ServerWebSocket.terminate(): close a TLS socket without waiting for the peer - #43013
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WebSocket::close() passed close code 0. On a TLS socket that code is the graceful close: usockets sends close_notify and keeps the socket open until the peer answers. A peer that does not read never answers, so ServerWebSocket.terminate() never ran the close handler, kept the fd, and kept delivering messages. forceClose() with no reason had the same close code. close() now asks for a fast shutdown, a FIN like a plain socket sends. If the socket is still open after that, usockets parked the close behind its ciphertext spill, and close() closes again with a reset, as the valkey client does since #39548. forceClose() with no reason goes through close().
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Navigate logical layers of code changes, visualize relationships, and explore their blast radius. WalkthroughThe change updates WebSocket forced-close handling and adds ws/wss coverage. Empty forced-close reasons now use the WebSocket close path. Tests verify synchronous ChangesWebSocket forced-close handling
Suggested reviewers: Priority: ➖ Normal Merge Risk: ⚪ Minimal · up to Forced termination may discard queued sends when TLS shutdown is deferred, but the API defines termination as abrupt and does not promise to flush them. No blocking contract risk is established. 🚥 Pre-merge checks | ✅ 4✅ Passed checks (4 passed)
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Inline comments:
In `@test/js/bun/websocket/websocket-server-forced-close.test.ts`:
- Around line 9-10: Replace the manual scheme loop around the forced-close test
with Bun’s concurrent parameterized suite API, describe.concurrent.each(), while
preserving the ws and wss cases and the existing test body behavior.
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packages/bun-uws/src/WebSocket.hpackages/bun-uws/src/WebSocketContext.htest/js/bun/websocket/websocket-server-forced-close.test.ts
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The forced close tests now fail at once when the client errors, closes early, or does not get the 101, and do not wait for the test timeout.
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Updated 4:05 PM PT - Sep 25th, 2026
✅ @cirospaciari, your commit 3bfbf331d84540ba6e960eae3692c5d68a1732db passed in 🧪 To try this PR locally: bunx bun-pr 43013That installs a local version of the PR into your bun-43013 --bun |
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Review follow-up, pushed as fed761c:
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A note on the fallback in
I measured this on the same fallback in #41711 (
2 of 2 runs each, debug build, Linux x64. #41711 now uses the second |
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Inline comments:
In `@packages/bun-uws/src/WebSocket.h`:
- Line 80: Update the comment near the CONNECTION_RESET fallback in the
WebSocket close path to explain that FAST_SHUTDOWN may remain deferred while TLS
ciphertext is pending, and that CONNECTION_RESET provides synchronous close
cleanup but aborts the connection and drops pending send data.
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packages/bun-uws/src/WebSocket.hpackages/bun-uws/src/WebSocketContext.h
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Problem
Bun.serve({ tls }),ws.terminate()waits for the peer's TLS close_notify. A peer that does not read never sends it: theclosehandler does not run, the fd stays open, andmessage()keeps firing. Each inbound frame re-arms the idle timeout, so nothing bounds the wait. Plainws://closes at once.WebSocket::close()(packages/bun-uws/src/WebSocket.h:76):us_socket_close(s, 0, nullptr). On TLS, code 0 is the graceful close (us_internal_ssl_close,packages/bun-usockets/src/crypto/openssl.c:2194).forceClose()with no reason (a reserved opcode) passes the same code.Fix
WebSocket::close()closes withFAST_SHUTDOWN(a FIN, no close_notify). If the socket is still open, usockets parked the close behind its ciphertext spill, andclose()closes again withCONNECTION_RESET(the idiom of valkey: close at once when a TLS fast shutdown is deferred #39548).forceClose()with no reason callsclose().CloseCode,src/uws_sys/us_socket_t.rs:23). Plain sockets treat codes 0 and 2 alike. A peer that keeps up sees no change. Under send backpressure the close is now a reset (see Notes).test/js/bun/websocket/websocket-server-forced-close.test.ts, the 3wsscases fail without the fix. Alsotest/js/bun/websocket/,test/js/web/websocket/,test/js/first_party/ws/.Background
us_socket_close(s, code, reason)closes the fd and runs the close handler. On TLS, code 0 sends close_notify and waits for the peer, code 1 resets, and code 2 sends a FIN but waits while a spill is pending.close()is the forced close (1006, no Close frame).end(), the graceful close, does not change.WebSocket.Notes
Repro (1.4.3, canary c6b7fcb, and a debug build of main b8eacea). A
wss://server sends one message. The client callspause()and sends one message back. The server callsws.terminate()inmessage().idleTimeout: 8and a silent peer, the unfixed server closes at 8.0 s from the idle timer, with the reason "WebSocket timed out from inactivity".idleTimeout: 4and a paused peer that sends one frame each second, the unfixed server never closes. In 14 s it delivered 14 messages tomessage()afterterminate(), all withws.readyState === 3. The uWS parser stops only whenus_socket_is_closed()orisShuttingDownis true, and a deferred TLS close sets neither.Bun.connect({ tls })client sends a masked frame with opcode 3, and 300 ms later a valid text frame. Before: noclose, and the text frame reachesmessage(). After:close1006 at once. TheforceClose()calls that pass a reason already close at once, because the reason length is the close code and it is never 0.A peer that keeps up sees no change. Matrix:
ws.send(payload); ws.terminate()from a handler and from a timer, payload 100 B, 64 KB, 300 KB and 4 MB, 10 runs each, a BunWebSocketclient that reads. All 16 cells are the same forwsandwss, before and after: the same messages arrive, thenclose 1006, and noerrorevent. A nodewsclient also reportsclose 1006with noerrorevent, before and after.A peer under send backpressure gets a reset. A spill does not prove a dead peer. It means the last flush hit a full kernel buffer, which also happens with a slow peer that still reads. If the first close cannot drain the spill, the second close resets: the kernel drops its send buffer and the peer sees ECONNRESET. Before this change that peer got the kernel buffer and the spill, then close_notify, whenever the spill drained. Plain
ws://gives it the kernel buffer and a FIN. The uWS backpressure buffer is lost in every variant, so the stream ends in the middle of a message in every variant. The reset is the documented cost of a close that must finish now (CloseCode::failurenamesterminate()). The clientWebSocket.terminate()(#38243) andSocket.terminate()reset on every close. A FIN that keeps the kernel buffer needs a usockets close that drops the spill without a wait, which is the durable fix that #39548 names.Why a FIN first and not a reset for every TLS close. With a node TLS client, a server reset gives
error: ECONNRESET. A bare FIN givesend, thenclosewith no error, which is whatws://gives today. npmws8.18.3 does the same: itsterminate()issocket.destroy(), and the comment inus_internal_ssl_closerecords that node's destroy sends a bare FIN.Why the second close. A build with
FAST_SHUTDOWNonly still hangs in the backpressure test (paused client, the server sends 64 KB messages untilsend()returns -1, thenterminate()).us_internal_ssl_closedefers codes 0 and 2 until the spill drains. The check after the first close detects the deferral and does not predict it. usockets first tries to drain the spill, so a peer that recovered still gets a FIN. A check ofus_socket_ssl_spill_pending()before the close is not equivalent: it resets a peer that has recovered. #39548 records that.The read of the socket after the first close is safe.
us_internal_socket_close_rawlinks a socket into the loop's closed list only after the close handler returns, so JS that re-enters the event loop from the handler cannot free it.Other callers of
WebSocket::close()that get the same fix: theopen()exception path inServerWebSocket.rs, the HMR socket (hmr_socket.rs), andDevServerteardown, which hasdebug_assert!(self.active_websocket_connections.is_empty())right after it closes every socket.Not fixed here. These sites have the same exposure. Each needs its own repro and tests, and the durable fix is a usockets close that cannot defer (see the last Background bullet of #39548).
AsyncSocket<SSL>::close()(AsyncSocket.h:101) and the HTTP paths that use it. One case is reproduced:Bun.serve({ tls, idleTimeout: 4 })with a peer that completes the handshake and stops reading. The plain server socket is in FIN-WAIT-2 at 12 s. The TLS server socket is still ESTAB at 40 s.Http2Context.h.JSNodeHTTPServerSocket::close()(JSNodeHTTPServerSocket.cpp:90). It already usesFAST_SHUTDOWN, with no second close for a spill.closeOnBackpressureLimit. These are not forced closes.Order with #35874. That PR replaces the
forceClose()calls that pass no reason with a gracefulend(1002). If it merges first, thereason.empty()branch here has no caller and can go, and the reserved opcode test must expect the code that PR reports. If this PR merges first, #35874 needs no change toclose().Test file. The test is a sibling file and not part of
websocket-server.test.ts. That file has load-related timeouts on a debug build (8 here, insend(),sendText(),sendBinary()and the benchmark). The same tests pass alone. The twoterminate()tests fail at once on an unfixed build, withclose: 1006 ""missing betweenmessageandterminate() returned. The reserved opcode test times out there.Suites run on a debug+ASAN build: all of
test/js/bun/websocket/,websocket.test.js,websocket-pause.test.ts,websocket-client.test.ts,websocket-close-code.test.ts,websocket-close-fragmented.test.ts,websocket-proxy.test.ts,websocket-subprotocol-strict.test.ts,websocket-client-short-read.test.ts,websocket-close-connecting.test.ts,websocket-close-async-dispatch.test.ts,websocket-buffered-amount.test.ts,websocket-server-send-from-drain.test.ts,ws.test.ts,ws-upgrade-events.test.ts, and the pipelined upgrade tests inserve.test.ts. Failures that do not come from this change: twowebsocket.test.jstests that needws.postman-echo.com, and tests that spawn a debug build per case and go over 5 s when this machine is loaded ("should connect many times over https",ws-upgrade-events.test.ts). They pass alone.[human-review] gate passed · iteration 0 · 3 files touched
fails on main (without fix)
passes on PR (with fix)
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