19

What I'd like to do is find out what is the last/final URL after following the redirections.

I would prefer not to use cURL. I would like to stick with pure PHP (stream wrappers).

Right now I have a URL (let's say http://domain.test), and I use get_headers() to get specific headers from that page. get_headers will also return multiple Location: headers (see Edit below). Is there a way to use those headers to build the final URL? or is there a PHP function that would automatically do this?

Edit: get_headers() follows redirections and returns all the headers for each response/redirections, so I have all the Location: headers.

Weboide
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    There are *multiple* `Location:` headers in a single response? – Tomalak Sep 26 '10 at 18:08
  • get_headers does follow redirections automatically by defualt, so I get multiple `Location:` headers. What I'd like to have is the full final URL (http://domain.test/final/page.ext?attr...) – Weboide Sep 26 '10 at 18:11
  • I did not understand the question :( – Stewie Sep 26 '10 at 18:15
  • Try setting the `max_redirects` in the HTTP stream context to `1` (http://www.php.net/manual/en/context.http.php). This should disable auto-redirecting and you can follow redirects yourself. – Tomalak Sep 26 '10 at 18:16
  • Is there a specification on how to build the next URL using the previously URL and a Location header? – Weboide Sep 26 '10 at 18:18
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    @Webolde: Location header is defined as an absolute URI, but everyone and their dog uses relative URIs these days; so if it's an absolute URI, just redirect, if not, get domain+path of prev page, then make the new absolute URI from that and the Location field. – Piskvor left the building Sep 26 '10 at 18:22
  • Thanks for your reply Piskvor, that makes sense. I also found this on wikipedia, just for reference: http://en.wikipedia.org/wiki/HTTP_location – Weboide Sep 26 '10 at 18:34
  • @Webolde: ah, indeed, I forgot the citation: http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.30 – Piskvor left the building Sep 26 '10 at 18:43

6 Answers6

48
function getRedirectUrl ($url) {
    stream_context_set_default(array(
        'http' => array(
            'method' => 'HEAD'
        )
    ));
    $headers = get_headers($url, 1);
    if ($headers !== false && isset($headers['Location'])) {
        return $headers['Location'];
    }
    return false;
}

Additionally...

As was mentioned in a comment, the final item in $headers['Location'] will be your final URL after all redirects. It's important to note, though, that it won't always be an array. Sometimes it's just a run-of-the-mill, non-array variable. In this case, trying to access the last array element will most likely return a single character. Not ideal.

If you are only interested in the final URL, after all the redirects, I would suggest changing

return $headers['Location'];

to

return is_array($headers['Location']) ? array_pop($headers['Location']) : $headers['Location'];

... which is just if short-hand for

if(is_array($headers['Location'])){
     return array_pop($headers['Location']);
}else{
     return $headers['Location'];
}

This fix will take care of either case (array, non-array), and remove the need to weed-out the final URL after calling the function.

In the case where there are no redirects, the function will return false. Similarly, the function will also return false for invalid URLs (invalid for any reason). Therefor, it is important to check the URL for validity before running this function, or else incorporate the redirect check somewhere into your validation.

Community
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webjay
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  • Does this follow all the redirections and returns the final URL? – Weboide Sep 29 '11 at 15:43
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    Great yar.. Lot of time saved. +1 – Sekhar Babu Feb 22 '15 at 00:45
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    The marked answer to this question didn't follow all redirects. But this solution did. – Vishnu Ks Jun 12 '15 at 10:05
  • `get_headers` follows all redirects and thus returns an array in `$headers[`Location']`; the last entry being the final URL – cweiske Nov 12 '15 at 00:04
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    A note of caution on this answer. get_headers thinks `location` and `Location` are different headers. If you are following a chain of redirects which use different cases, you can't tell which header is the 'last' one, as you'll have urls in both `$headers['location']` and `$headers['Location']` – Paul Dixon Feb 21 '17 at 18:02
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    although it works fine beware of using this random in your code, because of the `stream_context_set_default` any following file operations like `file_get_contents` fail. A workaround would be to buffer the original context using `stream_context_get_default` and resetting it back to that when done. – tomvo Mar 14 '17 at 14:18
  • Its not returning the final (last) redirected url –  Jul 03 '21 at 07:01
38
/**
 * get_redirect_url()
 * Gets the address that the provided URL redirects to,
 * or FALSE if there's no redirect. 
 *
 * @param string $url
 * @return string
 */
function get_redirect_url($url){
    $redirect_url = null; 

    $url_parts = @parse_url($url);
    if (!$url_parts) return false;
    if (!isset($url_parts['host'])) return false; //can't process relative URLs
    if (!isset($url_parts['path'])) $url_parts['path'] = '/';

    $sock = fsockopen($url_parts['host'], (isset($url_parts['port']) ? (int)$url_parts['port'] : 80), $errno, $errstr, 30);
    if (!$sock) return false;

    $request = "HEAD " . $url_parts['path'] . (isset($url_parts['query']) ? '?'.$url_parts['query'] : '') . " HTTP/1.1\r\n"; 
    $request .= 'Host: ' . $url_parts['host'] . "\r\n"; 
    $request .= "Connection: Close\r\n\r\n"; 
    fwrite($sock, $request);
    $response = '';
    while(!feof($sock)) $response .= fread($sock, 8192);
    fclose($sock);

    if (preg_match('/^Location: (.+?)$/m', $response, $matches)){
        if ( substr($matches[1], 0, 1) == "/" )
            return $url_parts['scheme'] . "://" . $url_parts['host'] . trim($matches[1]);
        else
            return trim($matches[1]);

    } else {
        return false;
    }

}

/**
 * get_all_redirects()
 * Follows and collects all redirects, in order, for the given URL. 
 *
 * @param string $url
 * @return array
 */
function get_all_redirects($url){
    $redirects = array();
    while ($newurl = get_redirect_url($url)){
        if (in_array($newurl, $redirects)){
            break;
        }
        $redirects[] = $newurl;
        $url = $newurl;
    }
    return $redirects;
}

/**
 * get_final_url()
 * Gets the address that the URL ultimately leads to. 
 * Returns $url itself if it isn't a redirect.
 *
 * @param string $url
 * @return string
 */
function get_final_url($url){
    $redirects = get_all_redirects($url);
    if (count($redirects)>0){
        return array_pop($redirects);
    } else {
        return $url;
    }
}

And, as always, give credit:

http://w-shadow.com/blog/2008/07/05/how-to-get-redirect-url-in-php/

xaav
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  • You sir, just saved me few hours of searching. Everything works as expected. – Dave Oct 18 '11 at 05:00
  • I have to say that for my tests this solution with CURL is more reliable: http://stackoverflow.com/questions/17472329/php-get-url-of-redirect-from-source-url – Paolo Mioni May 05 '17 at 14:04
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    I see fsockopen is set to port 80, does this not support a SSL/HTTPS 443 port redirect? – ctrlbrk Apr 28 '20 at 01:15
10

While the OP wanted to avoid cURL, it's best to use it when it's available. Here's a solution which has the following advantages

  • uses curl for all the heavy lifting, so works with https
  • copes with servers which return lower cased location header name (both xaav and webjay's answers do not handle this)
  • allows you to control how deep you want you go before giving up

Here's the function:

function findUltimateDestination($url, $maxRequests = 10)
{
    $ch = curl_init();

    curl_setopt($ch, CURLOPT_HEADER, true);
    curl_setopt($ch, CURLOPT_NOBODY, true);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
    curl_setopt($ch, CURLOPT_MAXREDIRS, $maxRequests);
    curl_setopt($ch, CURLOPT_TIMEOUT, 15);

    //customize user agent if you desire...
    curl_setopt($ch, CURLOPT_USERAGENT, 'Mozilla/5.0 (Link Checker)');

    curl_setopt($ch, CURLOPT_URL, $url);
    curl_exec($ch);

    $url=curl_getinfo($ch, CURLINFO_EFFECTIVE_URL);

    curl_close ($ch);
    return $url;
}

Here's a more verbose version which allows you to inspect the redirection chain rather than let curl follow it.

function findUltimateDestination($url, $maxRequests = 10)
{
    $ch = curl_init();

    curl_setopt($ch, CURLOPT_HEADER, true);
    curl_setopt($ch, CURLOPT_NOBODY, true);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($ch, CURLOPT_TIMEOUT, 15);

    //customize user agent if you desire...
    curl_setopt($ch, CURLOPT_USERAGENT, 'Mozilla/5.0 (Link Checker)');

    while ($maxRequests--) {

        //fetch
        curl_setopt($ch, CURLOPT_URL, $url);
        $response = curl_exec($ch);

        //try to determine redirection url
        $location = '';
        if (in_array(curl_getinfo($ch, CURLINFO_HTTP_CODE), [301, 302, 303, 307, 308])) {
            if (preg_match('/Location:(.*)/i', $response, $match)) {
                $location = trim($match[1]);
            }
        }

        if (empty($location)) {
            //we've reached the end of the chain...
            return $url;
        }

        //build next url
        if ($location[0] == '/') {
            $u = parse_url($url);
            $url = $u['scheme'] . '://' . $u['host'];
            if (isset($u['port'])) {
                $url .= ':' . $u['port'];
            }
            $url .= $location;
        } else {
            $url = $location;
        }
    }

    return null;
}

As an example of redirection chain which this function handles, but the others do not, try this:

echo findUltimateDestination('http://dx.doi.org/10.1016/j.infsof.2016.05.005')

At the time of writing, this involves 4 requests, with a mixture of Location and location headers involved.

Paul Dixon
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3

xaav answer is very good; except for the following two issues:

  • It does not support HTTPS protocol => The solution was proposed as a comment in the original site: http://w-shadow.com/blog/2008/07/05/how-to-get-redirect-url-in-php/

  • Some sites will not work since they will not recognise the underlying user agent (client browser) => This is simply fixed by adding a User-agent header field: I added an Android user agent (you can find here http://www.useragentstring.com/pages/useragentstring.php other user agent examples according you your need):

    $request .= "User-Agent: Mozilla/5.0 (Linux; U; Android 4.0.3; ko-kr; LG-L160L Build/IML74K) AppleWebkit/534.30 (KHTML, like Gecko) Version/4.0 Mobile Safari/534.30\r\n";

Here's the modified answer:

/**
 * get_redirect_url()
 * Gets the address that the provided URL redirects to,
 * or FALSE if there's no redirect. 
 *
 * @param string $url
 * @return string
 */
function get_redirect_url($url){
    $redirect_url = null; 

    $url_parts = @parse_url($url);
    if (!$url_parts) return false;
    if (!isset($url_parts['host'])) return false; //can't process relative URLs
    if (!isset($url_parts['path'])) $url_parts['path'] = '/';

    $sock = fsockopen($url_parts['host'], (isset($url_parts['port']) ? (int)$url_parts['port'] : 80), $errno, $errstr, 30);
    if (!$sock) return false;

    $request = "HEAD " . $url_parts['path'] . (isset($url_parts['query']) ? '?'.$url_parts['query'] : '') . " HTTP/1.1\r\n"; 
    $request .= 'Host: ' . $url_parts['host'] . "\r\n"; 
    $request .= "User-Agent: Mozilla/5.0 (Linux; U; Android 4.0.3; ko-kr; LG-L160L Build/IML74K) AppleWebkit/534.30 (KHTML, like Gecko) Version/4.0 Mobile Safari/534.30\r\n";
    $request .= "Connection: Close\r\n\r\n"; 
    fwrite($sock, $request);
    $response = '';
    while(!feof($sock)) $response .= fread($sock, 8192);
    fclose($sock);

    if (preg_match('/^Location: (.+?)$/m', $response, $matches)){
        if ( substr($matches[1], 0, 1) == "/" )
            return $url_parts['scheme'] . "://" . $url_parts['host'] . trim($matches[1]);
        else
            return trim($matches[1]);

    } else {
        return false;
    }

}

/**
 * get_all_redirects()
 * Follows and collects all redirects, in order, for the given URL. 
 *
 * @param string $url
 * @return array
 */
function get_all_redirects($url){
    $redirects = array();
    while ($newurl = get_redirect_url($url)){
        if (in_array($newurl, $redirects)){
            break;
        }
        $redirects[] = $newurl;
        $url = $newurl;
    }
    return $redirects;
}

/**
 * get_final_url()
 * Gets the address that the URL ultimately leads to. 
 * Returns $url itself if it isn't a redirect.
 *
 * @param string $url
 * @return string
 */
function get_final_url($url){
    $redirects = get_all_redirects($url);
    if (count($redirects)>0){
        return array_pop($redirects);
    } else {
        return $url;
    }
}
Houssem BDIOUI
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0

Added to code from answers @xaav and @Houssem BDIOUI: 404 Error case and case when URL with no response. get_final_url($url) in that cases return strings: 'Error: 404 Not Found' and 'Error: No Responce'.

/**
 * get_redirect_url()
 * Gets the address that the provided URL redirects to,
 * or FALSE if there's no redirect,
 * or 'Error: No Responce',
 * or 'Error: 404 Not Found'
 *
 * @param string $url
 * @return string
 */
function get_redirect_url($url)
{
    $redirect_url = null;

    $url_parts = @parse_url($url);
    if (!$url_parts)
        return false;
    if (!isset($url_parts['host']))
        return false; //can't process relative URLs
    if (!isset($url_parts['path']))
        $url_parts['path'] = '/';

    $sock = @fsockopen($url_parts['host'], (isset($url_parts['port']) ? (int)$url_parts['port'] : 80), $errno, $errstr, 30);
    if (!$sock) return 'Error: No Responce';

    $request = "HEAD " . $url_parts['path'] . (isset($url_parts['query']) ? '?' . $url_parts['query'] : '') . " HTTP/1.1\r\n";
    $request .= 'Host: ' . $url_parts['host'] . "\r\n";
    $request .= "User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/80.0.3987.132 Safari/537.36\r\n";
    $request .= "Connection: Close\r\n\r\n";
    fwrite($sock, $request);
    $response = '';
    while (!feof($sock))
        $response .= fread($sock, 8192);
    fclose($sock);

    if (stripos($response, '404 Not Found') !== false)
    {
        return 'Error: 404 Not Found';
    }

    if (preg_match('/^Location: (.+?)$/m', $response, $matches))
    {
        if (substr($matches[1], 0, 1) == "/")
            return $url_parts['scheme'] . "://" . $url_parts['host'] . trim($matches[1]);
        else
            return trim($matches[1]);

    } else
    {
        return false;
    }

}

/**
 * get_all_redirects()
 * Follows and collects all redirects, in order, for the given URL.
 *
 * @param string $url
 * @return array
 */
function get_all_redirects($url)
{
    $redirects = array();
    while ($newurl = get_redirect_url($url))
    {
        if (in_array($newurl, $redirects))
        {
            break;
        }
        $redirects[] = $newurl;
        $url = $newurl;
    }
    return $redirects;
}

/**
 * get_final_url()
 * Gets the address that the URL ultimately leads to.
 * Returns $url itself if it isn't a redirect,
 * or 'Error: No Responce'
 * or 'Error: 404 Not Found',
 *
 * @param string $url
 * @return string
 */
function get_final_url($url)
{
    $redirects = get_all_redirects($url);
    if (count($redirects) > 0)
    {
        return array_pop($redirects);
    } else
    {
        return $url;
    }
}
slava
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0

After hours of reading Stackoverflow and trying out all custom functions written by people as well as trying all the cURL suggestions and nothing did more than 1 redirection, I managed to do a logic of my own which works.

$url = 'facebook.com';
// First let's find out if we just typed the domain name alone or we prepended with a protocol 
if (preg_match('/(http|https):\/\/[a-z0-9]+[a-z0-9_\/]*/',$url)) {
    $url = $url;
} else {
    $url = 'http://' . $url;
    echo '<p>No protocol given, defaulting to http://';
}
// Let's print out the initial URL
echo '<p>Initial URL: ' . $url . '</p>';
// Prepare the HEAD method when we send the request
stream_context_set_default(array('http' => array('method' => 'HEAD')));
// Probe for headers
$headers = get_headers($url, 1);
// If there is a Location header, trigger logic
if (isset($headers['Location'])) {
    // If there is more than 1 redirect, Location will be array
    if (is_array($headers['Location'])) {
        // If that's the case, we are interested in the last element of the array (thus the last Location)
        echo '<p>Redirected URL: ' . $headers['Location'][array_key_last($headers['Location'])] . '</p>';
        $url = $headers['Location'][array_key_last($headers['Location'])];
    } else {
        // If it's not an array, it means there is only 1 redirect
        //var_dump($headers['Location']);
        echo '<p>Redirected URL: ' . $headers['Location'] . '</p>';
        $url = $headers['Location'];
    }
} else {
    echo '<p>URL: ' . $url . '</p>';
}
// You can now send get_headers to the latest location
$headers = get_headers($url, 1);
Dharman
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Djongov
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