class ara::fw::FirewallStateSwitchInterface

The template class ara::fw::FirewallStateSwitchInterface is used in AUTOSAR Adaptive to switch between different Firewall states and associated filter rule sets. Following thread-safe creation via a ara::core::InstanceSpecifier [AP_SWS_Fw_82002], the state switch is initiated asynchronously using SwitchFirewallState and monitored via a ara::core::Future<void> [AP_SWS_Fw_82008]. The class enforces pure move semantics without copy capability, where the destructor and move operations are not thread-safe and errors are signaled asynchronously via the future.

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Context

The template class ara::fw::FirewallStateSwitchInterface serves within the functional cluster fw (Firewall) of the AUTOSAR Adaptive Platform as the primary interface for switching between different Firewall states. A Firewall state is understood to be a defined configuration of filter rule sets that secure network traffic. The template parameter EnumT represents an application-specific enumeration of all permitted Firewall states. Typical interaction partners are likely higher-level platform entities such as Mode Management, which adapt the filter rules to changed vehicle or operating modes. Question Q-5424cd3802d53915 (open)

Lifecycle

An instance is created explicitly via the constructor by specifying a ara::core::InstanceSpecifier [AP_SWS_Fw_82002]. This construction step is specified as thread-safe. The concrete mapping to a Firewall instance modeled in the platform manifest is presumably resolved via the InstanceSpecifier. Question Q-97db4416453c9885 (open)

The class is declared as final and implements pure move semantics: The copy constructor [AP_SWS_Fw_82004] and the copy assignment operator [AP_SWS_Fw_82005] are deleted (=delete), preventing duplication. Instead, move constructor [AP_SWS_Fw_82006] and move assignment operator [AP_SWS_Fw_82007] are provided, both defined as noexcept. Important for concurrency is that both the destructor [AP_SWS_Fw_82003] and the move operations are not thread-safe. The calling application must therefore ensure that lifecycle operations and ownership transfers run thread-locally or are synchronized.

Usage Path

The regular sequence for switching rule sets is divided into the following steps:

1. Initialization: The interface object is created specifying the target InstanceSpecifier [AP_SWS_Fw_82002].
2. Request state switch: The desired target state of type EnumT is passed via the method SwitchFirewallState [AP_SWS_Fw_82008].
3. Await asynchronous confirmation: The method returns a ara::core::Future<void> [AP_SWS_Fw_82008]. Callers can resolve the future in a blocking manner or monitor it asynchronously until the underlying rule set switch has been completed.

Sequence diagram: Typical sequence of asynchronous state switching. Sources: [AP_SWS_Fw_82002], [AP_SWS_Fw_82008].

Error Scenarios

The method SwitchFirewallState is declared with noexcept and does not throw any C++ exceptions [AP_SWS_Fw_82008]. Errors during switching are encapsulated in the returned ara::core::Future<void>. The following error codes are specified for the call [AP_SWS_Fw_82008]:

• FwErrc::kServiceNotAvailable: The responsible Firewall service is not available or does not respond [AP_SWS_Fw_82008].
• FwErrc::kInvalidStateDependentFirewall: The requested state is invalid for the referenced Firewall or not provided in the configuration [AP_SWS_Fw_82008].

As a precondition for switching, the interface object must be validly instantiated and a connection to the Firewall service must exist. As a postcondition, the new filter rule set is active in the event of success, whereas in the event of an error, the previous state remains unchanged.