fix(iroh): bound retry and lookup lifecycles

[azooz2003-bit]

Description

Hardens two per-peer actor lifecycles in the cmux Iroh v1.0 fork.

• Deduplicate pending path-open retries across connections.
• Cap retries at 64 distinct paths with oldest-first eviction.
• Give each address resolution an explicit cancellation lifetime.
• Drop a hanging lookup when its final waiting dial is cancelled and no path or connection remains.
• Preserve a shared lookup while another dial is still waiting.

Both fixes use red-test then green-fix commit pairs.

Breaking Changes

None.

Residual risk

Persistent path-ID exhaustion can still produce bounded retry CPU. The cancellation path is scoped to address resolution and does not alter established connection lifetime.

Verification

• 117 Iroh tests passed, 1 known flaky test ignored.
• 1 integration test and 26 doctests passed, 2 doctests ignored.
• All-feature clippy passed with warnings denied.
• Formatting and diff checks passed.

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Summary by CodeRabbit

• Bug Fixes

  • Cancelled connection attempts now promptly stop in-progress address lookups.
  • Prevented cancelled resolution requests from affecting other active requests.
  • Added safeguards to keep pending connection retries bounded and deduplicated.
  • Improved cleanup of abandoned address-resolution operations to prevent resource buildup.

• Tests

  • Expanded coverage for cancellation, cleanup, concurrent resolution requests, and bounded retry behavior.

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📝 Walkthrough

Walkthrough

A CancellationToken is threaded through the address-resolution path: Socket creates and passes it via ActorMessage::ResolveRemote into RemoteMap and RemoteStateActor, which now tracks cancellations, prunes cancelled queued resolves in RemotePathState, and bounds/deduplicates pending open-path retries. Tests validate drop-triggered cancellation and queue behavior.

Changes

Cancellable resolve_remote propagation

Layer / File(s)	Summary
Socket entry point creates and forwards cancellation token iroh/src/socket.rs	Socket::resolve_remote creates a CancellationToken with a drop guard, sends it in ActorMessage::ResolveRemote, and the actor handler forwards it to remote_map.resolve_remote.
RemoteMap forwards cancellation to actor iroh/src/socket/remote_map.rs	RemoteMap::resolve_remote gains a CancellationToken parameter forwarded in RemoteStateMessage::ResolveRemote; tests updated to pass tokens.
RemoteStateActor tracks and reacts to cancelled resolves iroh/src/socket/remote_map/remote_state.rs	Adds address_lookup_cancellations and a bounded/deduped PendingOpenPaths queue, registers cancellation futures in handle_msg_resolve_remote, prunes cancelled requests via handle_resolve_cancellation, switches retry scheduling to enqueue, and adds bound-check unit tests.
RemotePathState queues PendingResolveRequest with cancellation iroh/src/socket/remote_map/remote_state/path_state.rs	Pending resolve queue now stores PendingResolveRequest (reply + CancellationToken); resolve_remote returns queued status; prune_cancelled_resolve_requests removes stale entries; tests updated and extended.
End-to-end drop test for hanging address lookup iroh/src/address_lookup.rs	Test module adds sync imports and reworks a test to probe start/drop of a hanging resolve future, verifying cancellation propagates end-to-end.

Estimated code review effort: 4 (Complex) | ~60 minutes

Sequence Diagram(s)

sequenceDiagram
  participant Socket
  participant RemoteMap
  participant RemoteStateActor
  participant RemotePathState

  Socket->>Socket: create CancellationToken + drop_guard
  Socket->>RemoteMap: resolve_remote(addr, tx, cancellation)
  RemoteMap->>RemoteStateActor: ResolveRemote(addrs, tx, cancellation)
  RemoteStateActor->>RemotePathState: resolve_remote(tx, cancellation)
  RemotePathState-->>RemoteStateActor: queued = true/false
  RemoteStateActor->>RemoteStateActor: register cancellation.cancelled_owned()

  alt caller drops request
    Socket->>Socket: drop_guard triggers cancellation
    RemoteStateActor->>RemoteStateActor: cancellation future resolves
    RemoteStateActor->>RemotePathState: prune_cancelled_resolve_requests()
    RemoteStateActor->>RemoteStateActor: stop address-lookup stream if empty
  else resolution completes
    RemotePathState->>RemoteStateActor: emit_pending_resolve_requests()
    RemoteStateActor->>RemoteMap: reply via oneshot
  end

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🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly summarizes the main change: bounding retry and lookup lifecycles.
Description check	✅ Passed	The description covers the main changes, breaking changes, risks, and verification, but it omits the notes/open questions and checklist sections.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/cmux-iroh-1.0-bounds

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[azooz2003-bit]

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