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romanett
6ad0d95b26
# Description Fixes the reverse connect problem reported in #3985: a Client which uses one reverse connect listener port for several Servers connects to the first Server, and every following `WaitForConnectionAsync` times out. A separate listener port per Server was the only workaround. ## Root cause Confirming the analysis in [mrsuciu's comment on #3985](https://github.com/OPCFoundation/UA-.NETStandard/issues/3985): - Servers which send `ReverseHello` before the application registered a waiting connection for them are held in `OnConnectionWaitingAsync` for `HoldTime`. - All held connections share a single `CancellationTokenSource`, so `RegisterWaitingConnection` wakes up **every** held connection, not only the one it was registered for. - The hold loop was `while (!matched) { ... break; }` with an unconditional `break`, so each woken connection got exactly one re-match attempt. The connections which did not match the new registration fell out of the loop unaccepted, although most of their own hold time was left. - An unaccepted connection is force faulted by the listener (`TcpReverseConnectChannel`, "The reverse connection was rejected by the client"), so that Server is dropped and only returns on its next `ReverseHello` interval, long after the Client timed out waiting for it. Separate ports avoid the shared wakeup path, which is exactly why that workaround succeeds. ## Changes - `ReverseConnectManager.OnConnectionWaitingAsync` re-arms the hold after a wakeup: it re-matches, and if the registration which caused the wakeup was for another Server the connection keeps waiting for the remainder of its own hold time. The loop is still bounded by `HoldTime`, so a Server which is never registered for is rejected exactly as before. - A shutdown flag set by `StopService`/`Dispose` (cleared by `StartService`) releases held connections immediately during teardown, instead of parking them until the hold time expires. `Dispose` now also cancels the token source before disposing it, so a held callback can no longer read a disposed token. - `Docs/ReverseConnect.md`: new "Sharing a listener across multiple Servers" section documenting that the listener port staying in `LISTENING` is expected, that one shared `ReverseConnectManager` should serve all Servers on the same Client Url, and the `HoldTime`/`WaitTimeout` semantics. No public API, signature or serialization change. ## Validation - New `ReverseConnectManagerUnitTests` (3 tests): the two Server regression, hold time expiry still rejecting, and dispose releasing a held connection. They drive the callback through an internal test hook, so no listener or socket is involved. Verified that the regression test fails against the previous behaviour with "The reverse connection of the second server was released before its hold time expired." - New tests pass on net10.0 and net48. - Full reverse connect suite (`FullyQualifiedName~ReverseConnect`, including the existing `ReverseConnectTest` server fixture): 33/33 pass on net10.0. ## Related Issues - Relates to #3985. - `master` carries the identical defect: the same `break` survived #4009 and #4059 and is still present in `src/Opc.Ua.Client/ReverseConnectManager.cs`. The equivalent fix for `master` is #4342 (it uses `TimeProvider` and breaks on a pending callback drain instead of a new flag), so the issue is intentionally not auto closed here. ## Checklist - [x] I have signed the [CLA](https://opcfoundation.org/license/cla/ContributorLicenseAgreementv1.0.pdf) and read the [CONTRIBUTING](https://github.com/OPCFoundation/UA-.NETStandard/blob/master/CONTRIBUTING.md) doc. - [x] I have added tests that prove my fix is effective or that my feature works and increased code coverage. - [x] I have added all necessary documentation. - [x] I have verified that my changes do not introduce (new) build or analyzer warnings. - [ ] I ran **all** tests locally using the **UA.slnx** solution against at least .net **framework** and .net **10**, and all passed. - [ ] I fixed **all** failing and flaky tests in the CI pipelines and **all** CodeQL warnings. - [ ] I have addressed **all** PR feedback received. 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-authored-by: Claude Opus 5 <noreply@anthropic.com>