node:http2: check settings before callback in session.settings() by robobun · Pull Request #43605 · oven-sh/bun

robobun · 2026-09-20T02:07:37Z

Problem

Http2Session#settings(settings, callback) checks callback before settings. session.settings(null, 1) throws The "callback" argument must be of type function. Received type number (1). Node throws The "settings" argument must be of type object. Received null.
It also rejects null, 0, "" and false as the callback. Node validates only a truthy callback, so it ignores them.
The cause is the hand-written check at the top of both settings() methods (src/js/node/http2.ts:4623, :5556). Both server setTimeout() methods (:6496, :6630) have the same check ahead of this.timeout = ms. Node assigns the timeout first.

Fix

Both settings() methods run validateSettings(settings), then if (callback) validateFunction(callback, "callback"), as node does (core.js#L1559-L1564). Both server setTimeout() methods assign timeout, then validate a callback that is not undefined (core.js#L3502-L3509).
Correct because the rest of settings() already ignores a callback that is not a function. An ignored callback still takes the SETTINGS ACK of its own frame, as in node.
Verified: test/js/node/http2/node-http2.test.js (three new test cases, all fail on bun 1.4.3 and match node v26.3.0). Also the vendored node settings and timeout tests.
Self-reviewed: 6 concerns raised, 5 addressed. Not done: the same move in pushStream(). Notes give the reason, and one known limit with customSettings (node:http2: read customSettings keys and values the way node does #41322).

Background

session.settings() sends a SETTINGS frame. The peer answers with a SETTINGS ACK, and then the optional callback runs.
An ERR_INVALID_ARG_TYPE message names the argument. When two arguments are invalid, the check order decides which name the user sees.
validateFunction is the shared validator in src/js/internal/validators.ts. It throws the same error as the hand-written check.

Notes

Repro. Run with bun and with node:

const http2 = require("node:http2");
function run(label, f) {
  try { f(); console.log(label, "ok"); } catch (e) { console.log(label, "threw", e.code, "|", e.message); }
}
const server = http2.createServer();
server.on("session", session => {
  session.on("error", () => {});
  run("server settings(null, 1)", () => session.settings(null, 1));
  for (const cb of [null, 0, "", false]) run(`server settings({}, ${JSON.stringify(cb)})`, () => session.settings({}, cb));
  run("server settings({}, 1)", () => session.settings({}, 1));
});
server.listen(0, "127.0.0.1", () => {
  const client = http2.connect(`http://127.0.0.1:${server.address().port}`);
  client.on("error", () => {});
  client.on("connect", () => {
    run("client settings(null, 1)", () => client.settings(null, 1));
    for (const cb of [null, 0, "", false]) run(`client settings({}, ${JSON.stringify(cb)})`, () => client.settings({}, cb));
    run("client settings({}, 1)", () => client.settings({}, 1));
    setTimeout(() => { client.destroy(); server.close(); process.exit(0); }, 200);
  });
});

node v26.3.0, same for the client session and the server session:

settings(null, 1) threw ERR_INVALID_ARG_TYPE | The "settings" argument must be of type object. Received null
settings({}, null) ok
settings({}, 0) ok
settings({}, "") ok
settings({}, false) ok
settings({}, 1) threw ERR_INVALID_ARG_TYPE | The "callback" argument must be of type function. Received type number (1)

bun 1.4.3 before this change:

settings(null, 1) threw ERR_INVALID_ARG_TYPE | The "callback" argument must be of type function. Received type number (1)
settings({}, null) threw ERR_INVALID_ARG_TYPE | The "callback" argument must be of type function. Received null
settings({}, 0) threw ERR_INVALID_ARG_TYPE | The "callback" argument must be of type function. Received type number (0)
settings({}, "") threw ERR_INVALID_ARG_TYPE | The "callback" argument must be of type function. Received type string ('')
settings({}, false) threw ERR_INVALID_ARG_TYPE | The "callback" argument must be of type function. Received type boolean (false)
settings({}, 1) threw ERR_INVALID_ARG_TYPE | The "callback" argument must be of type function. Received type number (1)

server.setTimeout(123, 1) throws the same error in both. After the throw, server.timeout is 123 in node and was 0 in bun.

Known limit: customSettings with an invalid callback. Bun's validateSettings rejects some customSettings entries that node's first pass accepts, for example { abc: 5 }, { 1: "x" } and { 1: null }. Node checks the callback after its first pass and handles these entries in a second pass. So for one of these entries together with a truthy callback that is not a function, node throws the callback TypeError. Bun did the same before this change, because it checked the callback first. Bun now throws its settings RangeError. In a probe of 19 doubly-invalid and falsy-callback rows, 6 rows now match node and 7 rows changed this way. Every row still throws synchronously in both runtimes, and bun already rejects these entries when there is no callback. #41322 gives validateSettings node's first pass and adds the second pass (toNativeSettings). With both PRs, the order must be validateSettings(settings), then the callback check, then toNativeSettings(settings). The PR that lands second must keep that order and add the customSettings rows to the test.

The test. Each accepted call sends its own headerTableSize. The log of 'localSettings' events and callback calls then shows which ACK ran which callback. Node v26.3.0 gives the same log.

Other callback-taking methods, compared with node v26.3.0 over undefined, null, 0, "", false, NaN, 1, "x", true, {} and []: session.ping(), session.setTimeout(), session.close() and stream.setTimeout() already match node. stream.close() matches node on an open stream. This change does not touch them.

Not part of this PR:

stream.pushStream() has the same early callback check (src/js/node/http2.ts:3211). Node checks push-disabled and nested-push first. The preamble of pushStream() differs from node in more ways, and node:http2: validate the headers and options arguments like node #43491 and node:http2: refuse pushStream() and ping() after session.close() #43531 already edit it. A separate change must move that check.
stream.close() on a closed stream returns before it validates code and callback (src/js/node/http2.ts:2508). Node validates first.
http.Server#setTimeout(ms, callback) (src/js/node/_http_server.ts:1171) ignores a truthy callback that is not a function. Node passes it to this.on(), which throws ERR_INVALID_ARG_TYPE for listener.
validateSettings checks the settings in a different order than node, so a settings object with two invalid fields can report a different field.
server.updateSettings(undefined) throws in bun and not in node. node:http2: accept undefined in server.updateSettings() #43472 covers it. The if (settings === undefined) settings = {} lines in settings() stay, because the later code reads settings.maxConcurrentStreams and passes settings to the native parser.

Suites run on the debug build: all of test/js/node/http2/node-http2.test.js (389 pass, 6 skip, 0 fail), and these vendored node tests: test-http2-session-settings.js, test-http2-server-settimeout-no-callback.js, test-http2-client-settings-before-connect.js, test-http2-too-many-settings.js, test-http2-max-settings.js, test-http2-update-settings.js, test-http2-timeouts.js, test-http2-server-timeout.js, test-http2-session-timeout.js, test-http2-settings-unsolicited-ack.js, test-http2-ping-settings-heapdump.js, test-http2-compat-serverrequest-settimeout.js, test-http2-compat-serverresponse-settimeout.js, test-http2-server-push-stream-errors-args.js, test-http2-misused-pseudoheaders.js.

[human-review] gate passed · iteration 0 · 2 files touched

fails on main (without fix)

ASAN without fix: 3 failed, 6 skipped
$ BUN_DEBUG_QUIET_LOGS=1 bun scripts/build.ts --profile=debug --quiet test "--reporter=junit" "--reporter-outfile=/tmp/pr_gate.xml" "test/js/node/http2/node-http2.test.js"
bun test v1.4.3 (367d939d9)

test/js/node/http2/node-http2.test.js:
(pass) node none > Client Basics > should be able to send a GET request [823.57ms]
(pass) node none > Client Basics > should be able to send a POST request [550.87ms]
(pass) node none > Client Basics > constants [18.19ms]
(pass) node none > Client Basics > getDefaultSettings [6.85ms]
(pass) node none > Client Basics > getPackedSettings/getUnpackedSettings [16.52ms]
(pass) node none > Client Basics > getUnpackedSettings should throw if buffer is too small [5.54ms]
(pass) node none > Client Basics > getUnpackedSettings should throw if buffer is not a multiple of 6 bytes [3.10ms]
(pass) node none > Client Basics > getUnpackedSettings should throw if buffer is not a buffer [4.81ms]
(pass) node none > Client Basics > should be able to send data using end [574.55ms]
(pass) node none > Client Basics > should be able to mutiplex GET requests [565.60ms]
(pass) node none > Client Basics > http2 should receive remoteSettings when receiving d
... (truncated)

release without fix: 3 failed, 6 skipped
bun test v1.4.3-canary.1 (367d939d9)

test/js/node/http2/node-http2.test.js:
(pass) node none > Client Basics > constants [0.80ms]
(pass) node none > Client Basics > getDefaultSettings [0.15ms]
(pass) node none > Client Basics > getPackedSettings/getUnpackedSettings [0.26ms]
(pass) node none > Client Basics > getUnpackedSettings should throw if buffer is too small [0.13ms]
(pass) node none > Client Basics > getUnpackedSettings should throw if buffer is not a multiple of 6 bytes [0.03ms]
(pass) node none > Client Basics > getUnpackedSettings should throw if buffer is not a buffer [0.06ms]
(pass) node none > Client Basics > is possible to abort request [1.54ms]
(pass) node none > Client Basics > aborted event should work with abortController [0.67ms]
(pass) node none > Client Basics > aborted event should work with aborted signal [0.64ms]
(pass) node none > Client Basics > signal validation matches node: non-signal objects throw, duck-typed { aborted } is accepted [0.67ms]
(pass) node none > Client Basics > should fail to connect over HTTP/1.1 [28.46ms]
(skip) node none > Client Basics > should not leak memory
(pass) node none > Client Basics > headers cannot be bigge
... (truncated)

passes on PR (with fix)

ASAN with fix: 6 skipped
$ BUN_DEBUG_QUIET_LOGS=1 bun scripts/build.ts --profile=debug --quiet test "--reporter=junit" "--reporter-outfile=/tmp/pr_gate.xml" "test/js/node/http2/node-http2.test.js"
bun test v1.4.3 (367d939d9)

test/js/node/http2/node-http2.test.js:
(pass) node none > Client Basics > should be able to send a GET request [805.10ms]
(pass) node none > Client Basics > should be able to send a POST request [533.57ms]
(pass) node none > Client Basics > constants [17.39ms]
(pass) node none > Client Basics > getDefaultSettings [6.76ms]
(pass) node none > Client Basics > getPackedSettings/getUnpackedSettings [15.89ms]
(pass) node none > Client Basics > getUnpackedSettings should throw if buffer is too small [4.98ms]
(pass) node none > Client Basics > getUnpackedSettings should throw if buffer is not a multiple of 6 bytes [2.88ms]
(pass) node none > Client Basics > getUnpackedSettings should throw if buffer is not a buffer [4.61ms]
(pass) node none > Client Basics > should be able to send data using end [551.75ms]
(pass) node none > Client Basics > should be able to mutiplex GET requests [541.92ms]
(pass) node none > Client Basics > http2 should receive remoteSettings when receiving d
... (truncated)

release with fix: 6 skipped
$ bun scripts/build.ts --profile=release
[configured] bun-profile → bun (stripped)
  target       linux-x64-gnu
  build type   Release
  build dir    ./build/release
  revision     e6d564e121
  features     lto, baseline

23 deps, 131 codegen, 1176 objects in 759ms

ninja: Entering directory `/workspace/bun/build/release'
[1/1250] install /workspace/bun
bun install v1.4.3-canary.1 (367d939d9)

Checked 22 installs across 61 packages (no changes) [10.00ms]
[2/1250] install /workspace/bun/packages/bun-error
bun install v1.4.3-canary.1 (367d939d9)

Checked 1 install across 2 packages (no changes) [3.00ms]
[3/1250] gen ErrorCode+*.h
[4/1250] gen bindgenv2
[5/1250] install /workspace/bun/src/node-fallbacks
bun install v1.4.3-canary.1 (367d939d9)

Checked 111 installs across 104 packages (no changes) [16.00ms]
[6/1250] fetch tinycc
[tinycc] up to date
[7/1249] gen node-fallbacks/react-refresh.js
Bundled 1 module in 7ms

  react-refresh.js  4.81 KB  (entry point)

[8/1249] gen ProcessBindingConstants.lut.h
Generating /workspace/bun/build/release/codegen/ProcessBindingConstants.lut.h from /workspace/bun/src/jsc/bindings/ProcessBindingConstants.cpp
[9/1249] fetch libjpeg-tu
... (truncated)

diff hotspot

src/js/node/http2.ts                  |  24 ++++----
 test/js/node/http2/node-http2.test.js | 107 ++++++++++++++++++++++++++++++++++
 2 files changed, 117 insertions(+), 14 deletions(-)

gate history · 1 passed · 0 rejected · iteration 0

evidence per changed file

file                                   reads  edits  tests
src/js/node/http2.ts                       6      4     31
test/js/node/http2/node-http2.test.js      6      6     31

Http2Session#settings() validated the callback before the settings and rejected every non-function callback except undefined. Node validates the settings first and validates the callback only when it is truthy, so null, 0, "" and false are accepted and ignored. Http2Server#setTimeout() and Http2SecureServer#setTimeout() had the same hand-written callback check ahead of the timeout assignment. Node assigns the timeout first, then validates a callback that is not undefined.

robobun · 2026-09-20T02:07:49Z

^{Updated 8:31 PM PT - Sep 19th, 2026}

❌ @robobun, your commit e6d564e has 1 failures in Build #118795 (All Failures):

test/bake/deinitialization.test.ts - code 1: (unnamed) — expect(received).toBe(expected) on 🐧 3.23 aarch64

🧪 To try this PR locally:

bunx bun-pr 43605

That installs a local version of the PR into your bun-43605 executable, so you can run:

bun-43605 --bun

robobun · 2026-09-20T02:08:07Z

Status: the fix is ready for review. All review threads are resolved.

How I reproduced it. I ran the script from the PR Notes with bun 1.4.3 and with node v26.3.0, on a client session and on a server session.

session.settings(null, 1): bun reports the callback argument, node reports the settings argument.
session.settings({}, cb) with cb set to null, 0, "" or false: bun throws ERR_INVALID_ARG_TYPE, node accepts the call.
server.setTimeout(123, 1): both throw. After the throw, server.timeout is 123 in node and 0 in bun.

Proof. The three new test cases in test/js/node/http2/node-http2.test.js fail with the src/ tree of main and pass with this branch. Node v26.3.0 passes the same assertions as a standalone script.

CI. Build #118795 finished with 180 of 181 jobs passed. No lane reports a failure in test/js/node/http2/. One test fails: test/bake/deinitialization.test.ts on Alpine 3.23 aarch64. This PR does not touch that test or the dev server. The same test fails on main at the base commit of this branch (build #118758) and on other branches (builds #118781, #118761, #118740), so a new CI run does not help.

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Changes

HTTP/2 behavior alignment

Layer / File(s)	Summary
Session settings validation and acknowledgments `src/js/node/http2.ts`, `test/js/node/http2/node-http2.test.js`	`Http2Session.settings()` validates settings before truthy callbacks. Falsy callbacks are accepted, and tests cover acknowledgment ordering for client and server sessions.
Server timeout assignment and callback validation `src/js/node/http2.ts`, `test/js/node/http2/node-http2.test.js`	`Http2Server` and `Http2SecureServer` assign `timeout` before callback validation and register only valid callbacks. Tests cover rejected non-function callbacks.

Suggested reviewers: cirospaciari

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Title check	✅ Passed	The title clearly identifies the main change: updating `Http2Session.settings()` validation order and callback handling.
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In `@test/js/node/http2/node-http2.test.js`:
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test(http2): give each server kind its own setTimeout() test case

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node:http2: keep one permalink line above each reordered check

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node:http2: report a disabled or nested push before pushStream() validates callback #43609

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node:http2: check settings before callback in session.settings() - #43605

node:http2: check settings before callback in session.settings()#43605
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robobun/09e0accf/http2-settings-callback-check-order

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