encoder.inc in Simplenews Statistics 7

Encoder for IDs. Some logic borrowed from shorturl module.

File

simplenews_statistics_encoder/encoder.inc

<?php

/**
 * @file Encoder for IDs. Some logic borrowed from shorturl module.
 */

/**
 * Calculate factorial of a number.
 */
function simplenews_statistics_encoder_nfact($n) {
  if ($n == 0) {
    return 1;
  }
  else {
    return $n * nfact($n - 1);
  }
}

/**
 * Convert $var from (10) base notation to $base base notation.
 */
function simplenews_statistics_encoder_base_encode($var, $base) {
  if ($var < $base) {
    return $var;
  }
  else {
    return simplenews_statistics_encoder_base_encode(floor($var / $base), $base) . "-" . $var % $base;
  }
}
function simplenews_statistics_encoder_decode($input) {
  $num = 0;
  $mapping = simplenews_statistics_encoder_base_decode_mapping();
  $base = sizeof($mapping);

  // There's just no chance encoded input will ever be so long so if we get
  // something like that - somebody is messing with us trying to eat up CPU
  // cycles on decoding or cause some other kind of overflow.
  if (strlen($input) > 15) {
    return -1;
  }
  $seq = str_split($input);
  if (!is_array($seq) || !(sizeof($seq) > 0)) {
    return -1;
  }
  $seq = array_reverse(str_split($input));
  $i = 0;
  foreach ($seq as $c) {
    if (isset($mapping[$c])) {
      $val = (int) $mapping[$c];
      $num += $val * pow($base, $i);
      $i++;
    }
  }
  return $num;
}
function simplenews_statistics_encoder_encode($input) {
  $mapping = simplenews_statistics_encoder_base_encode_mapping();
  $var = simplenews_statistics_encoder_base_encode($input, sizeof($mapping));
  $arr = explode('-', $var);
  if (empty($arr)) {
    return $mapping[0];
  }
  if (!is_array($arr)) {
    $arr = array(
      $arr,
    );
  }
  $new_num = "";
  foreach ($arr as $pos) {
    $new_num .= $mapping[(int) trim($pos)];
  }
  return $new_num;
}
function simplenews_statistics_encoder_base_decode_mapping() {
  return array_flip(simplenews_statistics_encoder_base_encode_mapping());
}

/**
 * The very first 4-char number is 238328.
 * The very first 3-char number is 3844.
 */
function simplenews_statistics_encoder_base_encode_mapping() {
  return array(
    'q',
    'l',
    'i',
    '3',
    'O',
    'c',
    'x',
    'a',
    'C',
    '1',
    'r',
    'Y',
    'g',
    '4',
    '2',
    'T',
    'b',
    'j',
    'D',
    'W',
    'Z',
    'B',
    'K',
    'k',
    '0',
    '8',
    '9',
    'X',
    'I',
    '5',
    'N',
    'R',
    'n',
    'Q',
    'U',
    'P',
    'E',
    'm',
    'y',
    'V',
    'p',
    'd',
    'v',
    'w',
    'f',
    'G',
    '7',
    'A',
    'o',
    's',
    'H',
    '6',
    'F',
    'L',
    'M',
    'e',
    't',
    'z',
    'u',
    'J',
    'S',
    'h',
  );
}

/**
 * Generate a md5 hash for the given ID.
 */
function simplenews_statistics_encoder_generate_hash($id, $id_key) {
  $key = variable_get('simplenews_statistics_encoder_private_key', 0);
  return drupal_substr(md5($key . $id . $id_key), 0, 10) . $id;
}

/**
 * Decode a md5 hash and return an ID.
 *
 * @param $hash
 *   A hash generated by simplenews_statistics_encoder_generate_hash().
 *
 * @return
 *   Numeric ID or FALSE if the hash is invalid.
 */
function simplenews_statistics_encoder_decode_hash($hash, $id_key) {

  // Attempt to detect invalid format.
  if (!preg_match('/.{10}[0-9]+/', $hash)) {
    return FALSE;
  }
  $id = drupal_substr($hash, 10);
  if ($hash == simplenews_statistics_encoder_generate_hash($id, $id_key)) {
    return $id;
  }
  return FALSE;
}

Functions

Name	Description
simplenews_statistics_encoder_base_decode_mapping
simplenews_statistics_encoder_base_encode	Convert $var from (10) base notation to $base base notation.
simplenews_statistics_encoder_base_encode_mapping	The very first 4-char number is 238328. The very first 3-char number is 3844.
simplenews_statistics_encoder_decode
simplenews_statistics_encoder_decode_hash	Decode a md5 hash and return an ID.
simplenews_statistics_encoder_encode
simplenews_statistics_encoder_generate_hash	Generate a md5 hash for the given ID.
simplenews_statistics_encoder_nfact	Calculate factorial of a number.