Code/Projects/PacketLevelSignatureExtractor/src/main/java/edu/uci/iotproject/detection/layer2/Layer2RangeMatcher.java

   1 package edu.uci.iotproject.detection.layer2;
   2
   3 import edu.uci.iotproject.analysis.TriggerTrafficExtractor;
   4 import edu.uci.iotproject.util.PcapPacketUtils;
   5 import org.pcap4j.core.PcapPacket;
   6 import org.pcap4j.util.MacAddress;
   7
   8 import java.util.ArrayList;
   9 import java.util.List;
  10
  11 /**
  12  * Attempts to detect the presence of a specific packet sequence in the set of packets provided through multiple calls
  13  * to {@link #matchPacket(PcapPacket)}, considering only layer 2 information. This class has the same flavor as the
  14  * {@link Layer2SequenceMatcher} class.
  15  *
  16  * @author Janus Varmarken {@literal <jvarmark@uci.edu>}
  17  * @author Rahmadi Trimananda {@literal <rtrimana@uci.edu>}
  18  */
  19 public class Layer2RangeMatcher extends Layer2AbstractMatcher {
  20     /**
  21      * The range this {@link Layer2RangeMatcher} is searching for.
  22      */
  23     private final List<PcapPacket> mLowerBound;
  24     private final List<PcapPacket> mUpperBound;
  25     private final double mEps;
  26     private int mInclusionTimeMillis;
  27
  28     /**
  29      * Create a {@code Layer2RangeMatcher}.
  30      * @param lowerBound The lower bound of the sequence to match against (search for).
  31      * @param upperBound The upper bound of the sequence to match against (search for).
  32      * @param eps The epsilon value used in the DBSCAN algorithm.
  33      */
  34     public Layer2RangeMatcher(List<PcapPacket> lowerBound, List<PcapPacket> upperBound,
  35                               int inclusionTimeMillis, double eps) {
  36         // TODO: Just use the lower bound since both lower and upper bounds' packets essentially have the same direction
  37         // TODO: for the same position in the array. Both arrays also have the same length.
  38         super(lowerBound);
  39         mLowerBound = lowerBound;
  40         mUpperBound = upperBound;
  41         mEps = eps;
  42         mInclusionTimeMillis =
  43                 inclusionTimeMillis == 0 ? TriggerTrafficExtractor.INCLUSION_WINDOW_MILLIS : inclusionTimeMillis;
  44     }
  45
  46     /**
  47      * Attempt to advance this {@code Layer2RangeMatcher} by matching {@code packet} against the packet that this
  48      * {@code Layer2RangeMatcher} expects as the next packet of the sequence it is searching for.
  49      * @param packet
  50      * @return {@code true} if this {@code Layer2SequenceMatcher} could advance by adding {@code packet} to its set of
  51      *         matched packets, {@code false} otherwise.
  52      */
  53     public boolean matchPacket(PcapPacket packet) {
  54         if (getMatchedPacketsCount() == getTargetSequencePacketCount()) {
  55             // We already matched the entire sequence, so we can't match any more packets.
  56             return false;
  57         }
  58
  59         // Verify that new packet pertains to same flow as previously matched packets, if any.
  60         if (getMatchedPacketsCount() > 0) {
  61             MacAddress pktSrc = PcapPacketUtils.getEthSrcAddr(packet);
  62             MacAddress pktDst = PcapPacketUtils.getEthDstAddr(packet);
  63             MacAddress earlierPktSrc = PcapPacketUtils.getEthSrcAddr(mMatchedPackets.get(0));
  64             MacAddress earlierPktDst = PcapPacketUtils.getEthDstAddr(mMatchedPackets.get(0));
  65             if (!(pktSrc.equals(earlierPktSrc) && pktDst.equals(earlierPktDst) ||
  66                     pktSrc.equals(earlierPktDst) && pktDst.equals(earlierPktSrc))) {
  67                 return false;
  68             }
  69         }
  70
  71         // Get representative of the packet we expect to match next.
  72         PcapPacket expectedLowerBound = mLowerBound.get(mMatchedPackets.size());
  73         PcapPacket expectedUpperBound = mUpperBound.get(mMatchedPackets.size());
  74         int lowerBound = expectedLowerBound.getOriginalLength();
  75         int upperBound = expectedUpperBound.getOriginalLength();
  76         // Do strict matching if the lower and upper bounds are the same length
  77         // Do range matching with eps otherwise
  78         if (lowerBound != upperBound) {
  79             lowerBound = lowerBound - (int) mEps;
  80             upperBound = upperBound + (int) mEps;
  81         }
  82         // First verify if the received packet has the length we're looking for (the length should be within the range).
  83         if (lowerBound <= packet.getOriginalLength() && packet.getOriginalLength() <= upperBound){
  84             // If this is the first packet, we only need to verify that its length is correct. Time constraints are
  85             // obviously satisfied as there are no previous packets. Furthermore, direction matches by definition as we
  86             // don't know the MAC of the device (or phone) in advance, so we can't enforce a rule saying "first packet
  87             // must originate from this particular MAC".
  88             if (getMatchedPacketsCount() == 0) {
  89                 // Store packet as matched and advance.
  90                 mMatchedPackets.add(packet);
  91                 return true;
  92             }
  93             // Check if direction of packet matches expected direction.
  94             boolean actualDirection = getPacketDirection(mMatchedPackets.get(getMatchedPacketsCount()-1),
  95                     mPacketDirections[getMatchedPacketsCount()-1], packet);
  96             boolean expectedDirection = mPacketDirections[getMatchedPacketsCount()];
  97             if (actualDirection != expectedDirection) {
  98                 return false;
  99             }
 100             // Next apply timing constraints:
 101             // 1) to be a match, the packet must have a later timestamp than any other packet currently matched
 102             // 2) does adding the packet cause the max allowed time between first packet and last packet to be exceeded?
 103             if (!packet.getTimestamp().isAfter(mMatchedPackets.get(getMatchedPacketsCount()-1).getTimestamp())) {
 104                 return false;
 105             }
 106             if (packet.getTimestamp().isAfter(mMatchedPackets.get(0).getTimestamp().
 107                     plusMillis(mInclusionTimeMillis))) {
 108                 return false;
 109             }
 110             // If we made it here, it means that this packet has the expected length, direction, and obeys the timing
 111             // constraints, so we store it and advance.
 112             mMatchedPackets.add(packet);
 113             if (mMatchedPackets.size() == mLowerBound.size()) {
 114                 // TODO report (to observers?) that we are done?
 115             }
 116             return true;
 117         }
 118         return false;
 119     }
 120
 121     public int getTargetSequencePacketCount() {
 122         return mLowerBound.size();
 123     }
 124
 125     public List<PcapPacket> getTargetLowerBound() {
 126         return mLowerBound;
 127     }
 128
 129     public List<PcapPacket> getTargetUpperBound() {
 130         return mUpperBound;
 131     }
 132 }