code: function getFingerprintForURL(url) {
  	var domain = getDomain(url);
  	var found = global.requestSSLFingerprints[domain];
  	debug('getFingerprintForURL %s -> %s=%s',url,domain,found);
  	if (!found) {
  		// try a wildcard search
  		var u = urlib.parse(domain),
  			tokens = (u && u.host || domain).split('.');
  		domain = '*.'+tokens.splice(tokens.length > 1 ? 0 : 1).join('.');
  		found = global.requestSSLFingerprints[domain];
  		debug('getFingerprintForURL (wildcard) %s -> %s=%s',url,domain,found);
  	}
  	return found;
  }
docs: lookup a fingerprint for a given URL by using the domain. returns null if
  not found