egutierrez
e7d59fd01d
The H1 fix bounds each request (1 MiB control / 16 MiB blob) and the per-IP rate
limiter throttles a single source, but neither bounds the AGGREGATE memory across
concurrent requests. The re-audit (report 0006, N2) drove RSS to ~1.42 GB with 40
concurrent 16 MiB uploads, and noted that a multi-IP (botnet) flood scales without
a ceiling because the rate limit is per-IP.
Fix: a global, non-blocking, byte-counting limiter (pkg/membership/inflight.go).
ServeHTTP reserves a POST's worst-case buffered size (its route ceiling) from the
limiter before reading the body, and releases it when the request finishes. When
the global cap (maxInflightBytes = 128 MiB) is reached, further POSTs are shed
with 503 (backpressure) rather than parking goroutines, so total bytes buffered
in flight stays bounded regardless of connection count or source-IP spread. GETs
carry no body and do not consume the budget.
The limiter is implemented inside unibus (not delegated to the fn-registry, where
a generic concurrency primitive would normally live) because functions/core pulls
transitive deps requiring CGO (mattn/go-sqlite3) and external modules that are
incompatible with unibus's CGO_ENABLED=0 build, and because this work is scoped
to the unibus sub-repo. The type/method comments document this.
Verification:
- pkg/membership/inflight_test.go: TestInflightLimiter{Basics,Disabled,Concurrent}
cover golden/edge/error/disabled/over-release and a -race concurrency invariant
(inFlight returns to 0, never exceeds cap).
- pkg/membership/dos_concurrency_test.go: TestReaudit_DoSConcurrency fires 40
concurrent 16 MiB uploads from distinct IPs (the multi-IP shape) against a 48 MiB
test cap -> 200=3 503=37, RSS delta ~93 MiB (bound 256 MiB), inFlight()==0, and a
fresh upload still 200. With the limiter disabled the test fails (200=40 503=0),
confirming it is a real regression guard.
- CGO_ENABLED=0 go build ./... && go vet ./... && go test -count=1 ./... green;
CGO_ENABLED=1 go test -race ./pkg/membership/ green.
Residual (documented): under enforce the body is buffered twice (auth verify +
handler), so real RSS is ~2x the reserved bytes; closing that fully means
streaming blobs to disk (overlaps H9 / issue 0002).
Refs: report 0006 N2, issue 0005c.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>