FILS: Add Operating Class and Primary Channel in FD for non-PSC chan

If a non-PSC 6 GHz channel with bandwidth higher than 20 MHz is
configured, duplicate beacons/FD/UBPR will be transmitted in other 20
MHz channels of the current configured bandwidth to aid in faster scan.
In such cases the duplicate FD needs to carry the Operating Class and
Primary Channel subfields for non-AP STAs to identify the primary
non-PSC.

IEEE Std 802.11-2020, 9.6.7.36 (FILS Discovery frame format):
"The Operating Class subfield specifies the operating class of the
Primary Channel of the transmitting AP (see 9.4.1.36).

The Primary Channel subfield is set to the channel number of the primary
channel (see 11.15.2) if the FILS Discovery frame is transmitted as a
non-HT duplicate PPDU; otherwise, the subfield is not present."

Hence, add the Operating Class and Primary Channel subfields if the
current channel is non-PSC and the channel bandwidth is 40 MHz or
higher.

Signed-off-by: Sriram R <quic_srirrama@quicinc.com>
Signed-off-by: Karthikeyan Kathirvel <quic_kathirve@quicinc.com>

diff --git a/src/ap/beacon.c b/src/ap/beacon.c
index ce806edf1856e1f5cb9ca16cd1af7c572f5157d9..c214f52274ae5f2538779db77cc3b63c20fa694b 100644 (file)
--- a/src/ap/beacon.c
+++ b/src/ap/beacon.c
@@ -1948,6 +1948,17 @@ static u8 * hostapd_gen_fils_discovery(struct hostapd_data *hapd, size_t *len)
                FD_FRAME_CTL_CAP_PRESENT;
        total_len += 4 + 1 + 2;
 
+       /* Fill primary channel information for 6 GHz channels with over 20 MHz
+        * bandwidth, if the primary channel is not a PSC */
+       if (is_6ghz_op_class(hapd->iconf->op_class) &&
+           !is_6ghz_psc_frequency(ieee80211_chan_to_freq(
+                                          NULL, hapd->iconf->op_class,
+                                          hapd->iconf->channel)) &&
+           op_class_to_bandwidth(hapd->iconf->op_class) > 20) {
+               ctl |= FD_FRAME_CTL_PRI_CHAN_PRESENT;
+               total_len += 2;
+       }
+
        /* Check for optional subfields and calculate length */
        if (wpa_auth_write_fd_rsn_info(hapd->wpa_auth, fd_rsn_info)) {
                ctl |= FD_FRAME_CTL_RSN_INFO_PRESENT;
@@ -2009,9 +2020,11 @@ static u8 * hostapd_gen_fils_discovery(struct hostapd_data *hapd, size_t *len)
        WPA_PUT_LE16(pos, hostapd_fils_discovery_cap(hapd));
        pos += 2;
 
-       /* Operating Class - not present */
-
-       /* Primary Channel - not present */
+       /* Operating Class and Primary Channel - if a 6 GHz chan is non PSC */
+       if (ctl & FD_FRAME_CTL_PRI_CHAN_PRESENT) {
+               *pos++ = hapd->iconf->op_class;
+               *pos++ = hapd->iconf->channel;
+       }
 
        /* AP Configuration Sequence Number - not present */