如何在纯PHP中执行HTTP重定向后获得最终URL?

/**
 * 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;
    }
}

并且,一如既往地,给予信任:

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

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;
}

另外。。。

正如在评论中提到的那样 最终的 中的项目 $headers['Location'] 将是所有重定向后的最终URL。不过,值得注意的是,它不会 总是

如果你只对最终的网址感兴趣,在所有的重定向之后,我建议改变

return $headers['Location'];

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

... 这只是 if short-hand

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

此修复程序将处理任意一种情况(数组、非数组),并消除在调用函数后删除最终URL的需要。

在没有重定向的情况下,函数将返回 false . 同样,函数也将返回 假 对于无效的URL(由于任何原因无效)。因此,重要的是 check the URL for validity 之前 运行此函数,或者将重定向检查合并到验证中。

而警察想避免 cURL

• location 标题名(xaav和webjay的答案都不能处理这个问题)
• 允许你在放弃之前控制你想要的深度

函数如下:

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;
}

下面是一个更详细的版本,它允许您检查重定向链,而不是让curl跟随它。

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;
}

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

在撰写本文时,这涉及4个请求,其中包括 Location 和

xaav 答案很好;除了以下两个问题:

• 它不支持HTTPS协议=>解决方案是在原始站点中作为注释提出的: http://w-shadow.com/blog/2008/07/05/how-to-get-redirect-url-in-php/

• 有些网站无法工作,因为它们无法识别底层用户代理(客户端浏览器) =>这只是通过添加一个用户代理头字段来解决的:我添加了一个Android用户代理(您可以在这里找到 http://www.useragentstring.com/pages/useragentstring.php

  $request.=“用户代理:Mozilla/5.0(Linux;U;Android 4.0.3;ko kr;LG-L160L Build/IML74K)AppleWebkit/534.30(KHTML,如Gecko)版本/4.0 Mobile Safari/534.30\r\n”;

以下是修改后的答案:

/**
 * 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;
}

添加到answers@xaav和@Houssem BDIOUI的代码中:404错误案例和URL没有响应时的案例。 get_final_url($url) 在这种情况下,返回字符串:“Error:404notfound”和“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;
    }
}