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BGP Parser SPI
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/*
 * Copyright (c) 2013 Cisco Systems, Inc. and others.  All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0 which accompanies this distribution,
 * and is available at http://www.eclipse.org/legal/epl-v10.html
 */
package org.opendaylight.protocol.bgp.parser.spi;

import com.google.common.annotations.VisibleForTesting;
import com.google.common.primitives.UnsignedBytes;
import io.netty.buffer.ByteBuf;
import java.util.Arrays;
import java.util.List;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.message.rev200120.Update;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.message.rev200120.path.attributes.Attributes;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.message.rev200120.update.message.Nlri;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.multiprotocol.rev180329.AttributesReach;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.multiprotocol.rev180329.AttributesUnreach;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.multiprotocol.rev180329.attributes.reach.MpReachNlri;
import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.multiprotocol.rev180329.attributes.unreach.MpUnreachNlri;

public final class MessageUtil {

    @VisibleForTesting
    public static final int MARKER_LENGTH = 16;
    @VisibleForTesting
    public static final int COMMON_HEADER_LENGTH = 19;
    private static final byte[] MARKER = new byte[MARKER_LENGTH];

    static {
        Arrays.fill(MARKER, 0, MARKER_LENGTH, UnsignedBytes.MAX_VALUE);
    }

    private MessageUtil() {

    }

    /**
     * Adds header to message value.
     *
     * @param type of the message
     * @param body message body
     * @param buffer ByteBuf where the message will be copied with its header
     */
    public static void formatMessage(final int type, final ByteBuf body, final ByteBuf buffer) {
        buffer.writeBytes(MARKER);
        buffer.writeShort(body.writerIndex() + COMMON_HEADER_LENGTH);
        buffer.writeByte(type);
        buffer.writeBytes(body);
    }

    /**
     * Check for NLRI attribute in Update message.
     *
     * @param message Update message
     * @return true if any prefix or MP-REACH-NLRI attribute is present, false otherwise
     */
    public static boolean isAnyNlriPresent(final Update message) {
        if (message == null || message.getAttributes() == null) {
            return false;
        }
        final List nlri = message.getNlri();
        return nlri != null && !nlri.isEmpty()
            || getMpReachNlri(message.getAttributes()) != null;
    }

    /**
     * Finds MP-REACH-NLRI in Update message attributes.
     *
     * @param attrs Update message attributes
     * @return MP-REACH-NLRI if present in the attributes, null otherwise
     */
    public static MpReachNlri getMpReachNlri(final Attributes attrs) {
        if (attrs != null) {
            final AttributesReach aug = attrs.augmentation(AttributesReach.class);
            if (aug != null) {
                return aug.getMpReachNlri();
            }
        }

        return null;
    }

    /**
     * Finds MP-UNREACH-NLRI in Update message attributes.
     *
     * @param attrs Update message attributes
     * @return MP-UNREACH-NLRI if present in the attributes, null otherwise
     */
    public static MpUnreachNlri getMpUnreachNlri(final Attributes attrs) {
        if (attrs != null) {
            final AttributesUnreach aug =  attrs.augmentation(AttributesUnreach.class);
            if (aug != null) {
                return aug.getMpUnreachNlri();
            }
        }

        return null;
    }
}