[PATCH 02/11] shared/gatt-db: Add gatt_db_attribute_indicate()

[Cheng Jiang <cheng.jiang@oss.qualcomm.com>]

The notify callback leaves the choice between a notification and an
indication entirely to the CCC value written by the client, preferring
notifications whenever the client enabled them. Some services need the
indication transport for a given characteristic regardless: the Ranging
Service must indicate Ranging Data Ready and Ranging Data Overwritten
even when the client subscribed to both transports (RAS 3.4.2, 3.5.2).

Add gatt_db_attribute_indicate() alongside gatt_db_attribute_notify() and
let the callback query which of the two it was invoked from through
gatt_db_attribute_indicate_only(). Both entry points share a helper, so
the CCC lookup stays in one place, and neither gatt_db_notify_t nor the
existing gatt_db_attribute_notify() callers change.

gatt-database honors the request by skipping the notification branch and
sending an indication instead, provided the client enabled indications.

Assisted-by: Claude:claude-opus-4.8
---
 src/gatt-database.c  |  7 ++++++-
 src/shared/gatt-db.c | 35 +++++++++++++++++++++++++++++++++--
 src/shared/gatt-db.h | 17 +++++++++++++++++
 unit/test-rap.c      | 13 +++++++++----
 4 files changed, 65 insertions(+), 7 deletions(-)

diff --git a/src/gatt-database.c b/src/gatt-database.c
index 18b7aa667..800f76032 100644
--- a/src/gatt-database.c
+++ b/src/gatt-database.c
@@ -168,6 +168,7 @@ struct notify {
 	uint16_t len;
 	bt_gatt_server_conf_func_t conf;
 	void *user_data;
+	bool indicate_only;
 };
 
 #define CLI_FEAT_SIZE 1
@@ -1446,7 +1447,7 @@ static void send_notification_to_device(void *data, void *user_data)
 	 * TODO: If the device is not connected but bonded, send the
 	 * notification/indication when it becomes connected.
 	 */
-	if (ccc->value & 0x0001) {
+	if (!notify->indicate_only && (ccc->value & 0x0001)) {
 		DBG("GATT server sending notification");
 		bt_gatt_server_send_notification(server,
 					notify->handle, notify->value,
@@ -1455,6 +1456,9 @@ static void send_notification_to_device(void *data, void *user_data)
 		return;
 	}
 
+	if (!(ccc->value & 0x0002))
+		return;
+
 	DBG("GATT server sending indication");
 	bt_gatt_server_send_indication(server, notify->handle, notify->value,
 						notify->len, notify->conf,
@@ -1486,6 +1490,7 @@ static void gatt_notify_cb(struct gatt_db_attribute *attrib,
 	notify.ccc_handle = gatt_db_attribute_get_handle(ccc);
 	notify.value = (void *) value;
 	notify.len = len;
+	notify.indicate_only = gatt_db_attribute_indicate_only(attrib);
 
 	if (attrib == database->svc_chngd)
 		notify.conf = service_changed_conf;
diff --git a/src/shared/gatt-db.c b/src/shared/gatt-db.c
index 751d4c3da..1f6e9ae14 100644
--- a/src/shared/gatt-db.c
+++ b/src/shared/gatt-db.c
@@ -123,6 +123,11 @@ struct gatt_db_attribute {
 
 	unsigned int next_notify_id;
 	struct queue *notify_list;
+
+	/* Set only while notify_func is being called on behalf of
+	 * gatt_db_attribute_indicate().
+	 */
+	bool indicate_only;
 };
 
 struct gatt_db_service {
@@ -2440,9 +2445,9 @@ gatt_db_attribute_get_ccc(struct gatt_db_attribute *attrib)
 	return ccc;
 }
 
-bool gatt_db_attribute_notify(struct gatt_db_attribute *attrib,
+static bool attribute_notify(struct gatt_db_attribute *attrib,
 					const uint8_t *value, size_t len,
-					struct bt_att *att)
+					struct bt_att *att, bool indicate_only)
 {
 	struct gatt_db_attribute *ccc;
 	struct gatt_db *db;
@@ -2468,11 +2473,37 @@ bool gatt_db_attribute_notify(struct gatt_db_attribute *attrib,
 	else
 		notify_user_data = ccc->user_data;
 
+	attrib->indicate_only = indicate_only;
+
 	attrib->notify_func(attrib, ccc, value, len, att, notify_user_data);
 
+	attrib->indicate_only = false;
+
 	return true;
 }
 
+bool gatt_db_attribute_notify(struct gatt_db_attribute *attrib,
+					const uint8_t *value, size_t len,
+					struct bt_att *att)
+{
+	return attribute_notify(attrib, value, len, att, false);
+}
+
+bool gatt_db_attribute_indicate(struct gatt_db_attribute *attrib,
+					const uint8_t *value, size_t len,
+					struct bt_att *att)
+{
+	return attribute_notify(attrib, value, len, att, true);
+}
+
+bool gatt_db_attribute_indicate_only(const struct gatt_db_attribute *attrib)
+{
+	if (!attrib)
+		return false;
+
+	return attrib->indicate_only;
+}
+
 bool gatt_db_attribute_reset(struct gatt_db_attribute *attrib)
 {
 	if (!attrib)
diff --git a/src/shared/gatt-db.h b/src/shared/gatt-db.h
index da0600c01..63d7f3464 100644
--- a/src/shared/gatt-db.h
+++ b/src/shared/gatt-db.h
@@ -300,6 +300,23 @@ bool gatt_db_attribute_notify(struct gatt_db_attribute *attrib,
 					const uint8_t *value, size_t len,
 					struct bt_att *att);
 
+/* Same as gatt_db_attribute_notify() but requests an indication even when the
+ * client has also enabled notifications. Some profiles mandate the indication
+ * transport for specific characteristics (e.g. the RAS Ranging Data Ready and
+ * Ranging Data Overwritten characteristics), which gatt_db_attribute_notify()
+ * cannot express since it prefers notifications whenever the client enabled
+ * them.
+ */
+bool gatt_db_attribute_indicate(struct gatt_db_attribute *attrib,
+					const uint8_t *value, size_t len,
+					struct bt_att *att);
+
+/* Valid only while a gatt_db_notify_t callback is running: tells whether it was
+ * triggered by gatt_db_attribute_indicate() rather than
+ * gatt_db_attribute_notify().
+ */
+bool gatt_db_attribute_indicate_only(const struct gatt_db_attribute *attrib);
+
 bool gatt_db_attribute_reset(struct gatt_db_attribute *attrib);
 
 void *gatt_db_attribute_get_user_data(struct gatt_db_attribute *attrib);
diff --git a/unit/test-rap.c b/unit/test-rap.c
index d7da2ff45..5c6033a4e 100644
--- a/unit/test-rap.c
+++ b/unit/test-rap.c
@@ -167,10 +167,15 @@ static void gatt_notify_cb(struct gatt_db_attribute *attrib,
 
 	printf("%s: notify.value:%d notify->len:%d\n", __func__,
 		(int)*(notify.value), notify.len);
-	if (!bt_gatt_server_send_notification(data->server,
-			notify.handle, notify.value,
-			notify.len, false))
-		printf("%s: Failed to send notification\n", __func__);
+	if (gatt_db_attribute_indicate_only(attrib)) {
+		if (!bt_gatt_server_send_indication(data->server, notify.handle,
+				notify.value, notify.len, NULL, NULL, NULL) &&
+				tester_use_debug())
+			tester_debug("Failed to send indication");
+	} else if (!bt_gatt_server_send_notification(data->server,
+			notify.handle, notify.value, notify.len, false) &&
+			tester_use_debug())
+		tester_debug("Failed to send notification");
 }
 
 static void gatt_ccc_write_cb(struct gatt_db_attribute *attrib,
-- 
2.43.0