rem: len = string_to_number(s, 0, 0xFFFF);  if (len == -1)
add: if (string_to_number(s, 0, 0xFFFF, &len) == -1)
context: parse_length(const char *s){	int len;		len = string_to_number(s, 0, 0xFFFF);		if (len == -1)		exit_error(PARAMETER_PROBLEM, "length invalid: `%s'\n", s);	else		return (u_int16_t )len;}