[robobun]

Behaviour change: none

Problem

• A Bun.connect or Bun.listen TLS socket calls shutdown() while its handshake runs, and its peer then ends the connection. The socket gets close and no handshake call. Without the shutdown() it gets handshake(false, ECONNRESET) first.
• No text says so. bun.d.ts says "Called when the TLS handshake completes", and the arm that closes the socket (packages/bun-usockets/src/loop.c:914) states no rule.

Fix

• The JSDoc of handshake and open now names the failed report, and the two orders in which no handshake call comes before close.
• One comment at the arm states the rule.
• The JSDoc of shutdown() had its two cases the wrong way round. It now names the allowHalfOpen condition of shutdown(true), and what Windows does.
• Verified: 26 new tests in test/js/bun/net/socket.test.ts pin the rows on 1.4.2 and main: 14 for a peer FIN, reset and alert, 12 for shutdown(true). Also test/integration/bun-types/bun-types.test.ts.

Background

• The arm closes with no report on purpose. 9480d65 (socket: replace us_socket_context_t with embedded groups + kind dispatch #29932) made the closes that the loop does for the peer raw closes, because a reset during a handshake reached tlsClientError and then node:http2 as an uncaught error.
• net,tls: port Node.js net/tls compatibility tests and fix the gaps they surface — half-open/reset/write semantics, server TLSSocket wrap, session/keylog, SNICallback/ALPNCallback, pfx, OpenSSL error shapes, addCACert, local binding (+305 tests) #31155 lists a report from the close path as a follow-up that needs work in node:tls first.
• Considered a report from the arm, with a rule in net.ts so that node:tls keeps Node's result. No user asked for it, and a peer reset stays close-only. A flag that handshake sets and close reads covers both orders.

Notes

Question for a maintainer

Is close with no handshake call the wanted result for a socket that shut down? If the report is wanted, it is a change of about 15 lines in loop.c and openssl.c plus one rule in ServerHandlers.handshake of net.ts. It is not in this PR.

Rows, Linux x64, Bun.connect

The handshake is not complete in each row. shutdown() is the call with no argument, after the ClientHello left.

Order	1.3.13	1.4.2	main
The peer ends the connection	handshake(false, ECONNRESET), close	same	same
shutdown(), the peer sends nothing and ends the connection	close	close	close
shutdown(), the peer sends 5 bytes of a record and ends the connection	handshake(false, null), close	same	close (since #43947)
shutdown(), a TLS 1.2 server sends its first flight and ends the connection	handshake(false, null), close	close	close
shutdown(), then close() or end()	handshake(false, null), close	same	same
shutdown() inside open	handshake(false, null), close	same	same
The peer sends a fatal alert and ends or resets the connection, with or without shutdown()	handshake(false, null), close	handshake(false, EPROTO), close	same as 1.4.2
The peer resets the connection	handshake(false, ECONNRESET), close	close with ECONNRESET	same as 1.4.2
shutdown(), the peer resets the connection	close	close with ECONNRESET	same as 1.4.2

With a handshake handler, open comes first in each row, when the socket connects. With no handshake handler, open takes the place of handshake, and in the rows with close only it is never called. An accepted Bun.listen socket gives the same result on main for a peer that sends nothing and ends or resets the connection.

On 1.4.2 and on main the handshake of a socket that shut down continues. It completes when a TLS 1.3 peer sends its flight: handshake(true), then close. On 1.3.13 the same order gives close only.

What a caller can do today

Bun.connect({
  data: { reported: false },
  socket: {
    handshake(socket, success, error) {
      socket.data.reported = true;
    },
    close(socket, error) {
      if (!socket.data.reported) {
        // The connection closed before the handshake completed.
      }
    },
  },
});

node:tls

This PR changes nothing for node:tls. Its client reports what Node v26.3.0 reports in these orders: error ECONNRESET ("Client network socket disconnected before secure TLS connection was established"), with and without end(). #44021 adds the tlsClientError of a tls.Server.

Found on the way

• A TLS socket that shut down and waits in the low-priority handshake queue is closed with the peer's bytes unread. usockets: read a parked socket before acting on its hangup #44229 fixes that.
• The JSDoc of shutdown(halfClose) in bun.d.ts said the opposite of the code (fn shutdown in src/runtime/socket/socket_body.rs, bsd_shutdown_socket and bsd_shutdown_socket_read in bsd.c). Measured on 1.4.2 and on main: after shutdown() a write returns -1, the peer gets end, and the socket still gets the peer's data. After shutdown(true) a write succeeds and the socket gets end. A default socket then closes. A socket with allowHalfOpen: true stays open, and its later writes reach the peer. These rows are from Linux, and macOS gives the same rows. On Windows (2019 x64 and 11 aarch64) a TCP socket gets no end call after shutdown(true) and stays open: a later write returns 2 and reaches the peer, with and without allowHalfOpen. This PR corrects the text. The code is the same.
• A TLS socket on a TCP connection takes the same path (us_socket_shutdown_read in socket.c). Measured on Linux, on 1.4.2 and on main: after the handshake, shutdown(true) gives the calls of a TCP socket. Before the handshake completes it gives handshake(false, ECONNRESET), then close, and no end, with and without allowHalfOpen. The 8 TLS tests skip Windows: I cannot run Windows, and no test lane measured these rows. TLS over a Duplex stream or a Windows named pipe takes another path (SSLWrapper::shutdown_read), which this PR does not measure.

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Walkthrough

The PR updates Socket.shutdown and TLS callback documentation, clarifies a FIN-handling comment, and adds tests for peers that close before a TLS handshake completes. The tests cover client and accepted sockets, shutdown states, and callback ordering.

Changes

TLS socket callback behavior

Layer / File(s)	Summary
Socket shutdown behavior packages/bun-types/bun.d.ts, test/js/bun/net/socket.test.ts	The documentation describes which socket side is shut down for each Socket.shutdown argument. Tests check reads and writes with both allowHalfOpen settings for connected and accepted sockets.
Handshake failure and close callbacks packages/bun-types/bun.d.ts, packages/bun-usockets/src/loop.c, test/js/bun/net/socket.test.ts	The documentation covers failed or interrupted TLS handshakes. The FIN comment identifies a peer-initiated close while a handshake is pending. Tests check callback behavior for client and accepted sockets when peers send FINs, resets, or fatal TLS alerts.

Suggested reviewers: jarred-sumner

Priority: ⬇️ Low

Merge Risk: 🔵 Low · up to 296b3

The new shutdown documentation overgeneralizes plain-TCP behavior to TLS, where a local end event may not occur as described. Clarifying the TLS exception is a bounded documentation fix that helps users avoid relying on incorrect callback expectations.

🚥 Pre-merge checks | ✅ 4

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly identifies the main change: documenting when Bun TLS sockets close without a handshake callback.
Description check	✅ Passed	The description explains the problem, proposed documentation fix, verification, behavior scope, and background. It does not use the exact template headings, but it provides the required information.
Linked Issues check	✅ Passed	The description references related issues and pull requests, including #29932, #31155, #43947, #44021, and #44229. These references are relevant to the documented behavior and follow-up work.
Out of Scope Changes check	✅ Passed	The changes remain within scope. They update documentation, clarify one internal comment, and add tests without changing runtime behavior.

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[robobun]

Status

How to see the rows, on main (9f70da0) and on 1.4.2:

• bun bd test test/js/bun/net/socket.test.ts -t "the peer closes the connection before the handshake completes" passes 14 of 14, with and without this PR.
• The peer ends the connection: a client that called shutdown() gets open, then close. A client that did not gets open, handshake(false, ECONNRESET), then close.
• The peer resets the connection: open, then close with ECONNRESET, with and without shutdown().
• The peer sends a fatal alert first: open, handshake(false, EPROTO), then close, with and without shutdown().
• bun bd test test/js/bun/net/socket.test.ts -t "shutdown\(true\)" passes 12 of 12 on Linux. After shutdown(true) a TCP socket, or a TLS socket that completed its handshake, gets end. A default socket then closes, and a socket with allowHalfOpen: true stays open for writes. A TLS socket that did not complete its handshake gets handshake(false, ECONNRESET), then close.
• On Windows a TCP socket gets no end call after shutdown(true). It stays open, and a later write returns 2, with and without allowHalfOpen. I cannot run Windows. These rows are from the Windows 2019 x64 and Windows 11 aarch64 test lanes. The TLS tests skip Windows.

This PR changes no behaviour. It writes these rows down, and it corrects the JSDoc of shutdown().

[claude]

Nothing blocking. The comments below are optional suggestions. There is no need to push a fix for them before merging.

[coderabbitai]

Caution

Some comments are outside the diff and can’t be posted inline due to GitHub limitations.

⚠️ Outside diff range comments (1)

🟡 Minor · Describe the missing handshake call without excluding open. · bun.d.ts:7217

packages/bun-types/bun.d.ts:7217
🎯 Functional Correctness | 🟡 Minor | ⚡ Quick win

Describe the missing handshake call without excluding open.

The tests expect open, then close when a peer resets some client connections or ends a connection after shutdown(). Thus, close is not always the only callback. Say that close occurs without a handshake call and that open may already have run. Make the same correction to the comment at test/js/bun/net/socket.test.ts Line 3772. (github.com)

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Review comment at @packages/bun-types/bun.d.ts at line 7217:
Update the socket lifecycle comments describing a connection ending after
shutdown or a peer reset: state that close occurs without a handshake call and
that open may already have run. Make the same wording correction in both the
lifecycle comment near handshake/close and the corresponding test comment.

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Outside diff comments:
Review comments at @packages/bun-types/bun.d.ts:
- Line 7217: Update the socket lifecycle comments describing a connection ending
after shutdown or a peer reset: state that close occurs without a handshake call
and that open may already have run. Make the same wording correction in both the
lifecycle comment near handshake/close and the corresponding test comment.

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[claude]

Nothing blocking. The comments below are optional suggestions. There is no need to push a fix for them before merging.

The second push addresses everything I raised on the first version (reset rows pinned, failure events wired to reject, open JSDoc names where the result goes, shutdown() JSDoc corrected). Beyond the inline finding, I also checked the new shutdown(halfClose) polarity against src/runtime/socket/socket_body.rs:3234-3238 and bsd.c (no-arg is SHUT_WR, true is SHUT_RD, so the reversed text now matches the runtime), and the new loop.c:915 cross-reference to the recv-error branch at loop.c:841-860, which does raw-close without an on_handshake call as the comment states.

Extended reasoning...

The PR is docs, a comment, and tests only: JSDoc for Socket.shutdown and SocketHandler.open/handshake in bun.d.ts, a two-line comment in us_internal_dispatch_ready_poll, and a 12-case matrix in socket.test.ts pinning handler call order when a TLS peer ends or resets before the handshake completes. No runtime code or security-sensitive path changes. One verified nit on the breadth of the close-only claim is posted inline and further verified findings were held back, so this is not an approval; the second commit resolved all four prior inline comments from this reviewer.

[robobun]

The note about close as "the only call" (outside the diff, bun.d.ts:7217) is addressed in 4cd2d80. The JSDoc and the test comment now say that no handshake call comes. With a handshake handler, open runs first, when the socket connects.

[claude]

Nothing blocking. The comments below are optional suggestions. There is no need to push a fix for them before merging.

Beyond the inline note, I checked the corrected shutdown(halfClose) JSDoc against the runtime: src/runtime/socket/socket_body.rs:3234-3238 calls shutdown_read() only for a truthy argument and shutdown() (write side) otherwise, so the new text matches the code. The reset rows, the alert qualification on the handshake JSDoc, and the fail/step wiring in the new tests cover what the earlier threads on this PR raised.

Extended reasoning...

This push touches only JSDoc in bun.d.ts, a two-line comment in loop.c, and a new test block in socket.test.ts; no runtime code changes and no security-sensitive surface. The shutdown() polarity correction was verified against socket_body.rs. One verified finding about a concurrency-sensitive test row is posted inline and further verified findings were not posted, so approval is not appropriate.

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Actionable comments posted: 1

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• 🪄 Fix CodeRabbit comments on this PR

🤖 Prompt to fix review comments

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only still-valid issues, skip the rest with a brief reason, keep changes
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Inline comments:
Review comments at @packages/bun-types/bun.d.ts:
- Around line 6779-6795: Update the `Socket.shutdown` documentation to scope the
`true` behavior and platform-specific `end` handling to plain TCP sockets, and
clarify that TLS sockets suppress `data` callbacks while waiting for the peer’s
shutdown rather than locally shutting down reads. Scope the syscall statement to
the plain TCP read-shutdown operation.

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[claude]

Code review found no issues

No high-confidence issues detected in this change.

[claude]

Code review found no issues

No high-confidence issues detected in this change.

[Jarred-Sumner]

Superseded by #44618, which consolidates the open TLS pull requests. This fix and its tests are in there, either as written, rewritten smaller, or merged with the other PRs that patched the same cause (see the "By area" list in that PR). Closing in favor of it.