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.slf4j.Logger;
  17 import org.slf4j.LoggerFactory;
  18
  19
  20 import org.opendaylight.protocol.bgp.concepts.BGPAddressFamily;
  21 import org.opendaylight.protocol.bgp.concepts.BGPSubsequentAddressFamily;
  22 import org.opendaylight.protocol.bgp.concepts.BGPTableType;
  23 import org.opendaylight.protocol.bgp.parser.BGPDocumentedException;
  24 import org.opendaylight.protocol.bgp.parser.BGPError;
  25 import org.opendaylight.protocol.bgp.parser.BGPMessageHeader;
  26 import org.opendaylight.protocol.bgp.parser.BGPParsingException;
  27 import org.opendaylight.protocol.bgp.parser.BGPUpdateEvent;
  28 import org.opendaylight.protocol.bgp.parser.BGPUpdateSynchronized;
  29 import org.opendaylight.protocol.bgp.parser.impl.BGPUpdateEventBuilder;
  30 import org.opendaylight.protocol.bgp.parser.impl.IPv6MP;
  31 import org.opendaylight.protocol.bgp.parser.impl.PathAttribute;
  32 import org.opendaylight.protocol.bgp.parser.impl.PathAttribute.TypeCode;
  33 import org.opendaylight.protocol.bgp.parser.impl.message.update.PathAttributeParser;
  34 import org.opendaylight.protocol.util.ByteArray;
  35 import org.opendaylight.protocol.concepts.IPv4;
  36 import org.opendaylight.protocol.concepts.IPv4Address;
  37 import org.opendaylight.protocol.concepts.Prefix;
  38 import com.google.common.collect.Lists;
  39
  40 /**
  41  * LENGTH fields, that denote the length of the fields with variable length, have fixed SIZE.
  42  *
  43  * @see <a href="http://tools.ietf.org/html/rfc4271#section-4.3">BGP-4 Update Message Format</a>
  44  *
  45  */
  46 public class BGPUpdateMessageParser {
  47
  48         private static Logger logger = LoggerFactory.getLogger(BGPUpdateMessageParser.class);
  49
  50         /**
  51          * Size of the withdrawn_routes_length field, in bytes.
  52          */
  53         public static final int WITHDRAWN_ROUTES_LENGTH_SIZE = 2;
  54
  55         /**
  56          * Size of the total_path_attr_length field, in bytes.
  57          */
  58         public static final int TOTAL_PATH_ATTR_LENGTH_SIZE = 2;
  59
  60         // Constructors -------------------------------------------------------
  61
  62         public BGPUpdateMessageParser() {
  63
  64         }
  65
  66         // Getters & setters --------------------------------------------------
  67
  68         public static BGPUpdateEvent parse(final byte[] bytes, final int msgLength) throws BGPDocumentedException {
  69                 if (bytes == null || bytes.length == 0)
  70                         throw new IllegalArgumentException("Byte array cannot be null or empty.");
  71                 logger.trace("Started parsing of update message: {}", Arrays.toString(bytes));
  72
  73                 int byteOffset = 0;
  74
  75                 final int withdrawnRoutesLength = ByteArray.bytesToInt(ByteArray.subByte(bytes, byteOffset, WITHDRAWN_ROUTES_LENGTH_SIZE));
  76                 byteOffset += WITHDRAWN_ROUTES_LENGTH_SIZE;
  77
  78                 final BGPUpdateEventBuilder eventBuilder = new BGPUpdateEventBuilder();
  79                 eventBuilder.setWithdrawnRoutesLength(withdrawnRoutesLength);
  80
  81                 Set<Prefix<IPv4Address>> withdrawnRoutes;
  82                 if (withdrawnRoutesLength > 0) {
  83                         withdrawnRoutes = IPv4.FAMILY.prefixListForBytes(ByteArray.subByte(bytes, byteOffset, withdrawnRoutesLength));
  84                         byteOffset += withdrawnRoutesLength;
  85                 } else {
  86                         withdrawnRoutes = Collections.emptySet();
  87                 }
  88                 eventBuilder.setWithdrawnRoutes(withdrawnRoutes);
  89
  90                 final int totalPathAttrLength = ByteArray.bytesToInt(ByteArray.subByte(bytes, byteOffset, TOTAL_PATH_ATTR_LENGTH_SIZE));
  91                 byteOffset += TOTAL_PATH_ATTR_LENGTH_SIZE;
  92                 eventBuilder.setTotalPathAttrLength(totalPathAttrLength);
  93
  94                 if (withdrawnRoutesLength + totalPathAttrLength + BGPMessageHeader.COMMON_HEADER_LENGTH > msgLength)
  95                         throw new BGPDocumentedException("Message length inconsistent with withdrawn router length.", BGPError.MALFORMED_ATTR_LIST);
  96
  97                 if (withdrawnRoutesLength == 0 && totalPathAttrLength == 0) {
  98                         final BGPUpdateSynchronized event = new BGPUpdateSynchronized() {
  99
 100                                 private static final long serialVersionUID = 5709361453437508337L;
 101
 102                                 @Override
 103                                 public BGPTableType getTableType() {
 104                                         return new BGPTableType(BGPAddressFamily.IPv4, BGPSubsequentAddressFamily.Unicast);
 105                                 }
 106                         };
 107                         return event;
 108                 }
 109
 110                 List<PathAttribute> pathAttributes;
 111                 if (totalPathAttrLength > 0) {
 112                         pathAttributes = parsePathAttributes(ByteArray.subByte(bytes, byteOffset, totalPathAttrLength));
 113                         byteOffset += totalPathAttrLength;
 114                         if (pathAttributes.get(0).getType() == TypeCode.MP_UNREACH_NLRI && totalPathAttrLength == 6) {
 115                                 if (pathAttributes.get(0).getValue() instanceof IPv6MP) {
 116                                         final BGPUpdateEvent event = new BGPUpdateSynchronized() {
 117
 118                                                 private static final long serialVersionUID = -6026212683738125407L;
 119
 120                                                 @Override
 121                                                 public BGPTableType getTableType() {
 122                                                         return new BGPTableType(BGPAddressFamily.IPv6, BGPSubsequentAddressFamily.Unicast);
 123                                                 }
 124
 125                                         };
 126                                         return event;
 127                                 } else if (pathAttributes.get(0).getValue() == null) {
 128                                         final BGPUpdateSynchronized event = new BGPUpdateSynchronized() {
 129
 130                                                 private static final long serialVersionUID = 5888562784007786559L;
 131
 132                                                 @Override
 133                                                 public BGPTableType getTableType() {
 134                                                         return new BGPTableType(BGPAddressFamily.LinkState, BGPSubsequentAddressFamily.Unicast);
 135                                                 }
 136
 137                                         };
 138                                         return event;
 139                                 }
 140                         }
 141                 } else {
 142                         pathAttributes = Collections.emptyList();
 143                 }
 144                 eventBuilder.setPathAttributes(pathAttributes);
 145
 146                 final Set<Prefix<IPv4Address>> nlri = IPv4.FAMILY.prefixListForBytes(ByteArray.subByte(bytes, byteOffset, bytes.length - byteOffset));
 147                 eventBuilder.setNlri(nlri);
 148
 149                 try {
 150                         logger.trace("Update message was parsed.");
 151                         return eventBuilder.buildEvent();
 152                 } catch (final BGPParsingException e) {
 153                         throw new BGPDocumentedException("Parsing unsuccessful: {}" + e.getMessage(), BGPError.MALFORMED_ATTR_LIST);
 154                 }
 155         }
 156
 157         /**
 158          * Parse different Path Attributes from given bytes.
 159          *
 160          * @param bytes byte array to be parsed
 161          * @return list of Path Attributes
 162          * @throws BGPParsingException
 163          */
 164         private static List<PathAttribute> parsePathAttributes(byte[] bytes) throws BGPDocumentedException {
 165                 if (bytes.length == 0) {
 166                         return Collections.emptyList();
 167                 }
 168                 final List<PathAttribute> list = Lists.newArrayList();
 169                 while (bytes.length != 0) {
 170                         PathAttribute attr;
 171                         try {
 172                                 attr = PathAttributeParser.parseAttribute(bytes);
 173                                 bytes = ByteArray.cutBytes(bytes,
 174                                                 PathAttribute.ATTR_FLAGS_SIZE + PathAttribute.ATTR_TYPE_CODE_SIZE + attr.getAttrLengthSize() + attr.getLength());
 175                                 list.add(attr);
 176                         } catch (final BGPParsingException e) {
 177                                 logger.warn("Could not parse BGP attributes: {}", e.getMessage(), e);
 178                                 throw new BGPDocumentedException("Could not parse BGP attributes.", BGPError.MALFORMED_ATTR_LIST);
 179                         }
 180                 }
 181                 return list;
 182         }
 183 }