Code/Projects/SmartPlugDetector/src/main/java/edu/uci/iotproject/analysis/PcapHandleReader.java

   1 package edu.uci.iotproject.analysis;
   2
   3 import org.pcap4j.core.*;
   4
   5 import java.io.EOFException;
   6 import java.util.concurrent.TimeoutException;
   7
   8 /**
   9  * Reads packets from a {@link PcapHandle} (online or offline) and delivers those packets that pass the test exercised
  10  * by the provided {@link PcapPacketFilter} onto the provided {@link PacketListener}s.
  11  *
  12  * @author Janus Varmarken
  13  */
  14 public class PcapHandleReader {
  15
  16     private final PcapPacketFilter mPacketFilter;
  17     private final PcapHandle mHandle;
  18     private final PacketListener[] mPacketListeners;
  19
  20     public PcapHandleReader(PcapHandle handle, PcapPacketFilter packetFilter, PacketListener... packetListeners) {
  21         mHandle = handle;
  22         mPacketFilter = packetFilter;
  23         mPacketListeners = packetListeners;
  24     }
  25
  26
  27     /**
  28      * Start reading (and filtering) packets from the provided {@link PcapHandle}.
  29      * @throws PcapNativeException if an error occurs in the pcap native library.
  30      * @throws NotOpenException if the provided {@code PcapHandle} is not open.
  31      * @throws TimeoutException if packets are being read from a live capture and the timeout expired.
  32      */
  33     public void readFromHandle() throws PcapNativeException, NotOpenException, TimeoutException {
  34         try {
  35             PcapPacket prevPacket = null;
  36             PcapPacket packet;
  37             while ((packet = mHandle.getNextPacketEx()) != null) {
  38                 if (prevPacket != null && packet.getTimestamp().isBefore(prevPacket.getTimestamp())) {
  39                     // Fail early if assumption doesn't hold.
  40                     mHandle.close();
  41                     throw new AssertionError("Packets not in ascending temporal order");
  42                 }
  43                 if (mPacketFilter.shouldIncludePacket(packet)) {
  44                     // Packet accepted for inclusion; deliver it to observing client code.
  45                     for (PacketListener consumer : mPacketListeners) {
  46                         consumer.gotPacket(packet);
  47                     }
  48                 }
  49                 prevPacket = packet;
  50             }
  51         } catch (EOFException eof) {
  52             // Reached end of file. All good.
  53             System.out.println(String.format("%s: finished reading pcap file", getClass().getSimpleName()));
  54         }
  55         mHandle.close();
  56     }
  57
  58 }