src/be/nikiroo/utils/CookieUtils.java

   1 package be.nikiroo.utils;
   2
   3 import java.util.Date;
   4
   5 /**
   6  * Some utilities for cookie management.
   7  *
   8  * @author niki
   9  */
  10 public class CookieUtils {
  11         /**
  12          * The number of seconds for the period (we accept the current or the
  13          * previous period as valid for a cookie, via "offset").
  14          */
  15         static public int GRACE_PERIOD = 3600 * 1000; // between 1 and 2h
  16
  17         /**
  18          * Generate a new cookie value from the user (email) and an offset.
  19          * <p>
  20          * You should use an offset of "0" when creating the cookie, and an offset
  21          * of "0" or "-1" if required when checking for the value (the idea is to
  22          * allow a cookie to persist across two timespans; if not, the cookie will
  23          * be expired the very second we switch to a new timespan).
  24          *
  25          * @param value
  26          *            the value to generate a cookie for -- you must be able to
  27          *            regenerate it in order to check it later
  28          * @param offset
  29          *            the offset (should be 0 for creating, 0 then -1 if needed for
  30          *            checking)
  31          *
  32          * @return the new cookie
  33          */
  34         static public String generateCookie(String value, int offset) {
  35                 long unixTime = (long) Math.floor(new Date().getTime() / GRACE_PERIOD)
  36                                 + offset;
  37                 return HashUtils.sha512(value + Long.toString(unixTime));
  38         }
  39
  40         /**
  41          * Check the given cookie.
  42          *
  43          * @param value
  44          *            the value to generate a cookie for -- you must be able to
  45          *            regenerate it in order to check it later
  46          * @param cookie
  47          *            the cookie to validate
  48          *
  49          * @return TRUE if it is correct
  50          */
  51         static public boolean validateCookie(String value, String cookie) {
  52                 if (cookie != null)
  53                         cookie = cookie.trim();
  54
  55                 String newCookie = generateCookie(value, 0);
  56                 if (!newCookie.equals(cookie)) {
  57                         newCookie = generateCookie(value, -1);
  58                 }
  59
  60                 return newCookie.equals(cookie);
  61         }
  62 }