1 package edu.uci.iotproject.analysis;
3 import edu.uci.iotproject.Conversation;
4 import edu.uci.iotproject.DnsMap;
5 import edu.uci.iotproject.util.PcapPacketUtils;
6 import org.pcap4j.core.PcapPacket;
7 import org.pcap4j.packet.IpV4Packet;
8 import org.pcap4j.packet.TcpPacket;
11 import java.util.stream.Collectors;
12 import java.util.stream.Stream;
14 import static edu.uci.iotproject.util.PcapPacketUtils.*;
17 * Utility functions for analyzing and structuring (sets of) {@link Conversation}s.
19 * @author Janus Varmarken {@literal <jvarmark@uci.edu>}
20 * @author Rahmadi Trimananda {@literal <rtrimana@uci.edu>}
22 public class TcpConversationUtils {
26 * Given a {@link Conversation}, extract its set of "packet pairs", i.e., pairs of request-reply packets.
29 * <b>Note:</b> in the current implementation, if one endpoint sends multiple packets back-to-back with no
30 * interleaved reply packets from the other endpoint, such packets are converted to one-item pairs (i.e., instances
31 * of {@lin PcapPacketPair} where {@link PcapPacketPair#getSecond()} is {@code null}).
33 * @param conv The {@code Conversation} for which packet pairs are to be extracted.
34 * @return The packet pairs extracted from {@code conv}.
36 public static List<PcapPacketPair> extractPacketPairs(Conversation conv) {
37 List<PcapPacket> packets = conv.getPackets();
38 List<PcapPacketPair> pairs = new ArrayList<>();
40 while (i < packets.size()) {
41 PcapPacket p1 = packets.get(i);
42 String p1SrcIp = p1.get(IpV4Packet.class).getHeader().getSrcAddr().getHostAddress();
43 int p1SrcPort = p1.get(TcpPacket.class).getHeader().getSrcPort().valueAsInt();
44 if (i+1 < packets.size()) {
45 PcapPacket p2 = packets.get(i+1);
46 if (PcapPacketUtils.isSource(p2, p1SrcIp, p1SrcPort)) {
47 // Two packets in a row going in the same direction -> create one item pair for p1
48 pairs.add(new PcapPacketPair(p1, null));
49 // Advance one packet as the following two packets may form a valid two-item pair.
52 // The two packets form a response-reply pair, create two-item pair.
53 pairs.add(new PcapPacketPair(p1, p2));
54 // Advance two packets as we have already processed the packet at index i+1 in order to create the pair.
58 // Last packet of conversation => one item pair
59 pairs.add(new PcapPacketPair(p1, null));
60 // Advance i to ensure termination.
65 // TODO: what if there is long time between response and reply packet? Should we add a threshold and exclude those cases?
69 * Given a collection of TCP conversations and associated DNS mappings, groups the conversations by hostname.
70 * @param tcpConversations The collection of TCP conversations.
71 * @param ipHostnameMappings The associated DNS mappings.
72 * @return A map where each key is a hostname and its associated value is a list of conversations where one of the
73 * two communicating hosts is that hostname (i.e. its IP maps to the hostname).
75 public static Map<String, List<Conversation>> groupConversationsByHostname(Collection<Conversation> tcpConversations, DnsMap ipHostnameMappings) {
76 HashMap<String, List<Conversation>> result = new HashMap<>();
77 for (Conversation c : tcpConversations) {
78 if (c.getPackets().size() == 0) {
79 String warningStr = String.format("Detected a %s [%s] with no payload packets.",
80 c.getClass().getSimpleName(), c.toString());
81 System.err.println(warningStr);
84 IpV4Packet firstPacketIp = c.getPackets().get(0).get(IpV4Packet.class);
85 String ipSrc = firstPacketIp.getHeader().getSrcAddr().getHostAddress();
86 String ipDst = firstPacketIp.getHeader().getDstAddr().getHostAddress();
87 // Check if src or dst IP is associated with one or more hostnames.
88 Set<String> hostnames = ipHostnameMappings.getHostnamesForIp(ipSrc);
89 if (hostnames == null) {
90 // No luck with src ip (possibly because it's a client->srv packet), try dst ip.
91 hostnames = ipHostnameMappings.getHostnamesForIp(ipDst);
93 if (hostnames != null) {
94 // Put a reference to the conversation for each of the hostnames that the conversation's IP maps to.
95 for (String hostname : hostnames) {
96 List<Conversation> newValue = new ArrayList<>();
98 result.merge(hostname, newValue, (l1, l2) -> { l1.addAll(l2); return l1; });
100 if (hostnames.size() > 1) {
101 // Print notice of IP mapping to multiple hostnames (debugging)
102 System.err.println(String.format("%s: encountered an IP that maps to multiple (%d) hostnames",
103 TcpConversationUtils.class.getSimpleName(), hostnames.size()));
106 // If no hostname mapping, store conversation under the key that is the concatenation of the two IPs.
107 // In order to ensure consistency when mapping conversations, use lexicographic order to select which IP
109 String delimiter = "_";
110 // Note that the in case the comparison returns 0, the strings are equal, so it doesn't matter which of
111 // ipSrc and ipDst go first (also, this case should not occur in practice as it means that the device is
112 // communicating with itself!)
113 String key = ipSrc.compareTo(ipDst) <= 0 ? ipSrc + delimiter + ipDst : ipDst + delimiter + ipSrc;
114 List<Conversation> newValue = new ArrayList<>();
116 result.merge(key, newValue, (l1, l2) -> { l1.addAll(l2); return l1; });
122 public static Map<String, Integer> countPacketSequenceFrequencies(Collection<Conversation> conversations) {
123 Map<String, Integer> result = new HashMap<>();
124 for (Conversation conv : conversations) {
125 if (conv.getPackets().size() == 0) {
126 // Skip conversations with no payload packets.
129 StringBuilder sb = new StringBuilder();
130 for (PcapPacket pp : conv.getPackets()) {
131 sb.append(pp.length() + " ");
133 result.merge(sb.toString(), 1, (i1, i2) -> i1+i2);
139 * Given a {@link Collection} of {@link Conversation}s, builds a {@link Map} from {@link String} to {@link List}
140 * of {@link Conversation}s such that each key is the <em>concatenation of the packet lengths of all payload packets
141 * (i.e., the set of packets returned by {@link Conversation#getPackets()}) separated by a delimiter</em> of any
142 * {@link Conversation} pointed to by that key. In other words, what the {@link Conversation}s {@code cs} pointed to
143 * by the key {@code s} have in common is that they all contain exactly the same number of payload packets <em>and
144 * </em> these payload packets are identical across all {@code Conversation}s in {@code cs} in terms of packet
145 * length and packet order. For example, if the key is "152 440 550", this means that every individual
146 * {@code Conversation} in the list of {@code Conversation}s pointed to by that key contain exactly three payload
147 * packet of lengths 152, 440, and 550, and these three packets are ordered in the order prescribed by the key.
149 * @param conversations The collection of {@code Conversation}s to group by packet sequence.
150 * @param verbose If set to {@code true}, the grouping (and therefore the key) will also include SYN/SYNACK,
151 * FIN/FINACK, RST packets, and each payload-carrying packet will have an indication of the direction
152 * of the packet prepended.
153 * @return a {@link Map} from {@link String} to {@link List} of {@link Conversation}s such that each key is the
154 * <em>concatenation of the packet lengths of all payload packets (i.e., the set of packets returned by
155 * {@link Conversation#getPackets()}) separated by a delimiter</em> of any {@link Conversation} pointed to
158 public static Map<String, List<Conversation>> groupConversationsByPacketSequence(Collection<Conversation> conversations, boolean verbose) {
159 return conversations.stream().collect(Collectors.groupingBy(c -> toSequenceString(c, verbose)));
162 public static Map<String, List<Conversation>> groupConversationsByTlsApplicationDataPacketSequence(Collection<Conversation> conversations) {
163 return conversations.stream().collect(Collectors.groupingBy(
164 c -> c.getTlsApplicationDataPackets().stream().map(p -> Integer.toString(p.getOriginalLength())).
165 reduce("", (s1, s2) -> s1.length() == 0 ? s2 : s1 + " " + s2))
170 * Given a {@link Conversation}, counts the frequencies of each unique packet length seen as part of the
171 * {@code Conversation}.
172 * @param c The {@code Conversation} for which unique packet length frequencies are to be determined.
173 * @return A mapping from packet length to its frequency.
175 public static Map<Integer, Integer> countPacketLengthFrequencies(Conversation c) {
176 Map<Integer, Integer> result = new HashMap<>();
177 for (PcapPacket packet : c.getPackets()) {
178 result.merge(packet.length(), 1, (i1, i2) -> i1 + i2);
184 * Like {@link #countPacketLengthFrequencies(Conversation)}, but counts packet length frequencies for a collection
185 * of {@code Conversation}s, i.e., the frequency of a packet length becomes the total number of packets with that
186 * length across <em>all</em> {@code Conversation}s in {@code conversations}.
187 * @param conversations The collection of {@code Conversation}s for which packet length frequencies are to be
189 * @return A mapping from packet length to its frequency.
191 public static Map<Integer, Integer> countPacketLengthFrequencies(Collection<Conversation> conversations) {
192 Map<Integer, Integer> result = new HashMap<>();
193 for (Conversation c : conversations) {
194 Map<Integer, Integer> intermediateResult = countPacketLengthFrequencies(c);
195 for (Map.Entry<Integer, Integer> entry : intermediateResult.entrySet()) {
196 result.merge(entry.getKey(), entry.getValue(), (i1, i2) -> i1 + i2);
202 public static Map<String, Integer> countPacketPairFrequencies(Collection<PcapPacketPair> pairs) {
203 Map<String, Integer> result = new HashMap<>();
204 for (PcapPacketPair ppp : pairs) {
205 result.merge(ppp.toString(), 1, (i1, i2) -> i1 + i2);
210 public static Map<String, Map<String, Integer>> countPacketPairFrequenciesByHostname(Collection<Conversation> tcpConversations, DnsMap ipHostnameMappings) {
211 Map<String, List<Conversation>> convsByHostname = groupConversationsByHostname(tcpConversations, ipHostnameMappings);
212 HashMap<String, Map<String, Integer>> result = new HashMap<>();
213 for (Map.Entry<String, List<Conversation>> entry : convsByHostname.entrySet()) {
214 // Merge all packet pairs exchanged during the course of all conversations with hostname into one list
215 List<PcapPacketPair> allPairsExchangedWithHostname = new ArrayList<>();
216 entry.getValue().forEach(conversation -> allPairsExchangedWithHostname.addAll(extractPacketPairs(conversation)));
217 // Then count the frequencies of packet pairs exchanged with the hostname, irrespective of individual
219 result.put(entry.getKey(), countPacketPairFrequencies(allPairsExchangedWithHostname));
225 * Given a {@link Conversation}, extract its packet length sequence.
226 * @param c The {@link Conversation} from which a packet length sequence is to be extracted.
227 * @return An {@code Integer[]} that holds the packet lengths of all payload-carrying packets in {@code c}. The
228 * packet lengths in the returned array are ordered by packet timestamp.
230 public static Integer[] getPacketLengthSequence(Conversation c) {
231 return getPacketLengthSequence(c.getPackets());
236 * Given a {@link Conversation}, extract its packet length sequence, but only include packet lengths of those
237 * packets that carry TLS Application Data.
238 * @param c The {@link Conversation} from which a TLS Application Data packet length sequence is to be extracted.
239 * @return An {@code Integer[]} that holds the packet lengths of all packets in {@code c} that carry TLS Application
240 * Data. The packet lengths in the returned array are ordered by packet timestamp.
242 public static Integer[] getPacketLengthSequenceTlsAppDataOnly(Conversation c) {
244 throw new IllegalArgumentException("Provided " + c.getClass().getSimpleName() + " was not a TLS session");
246 return getPacketLengthSequence(c.getTlsApplicationDataPackets());
250 * Given a list of packets, extract the packet lengths and wrap them in an array such that the packet lengths in the
251 * resulting array appear in the same order as their corresponding packets in the input list.
252 * @param packets The list of packets for which the packet lengths are to be extracted.
253 * @return An array containing the packet lengths in the same order as their corresponding packets in the input list.
255 private static Integer[] getPacketLengthSequence(List<PcapPacket> packets) {
256 return packets.stream().map(pkt -> pkt.getOriginalLength()).toArray(Integer[]::new);
260 * Builds a string representation of the sequence of packets exchanged as part of {@code c}.
261 * @param c The {@link Conversation} for which a string representation of the packet sequence is to be constructed.
262 * @param verbose {@code true} if set to true, the returned sequence string will also include SYN/SYNACK,
263 * FIN/FINACK, RST packets, as well as an indication of the direction of payload-carrying packets.
264 * @return a string representation of the sequence of packets exchanged as part of {@code c}.
266 private static String toSequenceString(Conversation c, boolean verbose) {
267 // Payload-parrying packets are always included, but only prepend direction if verbose output is chosen.
268 Stream<String> s = c.getPackets().stream().map(p -> verbose ? c.getDirection(p).toCompactString() + p.getOriginalLength() : Integer.toString(p.getOriginalLength()));
270 // In the verbose case, we also print SYN, FIN and RST packets.
271 // Convert the SYN packets to a string representation and prepend them in front of the payload packets.
272 s = Stream.concat(c.getSynPackets().stream().map(p -> isSyn(p) && isAck(p) ? "SYNACK" : "SYN"), s);
273 // Convert the FIN packets to a string representation and append them after the payload packets.
274 s = Stream.concat(s, c.getFinAckPairs().stream().map(f -> f.isAcknowledged() ? "FINACK" : "FIN"));
275 // Convert the RST packets to a string representation and append at the end.
276 s = Stream.concat(s, c.getRstPackets().stream().map(r -> "RST"));
279 * Note: the collector internally uses a StringBuilder, which is more efficient than simply doing string
280 * concatenation as in the following example:
281 * s.reduce("", (s1, s2) -> s1.length() == 0 ? s2 : s1 + " " + s2);
282 * (above code is O(N^2) where N is the number of characters)
284 return s.collect(Collectors.joining(" "));
288 * Appends a space to {@code sb} <em>iff</em> {@code sb} already contains some content.
289 * @param sb A {@link StringBuilder} that should have a space appended <em>iff</em> it is not empty.
291 private static void appendSpaceIfNotEmpty(StringBuilder sb) {
292 if (sb.length() != 0) {