node:http2: report an injected socket's error on the session instead of leaving it uncaught

[robobun]

Problem

• Http2SecureServer#emit('connection', rawSocket) (the http2-wrapper / crawlee pattern for upgrading a plain connection to h2) upgrades rawSocket through the stream-level TLS engine, but only listens to its 'data', 'end', 'drain' and 'close' events (src/js/node/_http2_upgrade.ts, upgradeRawSocketToH2). Once the socket has been handed over nothing listens to its 'error', so a transport failure after the upgrade (a reset, EPIPE on a write the peer never read, the owner calling rawSocket.destroy(err)) is an uncaught exception: error: transport failed thrown from the socket's own 'error' emission, and the process exits.
• Node reports the same failure as the server's 'sessionError': tls.Server's connection listener wraps the injected socket in a TLSSocket, whose _init re-emits the wrapped socket's errors on itself (lib/internal/tls/wrap.js L977 in v26.3.0), and the session's socket error handler destroys the session with it.
• Same function, same shape (found in review): when the upgrade itself throws, which happens for unusable credentials since bun builds them on first use, the catch block did rawSocket.destroy(e), so the credentials error was also thrown out of rawSocket's 'error', even with an 'error' listener on the server: error: error:0900006e:PEM routines:OPENSSL_internal:NO_START_LINE.
• The four net.ts sites that run the same engine (tls.connect({ socket }), new TLSSocket(socket, { isServer: true })) have the same missing listener; node:tls: make client-side new TLSSocket(socket) upgrade the socket it wraps #37664 adds it there, so this PR only covers the http2 site.

Fix

• upgradeRawSocketToH2 attaches an 'error' listener to rawSocket that destroys the proxy duplex the h2 session runs on with the error. That proxy is the TLSSocket stand-in for this path, and destroying it with an error is exactly what the engine's own error callback (socketError) already does for TLS-level failures, so the session teardown and the server's 'sessionError' come out of the existing path.
• The listener is not removed in onTlsClose with the other four: the raw socket is still flushing close_notify after the session is gone, and a write failure at that point would otherwise be uncaught again. The destroyed check makes it a no-op once the proxy is down, which is also the net effect in node (the forwarded error reaches a session that is already destroyed).
• The catch block now closes the connection quietly and emits the error on the server, which is what tls.Server's own connection listener does for the same lazily-detected credentials failure (src/js/node/tls.ts, the 'connection' listener, and the existing "natively-rejected key on the server 'error' event" test in node-tls-server.test.ts). Node detects bad credentials in createSecureServer() itself, so the server is the closest equivalent surface; the injected socket is not a surface at all, nothing of the caller's listens on it.
• Verified with test/js/node/http2/node-http2-upgrade.test.mts, two new tests: "an error on rawSocket is the session's error, not an uncaught exception" and "unusable credentials are the server's error, and the injected connection is closed". Without the _http2_upgrade.ts change they fail with the two uncaught errors quoted above (Linux debug build and Windows x64 debug build); with it the whole file passes on both (17/17), and the file also runs itself under node v26.3.0 (16/16 there: node takes the credentials test's createSecureServer() branch).

Background

• upgradeDuplexToTLS is the TLS engine node:tls uses when it cannot adopt a connection's fd into a native TLS socket: it runs BoringSSL over the stream's JS events and write(), and returns the handlers the caller has to attach to the stream. _http2_upgrade.ts uses it for every socket injected into an Http2SecureServer, feeding the decrypted bytes into a plain Duplex that the h2 session treats as its socket.
• 'sessionError' is how an Http2Server surfaces a session-level error (a socket error included) to the application; it is what node emits for this scenario, and what bun emits once the proxy is destroyed with the error.
• Http2SecureServer is a tls.Server; its 'error' event is where bun's tls.Server already reports credentials it cannot load (bun builds them lazily, node throws from the constructor), which is why the catch block reports there.

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Review details

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Reviewing files that changed from the base of the PR and between 28a41ae and 0321e26.

📒 Files selected for processing (2)

• src/js/node/_http2_upgrade.ts
• test/js/node/http2/node-http2-upgrade.test.mts

Walkthrough

The HTTP/2 upgrade path now forwards raw-socket errors to the TLS proxy, cleans up failed upgrades, and emits server errors. Tests cover transport errors and invalid TLS credentials.

Changes

HTTP/2 upgrade error handling

Layer / File(s)	Summary
Socket error propagation and cleanup src/js/node/_http2_upgrade.ts	Raw-socket errors are forwarded to the TLS proxy. Failed upgrades destroy both sockets without passing the caught error, then emit the error through the server.
Upgrade error regression coverage test/js/node/http2/node-http2-upgrade.test.mts	Tests verify session destruction and sessionError reporting for transport errors. Tests also verify server error emission and raw-socket destruction for invalid TLS credentials.

Suggested reviewers: jarred-sumner, cirospaciari

🚥 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 states the main change: reporting injected socket errors through the HTTP/2 session instead of leaving them uncaught.
Description check	✅ Passed	The description explains the problem, fix, background, verification steps, test results, and affected scope in sufficient detail.

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[robobun]

^{Updated 10:05 AM PT - Aug 13th, 2026}

❌ @robobun, your commit 0321e26 has 2 failures in Build #94541 (All Failures):

• test/cli/run/require-cache.test.ts - code 1 on 🐧 13 x64-asan
• test/js/sql/postgres-simple-query-pipeline.test.ts - code 1: error: Failed to start service postgres_plain (via coordinator): Docker is not available. Please … on 🐧 3.23 aarch64

---

🧪   To try this PR locally:

bunx bun-pr 38124

That installs a local version of the PR into your bun-38124 executable, so you can run:

bun-38124 --bun

[claude]

LGTM — small, well-scoped fix that routes the injected socket's transport error through the existing session teardown path, with a test that also runs under node. The one inline nit (pre-existing catch block still leaves rawSocket's error unhandled) is worth addressing but non-blocking; merging as-is strictly improves on the status quo.

Extended reasoning...

Overview

This PR adds a single 'error' listener to rawSocket in upgradeRawSocketToH2 (src/js/node/_http2_upgrade.ts), forwarding transport-level failures to the TLS proxy Duplex via destroy(err). That reuses the existing socketError teardown path so the h2 session is destroyed with the error and the server emits 'sessionError' — matching Node's behavior where TLSSocket._init re-emits the wrapped socket's errors on itself. A new test in node-http2-upgrade.test.mts reproduces the uncaught-exception failure on the unfixed build and asserts the exact error message, session identity, and destroyed state; the file also runs itself under node to confirm compat.

Security risks

None. This is error-propagation plumbing on an already-accepted connection; no auth, crypto config, or input parsing is touched. The TLS options passed to upgradeDuplexToTLS are unchanged.

Level of scrutiny

Low-to-medium. The change is ~20 lines (mostly comments), follows the file's established pattern of named module-scope handlers bound to tlsSocket, and reuses the existing destroy path rather than introducing new teardown logic. The PR description explicitly justifies the two non-obvious choices: why the listener is not removed in onTlsClose (rawSocket is still flushing close_notify after the session is gone) and why the destroyed guard makes it a safe no-op afterward. The sibling net.ts sites are called out as covered by #37664.

Other factors

• The test awaits real events (sessionReady, sessionClosed, sessionErrored) with no sleeps, asserts a combined object, and the comment on line 310 explains why events.once is avoided (the session emits 'error' before 'close').
• The one inline nit — that the listener is attached after the try/catch, so rawSocket.destroy(e) in the pre-existing catch block at L389 still emits unhandled — is a valid same-class observation, but the catch block predates this PR, the trigger (invalid TLS config on a never-listened h2Server) is narrow, and the fix is a one-line move the author can take or leave.
• No prior reviewer comments to address; CI is building.

[coderabbitai]

Actionable comments posted: 1

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Inline comments:
In `@test/js/node/http2/node-http2-upgrade.test.mts`:
- Around line 313-320: Update the test around rawSocket.destroy and
sessionErrored to store the transport failure Error in a named variable, then
assert that the received err is the identical object using strict identity
comparison. Preserve the existing message, sameSession, and destroyed assertions
while adding the original-error invariant.

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📒 Files selected for processing (2)

• src/js/node/_http2_upgrade.ts
• test/js/node/http2/node-http2-upgrade.test.mts

[robobun]

Status: ready for review; review follow-ups are in (catch-path reporting on the server with its own test in 1ad82ac, one-line comments in 24c2e18, error identity asserted in 0321e26), all threads resolved.

Reproduced on bun 1.4.0 and on a debug build of main with the script below (an Http2SecureServer fed a connection via emit('connection'), then the raw socket destroyed with an error after one request): bun exits with the uncaught transport failed; node v26.3.0 prints sessionError: transport failed and exits 0. With this branch bun prints the same as node (Linux and Windows x64 debug builds). The credentials variant reproduces on main as an uncaught ERR_OSSL_PEM_NO_START_LINE even with an 'error' listener on the server; with this branch it arrives on that listener.

The tls.connect({ socket }) / new TLSSocket(socket, { isServer: true }) sites with the same missing listener are covered by #37664; this PR is only the http2 site.

CI (build 94541): node-http2-upgrade.test.mts passed on every lane. The remaining red entries do not touch this change: test/js/sql/postgres-simple-query-pipeline.test.ts on alpine aarch64 (the lane had no Docker to start postgres) and test/cli/run/require-cache.test.ts on debian x64-asan, which also fails on main; both are reported separately. Everything else listed passed on retry.

Repro

import http2 from "node:http2";
import net from "node:net";
import { readFileSync } from "node:fs";

const TLS = {
  key: readFileSync("test/js/node/test/fixtures/keys/agent1-key.pem"),
  cert: readFileSync("test/js/node/test/fixtures/keys/agent1-cert.pem"),
};
let raw;
const h2 = http2.createSecureServer(TLS, (req, res) => res.end("done"));
h2.on("sessionError", e => console.log("sessionError:", e.message));
h2.on("session", session => session.on("close", () => { console.log("session closed"); server.close(); }));
const server = net.createServer(socket => { raw = socket; h2.emit("connection", socket); });
server.listen(0, "127.0.0.1", () => {
  const client = http2.connect(`https://127.0.0.1:${server.address().port}`, { rejectUnauthorized: false });
  client.on("error", () => {});
  client.request({ ":path": "/" }).on("end", () => raw.destroy(new Error("transport failed"))).resume();
});

node v26.3.0:  sessionError: transport failed / session closed   (exit 0)
bun 1.4.0:     error: transport failed                           (exit 1)
this branch:   sessionError: transport failed / session closed   (exit 0)

[claude]

LGTM — the catch-path concern from my earlier review is addressed (now mirrors the tls.Server 'connection' listener at tls.ts:1491-1496: socket.destroy() with no arg + server.emit('error', e)), the comment-cop and error-identity feedback are folded in, and both new tests exercise the exact uncaught-error paths the PR fixes.

Checked that leaving the onRawSocketError listener attached past onTlsClose is intentional and bounded: it holds tlsSocket only until rawSocket is collected, and the destroyed guard makes late errors a no-op. Also confirmed the credentials test's listener ordering — h2Server.on('error', ...) is attached before the net server accepts, so server.emit('error', e) inside the synchronous catch resolves it before emitReturned is read.

Extended reasoning...

Overview

Two files: src/js/node/_http2_upgrade.ts (the upgradeRawSocketToH2 path used when a raw TCP socket is injected into an Http2SecureServer via emit('connection', socket)) and its test file. The production change is ~10 lines: a bound 'error' listener on the injected rawSocket that destroys the TLS proxy Duplex with the error (so it surfaces as the session's 'sessionError' instead of an uncaught exception on a socket nobody listens to), and the pre-existing catch block reshaped from rawSocket.destroy(e) to rawSocket.destroy(); tlsSocket.destroy(); server.emit('error', e) — the exact shape tls.Server's own 'connection' listener uses for the same lazily-built-credentials failure at tls.ts:1491-1496.

Security risks

None. This is error-event routing in the Node-compat layer; no auth, crypto, or trust decisions change. The TLS credentials themselves are unchanged — only where a failure to build them is reported.

Level of scrutiny

Moderate — it's a small, mechanical change that follows an established sibling pattern in the same repo, with a Node source permalink for the ported behaviour. The upgrade path is somewhat niche (http2-wrapper / crawlee's connection-injection pattern), and the change is strictly additive to the existing listener set plus a reshape of an already-present catch block.

Other factors

• I left one inline nit on an earlier revision (the catch path still emitting an unhandled 'error' on rawSocket); commit 1ad82ac addressed it with the tls.ts shape and a dedicated test that fails on main with the uncaught PEM error. All threads are resolved.
• comment-cop's long-comment flags were addressed in 24c2e18 (comments cut to one line each with the Node permalink / sibling reference), and CodeRabbit's error-identity assertion request in 0321e26.
• Two new tests, both dual-runner (the file re-runs itself under Node), both awaiting real conditions with resources released in finally. PR description reports 17/17 on Linux and Windows debug builds, 16/16 under Node v26.3.0 (Node takes the createSecureServer throw branch in the credentials test), and that both tests fail on main with the quoted uncaught errors.
• Verified the not-removing-the-error-listener choice is deliberate (per the PR description, close_notify may still be flushing after the session is gone) and safe: the this.destroyed guard makes it a no-op once the proxy is down, and the bound closure's lifetime is bounded by rawSocket's.