down_for_everyone.php

<?php

function down_for_everyone($url) {
  if (strpos($url, '://') === FALSE) {
    $url = "http://$url";
  }

  if (filter_var($url, FILTER_VALIDATE_URL)) {
    $handle = curl_init($url);
    curl_setopt($handle, CURLOPT_FOLLOWLOCATION, TRUE);
    curl_setopt($handle, CURLOPT_RETURNTRANSFER, TRUE);
    curl_setopt($handle, CURLOPT_MAXREDIRS, 30);

    if (($response = curl_exec($handle)) !== FALSE) {
      $code = curl_getinfo($handle, CURLINFO_HTTP_CODE);
      return "It's just you, $url is up and returned an HTTP status: $code";
    }
    else {
      return "It's not just you, $url is down.";
    }

    curl_close($handle);
  }
  else {
    return "$url is like, totally malformed.";
  }
}