From 32f4e7b124f918a49de493b6adb068d7054dae5a Mon Sep 17 00:00:00 2001 From: David A Benjamin Date: Sun, 5 Sep 2010 19:04:10 +0300 Subject: [PATCH] wext: Fix scan result signal levels when driver reports in dBm wpa_supplicant showed signal levels incorrectly with some drivers: Jun 6 16:29:36 rupert wpa_supplicant[18945]: Current BSS: 00:0d:97:11:40:d6 level=190 Jun 6 16:29:36 rupert wpa_supplicant[18945]: Selected BSS: 00:0d:97:11:50:09 level=192 Judging from output from other tools (iwlist) and the min_diff block at the end of wpa_supplicant_need_to_roam, it seems these values should actually be negative. Specifically, if one treats that number as a signed char instead of unsigned, everything matches up. To be honest, I've little to no understanding of wireless, but looking at the source code for wireless-tools (iw_print_stats in iwlib.c), it seems that the fields of the iw_quality struct need to be decoded differently depending on various flags. I guess src/drivers/driver_wext.c should have similar logic in wext_get_scan_qual. I wrote a patch that attempts to replicate some of that logic, although it may be more complicated than is necessary; I think some of the complexity is for backwards-compatibility, which might not be necessary depending on wpa_supplicant's dependencies? In any case, it is attached. Again, I don't know how any of this works, so it's likely the patch is a bit off. But I think at least the logic to determine min_diff in wpa_supplicant_need_to_roam would be more accurate if level were determined correctly. --- src/drivers/driver_wext.c | 15 +++++++++++++-- src/drivers/driver_wext.h | 2 ++ 2 files changed, 15 insertions(+), 2 deletions(-) diff --git a/src/drivers/driver_wext.c b/src/drivers/driver_wext.c index d3629dd0d..f0de6aae3 100644 --- a/src/drivers/driver_wext.c +++ b/src/drivers/driver_wext.c @@ -1117,7 +1117,8 @@ static void wext_get_scan_freq(struct iw_event *iwe, } -static void wext_get_scan_qual(struct iw_event *iwe, +static void wext_get_scan_qual(struct wpa_driver_wext_data *drv, + struct iw_event *iwe, struct wext_scan_data *res) { res->res.qual = iwe->u.qual.qual; @@ -1131,6 +1132,14 @@ static void wext_get_scan_qual(struct iw_event *iwe, res->res.flags |= WPA_SCAN_NOISE_INVALID; if (iwe->u.qual.updated & IW_QUAL_DBM) res->res.flags |= WPA_SCAN_LEVEL_DBM; + if ((iwe->u.qual.updated & IW_QUAL_DBM) || + ((iwe->u.qual.level != 0) && + (iwe->u.qual.level > drv->max_level))) { + if (iwe->u.qual.level >= 64) + res->res.level -= 0x100; + if (iwe->u.qual.noise >= 64) + res->res.noise -= 0x100; + } } @@ -1406,7 +1415,7 @@ struct wpa_scan_results * wpa_driver_wext_get_scan_results(void *priv) wext_get_scan_freq(iwe, &data); break; case IWEVQUAL: - wext_get_scan_qual(iwe, &data); + wext_get_scan_qual(drv, iwe, &data); break; case SIOCGIWENCODE: wext_get_scan_encode(iwe, &data); @@ -1504,6 +1513,8 @@ static int wpa_driver_wext_get_range(void *priv) "assuming WPA is not supported"); } + drv->max_level = range->max_qual.level; + os_free(range); return 0; } diff --git a/src/drivers/driver_wext.h b/src/drivers/driver_wext.h index 9176dd879..6382bbbcd 100644 --- a/src/drivers/driver_wext.h +++ b/src/drivers/driver_wext.h @@ -47,6 +47,8 @@ struct wpa_driver_wext_data { int scan_complete_events; int cfg80211; /* whether driver is using cfg80211 */ + + u8 max_level; }; int wpa_driver_wext_get_bssid(void *priv, u8 *bssid);