gistfile1.php

<?php
// fetches the JRDD file for the given domain/identifier. $scheme
// is the scheme from user input, $domain is the domain, and $identifier is
// the normalized user input. Returns a the OpenID token endpoint URL or false.
function discover_openid_endpoint($curl, $scheme, $domain) {
  $query = '?format=json';

  // first try SSL
  curl_setopt($curl, CURLOPT_URL,
    'https://' . $domain . '/.well-known/host-meta' . $query);
  $jrdd = curl_exec($curl);

  // don't fallback to HTTP if the user explicitly said HTTPS
  if (!$jrdd && $scheme != 'https') {
    curl_setopt($curl, CURLOPT_URL,
      'http://' . $domain . '/.well-known/host-meta' . $query);
    $jrdd = curl_exec($curl);
  }
  
  // make sure we got something
  if (!$jrdd) {
    return false;
  }

  // make sure it has a links array
  $jrdd = json_decode($jrdd, true);
  if (!isset($jrdd['links'])) {
    return false;
  }

  // find the openid href
  foreach ($jrdd['link'] as $link) {
    if ($link['rel'] == 'openid') {
      return $link['href'];
    }
  }
  return false;
}

Shouldn't it be /.well-known/host-meta ?