HE: Fix HE Capabilities element variable length encoding

The HE Capibilities element has dynamic size due to the variable length
and optional fields at the end. Mask out the channel width capabilities
that are less than the configured. Only add the MCS/NSS sets for the
announced channel widths and also add the PPET elements.

Signed-off-by: Shashidhar Lakkavalli <slakkavalli@datto.com>
Signed-off-by: John Crispin <john@phrozen.org>

src/ap/ieee802_11_he.c

@@ -16,17 +16,69 @@
 #include "ieee802_11.h"
 #include "dfs.h"
 
+static u8 ieee80211_he_ppet_size(u8 ppe_thres_hdr, const u8 *phy_cap_info)
+{
+	u8 sz = 0, ru;
+
+	if ((phy_cap_info[HE_PHYCAP_PPE_THRESHOLD_PRESENT_IDX] &
+	     HE_PHYCAP_PPE_THRESHOLD_PRESENT_IDX) == 0)
+		return 0;
+
+	ru = (ppe_thres_hdr >> HE_PPE_THRES_RU_INDEX_BITMASK_SHIFT) &
+		HE_PPE_THRES_RU_INDEX_BITMASK_MASK;
+	while (ru) {
+		if (ru & 0x1)
+			sz++;
+		ru >>= 1;
+	}
+
+	sz *= 1 + (ppe_thres_hdr & HE_PPE_THRES_NSS_MASK);
+	sz = (sz * 6) + 7;
+	if (sz % 8)
+		sz += 8;
+	sz /= 8;
+
+	return sz;
+}
+
+
 u8 * hostapd_eid_he_capab(struct hostapd_data *hapd, u8 *eid)
 {
 	struct ieee80211_he_capabilities *cap;
 	struct hostapd_hw_modes *mode = hapd->iface->current_mode;
+	u8 he_oper_chwidth = ~HE_PHYCAP_CHANNEL_WIDTH_MASK;
 	u8 *pos = eid;
+	u8 ie_size = 0, mcs_nss_size = 0, ppet_size = 0;
 
 	if (!mode)
 		return eid;
 
+	ie_size = sizeof(struct ieee80211_he_capabilities);
+	ppet_size = ieee80211_he_ppet_size(mode->he_capab.ppet[0],
+					   mode->he_capab.phy_cap);
+
+	switch (hapd->iface->conf->he_oper_chwidth) {
+	case CHANWIDTH_80P80MHZ:
+		he_oper_chwidth |=
+			HE_PHYCAP_CHANNEL_WIDTH_SET_80PLUS80MHZ_IN_5G;
+		mcs_nss_size += 4;
+		/* fall through */
+	case CHANWIDTH_160MHZ:
+		he_oper_chwidth |= HE_PHYCAP_CHANNEL_WIDTH_SET_160MHZ_IN_5G;
+		mcs_nss_size += 4;
+		/* fall through */
+	case CHANWIDTH_80MHZ:
+	case CHANWIDTH_USE_HT:
+		he_oper_chwidth |= HE_PHYCAP_CHANNEL_WIDTH_SET_40MHZ_IN_2G |
+			HE_PHYCAP_CHANNEL_WIDTH_SET_40MHZ_80MHZ_IN_5G;
+		mcs_nss_size += 4;
+		break;
+	}
+
+	ie_size += mcs_nss_size + ppet_size;
+
 	*pos++ = WLAN_EID_EXTENSION;
-	*pos++ = 1 + sizeof(struct ieee80211_he_capabilities);
+	*pos++ = 1 + ie_size;
 	*pos++ = WLAN_EID_EXT_HE_CAPABILITIES;
 
 	cap = (struct ieee80211_he_capabilities *) pos;
@@ -36,8 +88,10 @@ u8 * hostapd_eid_he_capab(struct hostapd_data *hapd, u8 *eid)
 		  HE_MAX_MAC_CAPAB_SIZE);
 	os_memcpy(cap->he_phy_capab_info, mode->he_capab.phy_cap,
 		  HE_MAX_PHY_CAPAB_SIZE);
-	os_memcpy(cap->he_txrx_mcs_support, mode->he_capab.mcs,
-		  HE_MAX_MCS_CAPAB_SIZE);
+	os_memcpy(cap->optional, mode->he_capab.mcs, mcs_nss_size);
+	if (ppet_size)
+		os_memcpy(&cap->optional[mcs_nss_size], mode->he_capab.ppet,
+			  ppet_size);
 
 	if (hapd->iface->conf->he_phy_capab.he_su_beamformer)
 		cap->he_phy_capab_info[HE_PHYCAP_SU_BEAMFORMER_CAPAB_IDX] |=
@@ -60,7 +114,10 @@ u8 * hostapd_eid_he_capab(struct hostapd_data *hapd, u8 *eid)
 		cap->he_phy_capab_info[HE_PHYCAP_MU_BEAMFORMER_CAPAB_IDX] &=
 			~HE_PHYCAP_MU_BEAMFORMER_CAPAB;
 
-	pos += sizeof(*cap);
+	cap->he_phy_capab_info[HE_PHYCAP_CHANNEL_WIDTH_SET_IDX] &=
+		he_oper_chwidth;
+
+	pos += ie_size;
 
 	return pos;
 }

src/common/ieee802_11_defs.h

@@ -2105,8 +2105,9 @@ enum nr_chan_width {
 struct ieee80211_he_capabilities {
 	u8 he_mac_capab_info[6];
 	u8 he_phy_capab_info[11];
-	u8 he_txrx_mcs_support[12]; /* TODO: 4, 8, or 12 octets */
-	/* PPE Thresholds (optional) */
+	/* Followed by 4, 8, or 12 octets of Supported HE-MCS And NSS Set field
+	* and optional variable length PPE Thresholds field. */
+	u8 optional[];
 } STRUCT_PACKED;
 
 struct ieee80211_he_operation {
@@ -2135,6 +2136,15 @@ struct ieee80211_spatial_reuse {
 } STRUCT_PACKED;
 
 /* HE Capabilities Information defines */
+
+#define HE_PHYCAP_CHANNEL_WIDTH_SET_IDX		0
+#define HE_PHYCAP_CHANNEL_WIDTH_MASK		((u8) (BIT(1) | BIT(2) | \
+						      BIT(3) | BIT(4)))
+#define HE_PHYCAP_CHANNEL_WIDTH_SET_40MHZ_IN_2G         ((u8) BIT(1))
+#define HE_PHYCAP_CHANNEL_WIDTH_SET_40MHZ_80MHZ_IN_5G	((u8) BIT(2))
+#define HE_PHYCAP_CHANNEL_WIDTH_SET_160MHZ_IN_5G	((u8) BIT(3))
+#define HE_PHYCAP_CHANNEL_WIDTH_SET_80PLUS80MHZ_IN_5G	((u8) BIT(4))
+
 #define HE_PHYCAP_SU_BEAMFORMER_CAPAB_IDX	3
 #define HE_PHYCAP_SU_BEAMFORMER_CAPAB		((u8) BIT(7))
 #define HE_PHYCAP_SU_BEAMFORMEE_CAPAB_IDX	4
@@ -2142,6 +2152,14 @@ struct ieee80211_spatial_reuse {
 #define HE_PHYCAP_MU_BEAMFORMER_CAPAB_IDX	4
 #define HE_PHYCAP_MU_BEAMFORMER_CAPAB		((u8) BIT(1))
 
+#define HE_PHYCAP_PPE_THRESHOLD_PRESENT_IDX	6
+#define HE_PHYCAP_PPE_THRESHOLD_PRESENT		((u8) BIT(7))
+
+/* HE PPE Threshold define */
+#define HE_PPE_THRES_RU_INDEX_BITMASK_MASK	0xf
+#define HE_PPE_THRES_RU_INDEX_BITMASK_SHIFT	3
+#define HE_PPE_THRES_NSS_MASK			0x7
+
 /* HE Operation defines */
 /* HE Operation Parameters and BSS Color Information fields */
 #define HE_OPERATION_DFLT_PE_DURATION_MASK	((u32) (BIT(0) | BIT(1) | \