int silc_buffer_format(SilcBuffer dst, ...);

    Formats a buffer from a variable argument list.  Returns -1 on error
    and the length of the formatted buffer otherwise.

    ret = silc_buffer_format(buffer,
                             SILC_STR_INT(intval),
                             SILC_STR_CHAR(charval),
                             SILC_STR_INT(intval),
                             SILC_STR_SHORT(str_len),
                             SILC_STR_UI_XNSTRING(str, str_len),
                             SILC_STR_END);
    if (ret < 0)
      error;