[PATCH BlueZ] shared/gatt-client: Automatically add CCC when discovering

[Luiz Augusto von Dentz <luiz.dentz@gmail.com>]

From: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

The spec mandates that a CCC exists if either notify or indicate
property is marked:

BLUETOOTH CORE SPECIFICATION Version 5.1 | Vol 3, Part G page 2357

  "If set, the Client Characteristic Configuration Descriptor shall
  exist."
---
 src/shared/gatt-client.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/src/shared/gatt-client.c b/src/shared/gatt-client.c
index 225915d43..38a416ed3 100644
--- a/src/shared/gatt-client.c
+++ b/src/shared/gatt-client.c
@@ -659,6 +659,31 @@ static bool discover_descs(struct discovery_op *op, bool *discovering)
 
 		desc_start = chrc_data->value_handle + 1;
 
+		if (desc_start == chrc_data->end_handle &&
+			(chrc_data->properties & BT_GATT_CHRC_PROP_NOTIFY ||
+			 chrc_data->properties & BT_GATT_CHRC_PROP_INDICATE)) {
+			bt_uuid_t ccc_uuid;
+
+			/* If there is only one descriptor that must be the CCC
+			 * in case either notify or indicate are supported.
+			 */
+			bt_uuid16_create(&ccc_uuid,
+					GATT_CLIENT_CHARAC_CFG_UUID);
+			attr = gatt_db_insert_descriptor(client->db, desc_start,
+							&ccc_uuid, 0, NULL,
+							NULL, NULL);
+			if (attr) {
+				free(chrc_data);
+				continue;
+			}
+		}
+
+		/* Check if the start range is within characteristic range */
+		if (desc_start > chrc_data->end_handle) {
+			free(chrc_data);
+			continue;
+		}
+
 		client->discovery_req = bt_gatt_discover_descriptors(
 							client->att, desc_start,
 							chrc_data->end_handle,
-- 
2.21.0