学习php简单实现短网址(短链)还原的方法

<?php
$info1 = &#39;亲！暂不能解析此类短网址。&#39;;
$info2 = &#39;亲！网址解析失败，请重试。&#39;;
$info3 = &#39;<br/><b><a href="&#39;;
$info4 = &#39;" target="_blank">立即访问>></a></b>&#39;;
$info5 = &#39;亲！不是短网址或无效。&#39;;
function unshort($url)
{
global $info1,$info2,$info3,$info4;
 $curl = curl_init();
 curl_setopt($curl, CURLOPT_URL, $url);
 curl_setopt($curl, CURLOPT_RETURNTRANSFER,1);
 curl_setopt ($curl, CURLOPT_USERAGENT, &#39;Mozilla/8.0 (compatible; MSIE 8.0; Windows 7&#39;);
 curl_setopt($curl, CURLOPT_HEADER, 1);
 curl_setopt($curl, CURLOPT_NOBODY, 0);
 curl_setopt($curl, CURLOPT_TIMEOUT, 15);
 curl_setopt($curl,CURLOPT_ENCODING, &#39;gzip&#39;);
 $data = curl_exec($curl);
 if(!empty($data)){
 $message = curl_getinfo($curl);
  curl_close($curl);
   $status = $message[&#39;http_code&#39;];
   if ($status == &#39;301&#39; || $status == &#39;302&#39; ){
    $UrlHeader = (get_headers($url,1));
    $unurl = $UrlHeader[Location];
    if(is_array($unurl)) {
     $unurl = $unurl[0];
     $unurl .=$info3.$unurl.$info4;
     return $unurl;
     }
    else {
    $unurl .=$info3.$unurl.$info4;
    return $unurl;
    }
   }
  return $info1;
 }
 return $info2;
}
function adfunshort($url)
{
global $info3,$info4,$info5;
 $c = file_get_contents($url);
 $p = "/url = &#39;(.*)&#39;;/isU";
 preg_match($p, $c, $content);
 $unurl = $content[1];
 if($unurl == &#39;&#39;) {
  return $info5;
 }
 else {
  $unurl .=$info3.$unurl.$info4;
  return $unurl;
 }
}
?>
<form action="" method="post">
短网址：<input type="text" name="turl" class="inurl" size="26" />
<input type="hidden" name="url_done" value="done" />
<input type="submit" value="提交" class="suburl" />
</form>
<p id="trurl">
<?php
$turl = $_POST[&#39;turl&#39;]?$_POST[&#39;turl&#39;]:"";
$url_done= $_POST[&#39;url_done&#39;]?$_POST[&#39;url_done&#39;]:"";
if ($url_done == &#39;done&#39;){
$http = substr($turl,0,7);
 if ($http != &#39;http://&#39; && $http != &#39;https:/&#39;){
  $turl = &#39;http://&#39;.$turl;
  }
  $tturl = substr($turl,0,11);
  if ($tturl == &#39;http://adf.&#39;){
  $longurl = adfunshort($turl);
  }else {
  $longurl = unshort($turl);
 }echo "短网址 ".$turl." 的真实网址为：<br />$longurl ";
}
?>