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wpa_supplicant: Check rate sets before joining BSS

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IEEE Std 802.11-2007 7.3.2.2 demands that in order to join a BSS all
required basic rates have to be supported by the hardware.

Signed-off-by: Christian Lamparter <chunkeey@googlemail.com>
This commit is contained in:
Christian Lamparter 2011-10-23 11:58:54 +03:00 committed by Jouni Malinen
parent 6bf731e8ce
commit e1e8cae3c7
1 changed files with 112 additions and 0 deletions
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112
wpa_supplicant/events.c
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@ -478,6 +478,112 @@ static int freq_allowed(int *freqs, int freq)
}
static int ht_supported(const struct hostapd_hw_modes *mode)
{
if (!(mode->flags & HOSTAPD_MODE_FLAG_HT_INFO_KNOWN)) {
/*
* The driver did not indicate whether it supports HT. Assume
* it does to avoid connection issues.
*/
return 1;
}
/*
* IEEE Std 802.11n-2009 20.1.1:
* An HT non-AP STA shall support all EQM rates for one spatial stream.
*/
return mode->mcs_set[0] == 0xff;
}
static int rate_match(struct wpa_supplicant *wpa_s, struct wpa_scan_res *bss)
{
const struct hostapd_hw_modes *mode = NULL, *modes;
const u8 scan_ie[2] = { WLAN_EID_SUPP_RATES, WLAN_EID_EXT_SUPP_RATES };
const u8 *rate_ie;
int i, j, k;
modes = wpa_s->hw.modes;
if (modes == NULL) {
/*
* The driver does not provide any additional information
* about the utilized hardware, so allow the connection attempt
* to continue.
*/
return 1;
}
for (i = 0; i < wpa_s->hw.num_modes; i++) {
for (j = 0; j < modes[i].num_channels; j++) {
int freq = modes[i].channels[j].freq;
if (freq == bss->freq) {
if (mode &&
mode->mode == HOSTAPD_MODE_IEEE80211G)
break; /* do not allow 802.11b replace
* 802.11g */
mode = &modes[i];
break;
}
}
}
if (mode == NULL)
return 0;
for (i = 0; i < (int) sizeof(scan_ie); i++) {
rate_ie = wpa_scan_get_ie(bss, scan_ie[i]);
if (rate_ie == NULL)
continue;
for (j = 2; j < rate_ie[1] + 2; j++) {
int flagged = !!(rate_ie[j] & 0x80);
int r = (rate_ie[j] & 0x7f) * 5;
/*
* IEEE Std 802.11n-2009 7.3.2.2:
* The new BSS Membership selector value is encoded
* like a legacy basic rate, but it is not a rate and
* only indicates if the BSS members are required to
* support the mandatory features of Clause 20 [HT PHY]
* in order to join the BSS.
*/
if (flagged && ((rate_ie[j] & 0x7f) ==
BSS_MEMBERSHIP_SELECTOR_HT_PHY)) {
if (!ht_supported(mode)) {
wpa_dbg(wpa_s, MSG_DEBUG,
" hardware does not support "
"HT PHY");
return 0;
}
continue;
}
if (!flagged)
continue;
/* check for legacy basic rates */
for (k = 0; k < mode->num_rates; k++) {
if (mode->rates[k] == r)
break;
}
if (k == mode->num_rates) {
/*
* IEEE Std 802.11-2007 7.3.2.2 demands that in
* order to join a BSS all required rates
* have to be supported by the hardware.
*/
wpa_dbg(wpa_s, MSG_DEBUG, " hardware does "
"not support required rate %d.%d Mbps",
r / 10, r % 10);
return 0;
}
}
}
return 1;
}
static struct wpa_ssid * wpa_scan_res_match(struct wpa_supplicant *wpa_s,
int i, struct wpa_scan_res *bss,
struct wpa_ssid *group)
@ -610,6 +716,12 @@ static struct wpa_ssid * wpa_scan_res_match(struct wpa_supplicant *wpa_s,
continue;
}
if (!rate_match(wpa_s, bss)) {
wpa_dbg(wpa_s, MSG_DEBUG, " skip - rate sets do "
"not match");
continue;
}
#ifdef CONFIG_P2P
/*
* TODO: skip the AP if its P2P IE has Group Formation