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     /**
  21      * Create a {@code PcapHandleReader}.
  22      * @param handle An <em>open</em> {@link PcapHandle} that packets will be read from.
  23      * @param packetFilter A {@link PcapPacketFilter} that dictates which of the packets read from {@code handle} should
  24      *                     be delivered to {@code packetListeners}. Note that while a value of {@code null} is not
  25      *                     permitted here, the caller can instead simply provide an implementation that always returns
  26      *                     {@code true} if they want to include all packets read from {@code handle}.
  27      * @param packetListeners One or more {@link PacketListener}s to which those packets read from {@code handle} that
  28      *                        pass through {@code packetFilter} are delivered.
  29      */
  30     public PcapHandleReader(PcapHandle handle, PcapPacketFilter packetFilter, PacketListener... packetListeners) {
  31         mHandle = handle;
  32         mPacketFilter = packetFilter;
  33         mPacketListeners = packetListeners;
  34     }
  35
  36
  37     /**
  38      * Start reading (and filtering) packets from the provided {@link PcapHandle}.
  39      * @throws PcapNativeException if an error occurs in the pcap native library.
  40      * @throws NotOpenException if the provided {@code PcapHandle} is not open.
  41      * @throws TimeoutException if packets are being read from a live capture and the timeout expired.
  42      */
  43     public void readFromHandle() throws PcapNativeException, NotOpenException, TimeoutException {
  44         try {
  45             PcapPacket prevPacket = null;
  46             PcapPacket packet;
  47             while ((packet = mHandle.getNextPacketEx()) != null) {
  48                 if (prevPacket != null && packet.getTimestamp().isBefore(prevPacket.getTimestamp())) {
  49                     System.out.println("Out-of-order (in terms of timestamp) packet detected");
  50                     /*
  51                     // Fail early if assumption doesn't hold.
  52                     mHandle.close();
  53                     throw new AssertionError("Packets not in ascending temporal order");
  54                     */
  55                 }
  56                 if (mPacketFilter.shouldIncludePacket(packet)) {
  57                     // Packet accepted for inclusion; deliver it to observing client code.
  58                     for (PacketListener consumer : mPacketListeners) {
  59                         consumer.gotPacket(packet);
  60                     }
  61                 }
  62                 prevPacket = packet;
  63             }
  64         } catch (EOFException eof) {
  65             // Reached end of file. All good.
  66             System.out.println(String.format("%s: finished reading pcap file", getClass().getSimpleName()));
  67         }
  68         mHandle.close();
  69     }
  70
  71 }