Automatically Unshortening Links in Wordpress Posts

unshortening.php

function unshorten_url($url) {
    $ch = curl_init($url[0]);
    curl_setopt_array($ch, array(
        CURLOPT_FOLLOWLOCATION => TRUE,  // the magic sauce
        CURLOPT_RETURNTRANSFER => TRUE
        CURLOPT_HEADER => TRUE,
        CURLOPT_CONNECTTIMEOUT => 5,
        CURLOPT_SSL_VERIFYHOST => FALSE, // suppress certain SSL errors
        CURLOPT_SSL_VERIFYPEER => FALSE, 
    ));
    curl_exec($ch);
    $url = curl_getinfo($ch, CURLINFO_EFFECTIVE_URL);
    curl_close($ch);
    $url = preg_replace( '/&?utm_.+?(&|$|\s)/', '', $url );
    $url = str_replace("%5C", '', $url); // hack - sometimes wikipedia appends a backslash
    $url = rtrim($url, "?");
    return $url;
}

function find_links_for_unshortening($text) {
    $pattern = "#\b((?:[a-z][\w-]+:(?:\/{1,3}|[a-z0-9%])|www\d{0,3}[.])(?:[^\s()<>]+|\([^\s()<>]+\))+(?:\([^\s()<>]+\)|[^`!()\[\]{};:'\".,<>?«»“”‘’\s]))#i";
    $text = preg_replace_callback($pattern,'unshorten_url',$text);
    return $text;
}

add_filter('content_save_pre', 'find_links_for_unshortening', 999);

Updated 2015-08-20-1042 - fixed links & changed code for better regex and to contain url fixing to urls only (and not full text of post)
Updated 2015-08-21-1229 - added wikipedia hack

Just add this code to the functions.php of your WordPress theme and you’re on your way to abandoning shortened links whenever you save or update a post.

see http://www.davidnunez.com/2015/08/19/automatically-unshortening-links-in-wordpress-posts/