Crate zerodds_transport_uds

Expand description

Crate zerodds-transport-uds. Safety classification: STANDARD.

ZeroDDS Unix domain socket transport — container IPC for ZeroDDS.

§Spec

DDSI-RTPS 2.5 §9.4 — locator kind LOCATOR_KIND_UDS (vendor-reserved value 0x81000001, in crates/rtps/src/wire_types.rs).
ZeroDDS-UDS-Transport 1.0 — vendor-specific transport spec (filesystem path resolution, abstract namespace, SOCK_DGRAM wire format), docs/spec-coverage/zerodds-uds-transport-1.0.md.

§Note on OMG normativity

OMG does not standardize a UDS transport for DDS. Cyclone DDS and Fast DDS have no official UDS transport (they use iceoryx or shared memory). ZeroDDS defines its own variant explicitly as the ZeroDDS-UDS-Transport-1.0 spec.

§Use case

Container IPC when multicast is blocked and POSIX SHM is impractical cross-container (UID mapping, /dev/shm visibility, SELinux). A mounted volume with UDS sockets is the realistic Docker/Kubernetes pattern.

§Implemented (RC1)

SOCK_DGRAM over filesystem sockets (default mode).
Linux abstract-namespace support via the abstract_dgram module (datagrams without a filesystem inode).
Lazy base-directory creation with mode 0700.
TOCTOU-safe socket creation (path.exists + fail-fast).
Differentiated io::Error classification for diagnostics.

§Cross-vendor interop

Not intended — UDS is intra-container/intra-host IPC. Cross-vendor interop with Cyclone/Fast DDS stays in the UDP/TCP/SHM domain.

§Wire format

Every datagram is a SOCK_DGRAM message; the kernel preserves the message boundaries. Default path resolution: 16-byte Locator address → <base_dir>/<lowercase-hex>.sock. Default base_dir = /tmp/zerodds/uds.

§Safety / unsafe scope

The default DGRAM module (lib.rs) is safe-only (std::os::unix::net::UnixDatagram). The Linux-only abstract_dgram module uses libc::sendto/libc::recvfrom plus raw sockaddr_un construction for the abstract namespace — it contains limited unsafe blocks documented with SAFETY comments.

Modules§

abstract_dgram: SOCK_DGRAM with abstract namespace (Linux-only, T5). UDS SOCK_DGRAM with abstract namespace — Linux-only, containerized-IPC-optimized (WP 2.0b T5).

Structs§

UdsConfig: Configuration for opening a UdsTransport.
UdsTransport: UDS-based transport bound to a specific 16-byte locator ID.

Constants§

DEFAULT_BASE_DIR: Default base directory for UDS sockets.
DEFAULT_MAX_DATAGRAM: Maximum UDS datagram size we accept on receive. Linux default wmem_max is 212992 bytes; we cap a bit below to stay under the typical kernel limit and match the UDP-transport recv-buffer size.

Functions§

socket_path: Renders a locator ID (16 bytes) to a filesystem path under base_dir.