[PATCH 04/11] shared/rap: Add RAS Control Point Abort Operation

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

Implement the Abort_Operation procedure (Op Code 0x03) so a client can
cancel an On-demand Ranging Data transfer that is already in progress,
and advertise it through bit 2 of the RAS Features characteristic.

Abort clears the sending state and removes the pending segment timer.
Since the transfer keeps at most one segment outstanding, dropping that
timer stops the transfer instead of letting a queued backlog drain out.
The Control Point busy check lets Abort through while every other Op Code
is answered with Server Busy, so an abort is accepted mid-transfer.

On the requester side, an Abort is written when a Get_Ranging_Data
request times out and the peer advertises Abort support, so the responder
does not keep sending data for a request the requester gave up on.

The unit test Features value changes to 0x05 accordingly.

Assisted-by: Claude:claude-opus-4.8
---
 src/shared/rap.c | 35 ++++++++++++++++++++++++++++++-----
 unit/test-rap.c  |  6 +++---
 2 files changed, 33 insertions(+), 8 deletions(-)

diff --git a/src/shared/rap.c b/src/shared/rap.c
index a794de044..b45bfc9e6 100644
--- a/src/shared/rap.c
+++ b/src/shared/rap.c
@@ -312,8 +312,8 @@ struct cstracker {
 enum ras_cp_opcode {
 	RAS_CP_OP_GET_RANGING_DATA = 0x00,
 	RAS_CP_OP_ACK_RANGING_DATA = 0x01,
+	RAS_CP_OP_ABORT_OPERATION = 0x03,
 	/* 0x02 Retrieve_Lost_Ranging_Data_Segments,
-	 * 0x03 Abort_Operation,
 	 * 0x04 Set_Filter - optional, not implemented
 	 */
 };
@@ -366,6 +366,7 @@ struct ras_ondemand_client {
 	 * peer never sends a Control Point response.
 	 */
 	unsigned int        cp_timeout_id;
+	bool                abort_operation;
 };
 
 /* Ranging Service context */
@@ -1196,7 +1197,7 @@ static void ras_features_read_cb(struct gatt_db_attribute *attrib,
 {
 	struct ras *ras = user_data;
 	/* Real-time ranging and Abort Operation are supported. */
-	uint8_t value[4] = { 0x01, 0x00, 0x00, 0x00 };
+	uint8_t value[4] = { 0x05, 0x00, 0x00, 0x00 };
 
 	if (ras)
 		bt_rap_get_session(att, ras->rapdb->db);
@@ -1244,7 +1245,7 @@ static void ras_control_point_write_cb(struct gatt_db_attribute *attrib,
 		return;
 	}
 
-	if (rap->cache.sending) {
+	if (rap->cache.sending && value[0] != RAS_CP_OP_ABORT_OPERATION) {
 		ras_cp_send_response_code(rap, ras, RAS_CP_RSP_CODE_SERVER_BUSY);
 		goto done;
 	}
@@ -1269,6 +1270,22 @@ static void ras_control_point_write_cb(struct gatt_db_attribute *attrib,
 
 		send_ondemand_segment_data(rap, ras);
 		break;
+	case RAS_CP_OP_ABORT_OPERATION:
+		if (len != 1) {
+			ras_cp_send_response_code(rap, ras,
+					RAS_CP_RSP_CODE_INVALID_PARAMETER);
+			break;
+		}
+
+		if (rap->cache.sending) {
+			if (rap->cache.send_id)
+				timeout_remove(rap->cache.send_id);
+			rap->cache.send_id = 0;
+			rap->cache.sending = false;
+		}
+
+		ras_cp_send_response_code(rap, ras, RAS_CP_RSP_CODE_SUCCESS);
+		break;
 	case RAS_CP_OP_ACK_RANGING_DATA:
 		if (len != 3) {
 			ras_cp_send_response_code(rap, ras,
@@ -3352,6 +3369,10 @@ static bool ras_cp_timeout_cb(void *user_data)
 		 * on it.
 		 */
 		ras->client.cp_timeout_id = 0;
+		if (ras->client.pending_op == RAS_CP_PENDING_GET &&
+				ras->client.abort_operation)
+			ras_cp_write_op(rap, ras, RAS_CP_OP_ABORT_OPERATION,
+					ras->client.pending_counter);
 		ras_ondemand_client_reset(ras);
 	}
 
@@ -3397,8 +3418,10 @@ static bool ras_cp_write_op(struct bt_rap *rap, struct ras *ras,
 		return false;
 
 	value[0] = opcode;
-	put_le16(counter, value + 1);
-	length = sizeof(value);
+	if (opcode != RAS_CP_OP_ABORT_OPERATION) {
+		put_le16(counter, value + 1);
+		length = sizeof(value);
+	}
 
 	return bt_gatt_client_write_without_response(rap->client,
 					value_handle, false,
@@ -4265,6 +4288,8 @@ static void read_ras_features(struct bt_rap *rap, bool success,
 	supports_realtime = (features & 0x01) != 0;
 	retrieve_lost = (features & 0x02) != 0;
 	abort_operation = (features & 0x04) != 0;
+	if (ras)
+		ras->client.abort_operation = abort_operation;
 
 	DBG(rap, "RAS Features - Real-time: %s, Retrieve Lost: %s, Abort: %s",
 	    supports_realtime ? "Yes" : "No",
diff --git a/unit/test-rap.c b/unit/test-rap.c
index 5c6033a4e..349d06840 100644
--- a/unit/test-rap.c
+++ b/unit/test-rap.c
@@ -802,11 +802,11 @@ const struct test_config_rap cfg_cggit_discovery = {
  *       Handle: 0x0003 (RAS Features value handle)
  *
  *  ATT: Read Response (0x0b) len 5
- *       Value: 0x01 0x00 0x00 0x00
+ *       Value: 0x05 0x00 0x00 0x00
  *       Feature bits:
  *         Bit 0: Real-time ranging (1 = supported)
  *         Bit 1: Retrieve stored results (0 = not supported)
- *         Bit 2: Abort operation (0 = not supported)
+ *         Bit 2: Abort operation (1 = supported)
  *
  *  Note: The RAS Features characteristic is registered with
  *  BT_ATT_PERM_READ | BT_ATT_PERM_READ_ENCRYPT. Since the test sets
@@ -817,7 +817,7 @@ const struct test_config_rap cfg_cggit_discovery = {
 
 #define ATT_READ_RAS_FEATURES \
 	IOV_DATA(0x0a, 0x03, 0x00), \
-	IOV_DATA(0x0b, 0x01, 0x00, 0x00, 0x00)
+	IOV_DATA(0x0b, 0x05, 0x00, 0x00, 0x00)
 
 #define RAS_SR_RCO_BV_01_C \
 	ATT_EXCHANGE_MTU, \
-- 
2.43.0