Display Total Number of Social Shares

I have to display the total number of social shares, like mashable does in it´s website.

It´s not a problem, I found a php code that does the job.

function getTotalShares($atts) {
extract(shortcode_atts(array(
    'cache' => '3600',
    'url' => 0,
    'f' => 0,
    'bgcolor' => '#ffffff',
    'bordercolor' => '#ffffff',
    'borderwidth' => '0',
    'bordertype' => 'solid',
    'fontcolor' => '#7fc04c',
    'fontsize' => '55',
    'fontweight' => 'normal',
    'padding' => '1'
  ), $atts));

 $shareHash = "$cache.$url.$f.$bgcolor.$bordercolor.$borderwidth.$bordertype.$fontcolor.$fontsize.$fontweight.$padding";
 $totalShareRecord = 'totalshares_' . $shareHash;
 $cachedposts = get_transient($totalShareRecord);
 if ($cachedposts !== false) {
 return $cachedposts;

 } else {

   if (!$url) $url = get_permalink($post->ID);

   $json = file_get_contents("http://api.sharedcount.com/?url=" . rawurlencode($url));
    $counts = json_decode($json, true);
    $return = $counts['Twitter'] + $counts['Facebook']['total_count'] + $counts['GooglePlusOne'];
    if ($f) $return = '
' . $return . '';
    set_transient($totalShareRecord, $return, $cache);
    return $return;
 }
}
add_shortcode('totalshares','getTotalShares');

Now the problematic!

The code above get the numbers of shares based on the permalink, which is pulled by get_permalink($post->ID);. My website works as a content aggregator, so I want to pull the number of shares of the original post url, which in my website is filled in the post meta links_link_custom. My question is: Is this possible?

I hope this text is not confusing, please comment if more information is needed.