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; import com.google.common.base.Preconditions; import io.netty.buffer.ByteBuf; import io.netty.buffer.Unpooled; 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.AsPathAttributeParser; import org.opendaylight.protocol.bgp.parser.impl.message.update.NextHopAttributeParser; import org.opendaylight.protocol.bgp.parser.impl.message.update.OriginAttributeParser; import org.opendaylight.protocol.bgp.parser.spi.AttributeRegistry; import org.opendaylight.protocol.bgp.parser.spi.MessageParser; import org.opendaylight.protocol.bgp.parser.spi.MessageSerializer; import org.opendaylight.protocol.bgp.parser.spi.MessageUtil; import org.opendaylight.protocol.bgp.parser.spi.PeerSpecificParserConstraint; import org.opendaylight.protocol.util.ByteArray; import org.opendaylight.protocol.util.ByteBufWriteUtil; import org.opendaylight.protocol.util.Ipv4Util; import org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.ietf.inet.types.rev130715.Ipv4Prefix; import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.message.rev130919.Update; import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.message.rev130919.UpdateBuilder; 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.update.message.Nlri; import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.message.rev130919.update.message.NlriBuilder; import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.message.rev130919.update.message.WithdrawnRoutes; import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.message.rev130919.update.message.WithdrawnRoutesBuilder; import org.opendaylight.yangtools.yang.binding.Notification; import org.slf4j.Logger; import org.slf4j.LoggerFactory; /** * LENGTH fields, that denote the length of the fields with variable length, have fixed SIZE. * * @see <a href="http://tools.ietf.org/html/rfc4271#section-4.3">BGP-4 Update Message Format</a> */ public final class BGPUpdateMessageParser implements MessageParser, MessageSerializer { private static final Logger LOG = LoggerFactory.getLogger(BGPUpdateMessageParser.class); public static final int TYPE = 2; private static final int WITHDRAWN_ROUTES_LENGTH_SIZE = 2; private static final int TOTAL_PATH_ATTR_LENGTH_SIZE = 2; private final AttributeRegistry reg; public BGPUpdateMessageParser(final AttributeRegistry reg) { this.reg = Preconditions.checkNotNull(reg); } @Override public Update parseMessageBody(final ByteBuf buffer, final int messageLength) throws BGPDocumentedException { return parseMessageBody(buffer, messageLength, null); } @Override public void serializeMessage(final Notification message, final ByteBuf bytes) { Preconditions.checkArgument(message instanceof Update, "Message needs to be of type Update"); final Update update = (Update) message; final ByteBuf messageBody = Unpooled.buffer(); final WithdrawnRoutes withdrawnRoutes = update.getWithdrawnRoutes(); if (withdrawnRoutes != null) { final ByteBuf withdrawnRoutesBuf = Unpooled.buffer(); for (final Ipv4Prefix prefix : withdrawnRoutes.getWithdrawnRoutes()) { ByteBufWriteUtil.writeMinimalPrefix(prefix, withdrawnRoutesBuf); } messageBody.writeShort(withdrawnRoutesBuf.writerIndex()); messageBody.writeBytes(withdrawnRoutesBuf); } else { messageBody.writeZero(WITHDRAWN_ROUTES_LENGTH_SIZE); } if (update.getAttributes() != null) { final ByteBuf pathAttributesBuf = Unpooled.buffer(); this.reg.serializeAttribute(update.getAttributes(), pathAttributesBuf); messageBody.writeShort(pathAttributesBuf.writerIndex()); messageBody.writeBytes(pathAttributesBuf); } else { messageBody.writeZero(TOTAL_PATH_ATTR_LENGTH_SIZE); } final Nlri nlri = update.getNlri(); if (nlri != null && nlri.getNlri() != null) { for (final Ipv4Prefix prefix : nlri.getNlri()) { ByteBufWriteUtil.writeMinimalPrefix(prefix, messageBody); } } MessageUtil.formatMessage(TYPE, messageBody, bytes); } /** * Parse Update message from buffer. * Calls {@link #checkMandatoryAttributesPresence(Update)} to check for presence of mandatory attributes. * * @param buffer Encoded BGP message in ByteBuf * @param messageLength Length of the BGP message * @param constraint Peer specific constraints * @return Parsed Update message body * @throws BGPDocumentedException */ @Override public Update parseMessageBody(final ByteBuf buffer, final int messageLength, final PeerSpecificParserConstraint constraint) throws BGPDocumentedException { Preconditions.checkArgument(buffer != null && buffer.isReadable(), "Buffer cannot be null or empty."); final UpdateBuilder builder = new UpdateBuilder(); final int withdrawnRoutesLength = buffer.readUnsignedShort(); if (withdrawnRoutesLength > 0) { // TODO handle NLRI with multiple paths - requires modified yang data model final List<Ipv4Prefix> withdrawnRoutes = Ipv4Util .prefixListForBytes(ByteArray.readBytes(buffer, withdrawnRoutesLength)); builder.setWithdrawnRoutes(new WithdrawnRoutesBuilder().setWithdrawnRoutes(withdrawnRoutes).build()); } final int totalPathAttrLength = buffer.readUnsignedShort(); if (withdrawnRoutesLength == 0 && totalPathAttrLength == 0) { return builder.build(); } if (totalPathAttrLength > 0) { try { final Attributes attributes = this.reg.parseAttributes(buffer.readSlice(totalPathAttrLength), constraint); builder.setAttributes(attributes); } catch (final RuntimeException | BGPParsingException e) { // Catch everything else and turn it into a BGPDocumentedException throw new BGPDocumentedException("Could not parse BGP attributes.", BGPError.MALFORMED_ATTR_LIST, e); } } final List<Ipv4Prefix> nlri = Ipv4Util.prefixListForBytes(ByteArray.readAllBytes(buffer)); if (!nlri.isEmpty()) { // TODO handle NLRI with multiple paths - requires modified yang data model builder.setNlri(new NlriBuilder().setNlri(nlri).build()); } final Update msg = builder.build(); checkMandatoryAttributesPresence(msg); LOG.debug("BGP Update message was parsed {}.", msg); return msg; } /** * Check for presence of well known mandatory path attributes * ORIGIN, AS_PATH and NEXT_HOP in Update message * * @param message Update message * @throws BGPDocumentedException */ private void checkMandatoryAttributesPresence(final Update message) throws BGPDocumentedException { Preconditions.checkNotNull(message, "Update message cannot be null"); final Attributes attrs = message.getAttributes(); if (message.getNlri() != null) { if (attrs == null || attrs.getCNextHop() == null) { throw new BGPDocumentedException(BGPError.MANDATORY_ATTR_MISSING_MSG + "NEXT_HOP", BGPError.WELL_KNOWN_ATTR_MISSING, new byte[] { NextHopAttributeParser.TYPE }); } } if (MessageUtil.isAnyNlriPresent(message)) { if (attrs == null || attrs.getOrigin() == null) { throw new BGPDocumentedException(BGPError.MANDATORY_ATTR_MISSING_MSG + "ORIGIN", BGPError.WELL_KNOWN_ATTR_MISSING, new byte[] { OriginAttributeParser.TYPE }); } if (attrs == null || attrs.getAsPath() == null) { throw new BGPDocumentedException(BGPError.MANDATORY_ATTR_MISSING_MSG + "AS_PATH", BGPError.WELL_KNOWN_ATTR_MISSING, new byte[] { AsPathAttributeParser.TYPE }); } } } }