beacon/proberesp/assocresp_ie have nothing to do with acutal frame?

[Jeon]

I am trying to put my own vendor specific Information Element (IE) to
beacon and probe response frames.

With some investingation, I've found that
`ieee802_11_build_ap_params()` in `beacon.c` and
`hostapd_build_ap_extra_ies()` in `ap_drv_opc.c` are relevant to what
I am looking for.

First, I've implemented code putting my own IE in
`hostapd_build_ap_extra_ies()` and checked that `beacon_ies` contains
my own IE:

> $ sudo ./hostapd hostapd.conf -dd
> ...
> nl80211: beacon_ies - hexdump(len=13) 7f 08 00 00 00 00 00 00 00 40 ff 01 01
> nl80211: proberesp_ies - hexdump(len=13) 7f 08 00 00 00 00 00 00 00 40 ff 01 01
> nl80211: assocresp_ies - hexdump(len=10) 7f 08 00 00 00 00 00 00 00 40
> ...

The last 3 octets (`ff 01 01`) are added IE. However, when I capture
beacon frames and probe response frames via Wireshark, the added IE
did not appear.

Secondly, I moved the implemented code from
`hostapd_build_ap_extra_ies()` to `ieee802_11_build_ap_params()` and
make params.tail contain my own IE. Then, I can see that beacon frames
contain the added IE. while probe response frames don't.

It's okay, it may be done with `hostapd_gen_probe_resp()`. But I am
curious, what is real purposes of beacon/proberesp/assocresp_ie, if
they are actually transmitted?

Regards,
Jeon.