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.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.BGPTableType;
  20 import org.opendaylight.protocol.bgp.parser.BGPUpdateEvent;
  21 import org.opendaylight.protocol.bgp.parser.BGPUpdateSynchronized;
  22 import org.opendaylight.protocol.bgp.parser.impl.BGPMessageFactoryImpl;
  23 import org.opendaylight.protocol.bgp.parser.impl.BGPUpdateEventBuilder;
  24 import org.opendaylight.protocol.bgp.parser.impl.IPv6MP;
  25 import org.opendaylight.protocol.bgp.parser.impl.PathAttribute;
  26 import org.opendaylight.protocol.bgp.parser.impl.PathAttribute.TypeCode;
  27 import org.opendaylight.protocol.bgp.parser.impl.message.update.PathAttributeParser;
  28 import org.opendaylight.protocol.concepts.IPv4;
  29 import org.opendaylight.protocol.concepts.IPv4Address;
  30 import org.opendaylight.protocol.concepts.Prefix;
  31 import org.opendaylight.protocol.util.ByteArray;
  32 import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.linkstate.rev130918.LinkstateAddressFamily;
  33 import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.types.rev130919.Ipv4AddressFamily;
  34 import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.types.rev130919.Ipv6AddressFamily;
  35 import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.types.rev130919.UnicastSubsequentAddressFamily;
  36 import org.slf4j.Logger;
  37 import org.slf4j.LoggerFactory;
  38
  39 import com.google.common.collect.Lists;
  40
  41 /**
  42  * LENGTH fields, that denote the length of the fields with variable length, have fixed SIZE.
  43  *
  44  * @see <a href="http://tools.ietf.org/html/rfc4271#section-4.3">BGP-4 Update Message Format</a>
  45  *
  46  */
  47 public class BGPUpdateMessageParser {
  48
  49         private static Logger logger = LoggerFactory.getLogger(BGPUpdateMessageParser.class);
  50
  51         /**
  52          * Size of the withdrawn_routes_length field, in bytes.
  53          */
  54         public static final int WITHDRAWN_ROUTES_LENGTH_SIZE = 2;
  55
  56         /**
  57          * Size of the total_path_attr_length field, in bytes.
  58          */
  59         public static final int TOTAL_PATH_ATTR_LENGTH_SIZE = 2;
  60
  61         // Constructors -------------------------------------------------------
  62
  63         public BGPUpdateMessageParser() {
  64
  65         }
  66
  67         // Getters & setters --------------------------------------------------
  68
  69         public static BGPUpdateEvent parse(final byte[] bytes, final int msgLength) throws BGPDocumentedException {
  70                 if (bytes == null || bytes.length == 0) {
  71                         throw new IllegalArgumentException("Byte array cannot be null or empty.");
  72                 }
  73                 logger.trace("Started parsing of update message: {}", Arrays.toString(bytes));
  74
  75                 int byteOffset = 0;
  76
  77                 final int withdrawnRoutesLength = ByteArray.bytesToInt(ByteArray.subByte(bytes, byteOffset, WITHDRAWN_ROUTES_LENGTH_SIZE));
  78                 byteOffset += WITHDRAWN_ROUTES_LENGTH_SIZE;
  79
  80                 final BGPUpdateEventBuilder eventBuilder = new BGPUpdateEventBuilder();
  81                 eventBuilder.setWithdrawnRoutesLength(withdrawnRoutesLength);
  82
  83                 Set<Prefix<IPv4Address>> withdrawnRoutes;
  84                 if (withdrawnRoutesLength > 0) {
  85                         withdrawnRoutes = IPv4.FAMILY.prefixListForBytes(ByteArray.subByte(bytes, byteOffset, withdrawnRoutesLength));
  86                         byteOffset += withdrawnRoutesLength;
  87                 } else {
  88                         withdrawnRoutes = Collections.emptySet();
  89                 }
  90                 eventBuilder.setWithdrawnRoutes(withdrawnRoutes);
  91
  92                 final int totalPathAttrLength = ByteArray.bytesToInt(ByteArray.subByte(bytes, byteOffset, TOTAL_PATH_ATTR_LENGTH_SIZE));
  93                 byteOffset += TOTAL_PATH_ATTR_LENGTH_SIZE;
  94                 eventBuilder.setTotalPathAttrLength(totalPathAttrLength);
  95
  96                 if (withdrawnRoutesLength + totalPathAttrLength + BGPMessageFactoryImpl.COMMON_HEADER_LENGTH > msgLength) {
  97                         throw new BGPDocumentedException("Message length inconsistent with withdrawn router length.", BGPError.MALFORMED_ATTR_LIST);
  98                 }
  99
 100                 if (withdrawnRoutesLength == 0 && totalPathAttrLength == 0) {
 101                         final BGPUpdateSynchronized event = new BGPUpdateSynchronized() {
 102                                 @Override
 103                                 public BGPTableType getTableType() {
 104                                         return new BGPTableType(Ipv4AddressFamily.class, UnicastSubsequentAddressFamily.class);
 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                                                 @Override
 118                                                 public BGPTableType getTableType() {
 119                                                         return new BGPTableType(Ipv6AddressFamily.class, UnicastSubsequentAddressFamily.class);
 120                                                 }
 121                                         };
 122                                         return event;
 123                                 } else if (pathAttributes.get(0).getValue() == null) {
 124                                         final BGPUpdateSynchronized event = new BGPUpdateSynchronized() {
 125                                                 @Override
 126                                                 public BGPTableType getTableType() {
 127                                                         return new BGPTableType(LinkstateAddressFamily.class, UnicastSubsequentAddressFamily.class);
 128                                                 }
 129                                         };
 130                                         return event;
 131                                 }
 132                         }
 133                 } else {
 134                         pathAttributes = Collections.emptyList();
 135                 }
 136                 eventBuilder.setPathAttributes(pathAttributes);
 137
 138                 final Set<Prefix<IPv4Address>> nlri = IPv4.FAMILY.prefixListForBytes(ByteArray.subByte(bytes, byteOffset, bytes.length - byteOffset));
 139                 eventBuilder.setNlri(nlri);
 140
 141                 try {
 142                         logger.trace("Update message was parsed.");
 143                         return eventBuilder.buildEvent();
 144                 } catch (final BGPParsingException e) {
 145                         throw new BGPDocumentedException("Parsing unsuccessful: {}" + e.getMessage(), BGPError.MALFORMED_ATTR_LIST);
 146                 }
 147         }
 148
 149         /**
 150          * Parse different Path Attributes from given bytes.
 151          *
 152          * @param bytes byte array to be parsed
 153          * @return list of Path Attributes
 154          * @throws BGPParsingException
 155          */
 156         private static List<PathAttribute> parsePathAttributes(byte[] bytes) throws BGPDocumentedException {
 157                 if (bytes.length == 0) {
 158                         return Collections.emptyList();
 159                 }
 160                 final List<PathAttribute> list = Lists.newArrayList();
 161                 while (bytes.length != 0) {
 162                         PathAttribute attr;
 163                         try {
 164                                 attr = PathAttributeParser.parseAttribute(bytes);
 165                                 bytes = ByteArray.cutBytes(bytes,
 166                                                 PathAttribute.ATTR_FLAGS_SIZE + PathAttribute.ATTR_TYPE_CODE_SIZE + attr.getAttrLengthSize() + attr.getLength());
 167                                 list.add(attr);
 168                         } catch (final BGPParsingException e) {
 169                                 logger.warn("Could not parse BGP attributes: {}", e.getMessage(), e);
 170                                 throw new BGPDocumentedException("Could not parse BGP attributes.", BGPError.MALFORMED_ATTR_LIST);
 171                         }
 172                 }
 173                 return list;
 174         }
 175 }