
+        }
+
+        @Override
+        public Builder setAsNumber(short asNumber) {
+            this.asNumber = asNumber;
+            this.isAsNumSet = true;
+            return this;
+        }
+
+        @Override
+        public Builder setBgpId(int bgpId) {
+            this.bgpId = bgpId;
+            this.isBgpIdSet = true;
+            return this;
+        }
+
+        @Override
+        public Builder setCapabilityTlv(LinkedList<BGPValueType> capabilityTlv) {
+            this.capabilityTlv = capabilityTlv;
+            return this;
+        }
+    }
+
+    @Override
+    public void writeTo(ChannelBuffer cb) {
+        try {
+            WRITER.write(cb, this);
+        } catch (BGPParseException e) {
+            log.debug("[writeTo] Error: " + e.toString());
+        }
+    }
+
+    public static final Writer WRITER = new Writer();
+
+    /**
+     * Writer class for writing BGP open message to channel buffer.
+     */
+    public static class Writer implements BGPMessageWriter<BGPOpenMsgVer4> {
+
+        @Override
+        public void write(ChannelBuffer cb, BGPOpenMsgVer4 message) throws BGPParseException {
+
+            int optParaLen = 0;
+
+            int startIndex = cb.writerIndex();
+
+            // write common header and get msg length index
+            int msgLenIndex = message.bgpMsgHeader.write(cb);
+
+            if (msgLenIndex <= 0) {
+                throw new BGPParseException("Unable to write message header.");
+            }
+
+            // write version in 1-octet
+            cb.writeByte(message.version);
+
+            // TODO : Write AS number based on capabilities
+            cb.writeShort(message.asNumber);
+
+            // write HoldTime in next 2-octet
+            cb.writeShort(message.holdTime);
+
+            // write BGP Identifier in next 4-octet
+            cb.writeInt(message.bgpId);
+
+            // store the index of Optional parameter length
+            int optParaLenIndex = cb.writerIndex();
+
+            // set optional parameter length as 0
+            cb.writeByte(0);
+
+            // Pack capability TLV
+            optParaLen = message.packCapabilityTlv(cb, message);
+
+            if (optParaLen != 0) {
+                // Update optional parameter length
+                cb.setByte(optParaLenIndex, (byte) (optParaLen + 2)); //+2 for optional parameter type.
+            }
+
+            // write OPEN Object Length
+            int length = cb.writerIndex() - startIndex;
+            cb.setShort(msgLenIndex, (short) length);
+            message.bgpMsgHeader.setLength((short) length);
+        }
+    }
+
+    /**
+     * returns length of capability tlvs.
+     *
+     * @param cb of type channel buffer
+     * @param message of type BGPOpenMsgVer4
+     * @return capParaLen of open message
+     */
+    protected int packCapabilityTlv(ChannelBuffer cb, BGPOpenMsgVer4 message) {
+        int startIndex = cb.writerIndex();
+        int capParaLen = 0;
+        int capParaLenIndex = 0;
+
+        LinkedList<BGPValueType> capabilityTlv = message.capabilityTlv;
+        ListIterator<BGPValueType> listIterator = capabilityTlv.listIterator();
+
+        if (listIterator.hasNext()) {
+            // Set optional parameter type as 2
+            cb.writeByte(OPT_PARA_TYPE_CAPABILITY);
+
+            // Store the index of capability parameter length and update length at the end
+            capParaLenIndex = cb.writerIndex();
+
+            // Set capability parameter length as 0
+            cb.writeByte(0);
+
+            // Update the startIndex to know the length of capability tlv
+            startIndex = cb.writerIndex();
+        }
+
+        while (listIterator.hasNext()) {
+            BGPValueType tlv = listIterator.next();
+            if (tlv == null) {
+                log.debug("Warning: tlv is null from CapabilityTlv list");
+                continue;
+            }
+            tlv.write(cb);
+        }
+
+        capParaLen = cb.writerIndex() - startIndex;
+
+        if (capParaLen != 0) {
+            // Update capability parameter length
+            cb.setByte(capParaLenIndex, (byte) capParaLen);
+        }
+        return capParaLen;
+    }
+
+    @Override
+    public String toString() {
+        return MoreObjects.toStringHelper(getClass())
+            .add("bgpMsgHeader", bgpMsgHeader)
+            .add("version", version)
+            .add("holdTime", holdTime)
+            .add("asNumber", asNumber)
+            .add("bgpId", bgpId)
+            .add("capabilityTlv", capabilityTlv)
+            .toString();
+    }
+}