[robobun]

Problem

• setTypeOfService() and getTypeOfService() throw where Node keeps the value: EINVAL on a unix socket, EBADF on TLS over a stream. A 1.4 regression (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), no user report.
• Bundled undici 7.23 to 8.7 calls the setter per request. Over socketPath it fails: EINVAL setTypeOfService EINVAL. Through an https proxy to an https origin the process exits: error: setTypeOfService EBADF.
• net.connect({ typeOfService }) drops the option unvalidated.

Fix

• Socket validates and stores the option like Node, after the fd type check. tls.ts strips it, like Node's TLSSocket.
• Both methods keep the value when the native call answers EINVAL, or EBADF while not connecting.
• Correct: Node's handles for those sockets (Pipe, TLSWrap) have no type of service. Node answers from the stored value.
• Verified: test/js/node/net/node-net.test.ts (14 of 16 new tests fail on main). Also test/js/node/net/, TLS suites. Self-reviewed: 7 concerns raised, 5 addressed, 2 in Notes.

Background

• Type of service is a packet's IP_TOS byte. A unix socket has none.
• One native class backs TCP and unix sockets. It answers -EINVAL for a unix socket, -EBADF with no fd.
• Considered a native "is a pipe" predicate (first version, 765794a). Other open PRs answer that question differently, so it needs its own decision. The errno check needs no native code.

Downsides

• A kernel EINVAL on an IP socket is kept. Node throws. macOS can return it (nodejs/undici#5544). No case found on Linux.
• Per new net.Socket(): +5 bytecode instructions. Release binary: +567 bytes.
• An invalid typeOfService throws, like Node. A 'connectionAttempt' listener of a unix dial still gets EBADF.

Notes

Every number below compares release builds on Linux x64: main at 5f5799e, and the same tree with this PR's source diff (86e832b). Node is v26.3.0. macOS and Windows were not run locally.

What changed since the first version. Up to 765794a this PR added a private native isPipeSocket() (112 lines of Rust) and asked it after a failed native call. A review of my own diff found that both undici failures need no native code, and that the predicate is a shared abstraction that needs its own decision. The Rust is removed here. The errno check gives the same result in every tested state but one: a 'connectionAttempt' listener of a unix dial, which runs before the native dial starts.

Repro 1, a unix socket. Run with a fresh socket path as the argument.

const net = require("node:net");
const p = process.argv[2];
const out = {};
const attempt = (name, socket) => {
  try { socket.setTypeOfService(0x10); out[name] = "set ok, get " + socket.getTypeOfService(); }
  catch (e) { out[name] = "threw " + (e.code ?? e.name) + " (" + e.syscall + ")"; }
};
const server = net.createServer(c => { attempt("accepted", c); c.end(); });
server.listen(p, () => {
  const s = net.connect(p);
  attempt("connecting", s);
  s.on("connect", () => { attempt("connected", s); });
  s.on("close", () => { server.close(); console.log(JSON.stringify(out)); });
  s.resume();
});

node v26.3.0:        {"connecting":"set ok, get 16","accepted":"set ok, get 16","connected":"set ok, get 16"}
bun 1.4.2 and main:  {"connecting":"threw EINVAL (setTypeOfService)","accepted":"threw EINVAL (setTypeOfService)","connected":"threw EINVAL (getTypeOfService)"}
this PR:             {"connecting":"set ok, get 16","accepted":"set ok, get 16","connected":"set ok, get 16"}

Repro 2, undici. undici 7.23.0 to 7.30.1 and 8.0.0 to 8.7.0 run socket.setTypeOfService(request.typeOfService) (default 0) before each HTTP/1.1 request, with no try/catch (lib/dispatcher/client-h1.js:1253 in 7.30.0). 7.22.0 has no such call. 8.8.0 catches the error. 7.30.1 is the newest 7.x release. The bare specifier undici resolves to Bun's built-in module, so only an undici that is bundled or loaded by path runs this code. All runs below load undici 7.30.0 by path.

Program	node v26.3.0	bun 1.3.13	bun 1.4.2 and main	this PR
new Client("http://localhost", { socketPath }), one GET	200	200	request failed: EINVAL setTypeOfService EINVAL	200
ProxyAgent with an https proxy, one GET to an https origin	200	200	uncaught error: setTypeOfService EBADF, exit 1	200

In the proxy case the request socket is a TLS socket inside the TLS tunnel. It has no fd of its own. undici calls the setter from its 'connect' listener, so the caller of request() cannot catch the error. bun 1.3.13 has neither method, and undici skips the call.

Repro 3, the option. net.connect({ port, host: "127.0.0.1", typeOfService: 0x10 }), then getTypeOfService() in the connect callback: node 16, main 0, this PR 16. The test also reads the kernel with getsockopt(IP_TOS).

Validation, new net.Socket({ typeOfService: v }), identical to node v26.3.0 in name, code and message. main accepts all of these.

999  | RangeError | ERR_OUT_OF_RANGE     | The value of "options.typeOfService" is out of range. It must be >= 0 && <= 255. Received 999
1.5  | RangeError | ERR_OUT_OF_RANGE     | The value of "options.typeOfService" is out of range. It must be an integer. Received 1.5
'16' | TypeError  | ERR_INVALID_ARG_TYPE | The "options.typeOfService" property must be of type number. Received type string ('16')
null | TypeError  | ERR_INVALID_ARG_TYPE | The "options.typeOfService" property must be of type number. Received null

Callers of the option. undici's connector passes connect.typeOfService to net.connect. http.request, http.Agent and http2.connect reach the same constructor. An invalid value now throws synchronously from those calls, as in Node.

Where the option is checked. Node checks it after it has created the handle for options.fd. Here the check sits between the fd type check and the fd adoption. Placed later, a constructor that throws has already adopted the fd and closes it one tick later.

new net.Socket(...)	node v26.3.0	main	this PR
{ fd: <regular file>, writable: true, typeOfService: 999 }	ERR_INVALID_FD_TYPE	ERR_INVALID_FD_TYPE	ERR_INVALID_FD_TYPE
{ fd: <closed fd>, writable: true, typeOfService: 999 }	ERR_INVALID_FD_TYPE	ERR_INVALID_FD_TYPE	ERR_INVALID_FD_TYPE
{ fd: <FIFO>, writable: true, typeOfService: 999 }	ERR_OUT_OF_RANGE, fd open	no throw	ERR_OUT_OF_RANGE, fd open
{ typeOfService: 999, signal: {} }	ERR_INVALID_ARG_TYPE	ERR_INVALID_ARG_TYPE	ERR_OUT_OF_RANGE

The last row is the one pair that still differs. Node validates signal inside the stream constructor, first. On main the net.Socket constructor validates signal last, after every other check (for example { signal: 5, fd: <regular file>, writable: true } gives ERR_INVALID_FD_TYPE on main). That order is not changed here.

What now gives Node's result.

• A unix socket that is connecting, connected, or accepted by net.createServer().listen(path).
• An adopted unix fd: an extra stdio pipe of a child process (child.stdio[3]).
• TLS over a unix path: tls.connect({ path }) and the sockets of tls.createServer().listen(path).
• A TLS socket over a Duplex, and a TLS socket over a TLS socket: before the handshake, in 'secureConnect' and in 'end'.
• A value set before connect(path), and the typeOfService option with a path.
• Inside the listeners of a unix dial, from 'connect' to 'close'.
• A socket (unix or TCP) that sent its FIN first, inside its 'end' listener. Its native handle is closed there. Node's handle stays open until destroy(), and on Linux its TCP handle still takes the value. TCP threw EBADF (getTypeOfService) before.
• One net.Socket that connects to a unix socket, then over TCP, then to a unix socket again: the value set over the unix socket is applied to the TCP connection.
• A TCP handle that is still connecting throws EBADF, as in Node.

Which errno means what. The native methods return a negative errno. -EINVAL comes from bsd_socket_tos_level (packages/bun-usockets/src/bsd.c:606) when the socket family is not IPv4 or IPv6. -EBADF comes from set_tos / get_tos (src/uws_sys/socket.rs:537) when the handle is not a connected fd: a handle that is still connecting, a handle that closed, or a TLS socket over a stream. socket.connecting separates the first of these, where Node also throws EBADF.

The kept kernel EINVAL. The errno check cannot tell a unix socket from an IP socket whose setsockopt failed with EINVAL. Node throws for the second. On Linux I found no case where setsockopt returns EINVAL for a value from 0 to 255. On macOS setsockopt can fail with EINVAL depending on the socket state, which is how nodejs/undici#5544 was reported against Node. With this PR such a call keeps the value and does not throw. A native predicate can restore the throw.

The TLS option strip. TLSSocket forwards all of its options to the net.Socket constructor. In node v26.3.0 tls.connect({ typeOfService: 999 }) is accepted and tls.connect({ typeOfService: 16 }) leaves getTypeOfService() at 0, because Node's TLSSocket passes a fixed option list. tls.ts now strips the option beside readable / writable.

Measurements (main against this PR).

• Native code: none changed. generated_js2native.rs is identical on both builds. No new host function.
• Type-of-service libc calls, counted with an LD_PRELOAD interposer, loop of N minus loop of 0: identical on both builds for a dialed and an accepted unix socket (2000 getsockname per 1000 set+get), a dialed and an accepted TCP socket (2000 getsockname, 1000 setsockopt, 1000 getsockopt), child.stdio[3] (100 per 100 gets) and Bun.connect({ unix }) (200 per 100 set+get).
• Bytecode, static instruction counts from BUN_JSC_dumpGeneratedBytecodes=1: Socket 481 to 500, TLSSocket 275 to 278, setTypeOfService 56 to 62, getTypeOfService 33 to 49, new keepsTypeOfService 8. connect 470, onconnection 208 and afterConnect 189 are unchanged.
• Executed per call: new net.Socket() without the option runs 5 more instructions (one property read of opts.typeOfService, one mov, three branches). new tls.TLSSocket() runs 2 more, plus those 5. A successful TCP setTypeOfService() / getTypeOfService() runs the same instructions as on main: every added instruction is behind the branch on a failed native call. A call on a unix socket runs 4 instructions of keepsTypeOfService.
• Process: 1 more Function cell after require("node:net") (987 to 988).
• Size: size build/release/bun text 106,006,149 to 106,006,716 (+567), data unchanged (115,160). Bundled net.js +500 bytes, tls.js +67.

Tests. 16 new tests in test/js/node/net/node-net.test.ts. 14 fail on main. The other two are guards that pass on main: the TLS option strip, and a TCP socket (dialed and accepted) whose value reaches the kernel. The tests that say "applied" read the kernel with getsockopt(fd, IPPROTO_IP, IP_TOS) through bun:ffi, so a socket that only answers from the stored value fails them. The same 16 test bodies pass under node v26.3.0 as a plain script (there the kernel read is Node's own getTypeOfService()). The kernel-dependent tests skip Windows: there the two methods report no error on any socket. Release builds of main and of this PR have the same 10 failures over test/js/node/net/, node-tls-connect.test.ts, node-tls-server.test.ts and test/js/bun/net/socket.test.ts (1086 tests), besides the 14 new tests that fail on main. The vendored test-net-socket-tos.js is unchanged and passes.

Self-review. 7 concerns came out of a review of the first version. 5 are addressed: the native code is out of this PR, with its performance branch and its errno pin. The option check moved after the fd type check. The "applied" tests read the kernel. The TLS-over-stream state has tests. The other 2 go with the native predicate and are the first two items below.

Left for other work.

• Node emits 'error' when it cannot apply the stored value at connect (lib/net.js L1681-L1688). afterConnect in net.ts discards the native result, as on main. A port of the emit needs the predicate: without it every unix dial with a stored value would emit setTypeOfService EINVAL.
• Inside 'connectionAttemptFailed' of a dial with two addresses (::1 refused, then 127.0.0.1), both methods throw EBADF. Node gives [0, true, 8]. The same on main.
• Inside 'connectionAttempt' of a unix dial, both methods throw EBADF. Node keeps the value. The same on main.
• A TLS socket over TCP that is still connecting throws EBADF. Node keeps the value. The same on main.
• resetAndDestroy() on a unix socket returns the socket. Node throws ERR_INVALID_HANDLE_TYPE. node:net: make resetAndDestroy() throw ERR_INVALID_HANDLE_TYPE on TLS and pipe sockets #38232 is open for it.
• A unix socket still issues one getsockname per call of either method, as on main.
• A socket without a native handle stores the value and never reaches the kernel: a TCP fd given to the constructor (new net.Socket({ fd, typeOfService: 16 }).getTypeOfService() is now 16, main 0), and node:http server sockets.
• The tls.ts strip is one more key on a denylist. Node passes a fixed list of options. A move to Node's list changes more than this option, for example blockList over TLS.

The native predicate. Commit 765794a of this PR holds it: NewSocket::is_pipe() reads the last dial, the accepting listener, and getsockname for an adopted fd. As its own PR it would cover the 'connectionAttempt' case, restore Node's throw for a kernel EINVAL, and gate the connect-time 'error'. It is a new shared abstraction, and these open PRs each carry their own answer to the same question: #45011 (isFailedPipeConnect), #38232 (kIsPipe), #44959 (is_unix_socket()), #45346 (a local_address length test). A maintainer decides if node:net gets one owner for it.

Related PRs.

• node:net: report a failed unix-socket connect on the next loop turn #45011 adds isFailedPipeConnect() to the first guard of the same two methods, for a unix socket whose connect failed. This PR changes the branch after the native call. A three-way merge of net.ts with that branch has no conflict. The two were not run together.
• The draft node:net: complete a failed unix-socket connect from the event loop #44959 changes what the two native methods return for a unix socket. This PR reads the current -EINVAL.
• net: route throws from socket lifecycle listeners to uncaughtException #29762 routes a throw from a socket lifecycle listener to uncaughtException. undici calls the setter from its 'connect' listener. Without this PR, that change turns the socketPath failure into a process exit, so this PR should land first. This was not run against that branch.

---

no test proof · iteration 0 · platform-specific test(s) that do not run on this machine, deferring to CI, which covers all platforms: test/js/node/net/node-net.test.ts

[robobun]

Status

Reproduced on bun 1.4.2 and on a release build of main (5f5799e), compared with node v26.3.0 and bun 1.3.13:

• On a unix socket, setTypeOfService() and getTypeOfService() throw EINVAL. Node keeps the value and returns it.
• undici 7.30.0 loaded by path, new Client("http://localhost", { socketPath }): the first request fails with EINVAL setTypeOfService EINVAL. Node and bun 1.3.13 answer 200.
• undici 7.30.0 ProxyAgent with an https proxy and an https origin: the process exits 1 with an uncaught error: setTypeOfService EBADF. Node and bun 1.3.13 answer 200.
• net.connect({ port, host: "127.0.0.1", typeOfService: 0x10 }) then getTypeOfService() gives 0. Node gives 16. new net.Socket({ typeOfService: 999 }) is accepted. Node throws ERR_OUT_OF_RANGE.

This PR is now JS only (src/js/node/net.ts, src/js/node/tls.ts, fb540d3). The native isPipeSocket() predicate of the first version is removed from it. That code stays in the history at 765794a. It needs a maintainer's decision before it becomes a PR of its own.

test/js/node/net/node-net.test.ts: 14 of the 16 new tests fail on main. All 16 pass on this branch, and the same test bodies pass under node v26.3.0.

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Walkthrough

Socket validates and caches typeOfService values. Native socket code identifies pipe connections and returns EINVAL for type-of-service calls on open pipes. TLSSocket excludes the option from delegated options. Tests cover TCP, Unix sockets, TLS, accepted sockets, and child-process pipes.

Changes

Socket type-of-service support

Layer / File(s)	Summary
Pipe connection classification src/runtime/node/node_net_binding.rs, src/runtime/socket/*, src/js/node/net.ts	Detached sockets receive a pipe flag. Native socket code classifies pipes from connection state or descriptor checks and exposes the result through isPipeSocket.
Type-of-service behavior on pipes src/runtime/socket/socket_body.rs, src/js/node/net.ts, test/js/bun/net/socket.test.ts	Native type-of-service calls return EINVAL for open pipes. Node socket methods use cached values for named-pipe handles and for non-connecting sockets when the native error is EBADF. Tests check error values for open and closed Unix sockets.
Type-of-service option handling and validation src/js/node/net.ts, src/js/node/tls.ts, test/js/node/net/node-net.test.ts	Socket validates and caches values from 0–255. TLSSocket excludes typeOfService from delegated options. Tests cover validation, defaults, TCP settings, Unix sockets, TLS, accepted sockets, child-process pipes, and connection states.

Suggested reviewers: alii

Priority: ➖ Normal

Merge Risk: ⚪ Minimal · up to 76579

No merge-blocking issue is established for the reviewed socket changes; normal platform checks can proceed.

Pre-merge checks: 4

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Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.
Title check		The title clearly identifies the main change: honoring typeOfService for Unix and TLS-over-stream sockets in node:net. It is specific and related to the changeset.
Description check		The description explains the problem, fix, scope, limitations, verification steps, test results, and remaining work. It does not use the exact template headings, but it provides the required informati…

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[claude]

LGTM — small, well-cited Node compat fix that mirrors the adjacent fd/keepAliveInitialDelay pattern.

What was reviewed:

• Constructor reads opts.typeOfService (own props via rest-destructure, matching Node's { ...options } copy) and stores into the existing kSetTOS slot; the connect/open handlers at lines 580 and 3413 already apply it, and getTypeOfService() already falls back to it.
• createConnection passes options straight to new Socket(options), so net.connect({ typeOfService }) is covered by the same path — matches the test's viaConnect case.
• TLS strip extends the existing readable/writable fast-path guard; options is always an object by that point (options || socket || {}), so the added .typeOfService read can't throw.
• Tests: port: 0 + 127.0.0.1, once() for readiness, try/finally cleanup, describe.concurrent, skipIf(isWindows) with a stated reason, combined-object .toEqual for the validation matrix — all in line with the test conventions.

Extended reasoning...

Overview

This PR wires the typeOfService option into the net.Socket constructor: it validates the value with validateInt32(..., 0, 255) and stores it in the existing kSetTOS symbol slot. The rest of the machinery (applying kSetTOS on connect, setTypeOfService/getTypeOfService prototype methods) already existed — this just fills in the constructor read that Node has at lib/net.js#L478-L481. The tls.TLSSocket constructor is updated to strip typeOfService before delegating to net.Socket, extending the exact pattern already in place for readable/writable, because Node's TLSSocket builds a fixed option list that omits it. Four new tests in node-net.test.ts cover the validation error-code matrix, the pre-connect getTypeOfService() return, TLS non-forwarding, and (non-Windows) that DSCP bits actually reach the kernel via both new Socket({...}).connect() and net.connect({...}).

Security risks

None. This is an IP TOS/DSCP hint byte; the change adds range validation (0-255) via the shared validateInt32 helper and stores it in a symbol-keyed slot. No parsing of untrusted data, no auth/crypto/permission surface, no new native code. The TLS change only removes an option from the object forwarded to the base constructor.

Level of scrutiny

Low-to-moderate. The net.ts change is 6 lines that copy the shape of the adjacent fd and keepAliveInitialDelay handling — read from opts (the rest of the destructure, i.e. own properties, matching Node's options = { ...options }), guard !== undefined, call the shared validator with the same "options.foo" argument-path spelling, and initialize an existing symbol slot. The tls.ts change extends a one-line ternary that already existed. The Node source lines are cited inline for both. I verified net.connect routes through new Socket(options) so both entry points are covered, and that getTypeOfService()'s !== undefined fallback means the new unconditional this[kSetTOS] = typeOfService (undefined when omitted) preserves the "returns 0 when unset" behavior — which the test also asserts.

Other factors

Tests follow the repo's conventions closely: added to the existing node-net.test.ts under describe.concurrent, use port: 0 with 127.0.0.1, await once(..., "listening")/once(..., "connect") rather than sleeping, clean up the server in finally, gate the kernel-read test with skipIf(isWindows) and a comment naming why (Windows ignores IP_TOS; Node's own test doesn't check it there), and assert error .code values via a single combined-object .toEqual. No CODEOWNERS entry covers these paths. The bug hunt exited on dry_streak with no findings and no ruled-out candidates.

[robobun]

^{Updated 9:51 PM PT - Oct 15th, 2026}

❌ @robobun, your commit fb540d3 has 1 failures in Build #126330 (All Failures):

• test/cli/install/bun-install-windows-rename-retry.test.ts - code 1 on 🪟 11 aarch64

---

🧪   To try this PR locally:

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Actionable comments posted: 1

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Inline comments:
Review comments at @test/js/node/net/node-net.test.ts:
- Line 2240: Update the “type of service of a unix socket” test group to use
describe.concurrent.skipIf(isWindows) so its independent socket and
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• src/runtime/socket/mod.rs
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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.

Beyond the inline finding, I checked the new native pipe detection in socket_body.rs: every reader of connection (do_connect, SNI/server-identity hostname, DNS error hostname, the Windows ENOENT probe) only acts on Host/Fd, and every dial path in connect_finish overwrites the field before do_connect reads it, so the seeded/cached Unix(empty) cannot be dialed. The -EINVAL short-circuit matches what usockets' bsd_socket_tos_level already returns for an AF_UNIX fd, so Bun.Socket set/getTypeOfService results are unchanged, only the getsockname syscall is skipped. Also ruled out: an fd-adopted pipe read after its native socket closed still answers EBADF rather than the cached value, which the new is_pipe fd probe cannot see once the fd is gone.

Extended reasoning...

The second commit adds native Rust pipe detection (fd-level getsockname probe, a connection seed at construction and a cache write in is_pipe) plus a short-circuit in the shared set/getTypeOfService host functions that the public Bun.Socket also uses; the JS side threads pipe into newDetachedSocket and gates ErrnoException throws on the new binding. No security-sensitive surface (no auth, crypto or input parsing beyond validateInt32 on a numeric option). Deferring rather than approving because the change touches shared socket-state fields and syscall-bearing native code, and an inline finding is already posted for the TCP 'end'-listener path.

[claude]

Code review completed

Nothing new to post: everything this review found is already covered by existing comments on this pull request or didn't merit a separate one.

[claude]

Code review found no issues

No high-confidence issues detected in this change.

[claude]

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

[claude]

🟡 nit (optional): the new fd-adoption test creates a throwaway file with tmpdirSync(), which the root CLAUDE.md tells tests not to use, and the file is never removed. Fix: build the scratch file with using dir = tempDir(...) from harness (or reuse the directory openFifo already made) so the directory is cleaned up with the test; the same rule applies to the pre-existing socket_domain and openFifo callers if they are touched.

Why this was flagged

The test at test/js/node/net/node-net.test.ts:1569-1598 calls fs.openSync(join(tmpdirSync(), "invalid-tos.txt"), "w") at line 1572 to get a regular-file fd for the ERR_INVALID_FD_TYPE case. CLAUDE.md line 101 says to use tempDir from harness and not tmpdirSync. The finally block closes the fd but never deletes the file or directory, so each run leaves a directory behind on the CI runner. This is a convention and hygiene nit, not a behavioral defect; the base branch has no such test.

Verification: nit. Triggering condition: every run of the new test. The diff adds at /home/claude/bun/test/js/node/net/node-net.test.ts:1572 const file = fs.openSync(join(tmpdirSync(), "invalid-tos.txt"), "w");. The test's finally at lines 1593-1598 only calls fs.closeSync on the fds; nothing removes the file or the mkdtemp directory, so each run leaves bun.test.XXXX/invalid-tos.txt behind.

[claude]

🟣 pre-existing, not blocking: pre-existing: a unix-socket dial still throws "EBADF" from set/getTypeOfService() inside its 'connectionAttempt' listener, where Node keeps the value. keepsTypeOfService at src/js/node/net.ts:2907 rescues EBADF only when socket.connecting is false, but connect(path) sets connecting at net.ts:2445 and emits 'connectionAttempt' at net.ts:3391 before the dial gives the detached handle an fd. Fix: decide "this handle has no IP socket" from what connect() already knows (a path dial, a wrapped socket/Duplex transport) rather than from errno plus connecting, while still throwing EBADF for a TCP dial that never opened, which the tcpConnecting assertion in node-net.test.ts requires.
A small fix can ride a push you are already making; otherwise a short reply is enough.

Why this was flagged

A user calls socket.getTypeOfService() or setTypeOfService(v) in a 'connectionAttempt' listener of net.connect(path). Socket.prototype.connect sets this.connecting = true at src/js/node/net.ts:2445 and creates a detached handle via newDetachedSocket at net.ts:2452; internalConnect emits 'connectionAttempt' at net.ts:3391 before kConnectPipe runs, so the native get_tos/set_tos answer -9. keepsTypeOfService at net.ts:2907 returns false because socket.connecting is true, so net.ts:2931 / net.ts:2948 throw ErrnoException(-9, ...). Node's unix handle is a Pipe with no setTypeOfService/getTypeOfService, so Node stores and returns the cached value. The base branch threw EBADF here too; the diff's rescue covers 'connect' through 'close' (the test at node-net.test.ts starts its listener matrix at 'connect') but not these two connecting-state sites.

Verification: Socket.prototype.connect sets this.connecting = true (src/js/node/net.ts:2445). internalConnect emits self.emit("connectionAttempt", address, port, addressType) at net.ts:3391, and only afterwards runs kConnectPipe at net.ts:3430. While still Detached, set_tos/get_tos return -9, and keepsTypeOfService (net.ts:2907) returns false because connecting is true, so net.ts:2931 / net.ts:2948 throw ErrnoException(EBADF).