Programming Languages Research Group: Git - pingpong.git/blob

   1 package edu.uci.iotproject.analysis;
   2
   3 import org.pcap4j.core.*;
   4
   5 import java.time.Instant;
   6 import java.util.Collections;
   7 import java.util.List;
   8 import java.util.concurrent.TimeoutException;
   9
  10 /**
  11  * TODO add class documentation.
  12  *
  13  * @author Janus Varmarken
  14  */
  15 public class TriggerTrafficExtractor implements PcapPacketFilter {
  16
  17     private final String mPcapFilePath;
  18     private final List<Instant> mTriggerTimes;
  19     private final String mDeviceIp;
  20
  21     private int mTriggerIndex = 0;
  22
  23
  24     private static final int INCLUSION_WINDOW_MILLIS = 3_000;
  25
  26     public TriggerTrafficExtractor(String pcapFilePath, List<Instant> triggerTimes, String deviceIp) throws PcapNativeException, NotOpenException {
  27         mPcapFilePath = pcapFilePath;
  28         // Ensure that trigger times are sorted in ascending as we rely on this fact in the logic that works out if a
  29         // packet is related to a trigger.
  30         Collections.sort(triggerTimes, (i1, i2) -> {
  31             if (i1.isBefore(i2)) return -1;
  32             else if (i2.isBefore(i1)) return 1;
  33             else return 0;
  34         });
  35         mTriggerTimes = Collections.unmodifiableList(triggerTimes);
  36         mDeviceIp = deviceIp;
  37     }
  38
  39
  40     public void performExtraction(PacketListener... extractedPacketsConsumers) throws PcapNativeException, NotOpenException, TimeoutException {
  41         PcapHandle handle;
  42         try {
  43             handle = Pcaps.openOffline(mPcapFilePath, PcapHandle.TimestampPrecision.NANO);
  44         } catch (PcapNativeException pne) {
  45             handle = Pcaps.openOffline(mPcapFilePath);
  46         }
  47         // Use the native support for BPF to immediately filter irrelevant traffic.
  48         handle.setFilter("ip host " + mDeviceIp, BpfProgram.BpfCompileMode.OPTIMIZE);
  49         PcapHandleReader pcapReader = new PcapHandleReader(handle, this, extractedPacketsConsumers);
  50         pcapReader.readFromHandle();
  51         // Reset trigger index (in case client code chooses to rerun the extraction)
  52         mTriggerIndex = 0;
  53     }
  54
  55     @Override
  56     public boolean shouldIncludePacket(PcapPacket packet) {
  57         if (mTriggerIndex >= mTriggerTimes.size()) {
  58             // Don't include packet if we've exhausted the list of trigger times.
  59             return false;
  60         }
  61
  62         // TODO hmm, is this correct?
  63         Instant trigger = mTriggerTimes.get(mTriggerIndex);
  64         if (trigger.isBefore(packet.getTimestamp()) &&
  65                 packet.getTimestamp().isBefore(trigger.plusMillis(INCLUSION_WINDOW_MILLIS))) {
  66             // Packet lies within INCLUSION_WINDOW_MILLIS after currently considered trigger, include it.
  67             return true;
  68         } else {
  69             if (!trigger.isBefore(packet.getTimestamp())) {
  70                 // Packet is before currently considered trigger, so it shouldn't be included
  71                 return false;
  72             } else {
  73                 // Packet is >= INCLUSION_WINDOW_MILLIS after currently considered trigger.
  74                 // Proceed to next trigger to see if it lies in range of that.
  75                 // Note that there's an assumption here that no two trigger intervals don't overlap!
  76                 mTriggerIndex++;
  77                 return shouldIncludePacket(packet);
  78             }
  79         }
  80     }
  81
  82 }