io.netlibs.bgp.netty.protocol.BGPv4Packet.java Source code

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Here is the source code for io.netlibs.bgp.netty.protocol.BGPv4Packet.java

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/**
 *  Copyright 2012 Rainer Bieniek (Rainer.Bieniek@web.de)
 *
 *  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 io.netlibs.bgp.netty.protocol;

import org.apache.commons.lang3.builder.ToStringBuilder;

import io.netlibs.bgp.protocol.BGPv4Constants;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;

/**
 * base class for all BGPv4 protocol packets
 *
 * @author Rainer Bieniek (Rainer.Bieniek@web.de)
 *
 */
public abstract class BGPv4Packet {

    /**
     * Dispatch to the visitor based on the packet type.
     *
     * Returns the value returned by the visitor.
     *
     */

    public abstract <T> T apply(BGPv4PacketVisitor<T> visitor);

    /**
     * build a binary representation of the protocol packet
     *
     * @return the encoded packet
     */

    public ByteBuf encodePacket() {
        ByteBuf encodedPayload = this.encodePayload();
        return this.wrapBufferHeader(this.encodePayload(), this.getType());
    }

    /**
     * encode the specific packet-type payload
     *
     * @return the encoded packet payload
     */
    protected abstract ByteBuf encodePayload();

    /**
     * obtain the BGP packet type code.
     *
     * @return
     */
    public abstract int getType();

    /**
     * wrap the BGP payload in a BGPv4 header field
     *
     * @param wrapped
     *          the packet payload
     * @param type
     *          the packet type code
     * @return the completely assembled BGPv4 packet
     */

    private ByteBuf wrapBufferHeader(final ByteBuf wrapped, final int type) {

        final int wrappedSize = (wrapped != null) ? wrapped.readableBytes() : 0;

        final ByteBuf buffer = Unpooled.buffer(wrappedSize + BGPv4Constants.BGP_PACKET_HEADER_LENGTH);

        for (int i = 0; i < BGPv4Constants.BGP_PACKET_MARKER_LENGTH; i++) {
            buffer.writeByte(0xff);
        }

        buffer.writeShort(wrappedSize + BGPv4Constants.BGP_PACKET_HEADER_LENGTH);
        buffer.writeByte(type);

        if (wrapped != null) {
            buffer.writeBytes(wrapped);
        }

        return buffer;
    }

    @Override
    public String toString() {
        return (new ToStringBuilder(this)).append("type", this.getType()).toString();
    }
}