NonceManager.java

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package com.sun.jersey.oauth.server;

import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
import java.util.SortedMap;
import java.util.TreeMap;

/**
 * Tracks the nonces for a given consumer key and/or token. Automagically
 * ensures timestamp is monotonically increasing and tracks all nonces
 * for a given timestamp.
 *
 * @author Paul C. Bryan <pbryan@sun.com>
 * @author Martin Matula
 */
public class NonceManager
{
    /** The maximum valid age of a nonce timestamp, in milliseconds. */
    private final long maxAge;

    /** Verifications to perform on average before performing garbage collection. */
    private final int gcPeriod;

    /** Counts number of verification requests performed to schedule garbage collection. */
    private int gcCounter = 0;

    /** Maps keys to nonces. */
    private final Map<String, Map<Long, Set<String>>> map = new HashMap<String, Map<Long, Set<String>>>();

    /** Index by timestamps (for garbage collection) */
    private final SortedMap<Long, String> tsIndex = new TreeMap<Long, String>();

    /**
     * TODO: Description.
     *
     * @param maxAge the maximum valid age of a nonce timestamp, in milliseconds.
     * @param gcPeriod verifications to perform on average before performing garbage collection.
     */
    public NonceManager(long maxAge, int gcPeriod)
    {
        if (maxAge <= 0 || gcPeriod <= 0) {
            throw new IllegalArgumentException();
        }

        this.maxAge = maxAge;
        this.gcPeriod = gcPeriod;
    }

    /**
     * Evaluates the timestamp/nonce combination for validity, storing and/or
     * clearing nonces as required.
     *
     * @param timestamp the oauth_timestamp value for a given consumer request.
     * @param nonce the oauth_nonce value for a given consumer request.
     * @return true if the timestamp/nonce are valid.
     */
    public synchronized boolean verify(String key, String timestamp, String nonce)
    {
        long now = System.currentTimeMillis();

        // convert timestap to milliseconds since epoch to deal with uniformly
        long stamp = longValue(timestamp) * 1000;

        // invalid timestamp supplied; automatically invalid
        if (stamp + maxAge < now) {
            return false;
        }

        Map<Long, Set<String>> timestamps = map.get(key);
        if (timestamps == null) {
            timestamps = new HashMap<Long, Set<String>>();
            map.put(key, timestamps);
        }

        Set<String> nonces = timestamps.get(stamp);
        if (nonces == null) {
            nonces = new HashSet<String>();
            timestamps.put(stamp, nonces);
            tsIndex.put(stamp, key);
        }

        boolean result = nonces.add(nonce);

        // perform garbage collection if counter is up to established number of passes
        if (++gcCounter >= gcPeriod) {
            gcCounter = 0;
            SortedMap<Long, String> toCollect = tsIndex.headMap(now - maxAge);
            for (Map.Entry<Long, String> entry : toCollect.entrySet()) {
                map.get(entry.getValue()).remove(entry.getKey());
            }
            toCollect.clear();
        }

        // returns false if nonce already encountered for given timestamp
        return result;
    }

    private static long longValue(String value) {
        try {
            return Long.valueOf(value);
        }
        catch (NumberFormatException nfe) {
            return -1;
        }
    }
}