int silc_buffer_unformat(SilcBuffer src, ...);

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

    ret = silc_buffer_unformat(buffer,
                               SILC_STR_UI_INT(&intval),
                               SILC_STR_CHAR(&charval),
                               SILC_STR_OFFSET(4),
                               SILC_STR_UI16_NSTRING_ALLOC(&str, &str_len),
                               SILC_STR_END);
    if (ret < 0)
      error;