On Fri, Jan 09, 2015 at 03:52:44PM +0000, Stuart Henderson wrote:
> This has been bugging me for ages but I forgot about it for quite a
> while (mostly because iwn scanning was broken on my laptop for ages).
> RSSI is a signed value, but various places are storing it unsigned,
> in particular ifconfig prints it that way (so the displayed strength
> is unfeasibly large; realistic values are maybe -40 [very strong
> signal] to -90 or so).
>
> Diff below fixes things for ifconfig and doesn't affect things used
> in other places in the kernel. Sample output from iwn scan below (and
> the values are sensible).
>
> OK?
OK. This aligns ifconfig output with what my wifi textbook says about
dBm and rssi. Before this diff ifconfig reported 196dB for some wifi
networks around here which (if I got the math right) corresponds to
60000000000000000 Watts of tx power which, hmm, exceeds regulatory limits.
Can you switch "dB" to "dBm" as well?
>
> nwid Y2 chan 104 bssid 04:4f:f5:0c:a7:ec -52dB 54M
> privacy,spectrum_mgmt,short_slottime,wpa2
> nwid Y2-x chan 5 bssid 04:4f:f5:4c:a7:e8 -53dB 54M
> privacy,short_preamble,short_slottime,wpa2,802.1x
> nwid BTHub3-MM9S chan 6 bssid 00:81:d8:1a:c5:22 -78dB 54M
> privacy,short_preamble,short_slottime,wpa2
> nwid BTHub3-C2KT chan 11 bssid 40:4d:8e:51:3f:b9 -83dB 54M
> privacy,short_slottime,wpa2
> nwid Laboratory chan 2 bssid 78:54:2e:8a:c9:7a -89dB 54M
> privacy,short_slottime,wpa2
>
> There are various other rssi values (variables and returned by
> functions) which also use u_int8_t - ni_rssi, ic_max_rssi,
> ic_node_getrssi(), and some in rateadapt - as well as rxi_rssi which
> was already signed (and is copied to various unsigned variables).
> These seem more risky to change (or at least more complicated)
> so I haven't touched them here, but I wonder, does anyone have a
> handle on what's going on with these?
>
> Index: sys/net80211/ieee80211_ioctl.h
> ===================================================================
> RCS file: /cvs/src/sys/net80211/ieee80211_ioctl.h,v
> retrieving revision 1.20
> diff -u -p -r1.20 ieee80211_ioctl.h
> --- sys/net80211/ieee80211_ioctl.h 24 Aug 2014 18:01:27 -0000 1.20
> +++ sys/net80211/ieee80211_ioctl.h 9 Jan 2015 15:27:10 -0000
> @@ -295,8 +295,8 @@ struct ieee80211_nodereq {
> u_int8_t nr_rates[IEEE80211_RATE_MAXSIZE]; /* rate set */
>
> /* Node status information */
> - u_int8_t nr_rssi; /* received signal strength */
> - u_int8_t nr_max_rssi; /* maximum rssi */
> + int8_t nr_rssi; /* received signal strength */
> + int8_t nr_max_rssi; /* maximum rssi */
> u_int8_t nr_tstamp[8]; /* from last received beacon */
> u_int16_t nr_intval; /* beacon interval */
> u_int16_t nr_capinfo; /* capabilities */
> Index: sbin/ifconfig/ifconfig.c
> ===================================================================
> RCS file: /cvs/src/sbin/ifconfig/ifconfig.c,v
> retrieving revision 1.293
> diff -u -p -r1.293 ifconfig.c
> --- sbin/ifconfig/ifconfig.c 6 Jan 2015 21:26:46 -0000 1.293
> +++ sbin/ifconfig/ifconfig.c 9 Jan 2015 15:27:10 -0000
> @@ -2087,7 +2087,7 @@ ieee80211_status(void)
> if (nr.nr_max_rssi)
> printf(" %u%%", IEEE80211_NODEREQ_RSSI(&nr));
> else
> - printf(" %udB", nr.nr_rssi);
> + printf(" %ddB", nr.nr_rssi);
> }
> }
>
> @@ -2318,7 +2318,7 @@ ieee80211_printnode(struct ieee80211_nod
> if (nr->nr_max_rssi)
> printf("%u%% ", IEEE80211_NODEREQ_RSSI(nr));
> else
> - printf("%udB ", nr->nr_rssi);
> + printf("%ddB ", nr->nr_rssi);
>
> if (nr->nr_pwrsave)
> printf("powersave ");
