The SDK memoizes INodeManager3.ValidateEventRolePermissions per (item, event type,
SourceNode). #826 kept it fresh by reflecting into the private
MonitoredNode2.InvalidatePermissionCaches (plus a detach/re-attach fallback). Since #855
condition events never take that channel, and the search for #878 found nothing
production-raised that does except a condition's SDK method audits, which reach it only
with auditing on, SignAndEncrypt and a SecurityAdmin session (nothing grants that role).
Under enforcement the channel verdict is now a flat deny for items on our nodes, so no
cached verdict depends on a grant, and InvalidateFolderEventVerdicts, the reflection,
the fallback, its counter and the guard test are removed. Method audits still reach
Server-object items, decided per event.
Tests: FolderEventVerdictInvalidationTests -> FolderEventVerdictFreshnessTests; new
revoked-grant test (positive control: a still-granted session) and method-audit test
(SecurityAdmin mapped for the test; positive controls: Server-object item, flag off);
the plain-event test runs each mode on a fresh server. Mutation-checked.
Claude-Session: https://claude.ai/code/session_01GT67ACmpMR7b9LGRPLijMi
Since #855 condition events are queued to folder event items under the node
manager Lock. At a full DiscardOldest queue the SDK's EventQueueHandler
dequeues the head of EventMonitoredItemQueue, a List.RemoveAt(0) shift of the
whole queue (~1 us/item at QueueSize 1000, ~10 us at 10000).
OtOpcUaSdkServer.CreateMonitoredItemQueueFactory now wraps the SDK factory in
RingEventQueueFactory: event queues are RingEventMonitoredItemQueue (O(1)
discard), data-change queues, durable requests and disposal go to the SDK
factory unchanged. A factory set through StandardServer.MonitoredItemQueueFactory
is used as-is.
The SDK queue is storage only (decompiled 2.0.1): DiscardOldest, overflow-event
positions and discarded/overflow counters live in EventQueueHandler, which is
unchanged. The ring reproduces QueueSize 0 initial + BadInternalError enqueue,
drop-oldest at Count == QueueSize, FIFO dequeue, SetQueueSize keep-newest /
keep-oldest, the newest-1000 duplicate window via IsEventRaisedFor, no-op
Dispose. RingEventMonitoredItemQueueParityTests drive both queues, and the SDK
EventQueueHandler over both factories, with the same random sequences.
FolderEventDeliveryPerfTests gains Ring_vs_sdk_event_queue (A/B in one process
via the internal OtOpcUaSdkServer.RingEventQueues switch).
Claude-Session: https://claude.ai/code/session_01GT67AD99zQQqpLCVm3p7xk
Condition events reaching one of our notifiers no longer go through the SDK
MonitoredNode2 channel: the walk serves the attached items itself, per item and
per event (audit guard, uncached INodeManager3 verdict, item gate/cut,
QueueEvent), as the Server-object path does. No notifier of ours defers any
more; the #838 deferral queue and the #854 cut stay as the safety net and
folder items share the cut (RefreshDirectItems, flag on and off). An event
whose walk suspends is marked deferred before it suspends.
Tests produce deferral with a notifier-stall probe instead of holding a folder
item's SDK lock (which would now block the reporter). New
FolderConditionRefreshWireTests; design note in docs/plans.
Claude-Session: https://claude.ai/code/session_01GT67AD99zQQqpLCVm3p7xk
EventQueueOverflowAclWireTests drives >4096 condition events at a folder notifier
item and a Server-object (i=2253) item with Security:Acl enforcement on, a
non-publishing client, and a second session reading a node-manager node throughout:
- denied (EqA-owned scripted) events interleaved with allowed native ones, under one
Lock hold and per-projection: no deadlock, reads stay bounded, deferral peak stays
within 2 x (MaxDeferredEventsPerCondition + 1), delivery <= item QueueSize, oldest
dropped / newest kept in report order, one EventQueueOverflowEventType published ahead
of the survivors (SDK DiscardOldest, Part 4 5.13.1.5), zero denied events delivered;
- a grant revoked (state.Apply -> revalidation, re-entering Lock) while a deferred tail
waits behind a full folder channel: neither the tail nor later events reach the
revoked session's folder or Server-object item; a still-granted session on the same
channel receives all of it.
Falsified: with enforcement off (and with the revocation removed) all three cases fail.
No production defect found.
Claude-Session: https://claude.ai/code/session_01GT67AD99zQQqpLCVm3p7xk
Review of 1622d07f:
1. Perf: every i=2253 refresh ran the whole notifier walk + permission checks +
QueueEvent under Lock. Now, with nothing deferred (the common case), the refresh is
the SDK-shaped walk off Lock (Lock only to copy the root notifiers), kept only if no
deferral episode existed at any moment of it (count 0 before and after, episode
unchanged); otherwise the cut path also runs and its later replay supersedes. The
cut path takes ACL/role verdicts off Lock, then one short Lock hold: watermark +
frozen snapshots of Retain conditions from _alarmConditions (no tree walk) + per-item
cut and "replay pending" marker; the replay is queued OFF Lock, one event per hold of
the item gate. While pending, a condition event newer than the cut marks its
condition so the older frozen entry is dropped rather than following it. A
concurrent fast-path refresh cancels a pending cut replay of the same item.
Measured, 3000 retained conditions, longest Lock wait seen by another thread during
one refresh: 1622d07f 95-106 ms idle / 102-127 ms deferring; now 0-3 ms idle /
23-32 ms deferring.
2. ACL: a retained condition omitted from the replay for want of a grant is never
withheld (RefreshCut.RetainedAtCut); only Retain=true events of a condition omitted
because it was NOT retained are.
3. One gate/cut state per item for its lifetime (ConditionalWeakTable keyed by the
item): an unsubscribe + resubscribe between refresh and drain keeps the cut.
4. Cuts carry their deferral episode; ClearStaleRefreshCuts runs when the count
returns to zero, and a stale-episode cut is inert.
5. Dispose guard for the custom refresh (ObjectDisposedException once disposing;
Dispose waits for refreshes in flight).
6. Docs: a refresh waits at most for one in-progress QueueEvent on the item.
Tests: resubscribe variants, ACL-grant-lands test, pending-replay probe test,
dispose test, 3000-condition Lock-hold measurement with a probe pinning that neither
path queues its replay under Lock; stress invariant tightened (never backwards outside a
refresh; each refresh ends on the newest delivered state) and tolerant of the SDK's own
BadRefreshInProgress overlap refusal. Each new test fails against its targeted mutation.
While a folder subscriber's SDK channel is full, a condition's later events wait in
its #838 deferral queue and reach i=2253 items only when the drain gets to them, off
Lock. A ConditionRefresh in that window replayed the current state, then the older
deferred events followed RefreshEnd (stale state, or a condition the refresh had just
dropped re-added until the newest drained).
- Condition events are reported as ConditionEventSnapshot (an InstanceStateSnapshot
carrying a report sequence, condition NodeId and Retain); events queued behind a
deferred report are marked Deferred.
- Server-object refresh (ConditionRefresh and ConditionRefresh2, flag on AND off) now
runs in RefreshServerObjectItems: watermark, "anything deferred?", the replay and its
queueing in ONE Lock hold, so the replay is exactly the state at the cut. Per item it
queues the replay and installs a RefreshCut under the item's gate.
- OnConditionReportEvent holds that gate across "superseded? -> QueueEvent" for
deferred events only. Withheld from that item alone: events at/below the cut whose
condition the replay re-sent, or Retain=true events of a condition it omitted; an
older Retain=false event of an omitted condition is still delivered. Queues, other
Server-object items and folder items are untouched; refresh never waits for a drain.
- Lock order Lock -> item gate -> SDK item lock, same as a synchronous report.
- Meter otopcua.opcua.condition_events.superseded.
- Folder items keep a documented residual (SDK channel backlog + memoised per-item
verdict leave no per-event hook).
Tests: ConditionRefreshDeferralWireTests (deterministic overload by holding the folder
item's SDK lock; 6 variants fail before the fix; probe-driven gate test fails with the
gate removed; concurrent reports/refreshes/stall stress test fails before the fix).
#838 review of 91e28e87:
1. Ghost events. The deferred report ran the SDK walk off Lock with no
liveness check, so an event waiting behind a full channel when a deploy
removed its condition still reached i=2253 subscribers after the NodeDeleted
(a ghost Retain alarm for ScadaBridge) and folder items. Delivery now walks
the SDK path itself (OnReportEvent, OnReportEventAsync, inverse notifiers,
then the Parent as BaseInstanceState does) re-checking before EVERY hop that
the condition is the live instance; OnConditionReportEvent checks the same,
which also stops a non-live scripted condition being admitted through its
old equipment folder (#808). A guard test pins that only NodeState and
BaseInstanceState define the walk. New wire test removes the condition in
the same Lock hold as a flood; the flag-off variant fails without the checks.
2. Back-pressure. Deferral is per condition (one condition's events stay
ordered; others are not held up). Overflow policy: coalesce, newest wins --
past 1024 waiting per condition or 65,536 total, the oldest not-yet-started
event is discarded (a condition event carries full state). Warning on
entering deferral (<=1/min), Information on draining, meters
otopcua.opcua.condition_events.deferred / .discarded{reason}.
3. Verified by decompiling SDK 2.0.1: the notifier list is snapshotted under the
node's own lock, MonitoredNode2.Dispose completes its writer (pending writes
fail with ChannelClosedException, swallowed), and the consumer catches
per-event exceptions -- no fix needed; documented.
4. ConditionRefresh does not flush deferrals; documented as a residual.
#844 review: DescribeCredential canonicalises the key id (trim, lowercase;
non-hex ids fold into one identity) and the username, since ConfigDbApiKeyStore
matches with SQL Server's case-insensitive, trailing-space-blind `=`.
#838(a): each notifier's SDK MonitoredNode2 drains a bounded channel (4096,
FullMode=Wait) and the synchronous NodeState.ReportEvent blocks when it is
full. Condition events are reported under Lock, and the delivery task takes
Lock on a verdict-cache miss (the SDK's own GetNodeMetadata, flag off too, and
#826's IsNotifierEventVisibleTo). A burst of >4096 events under one Lock hold
therefore deadlocked the node manager -- FolderEventFloodWireTests stalled at
exactly 4097 events with enforcement on AND off (so it predates #826).
ReportConditionEvent now goes through ReportEventWithoutBlocking:
ReportEventAsync completes inline while channels have room (unchanged normal
path); on overflow the report continues asynchronously holding no thread or
lock, and later reports queue behind it so events keep report order. The
deferred work holds only frozen snapshots and drains once Lock is released;
client delivery stays bounded by each item's queue.
#838(b): documented in docs/security.md that Part 3 ReceiveEvents applies to
the event's EventType and SourceNode (the SDK check, kept first), not to the
notifier; our decision is layered on top and non-condition events on a folder
item fail closed under enforcement. The reflection item stays open.
#844: a success cleared the whole per-client count, so a client holding a valid
key could make four guesses at another key id, sign in with its own, and repeat
forever. Failures are now charged to the (client, credential identity) pair --
IOpcUaUserAuthenticator.DescribeCredential, key:<keyId> for API keys -- and to
the client as a whole. A success clears only its own identity's count; the
per-identity threshold locks that identity; a new per-client cap
(OpcUa:CredentialLockout:MaxFailedAttemptsPerClient, default 2 x
MaxFailedAttempts) that a success never resets bounds spraying across key ids
and locks every credential. Slots are bounded on both counts; a waiter whose
identity has room is not held behind one whose identity has none.
#845: (1) store timeouts, miss-budget refusals, store/authenticator exceptions,
an unset pepper and cancellation are reported Transient
(OpcUaUserAuthResult.Unavailable) and released uncounted, so a ConfigDb stall
can no longer lock every keyed client out; the client still sees the same
opaque denial. (2) a full 4096-entry table defers its next prune until the
earliest entry could age out instead of rescanning under the lock per failure.
(3) ApplicationUri deliberately NOT added to the key: on a None channel it is a
free string, so it would let an attacker reset the count per guess --
documented. (4) wire tests: distinct client certificates on a Sign endpoint are
locked out separately; the ApplicationConfigPath branch keeps the SDK lockout
off (falsified by removing the loaded-branch disable).
A legitimate consumer opening several keyed sessions at once from one key
(e.g. a ScadaBridge site node behind one NAT IP on a None endpoint) must
never see BadUserAccessDenied for parallelism. BeginAsync now hands out at
most MaxFailedAttempts - recordedFailures verification slots per key;
further activations queue FIFO and are woken as slots free. A waiter is
refused only when the key locks out (never reaching the authenticator) or,
uncounted, after OpcUa:CredentialLockout:SlotWaitSeconds (default 10,
BadTimeout). Cancelled waiters are dequeued; pruning accounts for waiters.
The security property is unchanged: no more than MaxFailedAttempts
unverified guesses in progress-or-failed per window.
- Reserve an in-flight slot per client before authenticating (TryBegin /
Complete / Abandon under one lock); refuse once recorded failures +
in-flight attempts reach MaxFailedAttempts, so a parallel burst cannot
pass the check before its first failure is recorded.
- An expired lockout resets the count (LockoutSeconds < FailureWindowSeconds
relocked on every single failure after the first lockout).
- Validate OpcUa:CredentialLockout at host start: disabled, or both
durations > 0.
- Log the first refusal of a lockout episode at Information, the rest at
Debug.
- Document that on None endpoints the key is effectively IP-only (NAT
neighbours share a UserName count) and a null peer shares one key.
1. Orphaned subscriptions (session closed without deleting subs) have Session == null, so the public
MonitoredNode2.InvalidatePermissionCacheForSession never reached their items: a cached allow survived a
deploy, the moved alarm's events were queued and delivered on TransferSubscriptions. Each notifier's
cache is now cleared whole through the SDK's private MonitoredNode2.InvalidatePermissionCaches
(reflection, guard-tested; fallback = per-session drop + Remove/Add of session-less items).
2. The verdict is decided on the condition LIVE under the event's NodeId, not the event's own instance:
the SDK key has no instance identity, so a replaced instance's late event cached a deny its successor
inherited until the next invalidation.
3. Invalidation is skipped while enforcement is off (forced across an on/off authorizer transition) and is
one O(cache) clear per node instead of a whole-cache scan per item.
4. TagReferencingEquipment carries alarm-bearing raw tags only (TagConfigIntent.Alarm); the snapshot adopts
an OrdinalIgnoreCase set instead of copying it again.
Tests (each fails with its fix reverted): FolderEventVerdictInvalidationTests (orphan + deploy + transfer;
replaced instance's late event; ACL-off skip; SDK private-method guard), DeploymentArtifactScopePathTests
(alarm-bearing projection).
Event items on an equipment / raw device folder were fed by the SDK's MonitoredNode2 fan-out with no ACL
decision, so after a deploy moved a scripted alarm (or dropped the reference projecting a native alarm into
an equipment) the OLD folder's subscribers kept receiving it - EventId included - until the rebuild landed,
indefinitely after a failed apply.
- OtOpcUaNodeManager re-implements INodeManager3 so ValidateEventRolePermissions (the SDK's per-event,
per-item hook; base not virtual) adds IsNotifierEventVisibleTo: live condition instance, notifier still a
legitimate notifier of it, and the #586/#808 Server-object rule (IsConditionVisibleTo over
ConditionVisibilityScopes).
- The SDK memoizes that verdict per (item, event type, SourceNode): InvalidateFolderEventVerdicts runs on the
authority/authorizer setters, RevalidateMonitoredItems (deploy + timer) and CompleteAddressSpaceApply.
- ConditionRefresh on direct items goes through RefreshDirectItems (base loop + the same decision).
- New generation field TagReferencingEquipment (RawPath -> EquipmentIds, from the artifact's
UnsTagReferences via AclScopePathResolver.ResolveTagRawPath): a native alarm's wired equipment folder only
counts (folder delivery AND Server-object scopes) while the current generation still references it.
- Secondary #808 edge: UNS variables wired UNS->Raw Organizes by AddReference are tracked and always placed
as reference variables (an Area named like its equipment's id no longer narrows them).
Tests: UnsFolderScopeWireTests (moved alarm on a folder item + ConditionRefresh + rebuild; area named like
equipment id), NativeAlarmFolderEventAclWireTests (dropped reference: folder + Server object + refresh +
restore), DeploymentArtifactScopePathTests (projection). Rig/event tests now supply tag references.
OPC Foundation SDK 2.0.1's SessionManager lockout refused EVERY
activation (Anonymous included, before the token is read) from a client
with 5 failed identity validations in 60 s, for 5 minutes, keyed on cert
thumbprint else peer IP. Disable it (MaxFailedAuthenticationAttempts=0
on built and loaded configs) and enforce FailedCredentialLockout in the
identity-registry adapter instead: UserName activations only, keyed on
thumbprint+peer together, same 5/60s/300s defaults, configurable via
OpcUa:CredentialLockout.
Review of af5c9744:
1. UNS reference variables (s=Area/Line/Equip/Eff) of a moved or renamed
equipment stayed readable/writable under the OLD names' grants: they now
resolve as ReferenceVariable and are authorized at their split path only
while it equals their live equipment folder's placement (live chain ==
generation chain) + one name; otherwise denied (Read and Write).
2. TryPlaceScriptedCondition now also requires the owner folder's live chain
to match the generation (AuthorizeScriptedCondition gains ownerFolderChain),
so a moved equipment's alarm/children/commands follow its folder.
3. Identifiers containing NUL are denied before the decision cache, keeping
client ids disjoint from the NUL-prefixed resolved-scope keys (a client
could otherwise poison a real folder's cached verdict for its key shard).
4. An id no live node holds is Unknown: placed at [\0unknown] so only
Cluster / Namespace-uns grants decide it (a removed opaque id can no longer
split onto a same-named narrow grant; narrow grantees get no NodeDeleted for
removed UNS folders/vtags/conditions — documented); 4-segment
reference-shaped ids keep their split.
5. A wire test drives placements from DeploymentArtifact.ParseDataPlaneAuthority.
Baseline updates: #797 owner tests (unit + wire) and Sdk2RepeatedAlarmAuthority
now install folder scopes; Sdk2HistoryAuthority's UNS alias used the RAW path
as its UNS id (never minted in production) and now carries EqA/HistoryAlias.
Each new guard was falsified (reverting it fails its test).
UNS Area/Line/Equipment folders are minted under their opaque entity ids
(s=UA-/UL-/EQ-...), virtual tags under s=EQ-.../Name and scripted conditions
(+ #629 children) under s=<ScriptedAlarmId>[/...], while every UNS grant is
planted at a NAME path. DataPlaneAuthorizer split those ids, so with
Security:Acl:Enabled a narrow (Area/Line/Equipment) grant could not Browse,
Read, subscribe or HistoryRead them, and Server-object delivery never reached
it — so a narrow key never held the EventId Ack/Confirm/AddComment need.
- The generation carries UnsFolderScopes (folderId -> path + id chain), built
by DeploymentArtifact from the same AclScopePathResolver as the grants; ids
two entity kinds share are dropped; plumbed through IDataPlaneAuthoritySink.
- OtOpcUaNodeManager.ResolveUnsAclSubject reports live facts (folder id
ancestry / scripted owner binding); attached by the Authorizer setter.
- Evaluate places the subject against the CURRENT generation before the
decision cache, which now caches the walk keyed on the resolved scope.
Folders require live chain == generation chain (a moved equipment is denied
under old and new line until the rebuild). Owned nodes (vtags, conditions,
children) get owner path + a reserved segment, so Tag grants and their
Browse transit never expose them. Conditions share TryPlaceScriptedCondition
with the #797 command gate.
- Server-object visibility of a scripted condition is decided on the
condition alone, so a moved alarm cannot reach its old owner there.
Tests: UnsFolderScopeWireTests (opaque ids, end-to-end browse -> EventId ->
Acknowledge on an Equipment grant; sibling denied; Tag-only grant; moved alarm
and moved equipment stale windows). Rig tests now install folder scopes
explicitly (ServerEventRig.FolderScopes); the #797 recreate test deliberately
asserts the moved alarm is invisible to the Cluster observer in the window.
Review r0 of Integration-W3:
- I1: the effective FC16 cap is min(configured maxRegistersPerWrite, 123). The
driver trusts a larger configured cap and sends an over-ceiling FC16 (past 127
registers its byte-count byte wraps), which every conformant device refuses, so
such an array is never advertised writable.
- I2: a BitInRegister[] write reads its span first in one unchunked FC03, so it is
also bounded by min(configured maxRegistersPerRead, 125) (absent/0 = 125).
- m2: every span (registers and coils) must end at or before address 65535.
- m1: the String-node wording says it converts only when the text parses, which
the server cannot promise (DateTime never converts).
- m4: the parity device now enforces FC01/02 2000, FC03/04 125 (or a smaller
device read limit), FC15 1968, FC16 123, FC23 121/125, the FC15/FC16 byte-count
field (exception 03) and the address-space end (exception 02).
Tests: parity rows for each ceiling/cap/span boundary against the real write
path, and Core.Abstractions row tests. The configured-cap test that asserted a
cap of 200 lifts the ceiling now asserts the opposite.
Refs #741
Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT
The Modbus lane (#741 U3) gave the driver String[] and BitInRegister[] holding-register array encoders, and
moved address resolution to ModbusTagAddressResolution (keys first, a bit region coerced to Bool, strict key
reads), but DriverArrayWriteSupport still listed both array shapes read-only (follow-up F1), so a client
write was BadNotWritable before it reached the driver.
Modbus row now mirrors the driver end to end:
- Keys shape only (region + address both present). A string-only addressString tag is resolved by the
driver with its own family through a parser Core.Abstractions cannot reference, so it stays read-only
(pinned: the conservative direction).
- Strict reads as the resolver: address an integer 0-65535; a present region / dataType / byteOrder /
stringByteOrder string must name a member.
- Coils: any dataType (coerced to Bool), <= 1968 coils (FC15).
- HoldingRegisters (FC16, never Bool): numeric, String ((stringLength+1)/2 registers, stringLength >= 1),
BitInRegister (1 register, bitIndex 0-15, span ending <= 65535), all within maxRegistersPerWrite.
FC23 is opt-in and never changes the answer.
- Elements convert (ScadaBridge int[] -> Int16 stays writable); only a String / DateTime node over a
numeric or bit element is left out, since such an element never converts.
Tests: the parity test's PendingF1 exemption and its guard are gone; the parity matrix is now region x
element type x node type against the real WriteAsync with a spec-conformant device (FC15 > 1968 refused),
plus shape edges at every cap boundary (numeric, String, BitInRegister, coil), strict key reads, FC23
on/off, string-only, the ScadaBridge int[] shape and U3 wire bytes. Core.Abstractions row tests and a
composer test (String[] and BitInRegister[] writable; over-cap, no-stringLength and string-only read-only).
Docs: table XML doc, Uns.md, modbus-addressing.md, drivers/Modbus.md, data-plane rules.
Refs #741
Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT
The Wave-2 lanes gave AbCip, AbLegacy and TwinCAT real whole-array write
encoders (review 07 U10/U9), but the capability table still listed all three
as scalar-only, so every array node materialised read-only and a client write
was BadNotWritable before it reached the driver.
Rows added, each listing only what WriteAsync encodes end to end:
- AbCip: SInt/USInt/Int/UInt/DInt/UDInt/Real/Dt/LInt/ULInt/LReal, declared
length, not a safetyTag. BOOL/STRING/Structure arrays stay read-only.
- AbLegacy: Int/AnalogInt on N/B/A, Long on L, Float on F (file-width match),
plain <file><n>:<word> address, <= 256 elements; not /bit, .sub, indirect,
S:/I:/O:, nor native PLC-5.
- TwinCAT: every codec element type, declared length; not a BOOL bit-in-word
path.
Elements convert in all three encoders, so the rows never key on an exact
node DataType (ScadaBridge int[] -> Int16 stays writable); they leave out
only node types whose elements never convert (DateTime/String over numeric,
Boolean on AbLegacy, STRING under DateTime on TwinCAT: culture-dependent).
Tests: driver-level parity for each driver (every element type x node type
plus shape cases, against the real write path), the AbLegacy parity tests
un-skipped, Core.Abstractions row tests, a composer test (three drivers
writable, refused shapes read-only), and the existing AbCip negative cases
moved to a BOOL array. Docs: Uns.md table, per-driver docs, data-plane rules.
Refs #737#738#739
Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT
Keeps the root CLAUDE.md lean by lazy-loading per-area detail (drivers, topology,
data-plane auth, alarms, historian) only when matching files are touched.
Joseph Doherty