va_start(ap, error_string);
rpc->error_string = malloc(1024);
vsnprintf(rpc->error_string, 1024, error_string, ap);
va_end(ap);
va_start(ap, error_string);
rpc->error_string = malloc(1024);
vsnprintf(rpc->error_string, 1024, error_string, ap);
va_end(ap);