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 java.util.Arrays;
  12 import java.util.List;
  13
  14 import org.opendaylight.protocol.bgp.parser.BGPDocumentedException;
  15 import org.opendaylight.protocol.bgp.parser.BGPError;
  16 import org.opendaylight.protocol.bgp.parser.BGPParsingException;
  17 import org.opendaylight.protocol.bgp.parser.spi.AttributeRegistry;
  18 import org.opendaylight.protocol.bgp.parser.spi.MessageParser;
  19 import org.opendaylight.protocol.concepts.Ipv4Util;
  20 import org.opendaylight.protocol.util.ByteArray;
  21 import org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.ietf.inet.types.rev100924.Ipv4Prefix;
  22 import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.message.rev130918.Update;
  23 import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.message.rev130918.UpdateBuilder;
  24 import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.message.rev130918.update.NlriBuilder;
  25 import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.message.rev130918.update.PathAttributes;
  26 import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.message.rev130918.update.WithdrawnRoutesBuilder;
  27 import org.slf4j.Logger;
  28 import org.slf4j.LoggerFactory;
  29
  30 import com.google.common.base.Preconditions;
  31
  32 /**
  33  * LENGTH fields, that denote the length of the fields with variable length, have fixed SIZE.
  34  *
  35  * @see <a href="http://tools.ietf.org/html/rfc4271#section-4.3">BGP-4 Update Message Format</a>
  36  *
  37  */
  38 public class BGPUpdateMessageParser implements MessageParser {
  39         public static final int TYPE = 2;
  40
  41         private static Logger logger = LoggerFactory.getLogger(BGPUpdateMessageParser.class);
  42
  43         /**
  44          * Size of the withdrawn_routes_length field, in bytes.
  45          */
  46         public static final int WITHDRAWN_ROUTES_LENGTH_SIZE = 2;
  47
  48         /**
  49          * Size of the total_path_attr_length field, in bytes.
  50          */
  51         public static final int TOTAL_PATH_ATTR_LENGTH_SIZE = 2;
  52
  53         private final AttributeRegistry reg;
  54
  55         // Constructors -------------------------------------------------------
  56         public BGPUpdateMessageParser(final AttributeRegistry reg) {
  57                 this.reg = Preconditions.checkNotNull(reg);
  58         }
  59
  60         // Getters & setters --------------------------------------------------
  61
  62         @Override
  63         public Update parseMessageBody(final byte[] body, final int messageLength) throws BGPDocumentedException {
  64                 if (body == null || body.length == 0) {
  65                         throw new IllegalArgumentException("Byte array cannot be null or empty.");
  66                 }
  67                 logger.trace("Started parsing of update message: {}", Arrays.toString(body));
  68
  69                 int byteOffset = 0;
  70
  71                 final int withdrawnRoutesLength = ByteArray.bytesToInt(ByteArray.subByte(body, byteOffset, WITHDRAWN_ROUTES_LENGTH_SIZE));
  72                 byteOffset += WITHDRAWN_ROUTES_LENGTH_SIZE;
  73
  74                 final UpdateBuilder eventBuilder = new UpdateBuilder();
  75
  76                 if (withdrawnRoutesLength > 0) {
  77                         final List<Ipv4Prefix> withdrawnRoutes = Ipv4Util.prefixListForBytes(ByteArray.subByte(body, byteOffset, withdrawnRoutesLength));
  78                         byteOffset += withdrawnRoutesLength;
  79                         eventBuilder.setWithdrawnRoutes(new WithdrawnRoutesBuilder().setWithdrawnRoutes(withdrawnRoutes).build());
  80                 }
  81
  82                 final int totalPathAttrLength = ByteArray.bytesToInt(ByteArray.subByte(body, byteOffset, TOTAL_PATH_ATTR_LENGTH_SIZE));
  83                 byteOffset += TOTAL_PATH_ATTR_LENGTH_SIZE;
  84
  85                 if (withdrawnRoutesLength + totalPathAttrLength > body.length) {
  86                         throw new BGPDocumentedException("Message length inconsistent with withdrawn router length.", BGPError.MALFORMED_ATTR_LIST);
  87                 }
  88
  89                 if (withdrawnRoutesLength == 0 && totalPathAttrLength == 0) {
  90                         return eventBuilder.build();
  91                 }
  92
  93                 if (totalPathAttrLength > 0) {
  94                         try {
  95                                 final PathAttributes pathAttributes = reg.parseAttributes(ByteArray.subByte(body, byteOffset, totalPathAttrLength));
  96                                 byteOffset += totalPathAttrLength;
  97                                 eventBuilder.setPathAttributes(pathAttributes);
  98                         } catch (final BGPParsingException e) {
  99                                 logger.warn("Could not parse BGP attributes", e);
 100                                 throw new BGPDocumentedException("Could not parse BGP attributes.", BGPError.MALFORMED_ATTR_LIST, e);
 101                         }
 102                 }
 103
 104                 final List<Ipv4Prefix> nlri = Ipv4Util.prefixListForBytes(ByteArray.subByte(body, byteOffset, body.length - byteOffset));
 105                 if (nlri != null && !nlri.isEmpty()) {
 106                         eventBuilder.setNlri(new NlriBuilder().setNlri(nlri).build());
 107                 }
 108                 logger.trace("Update message was parsed.");
 109                 return eventBuilder.build();
 110         }
 111 }