[php][library][amazon]make AWS Signed URL

amazon_sign_api.php

<?php
// Create Signed Amazon REST API URL from old unsigned URL
//   Amazon API requires signature from 2009-08-15.
//   You can get sign key from management page of your AWS Access Key.
// See signature spec:
//   https://affiliate.amazon.co.jp/gp/associates/help/t126/a13?ie=UTF8&pf_rd_t=501&ref_=amb_link_84046416_5&pf_rd_m=AN1VRQENFRJN5&pf_rd_p=&pf_rd_s=center-1&pf_rd_r=&pf_rd_i=assoc_help_t126_a9
//
function amazon_sign_api($key, $url) {
  $pattern = '/^([^:]+):\/\/([^\/]+)([^\?]+)\?(.*)$/';
  preg_match($pattern, $url, $result);
  $protocol = $result[1];
  $host = $result[2];
  $path = $result[3];

  $params = split("&", $result[4]);
  $has_timestamp = false;
  for ($i = 0; $i < count($params); $i += 1) {
    $kv = split("=", $params[$i]);
    if (strcmp("Timestamp", $kv[0]) === 0) $has_timestamp = true;
    $params[$i] = $kv[0]."=".urlencode($kv[1]);
  }
  if (!$has_timestamp) {
    $time = gmdate('Y-m-d\TH:i:s\Z');
    array_push($params, "Timestamp=".urlencode($time));
  }
  sort($params);
  $query = implode("&", $params);

  $doc = "GET\n".$host."\n".$path."\n".$query;
  $mac = hash_hmac("sha256", $doc, $key, true);
  $sign = urlencode(base64_encode($mac));

  $url = $protocol."://".$host.$path."?".$query."&Signature=".$sign;
  return $url;
}
?>