[Audit-Medium] LoggerMiddleware treats DispatchException as a failed…

[pepone]

AI-generated audit finding — this issue was opened from an automated security/correctness audit. It has not been triaged by a human yet; verify the reasoning, reproducibility, and severity before acting on it.

Medium: LoggerMiddleware treats DispatchException as a failed dispatch even though IceRPC converts it into a normal non-OK response — CONFIRMED

Affected code:

• src/IceRpc.Logger/LoggerMiddleware.cs:35-54 — try { … } catch (Exception) { LogDispatchException(...); throw; } with no special-case for DispatchException
• src/IceRpc/DispatchException.cs — DispatchException is the standard way to signal a non-OK response
• src/IceRpc/Internal/IceRpcProtocolConnection.cs:1206, src/IceRpc/Internal/IceProtocolConnection.cs:1051 — protocol code converts DispatchException into an OutgoingResponse with StatusCode = dispatchException.StatusCode

Verification:

Confirmed. LoggerMiddleware.DispatchAsync wraps _next.DispatchAsync in a generic catch (Exception) at line 47. Any exception — including the library-idiomatic DispatchException used to signal NotFound, InvalidData, etc. — is logged with the DispatchException event and rethrown.

The protocol connection above the middleware then catches the rethrown DispatchException and turns it into a perfectly normal response with the carried status code. Operators see a double-signal: a "failed dispatch" log entry and a non-OK response, even though the library treats the flow as normal.

Impact:

• Server logs misclassify expected application outcomes as exceptional failures.
• Alerting and dashboards built on the DispatchException event ID or on exception-shape log queries overcount failures.
• Middleware logging contract diverges from the rest of IceRPC.

Recommendation:

• Add a catch (DispatchException dispatchException) { LogDispatch(...dispatchException.StatusCode...); throw; } branch before the general handler, or restructure so logging happens after the protocol-connection conversion.
• Add regression tests that throw DispatchException(StatusCode.NotFound) and DispatchException(StatusCode.InvalidData) and assert the Dispatch event (not DispatchException) is emitted.

Status: Valid, Medium severity.

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Source report: src-IceRpc.Logger-audit-2026-04-14.md (finding ``LoggerMiddlewaretreatsDispatchException` as a failed dispatch even though IceRPC converts it into a normal non-OK response — CONFIRMED`)

Severity (auditor-assigned): Medium