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.Collections;
  13 import java.util.List;
  14 import java.util.Set;
  15
  16 import org.opendaylight.protocol.bgp.concepts.BGPAddressFamily;
  17 import org.opendaylight.protocol.bgp.concepts.BGPSubsequentAddressFamily;
  18 import org.opendaylight.protocol.bgp.concepts.BGPTableType;
  19 import org.opendaylight.protocol.bgp.parser.BGPDocumentedException;
  20 import org.opendaylight.protocol.bgp.parser.BGPError;
  21 import org.opendaylight.protocol.bgp.parser.BGPParsingException;
  22 import org.opendaylight.protocol.bgp.parser.BGPUpdateEvent;
  23 import org.opendaylight.protocol.bgp.parser.BGPUpdateSynchronized;
  24 import org.opendaylight.protocol.bgp.parser.impl.BGPMessageFactoryImpl;
  25 import org.opendaylight.protocol.bgp.parser.impl.BGPUpdateEventBuilder;
  26 import org.opendaylight.protocol.bgp.parser.impl.IPv6MP;
  27 import org.opendaylight.protocol.bgp.parser.impl.PathAttribute;
  28 import org.opendaylight.protocol.bgp.parser.impl.PathAttribute.TypeCode;
  29 import org.opendaylight.protocol.bgp.parser.impl.message.update.PathAttributeParser;
  30 import org.opendaylight.protocol.concepts.IPv4;
  31 import org.opendaylight.protocol.concepts.IPv4Address;
  32 import org.opendaylight.protocol.concepts.Prefix;
  33 import org.opendaylight.protocol.util.ByteArray;
  34 import org.slf4j.Logger;
  35 import org.slf4j.LoggerFactory;
  36
  37 import com.google.common.collect.Lists;
  38
  39 /**
  40  * LENGTH fields, that denote the length of the fields with variable length, have fixed SIZE.
  41  *
  42  * @see <a href="http://tools.ietf.org/html/rfc4271#section-4.3">BGP-4 Update Message Format</a>
  43  *
  44  */
  45 public class BGPUpdateMessageParser {
  46
  47         private static Logger logger = LoggerFactory.getLogger(BGPUpdateMessageParser.class);
  48
  49         /**
  50          * Size of the withdrawn_routes_length field, in bytes.
  51          */
  52         public static final int WITHDRAWN_ROUTES_LENGTH_SIZE = 2;
  53
  54         /**
  55          * Size of the total_path_attr_length field, in bytes.
  56          */
  57         public static final int TOTAL_PATH_ATTR_LENGTH_SIZE = 2;
  58
  59         // Constructors -------------------------------------------------------
  60
  61         public BGPUpdateMessageParser() {
  62
  63         }
  64
  65         // Getters & setters --------------------------------------------------
  66
  67         public static BGPUpdateEvent parse(final byte[] bytes, final int msgLength) throws BGPDocumentedException {
  68                 if (bytes == null || bytes.length == 0)
  69                         throw new IllegalArgumentException("Byte array cannot be null or empty.");
  70                 logger.trace("Started parsing of update message: {}", Arrays.toString(bytes));
  71
  72                 int byteOffset = 0;
  73
  74                 final int withdrawnRoutesLength = ByteArray.bytesToInt(ByteArray.subByte(bytes, byteOffset, WITHDRAWN_ROUTES_LENGTH_SIZE));
  75                 byteOffset += WITHDRAWN_ROUTES_LENGTH_SIZE;
  76
  77                 final BGPUpdateEventBuilder eventBuilder = new BGPUpdateEventBuilder();
  78                 eventBuilder.setWithdrawnRoutesLength(withdrawnRoutesLength);
  79
  80                 Set<Prefix<IPv4Address>> withdrawnRoutes;
  81                 if (withdrawnRoutesLength > 0) {
  82                         withdrawnRoutes = IPv4.FAMILY.prefixListForBytes(ByteArray.subByte(bytes, byteOffset, withdrawnRoutesLength));
  83                         byteOffset += withdrawnRoutesLength;
  84                 } else {
  85                         withdrawnRoutes = Collections.emptySet();
  86                 }
  87                 eventBuilder.setWithdrawnRoutes(withdrawnRoutes);
  88
  89                 final int totalPathAttrLength = ByteArray.bytesToInt(ByteArray.subByte(bytes, byteOffset, TOTAL_PATH_ATTR_LENGTH_SIZE));
  90                 byteOffset += TOTAL_PATH_ATTR_LENGTH_SIZE;
  91                 eventBuilder.setTotalPathAttrLength(totalPathAttrLength);
  92
  93                 if (withdrawnRoutesLength + totalPathAttrLength + BGPMessageFactoryImpl.COMMON_HEADER_LENGTH > msgLength)
  94                         throw new BGPDocumentedException("Message length inconsistent with withdrawn router length.", BGPError.MALFORMED_ATTR_LIST);
  95
  96                 if (withdrawnRoutesLength == 0 && totalPathAttrLength == 0) {
  97                         final BGPUpdateSynchronized event = new BGPUpdateSynchronized() {
  98
  99                                 private static final long serialVersionUID = 5709361453437508337L;
 100
 101                                 @Override
 102                                 public BGPTableType getTableType() {
 103                                         return new BGPTableType(BGPAddressFamily.IPv4, BGPSubsequentAddressFamily.Unicast);
 104                                 }
 105                         };
 106                         return event;
 107                 }
 108
 109                 List<PathAttribute> pathAttributes;
 110                 if (totalPathAttrLength > 0) {
 111                         pathAttributes = parsePathAttributes(ByteArray.subByte(bytes, byteOffset, totalPathAttrLength));
 112                         byteOffset += totalPathAttrLength;
 113                         if (pathAttributes.get(0).getType() == TypeCode.MP_UNREACH_NLRI && totalPathAttrLength == 6) {
 114                                 if (pathAttributes.get(0).getValue() instanceof IPv6MP) {
 115                                         final BGPUpdateEvent event = new BGPUpdateSynchronized() {
 116
 117                                                 private static final long serialVersionUID = -6026212683738125407L;
 118
 119                                                 @Override
 120                                                 public BGPTableType getTableType() {
 121                                                         return new BGPTableType(BGPAddressFamily.IPv6, BGPSubsequentAddressFamily.Unicast);
 122                                                 }
 123
 124                                         };
 125                                         return event;
 126                                 } else if (pathAttributes.get(0).getValue() == null) {
 127                                         final BGPUpdateSynchronized event = new BGPUpdateSynchronized() {
 128
 129                                                 private static final long serialVersionUID = 5888562784007786559L;
 130
 131                                                 @Override
 132                                                 public BGPTableType getTableType() {
 133                                                         return new BGPTableType(BGPAddressFamily.LinkState, BGPSubsequentAddressFamily.Unicast);
 134                                                 }
 135
 136                                         };
 137                                         return event;
 138                                 }
 139                         }
 140                 } else {
 141                         pathAttributes = Collections.emptyList();
 142                 }
 143                 eventBuilder.setPathAttributes(pathAttributes);
 144
 145                 final Set<Prefix<IPv4Address>> nlri = IPv4.FAMILY.prefixListForBytes(ByteArray.subByte(bytes, byteOffset, bytes.length - byteOffset));
 146                 eventBuilder.setNlri(nlri);
 147
 148                 try {
 149                         logger.trace("Update message was parsed.");
 150                         return eventBuilder.buildEvent();
 151                 } catch (final BGPParsingException e) {
 152                         throw new BGPDocumentedException("Parsing unsuccessful: {}" + e.getMessage(), BGPError.MALFORMED_ATTR_LIST);
 153                 }
 154         }
 155
 156         /**
 157          * Parse different Path Attributes from given bytes.
 158          *
 159          * @param bytes byte array to be parsed
 160          * @return list of Path Attributes
 161          * @throws BGPParsingException
 162          */
 163         private static List<PathAttribute> parsePathAttributes(byte[] bytes) throws BGPDocumentedException {
 164                 if (bytes.length == 0) {
 165                         return Collections.emptyList();
 166                 }
 167                 final List<PathAttribute> list = Lists.newArrayList();
 168                 while (bytes.length != 0) {
 169                         PathAttribute attr;
 170                         try {
 171                                 attr = PathAttributeParser.parseAttribute(bytes);
 172                                 bytes = ByteArray.cutBytes(bytes,
 173                                                 PathAttribute.ATTR_FLAGS_SIZE + PathAttribute.ATTR_TYPE_CODE_SIZE + attr.getAttrLengthSize() + attr.getLength());
 174                                 list.add(attr);
 175                         } catch (final BGPParsingException e) {
 176                                 logger.warn("Could not parse BGP attributes: {}", e.getMessage(), e);
 177                                 throw new BGPDocumentedException("Could not parse BGP attributes.", BGPError.MALFORMED_ATTR_LIST);
 178                         }
 179                 }
 180                 return list;
 181         }
 182 }