Validates a token based on $value, the user session, and the private key.
$token: The token to be validated.
$value: An additional value to base the token on.
$skip_anonymous: Set to true to skip token validation for anonymous users.
True for a valid token, false for an invalid token. When $skip_anonymous is true, the return value will always be true for anonymous users.
function drupal_valid_token($token, $value = '', $skip_anonymous = FALSE) {
global $user;
return $skip_anonymous && $user->uid == 0 || $token == drupal_get_token($value);
}