CookieUtils.java

   1 package be.nikiroo.utils;
   2
   3 import java.util.Date;
   4
   5 public class CookieUtils {
   6         /**
   7          * The number of seconds for the period (we accept the current or the
   8          * previous period as valid for a cookie, via "offset").
   9          */
  10         static public int GRACE_PERIOD = 3600 * 1000; // between 1 and 2h
  11
  12         /**
  13          * Generate a new cookie value from the user (email) and an offset.
  14          * <p>
  15          * You should use an offset of "0" when creating the cookie, and an offset
  16          * of "0" or "-1" if required when checking for the value (the idea is to
  17          * allow a cookie to persist across two timespans; if not, the cookie will
  18          * be expired the very second we switch to a new timespan).
  19          *
  20          * @param value
  21          *            the value to generate a cookie for -- you must be able to
  22          *            regenerate it in order to check it later
  23          * @param offset
  24          *            the offset (should be 0 for creating, 0 then -1 if needed for
  25          *            checking)
  26          *
  27          * @return the new cookie
  28          */
  29         static public String generateCookie(String value, int offset) {
  30                 long unixTime = (long) Math.floor(new Date().getTime() / GRACE_PERIOD)
  31                                 + offset;
  32                 return HashUtils.sha512(value + Long.toString(unixTime));
  33         }
  34
  35         /**
  36          * Check the given cookie.
  37          *
  38          * @param value
  39          *            the value to generate a cookie for -- you must be able to
  40          *            regenerate it in order to check it later
  41          * @param cookie
  42          *            the cookie to validate
  43          *
  44          * @return TRUE if it is correct
  45          */
  46         static public boolean validateCookie(String value, String cookie) {
  47                 if (cookie != null)
  48                         cookie = cookie.trim();
  49
  50                 String newCookie = generateCookie(value, 0);
  51                 if (!newCookie.equals(cookie)) {
  52                         newCookie = generateCookie(value, -1);
  53                 }
  54
  55                 return newCookie.equals(cookie);
  56         }
  57 }