Release the opaque relay copy the interface declines to send

[caveman99]

relayOpaquePacket() allocates a copy and returns Router::send(relay) == ERRNO_OK, discarding ERRNO_SHOULD_RELEASE. The interface returns that for NODENUM_BROADCAST_NO_LORA (RadioLibInterface.cpp), so the copy is never freed and one pool slot leaks per frame.

The opaque path is taken when passesRoutingAuthGate returns OPAQUE_RELAY_ONLY, which is the verdict for a packet on a channel we hold no key for. No key, PSK or admin access is required: a frame with an unknown channel hash, to=NODENUM_BROADCAST_NO_LORA, a nonzero id and hop_limit > 0 leaks a slot on every default-configured rebroadcaster, and roughly MAX_PACKETS of them exhaust the pool until reboot.

#11087 fixed this same pattern in perhapsRebroadcast and the retransmission paths, and added the NODENUM_BROADCAST_NO_LORA guard now at NextHopRouter.cpp:180, but relayOpaquePacket was not covered.

Summary by CodeRabbit

• Bug Fixes
  • Fixed packet handling during relay operations to prevent resource leaks.
  • Improved relay result processing for more reliable packet delivery.

[coderabbitai]

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ℹ️ Recent review info

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Run ID: ae9fc256-6339-4259-be08-02418df1ce93

📥 Commits

Reviewing files that changed from the base of the PR and between ae16c05 and 315e3a9.

📒 Files selected for processing (1)

• src/mesh/NextHopRouter.cpp

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📝 Walkthrough

Walkthrough

relayOpaquePacket now handles the special Router::send release result by returning the relay packet to packetPool, while preserving success reporting for ERRNO_OK.

Changes

Opaque packet relay cleanup

Layer / File(s)	Summary
Relay send cleanup src/mesh/NextHopRouter.cpp	relayOpaquePacket captures the send result, releases relay when the result is ERRNO_SHOULD_RELEASE, and returns whether the result is ERRNO_OK.

Estimated code review effort: 2 (Simple) | ~5 minutes

Possibly related PRs

• meshtastic/firmware#11087: Updates related relay and retransmission paths to release cloned packets on ERRNO_SHOULD_RELEASE.

Suggested labels: bugfix

Suggested reviewers: nomdetom

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title matches the main change by describing the release of the opaque relay copy when the interface declines to send.
Description check	✅ Passed	The description clearly explains the bug, impact, and fix, but it omits the template's testing attestations.
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

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• Create PR with unit tests
• Commit unit tests in branch fix-opaque-relay-pool-leak

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