Java tutorial
/* * 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.impl.message.update; import com.google.common.base.Preconditions; import io.netty.buffer.ByteBuf; import io.netty.buffer.Unpooled; import java.util.ArrayList; import java.util.Collections; import java.util.List; import org.opendaylight.protocol.bgp.parser.BGPDocumentedException; import org.opendaylight.protocol.bgp.parser.BGPError; import org.opendaylight.protocol.bgp.parser.BGPParsingException; import org.opendaylight.protocol.bgp.parser.impl.message.update.AsPathSegmentParser.SegmentType; import org.opendaylight.protocol.bgp.parser.spi.AttributeParser; import org.opendaylight.protocol.bgp.parser.spi.AttributeSerializer; import org.opendaylight.protocol.bgp.parser.spi.AttributeUtil; import org.opendaylight.protocol.util.ReferenceCache; import org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.ietf.inet.types.rev130715.AsNumber; import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.message.rev130919.path.attributes.Attributes; import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.message.rev130919.path.attributes.AttributesBuilder; import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.message.rev130919.path.attributes.attributes.AsPath; import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.message.rev130919.path.attributes.attributes.AsPathBuilder; import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.message.rev130919.path.attributes.attributes.as.path.Segments; import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.message.rev130919.path.attributes.attributes.as.path.SegmentsBuilder; import org.opendaylight.yangtools.yang.binding.DataObject; import org.slf4j.Logger; import org.slf4j.LoggerFactory; public final class AsPathAttributeParser implements AttributeParser, AttributeSerializer { public static final int TYPE = 2; private final ReferenceCache refCache; private static final Logger LOG = LoggerFactory.getLogger(AsPathAttributeParser.class); private static final AsPath EMPTY = new AsPathBuilder().setSegments(Collections.<Segments>emptyList()).build(); public AsPathAttributeParser(final ReferenceCache refCache) { this.refCache = Preconditions.checkNotNull(refCache); } /** * Parses AS_PATH from bytes. * * @param refCache ReferenceCache shared reference of object * @param buffer bytes to be parsed * @return new ASPath object * @throws BGPDocumentedException if there is no AS_SEQUENCE present (mandatory) * @throws BGPParsingException */ private static AsPath parseAsPath(final ReferenceCache refCache, final ByteBuf buffer) throws BGPDocumentedException, BGPParsingException { if (!buffer.isReadable()) { return EMPTY; } final ArrayList<Segments> ases = new ArrayList<>(); boolean isSequence = false; while (buffer.isReadable()) { final int type = buffer.readUnsignedByte(); final SegmentType segmentType = AsPathSegmentParser.parseType(type); if (segmentType == null) { throw new BGPParsingException("AS Path segment type unknown : " + type); } final int count = buffer.readUnsignedByte(); final List<AsNumber> asList = AsPathSegmentParser.parseAsSegment(refCache, count, buffer.readSlice(count * AsPathSegmentParser.AS_NUMBER_LENGTH)); if (segmentType == SegmentType.AS_SEQUENCE) { ases.add(new SegmentsBuilder().setAsSequence(asList).build()); isSequence = true; } else { ases.add(new SegmentsBuilder().setAsSet(asList).build()); } } if (!isSequence) { throw new BGPDocumentedException("AS_SEQUENCE must be present in AS_PATH attribute.", BGPError.AS_PATH_MALFORMED); } ases.trimToSize(); return new AsPathBuilder().setSegments(ases).build(); } @Override public void parseAttribute(final ByteBuf buffer, final AttributesBuilder builder) throws BGPDocumentedException, BGPParsingException { builder.setAsPath(parseAsPath(this.refCache, buffer)); } @Override public void serializeAttribute(final DataObject attribute, final ByteBuf byteAggregator) { Preconditions.checkArgument(attribute instanceof Attributes, "Attribute parameter is not a PathAttribute object."); final Attributes pathAttributes = (Attributes) attribute; final AsPath asPath = pathAttributes.getAsPath(); if (asPath == null) { return; } final ByteBuf segmentsBuffer = Unpooled.buffer(); if (asPath.getSegments() != null) { for (final Segments segments : asPath.getSegments()) { if (segments.getAsSequence() != null) { AsPathSegmentParser.serializeAsList(segments.getAsSequence(), SegmentType.AS_SEQUENCE, segmentsBuffer); } else if (segments.getAsSet() != null) { AsPathSegmentParser.serializeAsList(segments.getAsSet(), SegmentType.AS_SET, segmentsBuffer); } else { LOG.warn("Segment doesn't have AsSequence nor AsSet list."); } } } AttributeUtil.formatAttribute(AttributeUtil.TRANSITIVE, TYPE, segmentsBuffer, byteAggregator); } }