source: trunk/EventBenchConsole/src/de/ugoe/cs/eventbench/web/WeblogParser.java

package de.ugoe.cs.eventbench.web;

import java.io.FileNotFoundException;
import java.io.IOException;
import java.net.URI;
import java.net.URISyntaxException;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Set;

import de.ugoe.cs.eventbench.web.data.WebEvent;
import de.ugoe.cs.util.FileTools;
import de.ugoe.cs.util.console.Console;

/**
 * <p>
 * Provides functionality to parse log files with web request.
 * </p>
 * 
 * @author Steffen Herbold
 * @version 1.0
 */
public class WeblogParser {

        /**
         * <p>
         * Timeout between two sessions in milliseconds.
         * </p>
         */
        private long timeout;

        /**
         * <p>
         * Minimal length of a session. All shorter sessions will be pruned.<br>
         * Default: 2
         * </p>
         */
        private int minLength = 2;

        /**
         * <p>
         * Maximal length of a session. All longer sessions will be pruned.<br>
         * Default: 100
         * </p>
         */
        private int maxLength = 100;

        /**
         * <p>
         * URL of the server that generated the log that is currently parser; null
         * of URL is not available.<br>
         * Default: null
         * </p>
         */
        private String url = null;

        /**
         * <p>
         * Collection of generated sequences.
         * </p>
         */
        private List<List<WebEvent>> sequences;

        /**
         * <p>
         * List that stores the users (identified through their cookie id) to each
         * sequence.
         * </p>
         */
        private List<String> users;

        /**
         * <p>
         * List that stores the frequent users (identified through their cookie id)
         * to each sequence.
         * </p>
         */
        private List<String> frequentUsers;

        /**
         * <p>
         * Sequences for all frequent users.
         * </p>
         */
        private List<Collection<List<WebEvent>>> sequencesFrequentUsers;

        /**
         * <p>
         * Threshold that defines how many sessions of a user are require to deem
         * the user frequent. Note, that only sessions whose lengths is in range if
         * {@link #minLength} and {@link #maxLength} are counted.
         * </p>
         */
        private int frequentUsersThreshold = -1;

        /**
         * <p>
         * Name and path of the robot filter.
         * </p>
         */
        private static final String ROBOTFILTERFILE = "misc/robotfilter.txt";

        /**
         * <p>
         * Field that contains a regular expression that matches all robots
         * contained in {@link #ROBOTFILTERFILE}.
         * </p>
         */
        private String robotRegex = null;

        /**
         * <p>
         * Constructor. Creates a new WeblogParser with a default timeout of
         * 3,600,000 milliseconds (1 hour).
         * </p>
         */
        public WeblogParser() {
                this(3600000);
        }

        /**
         * <p>
         * Constructor. Creates a new WeblogParser.
         * </p>
         * 
         * @param timeout
         *            session timeout
         */
        public WeblogParser(long timeout) {
                this.timeout = timeout;
        }

        /**
         * <p>
         * Returns the generated event sequences.
         * </p>
         * 
         * @return generated event sequences
         */
        public Collection<List<WebEvent>> getSequences() {
                return sequences;
        }

        /**
         * <p>
         * Sets the session timeout.
         * </p>
         * 
         * @param timeout
         *            new session timeout
         */
        public void setTimeout(long timeout) {
                this.timeout = timeout;
        }

        /**
         * <p>
         * Sets the minimal length of a session. All sessions that contain less
         * events will be pruned.
         * </p>
         * 
         * @param minLength
         *            new minimal length
         */
        public void setMinLength(int minLength) {
                this.minLength = minLength;
        }

        /**
         * <p>
         * Sets the maximal length of a session. All sessions that contain more
         * events will be pruned.
         * </p>
         * 
         * @param maxLength
         *            new maximal length
         */
        public void setMaxLength(int maxLength) {
                this.maxLength = maxLength;
        }

        /**
         * <p>
         * Sets the URL of the server from which this log was generated. Often
         * required for replay generation
         * </p>
         * 
         * @param url
         *            URL of the server
         */
        public void setUrl(String url) {
                this.url = url;
        }

        /**
         * <p>
         * Sets the threshold for frequent users.
         * </p>
         * 
         * @param threshold
         *            threshold value; if the value is &lt;1, the sessions of the
         *            frequent users will not be determined
         */
        public void setFrequentUserThreshold(int threshold) {
                this.frequentUsersThreshold = threshold;
        }

        /**
         * <p>
         * Returns the IDs of all frequent users.
         * </p>
         * 
         * @return IDs of the frequent users
         */
        public List<String> getFrequentUsers() {
                return frequentUsers;
        }

        /**
         * <p>
         * Returns the sequences of all frequent users.
         * </p>
         * </p>
         * 
         * @return list of the sequences of all frequent users
         */
        public List<Collection<List<WebEvent>>> getFrequentUserSequences() {
                return sequencesFrequentUsers;
        }

        /**
         * <p>
         * Parses a web log file.
         * </p>
         * 
         * @param filename
         *            name and path of the log file
         * @throws IOException
         *             thrown if there is a problem with reading the log file
         * @throws FileNotFoundException
         *             thrown if the log file is not found
         * @throws ParseException
         *             thrown the date format is invalid
         */
        public void parseFile(String filename) throws IOException,
                        FileNotFoundException, ParseException {
                String[] lines = FileTools.getLinesFromFile(filename);

                Map<String, List<Integer>> cookieSessionMap = new HashMap<String, List<Integer>>();
                int lastId = -1;

                SimpleDateFormat dateFormat = new SimpleDateFormat(
                                "yyyy-MM-dd HH:mm:ss");
                loadRobotRegex();

                sequences = new ArrayList<List<WebEvent>>();
                users = new ArrayList<String>();

                int lineCounter = 0;
                for (String line : lines) {
                        lineCounter++;
                        String[] values = line.substring(1, line.length() - 1).split(
                                        "\" \"");

                        // use cookie as session identifier
                        int cookieStart = values[0].lastIndexOf('.');
                        String cookie = values[0].substring(cookieStart + 1);
                        String dateString = values[1];
                        long timestamp = dateFormat.parse(dateString).getTime();
                        String uriString = values[2];
                        // String ref = values[3]; // referer is not yet used!
                        String agent;
                        if (values.length > 4) {
                                agent = values[4];
                        } else {
                                agent = "noagent";
                        }

                        List<String> postedVars = new ArrayList<String>();
                        if (values.length == 6) { // post vars found
                                for (String postVar : values[5].trim().split(" ")) {
                                        if (!isBrokenVariable(postVar)) {
                                                postedVars.add(postVar);
                                        }
                                }
                        }
                        if (!isRobot(agent)) {
                                try {
                                        URI uri = new URI(uriString);
                                        String path = uri.getPath();
                                        List<String> getVars = extractGetVarsFromUri(uri);
                                        
                                        WebEvent event = new WebEvent(url, path, timestamp,
                                                        postedVars, getVars);

                                        // find session and add event
                                        List<Integer> sessionIds = cookieSessionMap.get(cookie);
                                        if (sessionIds == null) {
                                                sessionIds = new ArrayList<Integer>();
                                                // start new session
                                                sessionIds.add(++lastId);
                                                cookieSessionMap.put(cookie, sessionIds);
                                                sequences.add(new LinkedList<WebEvent>());
                                                users.add(cookie);
                                        }
                                        Integer lastSessionIndex = sessionIds
                                                        .get(sessionIds.size() - 1);
                                        List<WebEvent> lastSession = sequences
                                                        .get(lastSessionIndex);
                                        long lastEventTime = timestamp;
                                        if (!lastSession.isEmpty()) {
                                                lastEventTime = lastSession.get(lastSession.size() - 1)
                                                                .getTimestamp();
                                        }
                                        if (timestamp - lastEventTime > timeout) {
                                                sessionIds.add(++lastId);
                                                List<WebEvent> newSession = new LinkedList<WebEvent>();
                                                newSession.add(event);
                                                sequences.add(newSession);
                                                users.add(cookie);
                                        } else {
                                                lastSession.add(event);
                                        }
                                } catch (URISyntaxException e) {
                                        Console.traceln("Ignored line " + lineCounter + ": "
                                                        + e.getMessage());
                                }
                        }
                }
                Console.traceln("" + sequences.size() + " user sequences found");
                pruneSequences();
                Console.traceln("" + sequences.size()
                                + " remaining after pruning of sequences shorter than "
                                + minLength);
                Set<String> uniqueUsers = new HashSet<String>(users);
                Console.traceln("" + uniqueUsers.size() + " unique users");
                if (frequentUsersThreshold > 0) {
                        generateFrequentUserSequences(uniqueUsers);
                }
        }

        /**
         * <p>
         * Generates the frequent user sequences, according to the threshold
         * {@link #frequentUsersThreshold}.
         * </p>
         * 
         * @param uniqueUsers
         *            set with all user IDs
         */
        private void generateFrequentUserSequences(Set<String> uniqueUsers) {
                frequentUsers = new ArrayList<String>();
                sequencesFrequentUsers = new ArrayList<Collection<List<WebEvent>>>();
                for (String user : uniqueUsers) {
                        List<String> tmp = new ArrayList<String>();
                        tmp.add(user);
                        List<String> usersCopy = new LinkedList<String>(users);
                        usersCopy.retainAll(tmp);
                        int size = usersCopy.size();
                        if (size >= frequentUsersThreshold) {
                                frequentUsers.add(user);
                                Collection<List<WebEvent>> sequencesUser = new ArrayList<List<WebEvent>>();
                                for (int i = 0; i < sequences.size(); i++) {
                                        if (users.get(i).equals(user)) {
                                                sequencesUser.add(sequences.get(i));
                                        }
                                }
                                sequencesFrequentUsers.add(sequencesUser);

                        }
                }
                Console.traceln("" + frequentUsers.size() + " users with more than "
                                + frequentUsersThreshold + " sequences");
        }

        /**
         * <p>
         * Prunes sequences shorter than {@link #minLength} and longer than
         * {@link #maxLength}.
         * </p>
         */
        private void pruneSequences() {
                int i = 0;
                while (i < sequences.size()) {
                        if ((sequences.get(i).size() < minLength)
                                        || sequences.get(i).size() > maxLength) {
                                sequences.remove(i);
                                users.remove(i);
                        } else {
                                i++;
                        }
                }

        }

        /**
         * <p>
         * Reads {@link #ROBOTFILTERFILE} and creates a regular expression that
         * matches all the robots defined in the file. The regular expression is
         * stored in the field {@link #robotRegex}.
         * </p>
         * 
         * @throws IOException
         *             thrown if there is a problem reading the robot filter
         * @throws FileNotFoundException
         *             thrown if the robot filter is not found
         */
        private void loadRobotRegex() throws IOException, FileNotFoundException {
                String[] lines = FileTools.getLinesFromFile(ROBOTFILTERFILE);
                StringBuilder regex = new StringBuilder();
                for (int i = 0; i < lines.length; i++) {
                        regex.append("(.*" + lines[i] + ".*)");
                        if (i != lines.length - 1) {
                                regex.append('|');
                        }
                }
                robotRegex = regex.toString();
        }

        /**
         * <p>
         * Checks whether an agent is a robot.
         * </p>
         * 
         * @param agent
         *            agent that is checked
         * @return true, if the agent is a robot; false otherwise
         */
        private boolean isRobot(String agent) {
                return agent.matches(robotRegex);
        }

        /**
         * <p>
         * Parses the URI and extracts the GET variables that have been passed.
         * </p>
         * 
         * @param uri
         *            URI that is parsed
         * @return a list with all GET variables
         * @throws URISyntaxException
         *             thrown if one of the variables seems to indicate that the
         *             request is a malicious attack on the web application
         */
        private List<String> extractGetVarsFromUri(URI uri)
                        throws URISyntaxException {
                List<String> getVars = new ArrayList<String>();
                String query = uri.getQuery();
                if (query != null) {
                        String[] paramPairs = query.split("&");
                        for (String paramPair : paramPairs) {
                                String[] paramSplit = paramPair.split("=");
                                if (!isBrokenVariable(paramSplit[0])) {
                                        for (int i = 1; i < paramSplit.length; i++) {
                                                checkForAttack(paramSplit[i]);
                                        }
                                        getVars.add(paramSplit[0]);
                                }
                        }
                }
                return getVars;
        }

        /**
         * <p>
         * Checks if a variable is broken.Currently, the check rather imprecise and
         * checks only if the term &quot;and&quot; is part of the variable name.
         * </p>
         * 
         * @param var
         *            variable that is checked
         * @return true if the variable is broken, false otherwise
         */
        private boolean isBrokenVariable(String var) {
                return var.contains("and");
        }

        /**
         * <p>
         * Checks if the variable name send with a request seems like an attack on the server.
         * </p>
         * @param value
         * @throws URISyntaxException
         */
        private void checkForAttack(String value) throws URISyntaxException {
                if (value.contains("UNION+") || value.contains("SELECT+")) {
                        throw new URISyntaxException(value, "possible injection attack");
                }
        }
}