[robobun]

Follow-up to #43924.

Problem

• On a half-closed socket the peer's flight can arrive in two reads. The writable event between them reports handshake(success=false, error=null) (ssl_update_handshake, packages/bun-usockets/src/crypto/openssl.c). BoringSSL then finishes the handshake, and a rejecting Bun.listen server passes an untrusted client's data to data().
• us_internal_ssl_verify_error answers "no error" for a half-closed or fatal socket.

Fix

• ssl_update_handshake takes fin_ends_handshake. Only the writable event passes 0.
• us_internal_ssl_verify_error reads the SSL on every open socket, like node's TLSWrap::VerifyError. After our FIN a failed handshake reports it only for a chain that it checked.
• on_handshake (socket_body.rs) closes a rejecting Bun.connect socket on every failed handshake.
• Verified: socket.test.ts (9 new, base fails 3), node-tls-duplex-end-verify.test.ts (15 new, base fails 3, Node v26.3.0 passes 31 of 31), node-tls-server.test.ts (1 new).

Background

• end() during a handshake sends a FIN and no alert. The socket keeps reading, so the handshake can still complete.
• node:tls reads a failed handshake with an X509 code as an established session, and one with no error after end() as its own close.
• Considered the close in on_handshake alone. The state machine would still report a live handshake as failed.

Downsides

• getAuthorizationError() on a half-closed socket answers UNABLE_TO_GET_ISSUER_CERT, not null, until its handshake reports.
• A rejecting Bun.connect socket whose handshake fails with no error now closes. It stayed open until the peer closed.
• Release .text: 58154908 B before and after. Each checked chain costs 1 store. A two-read flight on a half-closed socket costs 2 more SSL_do_handshake calls (6 to 8).

Notes

Cases, measured on the head of #43924 (a3b00db, merged as 92d6092) and with this change

The peer's certificate is untrusted unless the row says otherwise. "Two reads" means that the peer's last handshake flight arrives in two TCP segments, split inside a record. The peer chooses that.

Case	Node v26.3.0	#43924	This PR
Bun.listen, requestCert, rejectUnauthorized: true, shutdown() in the handshake, TLS 1.3, two reads	n/a	handshake(false, null), then data() delivers the client's bytes, socket stays open	handshake(true, authorized=false, error), close, no data
Same, trusted client	n/a	handshake(false, null), then data() with authorized=false	handshake(true, authorized=true, null), then data()
tls.createServer, requestCert, rejectUnauthorized: false, end() in the handshake, two reads	secureConnection authorized=false, then the data	tlsClientError ECONNRESET	same as Node
Same, rejectUnauthorized: true, trusted client	secureConnection authorized=true, then the data	tlsClientError ECONNRESET	same as Node
Bun.connect, rejectUnauthorized: true, shutdown() in open, peer never answers	n/a	handshake(false, null), socket stays open	handshake(false, null), close
tls.connect, default rejectUnauthorized, end() in 'connect', peer never answers	finish, stays readOnly	same as Node	same as Node
getAuthorizationError() on a half-closed socket before any handshake report	n/a	null	UNABLE_TO_GET_ISSUER_CERT
getAuthorizationError() after handshake(false, null) on a half-closed socket	n/a	null	null
tls.connect with the session of an earlier unauthorized connection, end() in 'connect', peer never answers	finish, no secureConnect	same as Node	same as Node

The tests of #43924 release a held flight in one write (5cee17a), so they do not reach the two-read rows.

Mechanism

• us_internal_ssl_on_data ends with ssl_retry_parked_write, which calls us_internal_ssl_on_writable, which calls ssl_update_handshake. So the state machine runs between two reads of one flight.
• On the base, ssl_update_handshake reports a failure when us_internal_ssl_is_shut_down is true, that is, for a sent FIN, a sent close_notify or a fatal error. The handshake state becomes HANDSHAKE_COMPLETED. The next read finishes the handshake inside SSL_read, and no second report follows.
• The Rust on_handshake marks a failed handshake as REJECTED. Only the write paths read that flag, so data() still runs.

The two traps from the review of #43924

• With no peer certificate the SSL answers UNABLE_TO_GET_ISSUER_CERT. ssl_failed_handshake_verify_error reads the SSL on a shut-down socket only when us_cert_verify_cb ran in this handshake (ssl_peer_chain_checked). So a handshake that failed after our FIN, with no certificate, still reports no error, and net.ts still reads it as its own close. On a socket that is not shut down the failure branch reads the SSL as before.
• SSL_get0_peer_certificates is not that test. It is not NULL after an empty Certificate message. Before the ServerHello it returns the chain of the session that the client offered, so the first version of this PR reported secureConnect for a handshake that the peer never answered.
• A failed handshake can report 0: the chain verified and the handshake failed later. on_handshake now closes a rejecting connection on success == 0, whatever the error value.

Where this differs from the request

• The close on a failed handshake does not apply to node:tls clients (Flags::DEFERS_SERVER_IDENTITY). With it, tls.connect() followed by end() in 'connect' emitted finish, end, close at once. Node and the base keep that socket readOnly until the peer closes. net.ts closes node:tls sockets on the failures that node closes on. The new end-strict row in node-tls-connect.test.ts pins this.
• It does not apply to server sockets. No flag tells a node:tls server socket from a Bun.listen one. net.ts closes a server socket whose handshake failed in a microtask. A failure that is reported inside a JS call (us_socket_sni_resolve) reached the native close first, and the socket never emitted 'close'. The new test in node-tls-server.test.ts pins this. On a server a failed handshake with no error follows the server's own shutdown(), and its first flight never left, so that handshake cannot finish. A fatal error reports EPROTO and closes as before.
• The ssl_flush_write_batch change is a separate PR, stacked on this one. It needs this one: without the flag, dropping the flight makes node-tls-wrapped-socket-close.test.ts fail 2 tests.

What does not change

• Every failed handshake on a socket that is not shut down reports the same pair as on the base. The three shapes of tls: end() and destroySoon() before the handshake completes now send the FIN #42181 (end, destroySoon, server-end) and test-https-agent-create-connection.js are unchanged.
• on_open, us_internal_ssl_close, us_socket_sni_resolve and us_socket_start_tls_handshake pass 1 and keep the old rule. us_internal_ssl_is_shut_down itself is not touched.
• getAuthorizationError() on an open socket reads the same sources in the same order. A handshake that failed with EPROTO still answers EPROTO. After a report, a shut-down socket answers what on_handshake stored.

Measurements

Base is the head of #43924. Call counts are gdb breakpoint hit counts on debug builds with the debug info stripped. Sizes are from release builds of both trees.

• Healthy handshake, 100 in-process Bun.listen / Bun.connect connections, on 771b423: SSL_do_handshake 600 and 600, verify reads 200 and 200, us_cert_verify_cb 100 and 100, BIO_s_custom_write 700 and 700, bsd_send 600 and 600, bsd_recv 600 and 600, ssl_flush_write_batch 300 and 300, us_internal_ssl_is_shut_down 1500 to 1400.
• us_cert_verify_cb now looks up its socket for every chain, to set ssl_peer_chain_checked. On the base only a client with a valid chain did that lookup. So a server, and a client whose chain fails, pay 2 ex_data reads per checked chain. Every checked chain pays 1 store.
• Release .text: 58154908 B both (size -A). Stripped bun: 80844320 B both. Symbols that changed: ssl_trigger_handshake 669 to 704 B, ssl_update_handshake 463 to 470 B, us_cert_verify_cb 269 to 351 B, on_handshake 3036 to 3083 B, getAuthorizationError 663 to 676 B.
• Measured on 49f139d, the first commit: a half-closed server with the flight in two reads runs SSL_do_handshake 8 times, not 6, because the handshake now runs to its end. With the flight in one read: 6 and 6. ssl_update_handshake nesting depth: 1 in every run. getAuthorizationError(), 50 calls: healthy socket 52 and 52 verify reads, half-closed socket with no report 0 to 50.
• Allocations: the change adds none. strace and perf are not installed on the test machine.

Tests

• test/js/bun/net/socket.test.ts, block "shutdown() while the handshake runs": 9 tests. The base fails 3: both two-read cells and the close of a rejecting client. The block is not concurrent: see the stacked PR.
• test/js/node/tls/node-tls-duplex-end-verify.test.ts: 15 new tests: two-read cells, trusted controls, Duplex twins of both, and the offered session under TLS 1.2 and TLS 1.3. The base fails 3, all on a TCP socket with two reads. Node v26.3.0 passes 31 of 31 (node --test).
• test/js/node/tls/node-tls-server.test.ts: 1 new test, the socket that calls end() while its SNICallback is pending. It passes on the base and failed on 49f139d.
• test/js/node/tls/node-tls-connect.test.ts: 1 new row, end-strict. It passes on the base, on this change and on Node.
• test/js/node/tls/ and test/js/bun/net/ together (717 tests), this change and the base side by side: no failure is only on this change. Failures on both: SNICallback runs even when the requested servername matches the bind hostname (localhost resolves to ::1 on the test machine), should not call drain before handshake (needs www.example.com), and 3 tests that wait for a garbage collection.
• After the rebase on main (e375701) the diff of src/ and packages/ is the same, byte for byte. The two directories have 753 tests there. 6 fail, and each of them failed on a build without this change before: the 2 above, the 3 that wait for a garbage collection, and root certificate initialization > concurrent Workers all see the same CA certificate lists.
• The vendored test-tls-* and test-https-* files: 250 pass. test-tls-client-allow-partial-trust-chain.js and test-https-timeout.js fail on the base too. With the stacked PR on top, test-http2-* (261) and test-net-* (150) pass as well.

[robobun]

^{Updated 4:48 PM PT - Sep 25th, 2026}

✅ @robobun, your commit ae1f6056145b104d0265fa01df57ac8d164634a7 passed in Build #120752! 🎉

---

🧪   To try this PR locally:

bunx bun-pr 43947

That installs a local version of the PR into your bun-43947 executable, so you can run:

bun-43947 --bun

[claude]

Beyond the inline findings, I also checked the dropped s_ssl(s) && guard in ssl_update_handshake (packages/bun-usockets/src/crypto/openssl.c:2138): the !s->ssl early return and the SSL_is_init_finished(s_ssl(s)) call above it already dereference the handle, so the guard was dead and removing it is safe. The s->ssl check inside ssl_failed_handshake_verify_error before SSL_get0_peer_certificates covers the shut-down-with-freed-SSL case, and the getAuthorizationError hoist of this.socket.get() into a local does not change the detach/verify-error read order.

Extended reasoning...

The change threads a fin_ends_handshake flag through the usockets TLS handshake state machine so a self-sent FIN no longer fails an in-progress handshake on the writable path, alters what verify error a failed handshake reports after our own FIN, and makes the Rust on_handshake close rejecting Bun.connect/Bun.listen sockets on any failed handshake. It touches TLS certificate-verification reporting and rejectUnauthorized enforcement, a security-sensitive surface. Four confirmed inline findings (TLS 1.2 rejected-client close, SNI-callback shutdown path, fabricated UNABLE_TO_GET_ISSUER_CERT verdict, getAuthorizationError behavior change) already signal a human review is needed; this note only records the additional native-safety checks that were examined and ruled out.

Findings marked 🟡 are optional suggestions and need no follow-up push.

[claude]

I reviewed the two follow-up commits (3709eed, 771b423) and found no bugs; they address the points from my earlier pass, but because this changes when a TLS handshake verdict is trusted after a local FIN, a human look at the native state machine would still be worthwhile.

What was reviewed:

• ssl_peer_chain_checked: set in us_cert_verify_cb for server and failed verifies, reset in us_internal_ssl_attach (which us_socket_adopt_tls also goes through); wrapper sockets never set it, so a shut-down wrapper handshake reports no error as before.
• The dropped s_ssl(s) && guard before SSL_get_shutdown: SSL_is_init_finished(s_ssl(s)) a few lines above already dereferences unguarded behind the !s->ssl early return, so no new NULL path.
• failed_native_client now excludes acts_as_tls_server(), so us_socket_sni_resolve passing fin_ends_handshake=1 no longer triggers a native close for node:tls servers; getAuthorizationError() on a shut-down socket after HANDSHAKE_COMPLETE answers from the stored verdict.
• Placement of the new "shutdown() while the handshake runs" block inside an outer describe.concurrent was looked at and not flagged.

Extended reasoning...

The PR touches the usockets TLS handshake state machine (openssl.c), a new per-socket bitfield in internal.h, and the Rust on_handshake/getAuthorizationError paths in socket_body.rs, plus ~600 lines of new tests. It is security-sensitive: it decides when a certificate verdict is reported and when a rejecting socket is closed after a locally sent FIN. The two new commits addressed the three earlier inline findings (peer-chain flag, node:tls server exclusion, stored verdict on shut-down sockets) and this run's hunt found no new bugs, but TLS verdict logic across client/server/wrapper/SNI paths is not something to approve without a human maintainer's read.

Still open from earlier reviews (1):

• Unresolved: 1 minor or pre-existing.

[robobun]

Status

How to reproduce, on main before this change:

• bun bd test test/js/bun/net/socket.test.ts -t "while the handshake runs" fails 3 of 9 tests: both cells with the flight in two reads, and the close of a rejecting client.
• bun bd test test/js/node/tls/node-tls-duplex-end-verify.test.ts fails 3 of 31 tests, all on a TCP socket with the flight in two reads. node --test passes 31 of 31.

With this PR all of them pass. #43924 is merged, and this branch is rebased on main. The stacked PR for the records that are sealed after a FIN is #43957.

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Walkthrough

The native TLS handshake driver now distinguishes writable events from other handshake calls when handling socket shutdown. Verification state and runtime authorization results are preserved across shutdown paths. Regression tests cover client and server handshakes, certificate trust, and partial handshake flights.

Changes

TLS handshake shutdown and verification

Layer / File(s)	Summary
Native handshake driving and verification packages/bun-usockets/src/internal/internal.h, packages/bun-usockets/src/crypto/openssl.c	Writable events can continue a pending handshake after socket shutdown. The native code records whether a peer certificate chain was checked and uses that state when reporting failed-handshake verification results.
Runtime handshake outcomes and authorization errors src/runtime/socket/socket_body.rs	Failed native TLS client handshakes can contribute to unauthorized rejection. After handshake completion, authorization queries on shut-down sockets return the stored verification error or null.
Socket shutdown during handshake tests test/js/bun/net/socket.test.ts	Tests cover trusted and untrusted peer certificates, partial certificate delivery, shutdown before and during handshakes, and authorization-error results.
Node TLS shutdown regression tests test/js/node/tls/node-tls-duplex-end-verify.test.ts, test/js/node/tls/node-tls-connect.test.ts, test/js/node/tls/node-tls-server.test.ts, test/js/node/tls/tls-shutdown-before-handshake-fixture.mjs	Tests cover strict verification after end(), split handshake flights over TCP and Duplex transports, offered sessions, and a pending asynchronous SNI callback during shutdown.

Suggested reviewers: alii

Priority: ➖ Normal

Merge Risk: ⚪ Minimal · up to ae1f6

The handshake change preserves processing of split peer flights, and the TLS 1.3 regression test cannot proceed without a captured session. The remaining stdout-read concern predates this PR, so no new merge risk was identified.

🚥 Pre-merge checks | ✅ 4

✅ Passed checks (4 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Title check	✅ Passed	The title clearly and concisely describes the main TLS handshake fix: a local FIN must not prematurely fail an ongoing handshake.
Description check	✅ Passed	The description provides detailed problem context, implementation details, verification results, test coverage, behavior changes, and known downsides. It does not use the template headings exactly, bu…

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Inline comments:
In `@src/uws/lib.rs`:
- Around line 927-929: Update the HandshakeOutcome::HandshakeError handling to
return the default no-peer X509 error only when sent_ssl_shutdown is set and
peer_chain_checked is false. Add peer_chain_checked to CallbackState and update
it from the Rust verification callbacks, preserving X509 errors once a peer
chain has been checked.

In `@test/js/node/tls/renegotiation.test.ts`:
- Around line 390-391: Update the port-reading logic in the server startup test
to accumulate stdout chunks until a complete newline-terminated line arrives,
then parse the port from that line. Use the stream reader and decoder so partial
reads cannot produce an incorrect port.
- Around line 360-363: Update the command in the Bun.spawn call to use nodeExe()
from harness instead of the bare "node" string, matching the executable
resolution used by the other TLS tests.

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In `@test/js/node/tls/node-tls-duplex-end-verify.test.ts`:
- Line 449: Update the session setup around `first` so TLS 1.3 waits for its
`session` event and asserts the ticket exists before creating the second
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[claude]

I re-reviewed the latest push and found no bugs; the new commits address the three points I raised earlier (server sockets excluded via acts_as_tls_server, the SSL verdict gated on ssl_peer_chain_checked instead of SSL_get0_peer_certificates, and getAuthorizationError() answering from the stored verdict on a shut-down socket). Because this changes how rejectUnauthorized behaves on a half-closed TLS handshake, a human look is still worthwhile.

What was reviewed:

• Every ssl_update_handshake caller now picks a fin_ends_handshake value; only the writable path passes 0, and the failure branch still fails on closed/fatal/peer-shutdown regardless.
• The dropped s_ssl(s) && guard before SSL_get_shutdown is redundant: SSL_is_init_finished(s_ssl(s)) already dereferences it earlier in the same function.
• ssl_peer_chain_checked is reset in us_internal_ssl_attach alongside ssl_identity_checked, the only reset site either flag has; it is consumed only by ssl_failed_handshake_verify_error.
• The offered-session Duplex test was checked for a vacuous pass (it can succeed without a session being offered), which is a test-strength nit rather than a runtime bug.

Extended reasoning...

The diff touches the usockets TLS handshake state machine (packages/bun-usockets/src/crypto/openssl.c, internal.h) and the Rust on_handshake/getAuthorizationError paths in src/runtime/socket/socket_body.rs, plus ~600 lines of tests. It is a security-sensitive surface: it decides when a rejectUnauthorized client or server closes on a handshake that was still running after the local FIN, and what verify error is reported on a half-closed socket. All three findings from my prior review are addressed in the new commits and no third-party objection is outstanding, but the state-machine interaction across the writable, close, sni_resolve and on_open callers is subtle enough that a maintainer should confirm the chosen semantics, so defer rather than approve.

[Jarred-Sumner]

@robobun fix clippy

[robobun]

The clippy error was no variant ... named NamedPipe for ListenerType at src/runtime/socket/Listener.rs:849. It came from main, not from this diff: the check builds the merge with main, and 4dbe5e0 fixed it there.

A review of this PR after the last push found two regressions that are on main now. #44021 fixes both, with a test for each:

• A TLS 1.2 client that called end() emits secureConnect twice when the server then asks for a renegotiation. Node emits it once.
• A node:tls server socket that called end() during its handshake reports no tlsClientError when its peer leaves in the middle of its flight. Node reports ECONNRESET.

It also found that four of the new tests ("two reads" on the client side over TCP) delivered the flight in one read. #44021 repairs their relay.