[PATCH v5 4/4] src/shared/att: Handle incoming response PDUs

[Arman Uguray <armansito@xxxxxxxxxxxx>]

This patch adds handling for incoming ATT protocol response PDUs. Basic
incoming PDU handling logic added to the io read handler.
---
 src/shared/att.c | 108 ++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 107 insertions(+), 1 deletion(-)

diff --git a/src/shared/att.c b/src/shared/att.c
index 000a227..f72aa9a 100644
--- a/src/shared/att.c
+++ b/src/shared/att.c
@@ -411,9 +411,102 @@ static void wakeup_writer(struct bt_att *att)
 	att->writer_active = true;
 }
 
+static bool request_complete(struct bt_att *att, uint8_t req_opcode,
+					uint8_t rsp_opcode, const void *param,
+					uint16_t len)
+{
+	struct att_send_op *op = att->pending_req;
+
+	if (!op) {
+		/* There is no pending request so the response is unexpected. */
+		wakeup_writer(att);
+		return false;
+	}
+
+	if (op->opcode != req_opcode) {
+		/* The request opcode corresponding to the received response
+		 * opcode does not match the currently pending request.
+		 */
+		return false;
+	}
+
+	if (op->callback)
+		op->callback(rsp_opcode, param, len, op->user_data);
+
+	destroy_att_send_op(op);
+	att->pending_req = NULL;
+
+	wakeup_writer(att);
+	return true;
+}
+
+static bool handle_error_rsp(struct bt_att *att, uint8_t opcode, uint8_t *pdu,
+								ssize_t pdu_len)
+{
+	struct bt_att_error_rsp_param param;
+	bool result;
+
+	if (pdu_len != 5)
+		return false;
+
+	memset(&param, 0, sizeof(param));
+	param.request_opcode = pdu[1];
+	param.handle = get_le16(pdu + 2);
+	param.error_code = pdu[4];
+
+	return request_complete(att, pdu[1], opcode, &param, sizeof(param));
+}
+
+static bool handle_mtu_rsp(struct bt_att *att, uint8_t opcode, uint8_t *pdu,
+								ssize_t pdu_len)
+{
+	struct bt_att_mtu_rsp_param param;
+	bool result;
+
+	if (pdu_len != 3)
+		return false;
+
+	memset(&param, 0, sizeof(param));
+	param.server_rx_mtu = get_le16(pdu + 1);
+
+	return request_complete(att, BT_ATT_OP_MTU_REQ, opcode,
+							&param, sizeof(param));
+}
+
+static void handle_rsp(struct bt_att *att, uint8_t opcode, uint8_t *pdu,
+								ssize_t pdu_len)
+{
+	bool success;
+
+	switch (opcode) {
+	case BT_ATT_OP_ERROR_RSP:
+		success = handle_error_rsp(att, opcode, pdu, pdu_len);
+		break;
+	case BT_ATT_OP_MTU_RSP:
+		success = handle_mtu_rsp(att, opcode, pdu, pdu_len);
+		break;
+	default:
+		success = false;
+		util_debug(att->debug_callback, att->debug_data,
+				"Unknown response opcode: 0x%02x", opcode);
+		break;
+	}
+
+	if (success)
+		return;
+
+	util_debug(att->debug_callback, att->debug_data,
+			"Failed to handle respone PDU; opcode: 0x%02x", opcode);
+
+	if (att->pending_req)
+		request_complete(att, att->pending_req->opcode,
+						BT_ATT_OP_ERROR_RSP, NULL, 0);
+}
+
 static bool can_read_data(struct io *io, void *user_data)
 {
 	struct bt_att *att = user_data;
+	uint8_t opcode;
 	uint8_t *pdu;
 	ssize_t bytes_read;
 
@@ -427,7 +520,20 @@ static bool can_read_data(struct io *io, void *user_data)
 	if (bytes_read < ATT_MIN_PDU_LEN)
 		return true;
 
-	/* TODO: Handle different types of PDUs here */
+	pdu = att->buf;
+	opcode = pdu[0];
+
+	/* Act on the received PDU based on the opcode type */
+	switch (get_op_type(opcode)) {
+	case ATT_OP_TYPE_RSP:
+		handle_rsp(att, opcode, pdu, bytes_read);
+		break;
+	default:
+		util_debug(att->debug_callback, att->debug_data,
+				"ATT opcode cannot be handled: 0x%02x", opcode);
+		break;
+	}
+
 	return true;
 }
 
-- 
1.8.3.2

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