Fix rfc8888 implementation

[5ur3]

Description

Issue 1 - unbounded growth of streamLog.log (memory exhaustion).

Entries are only removed while metricsAfter iterates upward from nextSequenceNumberToReport, so any entry left below that pointer is never freed. An entry lands below the pointer three ways:

1. A burst of more than maxReportBlocks packets between metricsAfter calls trips the cap, which advances the pointer past entries it hasn't deleted.
2. A permanently lost packet stalls the pointer; as later packets keep arriving, numReports exceeds maxReportBlocks and the same cap advances the pointer past still-stored sequence numbers. (1 and 2 share one root cause.)
3. A late or duplicate packet whose unwrapped sequence number is already below the pointer is inserted directly by add().

Issue 2 - possibility of make() called with negative len.

metricsAfter allocates its metricBlocks slice with a length up to maxReportBlocks. That value is derived in recorder.go from maxSize and the number of distinct SSRCs; with enough SSRCs in a session it becomes negative, so make() is called with a negative length and panics.

[Sean-Der]

Thanks @5ur3! I will get this merged now and cut a release :)

[codecov]

Codecov Report

❌ Patch coverage is 83.33333% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 80.05%. Comparing base (34107a4) to head (b5a0882).

Files with missing lines	Patch %	Lines
pkg/rfc8888/recorder.go	60.00%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #425      +/-   ##
==========================================
- Coverage   80.05%   80.05%   -0.01%     
==========================================
  Files          88       88              
  Lines        4608     4617       +9     
==========================================
+ Hits         3689     3696       +7     
- Misses        736      737       +1     
- Partials      183      184       +1     

Flag	Coverage Δ
go	80.05% <83.33%> (-0.01%)	⬇️

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[5ur3]

I will fix linter errors shortly

[Copilot]

Pull request overview

This PR addresses two correctness/stability issues in the RFC 8888 feedback implementation: preventing unbounded in-memory growth in per-stream packet logs and ensuring report-size budgeting cannot go negative (avoiding panics).

Changes:

• Prevent streamLog memory growth by dropping late/duplicate packets below the report pointer and reclaiming skipped entries when applying the report-block cap.
• Clamp the computed report-block budget to a non-negative value to avoid make() panics when many SSRCs are present.
• Add tests covering both the stream-log reclamation behavior and the non-positive per-stream budget scenario.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
pkg/rfc8888/stream_log.go	Drops packets below the report pointer and deletes log entries that would otherwise be skipped and leaked when capping report blocks.
pkg/rfc8888/stream_log_test.go	Adds regression tests ensuring the stream log does not retain entries below the report pointer.
pkg/rfc8888/recorder.go	Clamps report-block budget to avoid negative lengths in slice allocation.
pkg/rfc8888/recorder_test.go	Adds test ensuring large SSRC counts don’t cause panics and produce empty per-stream metric blocks.

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[5ur3]

Seems that such division by zero is unreachable (len(r.streams) is at least 1 when this code is triggered)

[JoTurk]

both BuildReport and NewRecorder are public. so it's reachable in custom user code.

[5ur3]

@JoTurk should I update this PR manually? Or will you commit this suggestion?

[JoTurk]

up to you :) you can apply it and amend your commit if you want, so it doesn't create extra noisy commit.

[5ur3]

I will just create extra commit myself

[JoTurk]

thank you.

[JoTurk]

should have squash merged.

[5ur3]

should have squash merged.

skill issue, I'm not using github a lot :) I'll remember that for next time