org.bgp4j.netty.NLRICodec.java Source code

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Here is the source code for org.bgp4j.netty.NLRICodec.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.
 * 
 * File: org.bgp4j.netty.NLRICodec.java 
 */
package org.bgp4j.netty;

import io.netty.buffer.ByteBuf;

import org.bgp4j.net.NetworkLayerReachabilityInformation;

/**
 * @author Rainer Bieniek (Rainer.Bieniek@web.de)
 *
 * Codec for handling network-layer reachability information
 */
public class NLRICodec {

    /**
     * Decode a network-layer reachability information from a byte buffer
     * 
     * @param buffer byte buffer
     * @return decoded network layer reachability information
     */
    public static NetworkLayerReachabilityInformation decodeNLRI(ByteBuf buffer) {
        NetworkLayerReachabilityInformation nlri = new NetworkLayerReachabilityInformation();
        int prefixLength = buffer.readUnsignedByte();
        byte[] prefixBytes = null;

        if (prefixLength > 0) {
            prefixBytes = new byte[NetworkLayerReachabilityInformation
                    .calculateOctetsForPrefixLength(prefixLength)];

            buffer.readBytes(prefixBytes);
        }
        nlri.setPrefix(prefixLength, prefixBytes);

        return nlri;
    }

    /**
     * Calculate the length of the binary representation of a netwotk-lyer reachability information
     * 
     * @param nlri
     * @return
     */
    public static int calculateEncodedNLRILength(NetworkLayerReachabilityInformation nlri) {
        return NetworkLayerReachabilityInformation.calculateOctetsForPrefixLength(nlri.getPrefixLength()) + 1;
    }

    /**
     * Encode a network-layer reachability information to its binary representation.
     * 
     * @param allocator the buffer allocator 
     * @param nlri the information to encode
     * @return the binary representation of the passed information
     */
    public static void encodeNLRI(ByteBuf buffer, NetworkLayerReachabilityInformation nlri) {
        buffer.writeByte(nlri.getPrefixLength());

        if (nlri.getPrefixLength() > 0) {
            buffer.writeBytes(nlri.getPrefix());
        }
    }

}