The per-write deadline that severs a stalled SSE reader was never cleared on
return. Server.WriteTimeout is deliberately unset -- a WriteTimeout would sever
a healthy long-lived stream -- and with it unset net/http never resets the
connection write deadline between keep-alive requests. So the deadline the last
writeChunk left set leaks onto the next request that reuses the pooled
connection and fails its first write for no reason. Clear it to the zero value
on return via a deferred rc.SetWriteDeadline; best-effort, a no-op on writers
without deadline support.
Also record honestly at the header flush that the connect-time stall stays
bounded only by the per-principal stream cap, not severed by this guard -- only
the mid-stream stall is closed. Adds a test pinning the clear (fails closed:
neutering the deferred clear leaves a +writeTimeout deadline set on return).
relayLogStream copied a pod-log follow to the client with a plain
flusher.Flush per event. On a client that stays connected but stops
reading (its TCP receive window shut), net/http buffers the small
"data:" line and only touches the socket at Flush, which then blocks
forever inside the write. The select's <-ctx.Done() branch is never
reached, because r.Context() cancels on an actual disconnect, not on a
stall, so the relay goroutine and its upstream apiserver follow leak for
the life of the process.
Route every event's write+flush through http.ResponseController with a
per-write deadline (writeTimeout, 30s): a stalled flush now returns
os.ErrDeadlineExceeded, the error plain http.Flusher.Flush swallows, and
the relay abandons the stream so the deferred cancel + src.Close release
the follow. SetWriteDeadline and rc.Flush are best-effort: a writer
without deadline support (httptest recorder; some HTTP/2 origins) ignores
the deadline and behaves exactly as before, so the guard degrades
gracefully.
This closes the leak the per-principal stream cap only bounded the blast
radius of. Verified by a deterministic test with a deadline-aware
ResponseWriter whose flush blocks until the deadline; the test times out
(fails closed) if the guard is removed.
The dual-faced felis-api: internal (service) and external (public/app/admin) routes behind a Zero-Trust guard. Includes the access domain (whitelist, ban, and LuckPerms permission/group control over the owner-gated RCON path), the modpack submission endpoints, and the admin-tier SysAdmin fleet read. Structured access fields are charset-validated before assembly so no field can splice a second RCON command.
Lemon-miaow
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