CAN (SocketCAN) reference connector

A fourth concrete connector instantiating the framework’s contracts. This parent feature :satisfies: Connector framework (FEAT_0030); its three capability clusters — frame transport (CAN frame transport (classi... (FEAT_0047)), the multi-interface gateway (Multi-interface gateway and... (FEAT_0048)), and bus health, error frames, and reconnect (Bus health, error frames, a... (FEAT_0049)) — each :satisfies: it, on their own pages (see the toctree). The connector-wide requirements below :satisfies: the parent feature directly.

Feature: CAN (SocketCAN) reference connector FEAT_0046

status: open satisfies: FEAT_0030 is satisfied by: REQ_0600, REQ_0601, REQ_0602, REQ_0603, REQ_0604, REQ_0605, REQ_0606, REQ_0607, REQ_0608, FEAT_0049, FEAT_0047, FEAT_0048, REQ_0640, REQ_0641, REQ_0642 links incoming: BB_0088

A fourth concrete connector instantiating the framework’s contracts: socketcan-backed CAN plugin and gateway exchanging classical CAN and CAN-FD frames on one or more Linux SocketCAN network interfaces, with internal error-frame-driven health, ReconnectPolicy-driven bus-off recovery, and a non-Linux MockCanInterface for layer-1 tests. The gateway owns N socketcan::CanSocket / CanFdSocket instances — one per registered interface — and runs the RX/TX loops on a tokio sidecar contained inside taktora-connector-can. Linux is the only supported host OS for real I/O; the in-process mock interface is portable.

• CAN frame transport (classical + FD)
• Multi-interface gateway and per-channel filtering
• Bus health, error frames, and reconnect

Requirement: CanConnector implements Connector REQ_0600

status: approved satisfies: FEAT_0046 is refined by: IMPL_0080 is implemented by: BB_0070, BB_0071 is verified by: TEST_0500

The connector crate shall expose CanConnector<C: PayloadCodec> that implements the Connector trait with type Routing = CanRouting and type Codec = C.

Requirement: CanRouting carries iface, can_id, mask, kind, fd_flags REQ_0601

status: approved satisfies: FEAT_0046 is refined by: IMPL_0080 is implemented by: BB_0071 is verified by: TEST_0501

The CanRouting struct shall identify one channel by Linux network interface name (iface, bounded ASCII string of IFNAMSIZ − 1 = 15 bytes), CAN identifier (can_id, with an explicit extended: bool flag distinguishing 11-bit from 29-bit IDs), kernel-style ID mask (mask: u32), frame kind (CanFrameKind::{Classical, Fd}), and FD bit-rate-switch / error-state-indicator flags (fd_flags: CanFdFlags, ignored when kind == Classical). It shall implement the Routing marker trait.

Requirement: Linux is the supported host OS for real I/O REQ_0602

status: open satisfies: FEAT_0046 is refined by: IMPL_0080 is implemented by: BB_0070

The CAN gateway shall open SocketCAN interfaces via the Linux PF_CAN socket family, requiring the CAP_NET_RAW capability on the gateway process (mirrors Linux raw socket required o... (REQ_0325)). The plugin-side CanConnector and the MockCanInterface shall remain portable to macOS and Windows for layer-1 development.

Requirement: socketcan-integration cargo feature gates the real socketcan dep REQ_0603

status: approved satisfies: FEAT_0046 is refined by: IMPL_0080 is implemented by: BB_0070 is verified by: TEST_0511

The socketcan crate shall be an optional dependency of taktora-connector-can, activated only by a default-off socketcan-integration cargo feature (mirrors zenoh-integration cargo fea... (REQ_0444)’s zenoh-integration posture and taktora-connector-ethercat (BB_0030)’s bus-integration posture).

Requirement: MockCanInterface ships unfeature-gated REQ_0604

status: approved satisfies: FEAT_0046 is refined by: IMPL_0080 is implemented by: BB_0070, BB_0075 is verified by: TEST_0511

MockCanInterface — an in-process loopback implementation of the CanInterfaceLike trait — shall ship in the default build, not gated by socketcan-integration. It exists so that the Layer-1 (pure-logic) test pyramid can exercise the full envelope ↔ interface ↔ envelope hop without depending on the real socketcan crate or a Linux kernel CAN module (mirrors MockZenohSession ships unfe... (REQ_0445)).

Requirement: Tokio sidecar contained inside the CAN connector crate REQ_0605

status: approved satisfies: FEAT_0046 is refined by: IMPL_0080 is implemented by: BB_0070, BB_0073 is verified by: TEST_0508

The CAN gateway shall host its RX/TX tasks on a tokio runtime contained inside taktora-connector-can. Tokio shall not leak into taktora-executor’s WaitSet thread (mirrors Tokio sidecar contained ins... (REQ_0321), Tokio sidecar inside the ga... (REQ_0258), Tokio sidecar contained ins... (REQ_0403)).

Requirement: CAN bridge channels are bounded REQ_0606

status: approved satisfies: FEAT_0046 is refined by: IMPL_0080 is implemented by: BB_0073 is verified by: TEST_0509, TEST_0510

The outbound (taktora-executor → tokio) and inbound (tokio → taktora-executor) bridges between the plugin and the CAN gateway sidecar shall be bounded channels with capacities configurable via CanConnectorOptions (outbound_bridge_capacity and inbound_bridge_capacity).

Requirement: Outbound bridge saturation surfaces as BackPressure REQ_0607

status: approved satisfies: FEAT_0046 is refined by: IMPL_0080 is implemented by: BB_0073 is verified by: TEST_0509

When the outbound bridge channel is full, ChannelWriter::send shall return ConnectorError::BackPressure and the gateway shall report ConnectorHealth::Degraded.

Requirement: Inbound bridge saturation drops frames and signals Degraded REQ_0608

status: open satisfies: FEAT_0046 is refined by: IMPL_0080 is implemented by: BB_0073 is verified by: TEST_0510

When the inbound bridge channel is full, the gateway shall (1) increment the per-channel inbound-drop counter exposed via InboundOutcome::Dropped { count } on the bridge’s try_send return, (2) drop the offending CAN frame for that callback, and (3) emit a ConnectorHealth::Degraded { reason: "dropped N inbound frames" } health transition when the cumulative inbound-drop count crosses the connector’s configured inbound_drop_threshold (default 1). The Degraded transition is emitted at most once until the connector recovers to Up via the underlying stack’s recovery path; the cumulative drop count itself is observable through every subsequent InboundOutcome::Dropped return.

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