Do not store ec=session_expired if the client never subscribed

Summary: related to T13152

Reviewers: ivica

Reviewed By: ivica

Subscribers: miljen, iljazovic

Differential Revision: https://repo.mireo.local/D26803

include/async_mqtt5/detail/internal_types.hpp

@@ -39,12 +39,23 @@ class session_state {
 	uint8_t _flags = 0b00;
 
 	static constexpr uint8_t session_present_flag = 0b01;
+	static constexpr uint8_t subscriptions_present_flag = 0b10;
 public:
 	void session_present(bool present) {
 		return update_flag(present, session_present_flag);
 	}
 
-	bool session_present() const { return _flags & session_present_flag; };
+	bool session_present() const {
+		return _flags & session_present_flag;
+	}
+
+	void subscriptions_present(bool present) {
+		return update_flag(present, subscriptions_present_flag);
+	}
+
+	bool subscriptions_present() const {
+		return _flags & subscriptions_present_flag;
+	}
 
 private:
 	void update_flag(bool set, uint8_t flag) {

include/async_mqtt5/impl/client_service.hpp

@@ -3,8 +3,8 @@
 
 #include <boost/asio/experimental/basic_concurrent_channel.hpp>
 
-#include <async_mqtt5/detail/internal_types.hpp>
 #include <async_mqtt5/detail/channel_traits.hpp>
+#include <async_mqtt5/detail/internal_types.hpp>
 
 #include <async_mqtt5/impl/assemble_op.hpp>
 #include <async_mqtt5/impl/async_sender.hpp>
@@ -40,6 +40,14 @@ public:
 		return _tls_context;
 	}
 
+	auto& session_state() {
+		return _mqtt_context.session_state;
+	}
+
+	const auto& session_state() const {
+		return _mqtt_context.session_state;
+	}
+
 	void will(will will) {
 		_mqtt_context.will = std::move(will);
 	}
@@ -78,6 +86,14 @@ public:
 		return _mqtt_context;
 	}
 
+	auto& session_state() {
+		return _mqtt_context.session_state;
+	}
+
+	const auto& session_state() const {
+		return _mqtt_context.session_state;
+	}
+
 	void will(will will) {
 		_mqtt_context.will = std::move(will);
 	}
@@ -289,12 +305,25 @@ public:
 		);
 	}
 
+	bool subscriptions_present() const {
+		return _stream_context.session_state().subscriptions_present();
+	}
+
+	void subscriptions_present(bool present) {
+		_stream_context.session_state().subscriptions_present(present);
+	}
+
 	void update_session_state() {
-		auto& session_state = _stream_context.mqtt_context().session_state;
+		auto& session_state = _stream_context.session_state();
+
 		if (!session_state.session_present()) {
-			channel_store_error(client::error::session_expired);
 			_replies.clear_pending_pubrels();
 			session_state.session_present(true);
+
+			if (session_state.subscriptions_present()) {
+				channel_store_error(client::error::session_expired);
+				session_state.subscriptions_present(false);
+			}
 		}
 	}
 

include/async_mqtt5/impl/subscribe_op.hpp

@@ -1,6 +1,8 @@
 #ifndef ASYNC_MQTT5_SUBSCRIBE_OP_HPP
 #define ASYNC_MQTT5_SUBSCRIBE_OP_HPP
 
+#include <algorithm>
+
 #include <boost/asio/detached.hpp>
 
 #include <async_mqtt5/error.hpp>
@@ -173,6 +175,15 @@ private:
 		error_code ec, uint16_t packet_id,
 		std::vector<reason_code> reason_codes, suback_props props
 	) {
+		if (!_svc_ptr->subscriptions_present()) {
+			bool has_success_rc = std::any_of(
+				reason_codes.cbegin(), reason_codes.cend(),
+				[](const reason_code& rc) { return !rc; }
+			);
+			if (has_success_rc)
+				_svc_ptr->subscriptions_present(true);
+		}
+
 		_svc_ptr->free_pid(packet_id);
 		_handler.complete(ec, std::move(reason_codes), std::move(props));
 	}