net: l2: ieee802154: mgmt: allow beacon payload

The standard does allow for a optional beacon payload, which gets lost
during scan, that could be interesting for the application to access
in the NET_EVENT_IEEE802154_SCAN_RESULT callback.

See section 7.3.1.6 in IEEE Std 802.15.4 for more information about
the beacon payload field. And section 7.3.1 and figure 7-5 about general
beacon frame format.

Signed-off-by: Fabian Pflug <fabian.pflug@grandcentrix.net>

include/zephyr/net/ieee802154_mgmt.h

@@ -330,6 +330,11 @@ struct ieee802154_req_params {
 	uint8_t len;
 	/** Link quality information, between 0 and 255 */
 	uint8_t lqi;
+
+	/** Additional payload of the beacon if any.*/
+	uint8_t *beacon_payload;
+	/** Length of the additional payload. */
+	size_t beacon_payload_len;
 };
 
 /**

subsys/net/l2/ieee802154/ieee802154_frame.c

@@ -194,30 +194,32 @@ ieee802154_validate_aux_security_hdr(uint8_t *buf, uint8_t **p_buf, uint8_t *len
 }
 #endif /* CONFIG_NET_L2_IEEE802154_SECURITY */
 
-static inline bool validate_beacon(struct ieee802154_mpdu *mpdu, uint8_t *buf, uint8_t length)
+int ieee802514_beacon_header_length(uint8_t *buf, uint8_t length)
 {
 	struct ieee802154_beacon *beacon = (struct ieee802154_beacon *)buf;
 	struct ieee802154_pas_spec *pas;
 	uint8_t len = IEEE802154_BEACON_SF_SIZE + IEEE802154_BEACON_GTS_SPEC_SIZE;
 
 	if (length < len) {
-		return false;
+		return -EINVAL;
 	}
 
+	/* see section 7.3.1.5 on how to calculate GTS length */
 	if (beacon->gts.desc_count) {
 		len += IEEE802154_BEACON_GTS_DIR_SIZE +
 		       beacon->gts.desc_count * IEEE802154_BEACON_GTS_SIZE;
 	}
 
 	if (length < len) {
-		return false;
+		return -EINVAL;
 	}
 
+	/* see section 7.3.1.6 on how to calculate pending address length */
 	pas = (struct ieee802154_pas_spec *)buf + len;
 
 	len += IEEE802154_BEACON_PAS_SPEC_SIZE;
 	if (length < len) {
-		return false;
+		return -EINVAL;
 	}
 
 	if (pas->nb_sap || pas->nb_eap) {
@@ -226,12 +228,10 @@ static inline bool validate_beacon(struct ieee802154_mpdu *mpdu, uint8_t *buf, u
 	}
 
 	if (length < len) {
-		return false;
+		return -EINVAL;
 	}
 
-	mpdu->beacon = beacon;
+	return len;
-
-	return true;
 }
 
 static inline bool validate_mac_command_cfi_to_mhr(struct ieee802154_mhr *mhr,
@@ -376,7 +376,7 @@ static inline bool validate_payload_and_mfr(struct ieee802154_mpdu *mpdu, uint8_
 	NET_DBG("Header size: %u, payload size %u", (uint32_t)(p_buf - buf), length);
 
 	if (type == IEEE802154_FRAME_TYPE_BEACON) {
-		if (!validate_beacon(mpdu, p_buf, length)) {
+		if (ieee802514_beacon_header_length(p_buf, length) < 0) {
 			return false;
 		}
 	} else if (type == IEEE802154_FRAME_TYPE_DATA) {

subsys/net/l2/ieee802154/ieee802154_frame.h

@@ -472,6 +472,20 @@ ieee802154_validate_aux_security_hdr(uint8_t *buf, uint8_t **p_buf, uint8_t *len
 struct ieee802154_fcf_seq *ieee802154_validate_fc_seq(uint8_t *buf, uint8_t **p_buf,
 						      uint8_t *length);
 
+/**
+ * @brief Calculate the beacon header length.
+ *
+ * @details Returns the length of the MAC payload without the beacon payload,
+ * see section 7.3.1.1, figure 7-5.
+ *
+ * @param buf pointer to the MAC payload
+ * @param length buffer length
+ *
+ * @retval -EINVAL The header is invalid.
+ * @return the length of the beacon header
+ */
+int ieee802514_beacon_header_length(uint8_t *buf, uint8_t length);
+
 bool ieee802154_validate_frame(uint8_t *buf, uint8_t length, struct ieee802154_mpdu *mpdu);
 
 void ieee802154_compute_header_and_authtag_len(struct net_if *iface, struct net_linkaddr *dst,

subsys/net/l2/ieee802154/ieee802154_mgmt.c

@@ -37,6 +37,7 @@ enum net_verdict ieee802154_handle_beacon(struct net_if *iface,
 					  uint8_t lqi)
 {
 	struct ieee802154_context *ctx = net_if_l2_data(iface);
+	int beacon_hdr_len;
 
 	NET_DBG("Beacon received");
 
@@ -64,6 +65,10 @@ enum net_verdict ieee802154_handle_beacon(struct net_if *iface,
 				IEEE802154_EXT_ADDR_LENGTH);
 	}
 
+	beacon_hdr_len = ieee802514_beacon_header_length(mpdu->payload, mpdu->payload_length);
+	ctx->scan_ctx->beacon_payload_len = mpdu->payload_length - beacon_hdr_len;
+	ctx->scan_ctx->beacon_payload = (uint8_t *)mpdu->payload + beacon_hdr_len;
+
 	net_mgmt_event_notify(NET_EVENT_IEEE802154_SCAN_RESULT, iface);
 
 	k_sem_give(&ctx->scan_ctx_lock);

tests/net/ieee802154/l2/src/ieee802154_shell_test.c

@@ -45,12 +45,16 @@ K_SEM_DEFINE(scan_lock, 0, 1);
 #define EXPECTED_ENDDEVICE_EXT_ADDR_STR    "08:07:06:05:04:03:02:01"
 #define EXPECTED_ENDDEVICE_SHORT_ADDR      0xaaaa
 
+#define EXPECTED_PAYLOAD_DATA EXPECTED_ENDDEVICE_EXT_ADDR_LE
+#define EXPECTED_PAYLOAD_LEN  8
+
 static void scan_result_cb(struct net_mgmt_event_callback *cb, uint32_t mgmt_event,
 			   struct net_if *iface)
 {
 	struct ieee802154_context *ctx = net_if_l2_data(iface);
 	struct ieee802154_req_params *scan_ctx = ctx->scan_ctx;
 	uint8_t expected_coordinator_address[] = {EXPECTED_COORDINATOR_ADDR_BE};
+	uint8_t expected_payload_data[] = {EXPECTED_PAYLOAD_DATA};
 
 	/* No need for scan_ctx locking as we should execute exclusively. */
 
@@ -63,6 +67,10 @@ static void scan_result_cb(struct net_mgmt_event_callback *cb, uint32_t mgmt_eve
 	zassert_equal(scan_ctx->lqi, EXPECTED_COORDINATOR_LQI,
 		      "Scan did not receive correct link quality indicator.");
 
+	zassert_equal(scan_ctx->beacon_payload_len, EXPECTED_PAYLOAD_LEN,
+		      "Scan did not include the payload");
+	zassert_mem_equal(scan_ctx->beacon_payload, expected_payload_data, EXPECTED_PAYLOAD_LEN);
+
 	k_sem_give(&scan_lock);
 }
 
@@ -201,7 +209,7 @@ ZTEST(ieee802154_l2_shell, test_active_scan)
 		0x00, 0xc0, /* Superframe Specification: PAN coordinator + association permitted */
 		0x00, /* GTS */
 		0x00, /* Pending Addresses */
-		0x00, 0x00 /* Payload */
+		EXPECTED_PAYLOAD_DATA /* Layer 3 payload */
 	};
 	struct net_pkt *pkt;