从双重缩短的URL获取最终URL（t.co - > bit.ly - > final）

Question

I couldn't convert a double shortened URL to expanded URL successfully using the below function I got from here:

function doShortURLDecode($url) {
        $ch = @curl_init($url);
        @curl_setopt($ch, CURLOPT_HEADER, TRUE);
        @curl_setopt($ch, CURLOPT_NOBODY, TRUE);
        @curl_setopt($ch, CURLOPT_FOLLOWLOCATION, FALSE);
        @curl_setopt($ch, CURLOPT_RETURNTRANSFER, TRUE);
        $response = @curl_exec($ch);
        preg_match('/Location: (.*)
/', $response, $a);
        if (!isset($a[1])) return $url;
        return $a[1];
    }

I got into trouble when the expanded URL I got was again a shortened URL, which has its expanded URL.

How do I get final expanded URL after it has run through both URL shortening services?

Answer 1

Finally found a way to get the final url of a double shortened url. The best way is to use longurl api for it.

I am not sure if it is the correct way, but i am at last getting the output as the final url needed :)

Here's what i did:

<?php
 function TextAfterTag($input, $tag)
 {
        $result = '';
        $tagPos = strpos($input, $tag);

        if (!($tagPos === false))
        {
                $length = strlen($input);
                $substrLength = $length - $tagPos + 1;
                $result = substr($input, $tagPos + 1, $substrLength); 
        }

        return trim($result);
 }

 function expandUrlLongApi($url)
 {
        $format = 'json';
        $api_query = "http://api.longurl.org/v2/expand?" .
                    "url={$url}&response-code=1&format={$format}";
        $ch = curl_init();
        curl_setopt ($ch, CURLOPT_URL, $api_query );
        curl_setopt ($ch, CURLOPT_RETURNTRANSFER, 1);
        curl_setopt ($ch, CURLOPT_CONNECTTIMEOUT, 0);
        curl_setopt($ch, CURLOPT_HEADER, false);
        $fileContents = curl_exec($ch);
        curl_close($ch);
        $s1=str_replace("{"," ","$fileContents");
        $s2=str_replace("}"," ","$s1");
        $s2=trim($s2);
        $s3=array();
        $s3=explode(",",$s2);
        $s4=TextAfterTag($s3[0],(':'));
        $s4=stripslashes($s4);
        return $s4;
 }
 echo expandUrlLongApi('http://t.co/dd4b3kOz');
?>

The output i get is:

"http://changeordie.therepublik.net/?p=371#proliferation"

The above code works.

The code that @cryptic shared is also correct ,but i could not get the result on my server (maybe because of some configuration issue).

If anyone thinks that it could be done by some other way, please feel free to share it.