mbssid: Functions for building Multiple BSSID elements

Add Multiple BSSID element data per IEEE Std 802.11ax-2021, 9.4.2.45.
Split the BSSes into multiple elements if the data does not fit in
the 255 bytes allowed for a single element.

Store the total count of elements created and the offset to the start
of each element in the provided buffer.

Set the DTIM periods of non-transmitted profiles equal to the EMA
profile periodicity if those are not a multiple of the latter already as
recommended in IEEE Std 802.11ax-2021, Annex AA (Multiple BSSID
configuration examples).

Signed-off-by: Aloka Dixit <quic_alokad@quicinc.com>
Co-developed-by: John Crispin <john@phrozen.org>
Signed-off-by: John Crispin <john@phrozen.org>

diff --git a/src/ap/ieee802_11.c b/src/ap/ieee802_11.c
index ba3c6009e485260fe52da0122020b4f3a2ea6e10..5ed91b4f389ae2200b9c8bf3437e3bf2e8f2c264 100644 (file)
--- a/src/ap/ieee802_11.c
+++ b/src/ap/ieee802_11.c
@@ -3116,6 +3116,23 @@ static void handle_auth(struct hostapd_data *hapd,
 }
 
 
+static u8 hostapd_max_bssid_indicator(struct hostapd_data *hapd)
+{
+       size_t num_bss_nontx;
+       u8 max_bssid_ind = 0;
+
+       if (!hapd->iconf->mbssid || hapd->iface->num_bss <= 1)
+               return 0;
+
+       num_bss_nontx = hapd->iface->num_bss - 1;
+       while (num_bss_nontx > 0) {
+               max_bssid_ind++;
+               num_bss_nontx >>= 1;
+       }
+       return max_bssid_ind;
+}
+
+
 int hostapd_get_aid(struct hostapd_data *hapd, struct sta_info *sta)
 {
        int i, j = 32, aid;
@@ -6705,4 +6722,205 @@ u8 * hostapd_eid_rnr(struct hostapd_data *hapd, u8 *eid, u32 type)
        return eid;
 }
 
+
+static size_t hostapd_eid_mbssid_elem_len(struct hostapd_data *hapd,
+                                         u32 frame_type, size_t *bss_index)
+{
+       size_t len = 3, i;
+
+       for (i = *bss_index; i < hapd->iface->num_bss; i++) {
+               struct hostapd_data *bss = hapd->iface->bss[i];
+               const u8 *auth, *rsn, *rsnx;
+               size_t nontx_profile_len, auth_len;
+
+               if (!bss || !bss->conf || !bss->started)
+                       continue;
+
+               /*
+                * Sublement ID: 1 octet
+                * Length: 1 octet
+                * Nontransmitted capabilities: 4 octets
+                * SSID element: 2 + variable
+                * Multiple BSSID Index Element: 3 octets (+2 octets in beacons)
+                * Fixed length = 1 + 1 + 4 + 2 + 3 = 11
+                */
+               nontx_profile_len = 11 + bss->conf->ssid.ssid_len;
+
+               if (frame_type == WLAN_FC_STYPE_BEACON)
+                       nontx_profile_len += 2;
+
+               auth = wpa_auth_get_wpa_ie(bss->wpa_auth, &auth_len);
+               if (auth) {
+                       rsn = get_ie(auth, auth_len, WLAN_EID_RSN);
+                       if (rsn)
+                               nontx_profile_len += 2 + rsn[1];
+
+                       rsnx = get_ie(auth, auth_len, WLAN_EID_RSNX);
+                       if (rsnx)
+                               nontx_profile_len += 2 + rsnx[1];
+               }
+
+               if (len + nontx_profile_len > 255)
+                       break;
+
+               len += nontx_profile_len;
+       }
+
+       *bss_index = i;
+       return len;
+}
+
+
+size_t hostapd_eid_mbssid_len(struct hostapd_data *hapd, u32 frame_type,
+                             u8 *elem_count)
+{
+       size_t len = 0, bss_index = 1;
+
+       if (!hapd->iconf->mbssid || hapd->iface->num_bss <= 1 ||
+           (frame_type != WLAN_FC_STYPE_BEACON &&
+            frame_type != WLAN_FC_STYPE_PROBE_RESP))
+               return 0;
+
+       if (frame_type == WLAN_FC_STYPE_BEACON) {
+               if (!elem_count) {
+                       wpa_printf(MSG_INFO,
+                                  "MBSSID: Insufficient data for Beacon frames");
+                       return 0;
+               }
+               *elem_count = 0;
+       }
+
+       while (bss_index < hapd->iface->num_bss) {
+               len += hostapd_eid_mbssid_elem_len(hapd, frame_type,
+                                                  &bss_index);
+
+               if (frame_type == WLAN_FC_STYPE_BEACON)
+                       *elem_count += 1;
+       }
+       return len;
+}
+
+
+static u8 * hostapd_eid_mbssid_elem(struct hostapd_data *hapd, u8 *eid, u8 *end,
+                                   u32 frame_type, u8 max_bssid_indicator,
+                                   size_t *bss_index, u8 elem_count)
+{
+       size_t i;
+       u8 *eid_len_offset, *max_bssid_indicator_offset;
+
+       *eid++ = WLAN_EID_MULTIPLE_BSSID;
+       eid_len_offset = eid++;
+       max_bssid_indicator_offset = eid++;
+
+       for (i = *bss_index; i < hapd->iface->num_bss; i++) {
+               struct hostapd_data *bss = hapd->iface->bss[i];
+               struct hostapd_bss_config *conf;
+               u8 *eid_len_pos, *nontx_bss_start = eid;
+               const u8 *auth, *rsn, *rsnx;
+               size_t auth_len = 0;
+               u16 capab_info;
+
+               if (!bss || !bss->conf || !bss->started)
+                       continue;
+               conf = bss->conf;
+
+               *eid++ = WLAN_MBSSID_SUBELEMENT_NONTRANSMITTED_BSSID_PROFILE;
+               eid_len_pos = eid++;
+
+               capab_info = hostapd_own_capab_info(bss);
+               *eid++ = WLAN_EID_NONTRANSMITTED_BSSID_CAPA;
+               *eid++ = sizeof(capab_info);
+               WPA_PUT_LE16(eid, capab_info);
+               eid += sizeof(capab_info);
+
+               *eid++ = WLAN_EID_SSID;
+               *eid++ = conf->ssid.ssid_len;
+               os_memcpy(eid, conf->ssid.ssid, conf->ssid.ssid_len);
+               eid += conf->ssid.ssid_len;
+
+               *eid++ = WLAN_EID_MULTIPLE_BSSID_INDEX;
+               if (frame_type == WLAN_FC_STYPE_BEACON) {
+                       *eid++ = 3;
+                       *eid++ = i; /* BSSID Index */
+                       if (hapd->iconf->mbssid == ENHANCED_MBSSID_ENABLED &&
+                           (conf->dtim_period % elem_count))
+                               conf->dtim_period = elem_count;
+                       *eid++ = conf->dtim_period;
+                       *eid++ = 0xFF; /* DTIM Count */
+               } else {
+                       /* Probe Request frame does not include DTIM Period and
+                        * DTIM Count fields. */
+                       *eid++ = 1;
+                       *eid++ = i; /* BSSID Index */
+               }
+
+               auth = wpa_auth_get_wpa_ie(bss->wpa_auth, &auth_len);
+               if (auth) {
+                       rsn = get_ie(auth, auth_len, WLAN_EID_RSN);
+                       if (rsn) {
+                               os_memcpy(eid, rsn, 2 + rsn[1]);
+                               eid += 2 + rsn[1];
+                       }
+
+                       rsnx = get_ie(auth, auth_len, WLAN_EID_RSNX);
+                       if (rsnx) {
+                               os_memcpy(eid, rsnx, 2 + rsnx[1]);
+                               eid += 2 + rsnx[1];
+                       }
+               }
+
+               *eid_len_pos = (eid - eid_len_pos) - 1;
+
+               if (((eid - eid_len_offset) - 1) > 255) {
+                       eid = nontx_bss_start;
+                       break;
+               }
+       }
+
+       *bss_index = i;
+       *max_bssid_indicator_offset = max_bssid_indicator;
+       if (*max_bssid_indicator_offset < 1)
+               *max_bssid_indicator_offset = 1;
+       *eid_len_offset = (eid - eid_len_offset) - 1;
+       return eid;
+}
+
+
+u8 * hostapd_eid_mbssid(struct hostapd_data *hapd, u8 *eid, u8 *end,
+                       unsigned int frame_stype, u8 elem_count,
+                       u8 **elem_offset)
+{
+       size_t bss_index = 1;
+       u8 elem_index = 0;
+
+       if (!hapd->iconf->mbssid || hapd->iface->num_bss <= 1 ||
+           (frame_stype != WLAN_FC_STYPE_BEACON &&
+            frame_stype != WLAN_FC_STYPE_PROBE_RESP))
+               return eid;
+
+       if (frame_stype == WLAN_FC_STYPE_BEACON && !elem_offset) {
+               wpa_printf(MSG_INFO,
+                          "MBSSID: Insufficient data for Beacon frames");
+               return eid;
+       }
+
+       while (bss_index < hapd->iface->num_bss) {
+               if (frame_stype == WLAN_FC_STYPE_BEACON) {
+                       if (elem_index == elem_count) {
+                               wpa_printf(MSG_WARNING,
+                                          "MBSSID: Larger number of elements than there is room in the provided array");
+                               break;
+                       }
+
+                       elem_offset[elem_index] = eid;
+                       elem_index = elem_index + 1;
+               }
+               eid = hostapd_eid_mbssid_elem(hapd, eid, end, frame_stype,
+                                             hostapd_max_bssid_indicator(hapd),
+                                             &bss_index, elem_count);
+       }
+
+       return eid;
+}
+
 #endif /* CONFIG_NATIVE_WINDOWS */

diff --git a/src/ap/ieee802_11.h b/src/ap/ieee802_11.h
index fa1f47b957e45d633c5448a9c0e5563830227b53..6fa7cc41d84c6e2da7d6b411559101ca581b9664 100644 (file)
--- a/src/ap/ieee802_11.h
+++ b/src/ap/ieee802_11.h
@@ -214,5 +214,10 @@ u16 copy_sta_eht_capab(struct hostapd_data *hapd, struct sta_info *sta,
                       enum ieee80211_op_mode opmode,
                       const u8 *he_capab, size_t he_capab_len,
                       const u8 *eht_capab, size_t eht_capab_len);
+size_t hostapd_eid_mbssid_len(struct hostapd_data *hapd, u32 frame_type,
+                             u8 *elem_count);
+u8 * hostapd_eid_mbssid(struct hostapd_data *hapd, u8 *eid, u8 *end,
+                       unsigned int frame_stype, u8 elem_count,
+                       u8 **elem_offset);
 
 #endif /* IEEE802_11_H */

diff --git a/src/common/ieee802_11_defs.h b/src/common/ieee802_11_defs.h
index 669f380d2fba7f2be7fcc68dd5fe359b0ec6fc27..023bbc3324aa0b6b6cd0989b8583916539f87254 100644 (file)
--- a/src/common/ieee802_11_defs.h
+++ b/src/common/ieee802_11_defs.h
@@ -588,6 +588,9 @@
 #define WLAN_RSNX_CAPAB_SECURE_RTT 9
 #define WLAN_RSNX_CAPAB_PROT_RANGE_NEG 10
 
+/* Multiple BSSID element subelements */
+#define WLAN_MBSSID_SUBELEMENT_NONTRANSMITTED_BSSID_PROFILE 0
+
 /* Action frame categories (IEEE Std 802.11-2016, 9.4.1.11, Table 9-76) */
 #define WLAN_ACTION_SPECTRUM_MGMT 0
 #define WLAN_ACTION_QOS 1