`zerodds-coap-bridge`

CoAP (Constrained Application Protocol, RFC 7252) complete stack set: wire codec, options + delta encoding, reliability with retransmit tracker (§4), request/response matching (§5.3), block-wise transfer (RFC 7959), resource discovery in CoRE-Link format (RFC 6690), observer pattern (RFC 7641), multicast operation (§8), caching + proxying (§5.6 + §5.7), DTLS mode marker (§9), and a bidirectional CoAP↔DDS topic bridge. no_std + alloc, forbid(unsafe_code). Safety classification: STANDARD.

Spec Mapping

Spec	Section
RFC 7252 (CoAP)	§3 (Message-Format), §3.1 (Option-Format), §4 (Reliability), §5 (Request/Response), §5.6 (Caching), §5.7 (Proxying), §5.8 (Method-Properties), §5.10 (Option-Number-Registry), §6 (URI-Scheme), §8 (Multicast), §9 (DTLS), §12.1 (Code-Registry)
RFC 7641	Observing Resources
RFC 7959	Block-Wise Transfer
RFC 6690	CoRE-Link-Format (Resource-Discovery)

What's Inside

CoapMessage / CoapCode / MessageType — message model (§3 + §12.1).
encode / decode — wire codec including options delta encoding and payload marker 0xFF.
CoapOption / OptionNumber / OptionValue — options with all registered numbers (Critical/Elective/Unsafe/NoCache-Key bits per §5.10).
BlockOption / BlockValue / BlockReassembler — block-wise transfer (RFC 7959) with Block1/Block2 options.
CoreLink / encode_links / decode_links — resource discovery via link-format string (RFC 6690).
OBSERVE_OPTION_NUMBER / ObserveRegistry / ObserverEntry — RFC 7641 observer state + notification numbering.
PendingConfirmable / ReliabilityTracker / TickOutput / ACK_TIMEOUT_MS / MAX_RETRANSMIT — §4 retransmit logic.
CoapDdsBridge / BridgeOp / BridgeError / map_method / parse_dds_path — CoAP↔DDS topic mapping (GET → read-by-key, PUT/POST → write, DELETE → dispose, Observe → subscriber).

Layer Position

Layer 5 — Bridges. Substrate for DDS↔IoT endpoint mapping (constrained devices, multicast discovery, observer pattern for DDS live updates).

Quickstart

use zerodds_coap_bridge::{decode, encode, CoapCode, CoapMessage, MessageType};

let msg = CoapMessage {
    version: 1,
    message_type: MessageType::Confirmable,
    token: Vec::new(),
    code: CoapCode::GET,
    message_id: 0xBEEF,
    options: Vec::new(),
    payload: Vec::new(),
};

let wire = encode(&msg).expect("encode");
let decoded = decode(&wire).expect("decode");
assert_eq!(decoded.code, CoapCode::GET);

Feature Flags

Feature	Default	Purpose
`std`	✅	`std::error::Error` impls.
`alloc`	✅ (via std)	`Vec` / `String` / `BTreeMap`.

no_std-capable: default-features = false, features = ["alloc"].

Stability

1.0.0-rc.1 is the initial release materialization. The public API, wire format (RFC 7252), and error discriminants are RC1-stable; breaking changes require a major bump.

Tests

cargo test -p zerodds-coap-bridge

145 tests passing:

141 unit tests (codec, options, reliability, block-wise, observe, CoRE-Link, matching, multicast, method properties, URI, DTLS mode, caching/proxying, bridge).
3 fuzz smoke tests (pseudo-random byte stream, no panic).
1 doc test.

License

Apache-2.0. See LICENSE.

zerodds-coap-bridge 1.0.0-rc.5

zerodds-coap-bridge