bgp/parser-impl/src/main/java/org/opendaylight/protocol/bgp/parser/impl/message/BGPUpdateMessageParser.java

   1 /*
   2  * Copyright (c) 2013 Cisco Systems, Inc. and others.  All rights reserved.
   3  *
   4  * This program and the accompanying materials are made available under the
   5  * terms of the Eclipse Public License v1.0 which accompanies this distribution,
   6  * and is available at http://www.eclipse.org/legal/epl-v10.html
   7  */
   8
   9 package org.opendaylight.protocol.bgp.parser.impl.message;
  10
  11 import io.netty.buffer.ByteBuf;
  12
  13 import java.util.Arrays;
  14 import java.util.List;
  15
  16 import org.opendaylight.protocol.bgp.parser.BGPDocumentedException;
  17 import org.opendaylight.protocol.bgp.parser.BGPError;
  18 import org.opendaylight.protocol.bgp.parser.BGPParsingException;
  19 import org.opendaylight.protocol.bgp.parser.spi.AttributeRegistry;
  20 import org.opendaylight.protocol.bgp.parser.spi.MessageParser;
  21 import org.opendaylight.protocol.concepts.Ipv4Util;
  22 import org.opendaylight.protocol.util.ByteArray;
  23 import org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.ietf.inet.types.rev100924.Ipv4Prefix;
  24 import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.message.rev130919.Update;
  25 import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.message.rev130919.UpdateBuilder;
  26 import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.message.rev130919.update.NlriBuilder;
  27 import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.message.rev130919.update.PathAttributes;
  28 import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.message.rev130919.update.WithdrawnRoutesBuilder;
  29 import org.slf4j.Logger;
  30 import org.slf4j.LoggerFactory;
  31
  32 import com.google.common.base.Preconditions;
  33
  34 /**
  35  * LENGTH fields, that denote the length of the fields with variable length, have fixed SIZE.
  36  *
  37  * @see <a href="http://tools.ietf.org/html/rfc4271#section-4.3">BGP-4 Update Message Format</a>
  38  *
  39  */
  40 public class BGPUpdateMessageParser implements MessageParser {
  41         public static final int TYPE = 2;
  42
  43         private static final Logger LOG = LoggerFactory.getLogger(BGPUpdateMessageParser.class);
  44
  45         /**
  46          * Size of the withdrawn_routes_length field, in bytes.
  47          */
  48         public static final int WITHDRAWN_ROUTES_LENGTH_SIZE = 2;
  49
  50         /**
  51          * Size of the total_path_attr_length field, in bytes.
  52          */
  53         public static final int TOTAL_PATH_ATTR_LENGTH_SIZE = 2;
  54
  55         private final AttributeRegistry reg;
  56
  57         // Constructors -------------------------------------------------------
  58         public BGPUpdateMessageParser(final AttributeRegistry reg) {
  59                 this.reg = Preconditions.checkNotNull(reg);
  60         }
  61
  62         // Getters & setters --------------------------------------------------
  63
  64         @Override
  65         public Update parseMessageBody(final ByteBuf buffer, final int messageLength) throws BGPDocumentedException {
  66                 Preconditions.checkArgument(buffer != null && buffer.readableBytes() != 0, "Byte array cannot be null or empty.");
  67                 LOG.trace("Started parsing of update message: {}", Arrays.toString(ByteArray.getAllBytes(buffer)));
  68
  69                 final int withdrawnRoutesLength = buffer.readUnsignedShort();
  70                 final UpdateBuilder eventBuilder = new UpdateBuilder();
  71
  72                 if (withdrawnRoutesLength > 0) {
  73                         final List<Ipv4Prefix> withdrawnRoutes = Ipv4Util.prefixListForBytes(ByteArray.readBytes(buffer, withdrawnRoutesLength));
  74                         eventBuilder.setWithdrawnRoutes(new WithdrawnRoutesBuilder().setWithdrawnRoutes(withdrawnRoutes).build());
  75                 }
  76                 final int totalPathAttrLength = buffer.readUnsignedShort();
  77
  78                 if (withdrawnRoutesLength == 0 && totalPathAttrLength == 0) {
  79                         return eventBuilder.build();
  80                 }
  81                 if (totalPathAttrLength > 0) {
  82                         try {
  83                                 final PathAttributes pathAttributes = this.reg.parseAttributes(buffer.slice(buffer.readerIndex(), totalPathAttrLength));
  84                                 buffer.skipBytes(totalPathAttrLength);
  85                                 eventBuilder.setPathAttributes(pathAttributes);
  86                         } catch (final BGPParsingException | RuntimeException e) {
  87                                 // Catch everything else and turn it into a BGPDocumentedException
  88                                 LOG.warn("Could not parse BGP attributes", e);
  89                                 throw new BGPDocumentedException("Could not parse BGP attributes.", BGPError.MALFORMED_ATTR_LIST, e);
  90                         }
  91                 }
  92                 final List<Ipv4Prefix> nlri = Ipv4Util.prefixListForBytes(ByteArray.readAllBytes(buffer));
  93                 if (nlri != null && !nlri.isEmpty()) {
  94                         eventBuilder.setNlri(new NlriBuilder().setNlri(nlri).build());
  95                 }
  96                 LOG.trace("Update message was parsed.");
  97                 return eventBuilder.build();
  98         }
  99 }