cgivre commented on a change in pull request #1898: DRILL-7443: Enable PCAP Plugin to Reassemble TCP Streams URL: https://github.com/apache/drill/pull/1898#discussion_r349429318
########## File path: exec/java-exec/src/main/java/org/apache/drill/exec/store/pcap/decoder/TcpSession.java ########## @@ -0,0 +1,334 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance + * with the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +package org.apache.drill.exec.store.pcap.decoder; + +import org.joda.time.Instant; +import org.joda.time.Period; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import java.net.InetAddress; +import java.util.ArrayList; +import java.util.Collections; + +import static org.apache.drill.exec.store.pcap.PcapFormatUtils.parseBytesToASCII; + +/** + * This class is the representation of a TCP session. + */ +public class TcpSession { + + private ArrayList<Packet> packetsFromSender; + private ArrayList<Packet> packetsFromReceiver; + + private long startTime; + private long endTime; + private long sessionLength; + private int packetCount; + private InetAddress srcIP; + private InetAddress dstIP; + private int srcPort; + private int dstPort; + private String srcMac; + private String dstMac; + private long sessionID; + private TcpHandshake handshake; + private long synTime; + private long ackTime; + private long connectTime; + private byte[] sentData; + private byte[] receivedData; + private int sentDataSize; + private int receivedDataSize; + private boolean hasCorruptedData = false; + + + private static final Logger logger = LoggerFactory.getLogger(TcpSession.class); + + public TcpSession (long sessionID) { + packetsFromSender = new ArrayList<>(); + packetsFromReceiver = new ArrayList<>(); + + handshake = new TcpHandshake(); + this.sessionID = sessionID; + } + + /** + * This function adds a packet to the TCP session. + * @param p The Packet to be added to the session + */ + public void addPacket(Packet p) { + + // Only attempt to add TCP packets to session + if (!p.getPacketType().equalsIgnoreCase("TCP")) { + return; + } + + // These variables should be consistent within a TCP session + if (packetCount == 0) { + srcIP = p.getSrc_ip(); + dstIP = p.getDst_ip(); + + srcPort = p.getSrc_port(); + dstPort = p.getDst_port(); + + srcMac = p.getEthernetSource(); + dstMac = p.getEthernetDestination(); + startTime = p.getTimestamp(); + } else if (p.getSessionHash() != sessionID) { + logger.warn("Attempting to add session {} to incorrect TCP session.", sessionID); + return; + } + + // Add packet to appropriate list and increment the data size counter + if (p.getSrc_ip().getHostAddress().equalsIgnoreCase(srcIP.getHostAddress())) { + packetsFromSender.add(p); + // Increment the data size counters + if (p.getData() != null) { + sentDataSize += p.getData().length; + } + + } else { + packetsFromReceiver.add(p); + if (p.getData() != null) { + receivedDataSize += p.getData().length; + } + } + + // Check flags if connection is not established + if (!handshake.isConnected()) { + if (p.getSynFlag() && p.getSrc_ip().getHostAddress().equalsIgnoreCase(srcIP.getHostAddress())) { + // This is part 1 of the TCP session handshake + // The host sends the first SYN packet + handshake.syn = true; + handshake.setSyn(); + synTime = p.getTimestamp(); + } else if (p.getSynFlag() && p.getAckFlag() && p.getSrc_ip().getHostAddress().equalsIgnoreCase(dstIP.getHostAddress())) { + // This condition represents the second part of the TCP Handshake, + // where the receiver sends a frame with the SYN/ACK flags set to the originator + handshake.synAck = true; + handshake.setAck(); + } else if (p.getAckFlag() && p.getSrc_ip().getHostAddress().equalsIgnoreCase(srcIP.getHostAddress())) { + // Finally, this condition represents a successful opening of a TCP session, when the originator sends a frame with only the ACK flag set. + // At this point we finalize the session object and clear out the flags. + handshake.ack = true; + handshake.setAck(); + ackTime = p.getTimestamp(); + connectTime = ackTime - synTime; + //handshake.setConnected(sessionID); + } + } else { + /* Check for flags to close connection. Closing a TCP session is more difficult than opening a session and there are + * a lot of ways that it can go wrong. See https://accedian.com/enterprises/blog/close-tcp-sessions-diagnose-disconnections/ for references on + * closing TCP sessions. + * + * To close a session correctly, there are four steps: + * 1. Party A sends a frame to party B with the FIN flag + * 2. Party B sends a frame with an ACK flag + * 3. Party B then follows with a frame with the FIN flag set + * 4. Party A then confirms with an ACK flag. + * + * Technically, the session is closed upon the first FIN flag and resources can be released at that point. However, a lot can go wrong, so to force the closing of a + * session, either party can send a frame with a RST flag set which forces the closing of the session. + * + * */ + + if (p.getRstFlag()) { + // This is the case for a forced closed connection. Session is immediately closed. + handshake.setRst(); + } else if (p.getFinFlag()) { + // This is the beginning of the normal session closure procedure. If a FIN flag has been seen, the session is basically closed even if one party continues to send + // data, + handshake.setFin(); + } else if (handshake.getCurrentSessionState() == TcpHandshake.State.CLOSE_WAIT) { + + } + if (p.getAckFlag() && p.getFinFlag()) { + handshake.setAck(); + handshake.finAck = true; + } + } + + // Augment the packet counter + packetCount++; + + if (p.isCorrupt()) { + hasCorruptedData = true; + } + + // Add the start and ending time stamp. The packets are not necessarily received in order, so we have to check the timestamps this way + if (p.getTimestampMicro() < startTime) { + startTime = p.getTimestamp(); + } + + if (p.getTimestampMicro() > endTime) { + endTime = p.getTimestamp(); + } + + // Close the session if the closing handshake is complete + if (handshake.isClosed()) { + closeSession(); + } + } + + /** + * This function returns true if the TCP session has been established, false if not. + * @return True if the session has been established, false if not. + */ + public boolean connectionEstablished() { + return handshake.isConnected(); + } + + public boolean connectionClosed() { + return handshake.isClosed(); + } + + public void closeSession() { + logger.debug("Closing session {}", sessionID); + // Write the sent and received data + sessionLength = endTime - startTime; + + /* The sent and received bytes cannot be written until the session is closed. + * Upon receipt of the FIN->FIN/ACK handshake, write everything. + * + * Since it cannot be assumed that the packets were received in the correct order, we must: + * 1. Sort them by TCP Sequence Number + * 2. Write the data to the respective byte array + */ + + Collections.sort(packetsFromSender); + Collections.sort(packetsFromReceiver); + + sentData = new byte[sentDataSize]; + receivedData = new byte[receivedDataSize]; + + byte[] dataFromPacket; + int dataOffset = 0; + // Now that the lists are sorted, add packet data to the lists + for (int i = 0; i < packetsFromSender.size(); i++) { + // Get the packet; + Packet p = packetsFromSender.get(i); + dataFromPacket = p.getData(); + if (dataFromPacket != null) { + for (int j = 0; j < dataFromPacket.length; j++) { + sentData[dataOffset] = dataFromPacket[j]; + dataOffset++; + } + } + } + + dataOffset = 0; + for (int i = 0; i < packetsFromReceiver.size(); i++) { + // Get the packet; + Packet p = packetsFromReceiver.get(i); + dataFromPacket = p.getData(); + if (dataFromPacket != null) { + for (int j = 0; j < dataFromPacket.length; j++) { + receivedData[dataOffset] = dataFromPacket[j]; + dataOffset++; + } + } + } + } + + @Override + public boolean equals (Object o) { Review comment: I'm not sure why I originally overwrote the method, but I removed it. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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