packethandler/implementation/src/main/java/org/opendaylight/l2switch/packethandler/decoders/IcmpDecoder.java

   1 /*
   2  * Copyright (c) 2016 Hewlett Packard Enterprise, Co. 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 package org.opendaylight.l2switch.packethandler.decoders;
   9
  10 import java.util.List;
  11 import org.opendaylight.controller.sal.binding.api.NotificationProviderService;
  12 import org.opendaylight.l2switch.packethandler.decoders.utils.BitBufferHelper;
  13 import org.opendaylight.l2switch.packethandler.decoders.utils.BufferException;
  14 import org.opendaylight.l2switch.packethandler.decoders.utils.NetUtils;
  15 import org.opendaylight.yang.gen.v1.urn.opendaylight.packet.basepacket.rev140528.packet.chain.grp.PacketChain;
  16 import org.opendaylight.yang.gen.v1.urn.opendaylight.packet.basepacket.rev140528.packet.chain.grp.PacketChainBuilder;
  17 import org.opendaylight.yang.gen.v1.urn.opendaylight.packet.basepacket.rev140528.packet.chain.grp.packet.chain.Packet;
  18 import org.opendaylight.yang.gen.v1.urn.opendaylight.packet.icmp.rev140528.IcmpPacketReceived;
  19 import org.opendaylight.yang.gen.v1.urn.opendaylight.packet.icmp.rev140528.IcmpPacketReceivedBuilder;
  20 import org.opendaylight.yang.gen.v1.urn.opendaylight.packet.icmp.rev140528.icmp.packet.received.packet.chain.packet.IcmpPacketBuilder;
  21 import org.opendaylight.yang.gen.v1.urn.opendaylight.packet.ipv4.rev140528.Ipv4PacketListener;
  22 import org.opendaylight.yang.gen.v1.urn.opendaylight.packet.ipv4.rev140528.Ipv4PacketReceived;
  23 import org.opendaylight.yang.gen.v1.urn.opendaylight.packet.ipv4.rev140528.KnownIpProtocols;
  24 import org.opendaylight.yang.gen.v1.urn.opendaylight.packet.ipv4.rev140528.ipv4.packet.received.packet.chain.packet.Ipv4Packet;
  25 import org.opendaylight.yangtools.yang.binding.NotificationListener;
  26 import org.slf4j.Logger;
  27 import org.slf4j.LoggerFactory;
  28
  29 public class IcmpDecoder extends AbstractPacketDecoder<Ipv4PacketReceived, IcmpPacketReceived>
  30         implements Ipv4PacketListener {
  31
  32     private static final Logger LOG = LoggerFactory.getLogger(IcmpDecoder.class);
  33
  34     public IcmpDecoder(NotificationProviderService notificationProviderService) {
  35         super(IcmpPacketReceived.class, notificationProviderService);
  36     }
  37
  38     /**
  39      * Decode an EthernetPacket into an IcmpPacket.
  40      */
  41     @Override
  42     public IcmpPacketReceived decode(Ipv4PacketReceived ipv4PacketReceived) {
  43         IcmpPacketReceivedBuilder icmpReceivedBuilder = new IcmpPacketReceivedBuilder();
  44
  45         // Find the latest packet in the packet-chain, which is an
  46         // EthernetPacket
  47         List<PacketChain> packetChainList = ipv4PacketReceived.getPacketChain();
  48         Ipv4Packet ipv4Packet = (Ipv4Packet) packetChainList.get(packetChainList.size() - 1).getPacket();
  49         int bitOffset = ipv4Packet.getPayloadOffset() * NetUtils.NUM_BITS_IN_A_BYTE;
  50         byte[] data = ipv4PacketReceived.getPayload();
  51
  52         IcmpPacketBuilder builder = new IcmpPacketBuilder();
  53         try {
  54             // Decode the ICMP type and ICMP code
  55             builder.setType(BitBufferHelper.getShort(BitBufferHelper.getBits(data, bitOffset + 0, 8)));
  56             builder.setCode(BitBufferHelper.getShort(BitBufferHelper.getBits(data, bitOffset + 8, 8)));
  57
  58             // Decode the checksum
  59             builder.setCrc(BitBufferHelper.getInt(BitBufferHelper.getBits(data, bitOffset + 16, 16)));
  60
  61             // Decode the identifier and sequence number
  62             builder.setIdentifier(BitBufferHelper.getInt(BitBufferHelper.getBits(data, bitOffset + 32, 16)));
  63             builder.setSequenceNumber(BitBufferHelper.getInt(BitBufferHelper.getBits(data, bitOffset + 48, 16)));
  64
  65             // Decode the ICMP Payload
  66             int payloadStartInBits = bitOffset + 64;
  67             int payloadEndInBits = data.length * NetUtils.NUM_BITS_IN_A_BYTE - payloadStartInBits - 4
  68                     * NetUtils.NUM_BITS_IN_A_BYTE;
  69             int start = payloadStartInBits / NetUtils.NUM_BITS_IN_A_BYTE;
  70             int end = start + payloadEndInBits / NetUtils.NUM_BITS_IN_A_BYTE;
  71             builder.setPayloadOffset(start);
  72             builder.setPayloadLength(end - start);
  73         } catch (BufferException e) {
  74             LOG.debug("Exception while decoding ICMP packet", e);
  75         }
  76
  77         // build icmp
  78         packetChainList.add(new PacketChainBuilder().setPacket(builder.build()).build());
  79         icmpReceivedBuilder.setPacketChain(packetChainList);
  80
  81         // carry forward the original payload.
  82         icmpReceivedBuilder.setPayload(ipv4PacketReceived.getPayload());
  83
  84         return icmpReceivedBuilder.build();
  85     }
  86
  87     @Override
  88     public NotificationListener getConsumedNotificationListener() {
  89         return this;
  90     }
  91
  92     @Override
  93     public void onIpv4PacketReceived(Ipv4PacketReceived notification) {
  94         decodeAndPublish(notification);
  95     }
  96
  97     @Override
  98     public boolean canDecode(Ipv4PacketReceived ipv4PacketReceived) {
  99         if (ipv4PacketReceived == null || ipv4PacketReceived.getPacketChain() == null) {
 100             return false;
 101         }
 102
 103         // Only decode the latest packet in the chain
 104         Ipv4Packet ipv4Packet = null;
 105         if (!ipv4PacketReceived.getPacketChain().isEmpty()) {
 106             Packet packet = ipv4PacketReceived.getPacketChain().get(ipv4PacketReceived.getPacketChain().size() - 1)
 107                     .getPacket();
 108             if (packet instanceof Ipv4Packet) {
 109                 ipv4Packet = (Ipv4Packet) packet;
 110             }
 111         }
 112
 113         return ipv4Packet != null && KnownIpProtocols.Icmp.equals(ipv4Packet.getProtocol());
 114     }
 115 }