在纯 PHP 中遵循 HTTP 重定向后如何获取最终 URL? [英] How to get final URL after following HTTP redirections in pure PHP?

问题描述

我想做的是找出重定向后的最后一个/最终 URL 是什么.

我不想使用 cURL.我想坚持使用纯 PHP(流包装器).

现在我有一个 URL(比方说 http://domain.test)，我使用 get_headers()从该页面获取特定标题.get_headers 还将返回多个 Location: 标头(请参阅下面的编辑).有没有办法使用这些标头来构建最终 URL?或者是否有 PHP 函数可以自动执行此操作?

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?

get_headers() 遵循重定向并返回每个响应/重定向的所有标头，因此我拥有所有 Location: 标头.

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

推荐答案

/**
 * 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
"; 
    $request .= 'Host: ' . $url_parts['host'] . "
"; 
    $request .= "Connection: Close

"; 
    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:

And, as always, give credit:

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

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