ifconfig(8): scan list SSID UTF-32 support

[enweiwu]

Summary

Below is the planned commit message:

ifconfig(8): scan list SSID UTF-32 support

    Originally, if SSID exist characters are not printable ASCII but is printable in UTF-32 (many language, for e.g. Chinese), they will be printed as hex. Fix it by turning normal character to wide character (wchar_t) and verify whether a wide character is printable by iswprint(). This is just a little hack and is not elegant. Maybe we can store SSID in wchar_t in the begining of ifconfig(8)?

Test Plan

We can make use of wtap(4) for simulating 802.11 device:

Load wtap.ko

Goto sys/modules/wtap, and load wtap.ko (may need the priority of super user):

kldload ./wtap.ko

Create two parent wlan devices wtap0, wtap1

Goto tools/tools/wtap/wtap, and follow the commands below (may need the priority of super user) :

./wtap c 0
./wtap c 1

Create two child wlan devices (vap) wlan0, wlan1 in IBSS mode

Follow the commands below (may need the priority of super user) :

ifconfig wlan0 create wlandev wtap0 wlanmode adhoc
ifconfig wlan1 create wlandev wtap1 wlanmode adhoc ssid <SSID you want to test>

Use visibility tool to enable communications between wlan0 and wlan1

Goto tools/tools/wtap/vis_map, and follow the commands below (may need the priority of super user) :

./vis_map o
./vis_map a 0 1
./vis_map a 1 0

SSID scan test

Bring up wlan0, wlan1:

ifconfig wlan0 up
ifconfig wlan1 up

Correctly setup locale:

export LC_ALL=<your locale>

Then perform scanning, and see whether the output is desired:

ifconfig wlan0 scan

[bz]

See also https://reviews.freebsd.org/D32847

[enweiwu]

In D37070#841801, @bz wrote:

See also https://reviews.freebsd.org/D32847

Hi, Bjoern,

Sorry for not seeing the diff D32847 before I made this diff. So we cannot assume that SSID is encoded in UTF-8, and we shall check bit 48 (SSID is UTF-8 encoded) in Extended Capabilities element (127, IEEE80211_ELEMID_EXTCAP).

But I have noticed this comment in D32847:

To my surprise, while most frames did contain extended capabilities, none of them indicated that SSID is UTF-8 encoded (while it really was) and one AP with non-Latin UTF-8 SSID did not send any EXPCAP element.

So the question seems to be very tricky...