Files
mxaccess/design
Joseph Doherty 321b7963a4 [M5] mxaccess-asb: F25 step 6 — Connect/AuthenticateMe handshake
Critical-path piece that turns a fresh TCP stream into an
authenticated session. With this slice landed, an `AsbClient` can
now do `send_preamble().await? -> connect().await? -> register_items()`
end-to-end against a peer.

Operations API additions:
* `build_connect_request_body(connection_id, public_key)` — first op
  on a fresh session. **Unsigned** (no ConnectionValidator header)
  because the authenticator hasn't received the service key yet.
  Wire shape: `<ConnectRequest xmlns="…messages/20111111">
    <ConnectionId>{guid-text}</ConnectionId>
    <ConsumerPublicKey><Data>{pubkey-bytes}</Data></ConsumerPublicKey>
  </ConnectRequest>` per `AsbContracts.cs:78-86`.
* `build_authenticate_me_request_body(data, iv)` — second op,
  **one-way + signed with `forceHmac=true`** per `MxAsbDataClient.cs
  :106-111`. Carries the encrypted `local_pub || remote_pub` blob
  produced by F23's `create_authentication_data()`.
* `ConnectResponse { service_public_key, service_authentication_data,
  connection_lifetime }` + `AuthenticationDataBytes { data, iv }`.
* `decode_connect_response(body, dict)` — extracts ServicePublicKey
  (required), optional ServiceAuthenticationData, optional
  ConnectionLifetime. The lifetime's `:V2` suffix is what F23
  inspects to toggle Apollo (raw AES) vs Baktun (deflate-then-AES)
  encryption.

Client API addition:
* `AsbClient::connect()` — orchestrates the full handshake:
  1. Build + send ConnectRequest (unsigned) carrying our DH public
     key + connection-id GUID.
  2. Decode ConnectResponse.
  3. `authenticator.accept_connect_response(...)` — feeds the
     service public key + lifetime into F23 so it derives the
     shared secret and picks Apollo/Baktun.
  4. `authenticator.create_authentication_data()` — encrypts
     `local_pub || remote_pub` under the derived AES key.
  5. Send AuthenticateMeRequest (one-way, signed with HMAC-SHA1
     forced).
  Returns the `ConnectResponse` so callers can inspect the
  negotiated connection lifetime.

6 new tests:
* ConnectRequest carries hyphenated GUID + raw public-key bytes.
* AuthenticateMe carries Data + IV bytes in order.
* ConnectResponse round-trip with all optional fields populated.
* ConnectResponse round-trip without optional fields.
* ConnectResponse decoder surfaces MissingField when
  ServicePublicKey is absent.
* End-to-end client::connect handshake via `tokio::io::duplex`
  peer that synthesises a ConnectResponse using bob's public key
  (so DH shared-secret derivation actually works) and drains the
  AuthenticateMe one-way SizedEnvelope.

Wire-byte caveat documented inline: WCF XML serialization may add
`xsi:type` attributes / distinct namespaces around <PublicKey> /
<AuthenticationData>; this builder ships the simplest plausible
shape and the live-probe iteration will reconcile.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-05-05 11:47:35 -04:00
..

design/ — Rust port architectural plan

This folder is the design contract for the Rust replacement of AVEVA/Wonderware MXAccess. It is the gap between the .NET reference in src/ and the Rust crates that will be written under a sibling rust/ workspace (per CLAUDE.md).

The folder is structured as a small set of focused documents. Read in order; each builds on the previous.

File Purpose
00-overview.md Mission, two-layer goal, architectural principles, non-goals
10-raw-layer.md Byte-accurate raw MXAccess layer (codec + transport + session)
20-async-layer.md Idiomatic Tokio async layer on top of the raw layer
30-crate-topology.md Cargo workspace, crates, dependencies, build/test commands
40-protocol-invariants.md Bill of materials: IIDs, opnums, envelope/handle bytes
50-error-model.md MxStatus, error types, panic/cancellation policy
60-roadmap.md Milestones M0..M6, validation strategy
70-risks-and-open-questions.md Parity gaps, unproven flows, cross-platform constraints
dependencies.md Cross- and within-milestone parallelism map; agent budget per phase
review.md Adversarial review log (BLOCKER/MAJOR/MINOR/NIT findings, all resolved)
prompt.md /loop driver prompt for autonomous M2M6 execution
followups.md Open / resolved deferred work items; auto-triaged by prompt.md Step 0 (created on first /loop run if missing)

The design is grounded in the .NET reference at src/ and the protocol artifacts in docs/, analysis/, and captures/. Do not introduce protocol behavior in these documents that is not already proven in the reference. When adding a new claim about wire format, cite either:

  • a .cs file path in src/MxNativeCodec/, src/MxNativeClient/, or src/MxAsbClient/, or
  • a docs/*.md spec file, or
  • a captures/0NN-frida-* directory or analysis/frida/*.tsv row.

This folder is documentation, not code. When the Rust workspace is created, the design here is the contract it must satisfy. When evidence in captures/ invalidates a design decision here, update the design first, then the code.

Reading order

  • New contributor: 00 → 30 → 10 → 40 → 20 → 50 → 60 → 70.
  • Protocol question: 40 first, then the relevant section of 10.
  • API question: 20 first, then 50.
  • Planning a milestone: 60 first, cross-reference 70 for blockers.
  • Scheduling concurrent work: dependencies.md for the per-phase parallelism map.
  • Driving M2M6 autonomously via /loop: prompt.md (and the followups.md triage log it maintains).