Files
mxaccess/design
Joseph Doherty d1e887b91b [M5] mxaccess-asb-nettcp/asb: Connect handshake live + SOAP fault detection
Live-bring-up reconciliation against AVEVA's MxDataProvider on Windows.
Connect now completes end-to-end (real DH key exchange, apollo:V2
encryption, ServicePublicKey/ServiceAuthenticationData populated). Five
fixes land:

1. NBFX `PrefixElement_a..z` (0x5E-0x77) and `PrefixAttribute_a..z`
   (0x26-0x3F) decode + encode arms. The server's ConnectResponse hit
   `0x65 = PrefixElement_h` for a dynamically-named element and our
   decoder bailed with `unknown NBFX record byte 0x65`. Both directions
   now round-trip; encoder picks short-form when prefix is a single
   lowercase ASCII letter.

2. xmlns redeclaration on `<Data>` AND `<InitializationVector>` inside
   `AuthenticationData` / `PublicKey`. `[XmlType(Namespace = ...)]` on
   AuthenticationData / PublicKey (`AsbContracts.cs:350-381`) means
   XmlSerializer emits `xmlns="..."` on each direct child. The default-
   ns scope ends at `</Data>`, so `<InitializationVector>` needs its own
   redeclaration to stay in the data namespace; without it the server
   fell back to messages-namespace and the deserialiser threw an
   `InternalServiceFault`.

3. SOAP-fault detection in `AsbClient::send_envelope`. New
   `ClientError::SoapFault { action, code, reason }` surfaces when the
   response Action header matches the canonical `dispatcher/fault`
   template; previously body decoders blindly ran and surfaced
   `MissingField { field: "Status" }` masking the actual fault. Reason
   text is extracted as the longest `NbfxText::Chars` in the body —
   robust against the `nbfs.rs` static-dictionary id mismatches.

4. Identified blocker (filed as F28): signed-request HMAC currently
   covers the NBFX wire bytes, but .NET's `AsbSystemAuthenticator.Sign`
   HMACs `Encoding.UTF8.GetBytes(request.ToXml())` — the canonical XML
   serialisation via `XmlSerializer` with namespace
   `urn:invensys.schemas` (`AsbSerialization.cs:12-48`). Until the Rust
   port emits identical XML bytes for `ConnectedRequest` subclasses,
   AuthenticateMe / RegisterItems / every signed RPC fault on the
   server. Connect itself is unsigned (`ServiceMessage` not
   `ConnectedRequest`) which is why it works today.

5. Identified `nbfs.rs` static-dictionary id drift (filed as F29): wire
   uses Fault=134/Code=142/Reason=144/Text=146/Value=154/Subcode=156
   but our table has them at 114/122/124/126/134/136. Off by 20 from
   id 114+ — 10 missing entries between `s` (id 112) and `Fault`. No
   request-side impact (we only encode IDs ≤44, all correct); the SOAP
   fault decode walks text records directly so it sidesteps the issue.

Workspace: 702 tests pass (no test count delta — wire-only fixes).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-05-05 16:29:12 -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).