.NET's Uri parses a zone ([fe80::1%eth0]) but drops it from Host, Authority,
AbsoluteUri and ToString(); only DnsSafeHost/IdnHost carry it. The shared
OpcUaEndpointUrlRewriter rebuilt the URL through UriBuilder, so the zone was
lost and link-local endpoints were unroutable. The SDK dials
new Uri(EndpointUrl).IdnHost (TcpByteTransport -> DnsEndPoint), which keeps
it, so splicing the zone back into the string is enough. Kept verbatim
(%eth0, %4, or RFC 6874 %25eth0) so the session dials exactly what
GetEndpoints reached. Applies to the driver, the AdminUI browser and the
Client CLI/UI (all share the rewriter).
Client.Shared now project-references Driver.OpcUaClient.Contracts (Core.Abstractions
only, no NuGet/SDK; pinned by ContractsIsDependencyLightTests) and delegates the
host/port rewrite to OpcUaEndpointUrlRewriter, deleting its own copy.
The two copies differed; reconciled toward the client so its pinned behaviour is
unchanged (EndpointSelectorRewriteParityTests, written green against the old copy):
- no-op rewrite (same host case-insensitively + same port) now returns the advertised
string verbatim in the shared rewriter too (it re-serialised: added a trailing slash
and case-folded a case-only host difference);
- a real rewrite serialises via AbsoluteUri, not Uri.ToString(), which un-escaped the
advertised path (/x%20y became /x y) in the driver + browser;
- unusable URLs: the rewriter still falls back to the configured URL (driver/browser);
the client keeps its loud failure as call-site validation (null -> InvalidOperation,
unparseable -> UriFormatException).
The AdminUI OPC UA browse picker connected to the EndpointUrl the server
advertised in GetEndpoints verbatim, so behind NAT / a container port
publish it dialled the server's private hostname + internal port and
failed DNS where the runtime driver (which rewrites per #676) connected.
- Move the rewrite to the shared OpcUaEndpointUrlRewriter (.Contracts,
pure Uri logic, no SDK dependency) and the policy+mode selection to
OpcUaEndpointSelection (.Session leaf). Driver and browser both select
through it, so the browse connects exactly where the driver does.
- Policy/mode filter, server certificate and strict browse PKI
(no auto-accept) are unchanged.
- Unit tests: rewrite (host/port differ, same, IPv6 both sides, path
kept, port-less, scheme mismatch untouched), browser selection seam.
- Live NAT tests (Fixture=opc-plc-nat, OPCUA_NAT_ENDPOINT): browse via a
published port with a premise check that the advertised host:port
differs and does not resolve, nsu= round-trip, unreachable endpoint
fails cleanly, SignAndEncrypt reaches the server and is refused
BadCertificateUntrusted. Verified red without the rewrite.
Refs #806
1. RewriteEndpointUrl keeps the advertised port when the configured URL names none
(Uri.Port -1 would have sent the session to 4840); port-less + IPv6 tests.
2. The trailing re-read repairs any (value, status) difference that is not older than
the last delivered value — Good->Bad/Uncertain included; a read without a source
timestamp counts as newer; an equal source time with different content is published
(repairs the replay guard's by-design equal-timestamp drop).
3. One driver-wide delivery lock makes decide+publish atomic across live notifications,
the recovery read and the trailing read, so an older value can never land after a
newer one (deterministic race test via a seam).
4. Known gap documented: a ConnectionLost raised while the host is not Connected is
swallowed and that session falls back to the watchdog.
5. Only a SERVER-reported subscription loss raises ConnectionLost; the publishing-stall
heuristic stays with the #527 watchdog.
6. Post-recovery timers run on Task.Delay(…, Clock, ct) with a session-work CTS
cancelled on session release and dispose.
7. Replay summary at Information only when something was dropped (Debug otherwise);
a re-arm reports the superseded window's drops and counts afresh.
8. DriverInstanceActor: AttachHostStatusSource doc comment restored; Reconnecting
swallows a stray DisconnectObserved (test).
9. Stall wire test: 120 s session timeout, 3000-cycle subscription lifetime, one further
bad keep-alive tick, 60 s headroom on the post-recovery waits (5/5 green).
- Endpoint rewrite: the driver now connects to the configured host AND port (scheme
match, advertised path kept) instead of the server-advertised URL — fixes NAT/port-map
upstreams and lets an in-test proxy carry the session (SDK SelectEndpoint rule).
- TcpStallProxy + OpcUaClientDriverStallWireTests: the in-place blip (#670) is now
wire-tested on loopback — one Bad, frozen read stamp, same session, identical value
republished Good, a post-recovery change arrives, no source-time regression after
the SDK's late backlog flush.
- Defect found by that test, fixed: a change published right after a stall rode a
Publish response the SDK timed out and never republished, leaving the node Good on
the pre-change value indefinitely. New trailing reconcile read (Timeout +
KeepAliveInterval after recovery) publishes any Good value newer than the last
accepted one, through the replay guard's mark.
- IDriverConnectionLossSource (Core.Abstractions): opt-in definitive-loss signal.
DriverInstanceActor attaches in PreStart / detaches in PostStop and turns a raise
into a disconnect only while Connected. OpcUaClient raises once per session on
keep-alive BadSessionIdInvalid/BadSessionClosed/BadSessionNotActivated/
BadServerHalted (measured: the SDK never re-opens a halted channel) or a dropped
subscription; ambiguous codes stay with the #527 watchdog.
- Replay guard: one Information summary per recovery when the window closes
("dropped N late notifications across M refs"), with a timer so quiet
subscriptions log it too.
- ReconnectPeriod deleted (options, AdminUI form, docs, tests); stored configs that
carry reconnectPeriod still parse in the factory, probe and browser.
- Docs: OpcUaClient.md, DriverLifecycle.md, driver-specs.md, CLAUDE.md.
Joseph Doherty