Add -sNODERAWSOCKETS backend for real TCP & UDP on Node.js#27080
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Add -sNODERAWSOCKETS backend for real TCP & UDP on Node.js#27080guybedford wants to merge 10 commits into
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Nice! I've not yet reviewed the meat of libsockfs.js but looks good so far.
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I still need to review the details of libsockfs_node.js but the general shape here LGTM!
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Nice work on all the test cases. I can't say I've read all the test code yet though..
Can you confirm they all run on linux and/or macOS nativly too? (at least the ones where it makes sense that they could).
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Adds a new NODERAWSOCKETS setting that backs the POSIX sockets API directly with Node.js's node:net module, giving real, non-blocking outgoing (client) TCP sockets without WebSockets, an external proxy process, or pthreads. This is the sockets counterpart to NODERAWFS: where NODERAWFS gives direct access to the host filesystem, this gives direct access to host sockets. Unlike PROXY_POSIX_SOCKETS this is single-threaded and event-driven: socket readiness is delivered through the same emscripten_set_socket_*_callback hooks the default WebSocket backend uses, so it drops into existing readiness reactors unchanged. This initial backend supports outgoing TCP only: connect, send, recv and close, plus get/setsockopt (SO_ERROR, TCP_NODELAY, SO_KEEPALIVE and the TCP keep-alive tunables). There is no bind/listen/accept (server) support and no UDP yet; those land in follow-ups. - new node backend in src/lib/libsockfs_node.js, pulled in only under -sNODERAWSOCKETS, implementing the sock_ops contract over net.createConnection - __syscall_setsockopt now lives in JS (routing to the backend under NODERAWSOCKETS, else reporting the option as unknown), avoiding a libstubs variation - test/sockets/test_tcp_echo.c: a plain POSIX outgoing connect/send/recv echo client that also builds and runs natively, run under node against a loopback echo server started by the test harness
Builds on the outgoing-TCP backend to add bind, listen and accept, so a
program can run a real TCP server under -sNODERAWSOCKETS.
Clients stay on the public node:net API: connect() goes through
net.createConnection and never touches a private handle. Servers need a
synchronous bind() that reports the assigned ephemeral port up front (so a
bind(:0) followed by getsockname() works), which net.Server.listen cannot do
because it is async. For that we use a low-level tcp_wrap TCP handle, whose
bind/getsockname are synchronous, and hand that handle to net.Server.listen for
accept. So process.binding('tcp_wrap') only fires for bind/listen/accept, plus
the rare client that bind()s a source port before connect().
- bind/listen/accept added to the node backend, with poll reporting a listener
readable when a connection is pending
- test/sockets/test_tcp_server.c: a self-contained loopback accept+echo that
also builds and runs natively
Adds connectionless UDP (SOCK_DGRAM) to the node socket backend: bind, sendto/recvfrom and a connect() that records a default peer. node:dgram has no synchronous bind and a dgram.Socket cannot adopt an external handle, so unlike TCP we cannot split UDP into a public client path and a private server path. For now the whole UDP path goes through a low-level udp_wrap handle, which does give a synchronous bind() + getsockname() (so bind(:0) followed by getsockname() returns the assigned port immediately). Once node gains a public dgram bindSync, UDP can move fully onto node:dgram with no private API. - UDP handle helper with onmessage receive wiring; recvStart is deferred until the handle is bound (an unbound handle rejects it), either by an explicit bind or by the auto-bind on first send - bind/connect/sendmsg/recvmsg/poll/close branch for SOCK_DGRAM, with datagram recv returning one message and truncating to the buffer - test/sockets/test_udp_echo.c: a self-contained loopback UDP echo that also builds and runs natively
The node socket backend already works in threaded builds without any backend changes: like the rest of the JS filesystem, socket syscalls are proxied to the main thread, so the node:net/tcp_wrap/udp_wrap handles and their event loop always live on the main thread, and a worker calling connect/send/recv blocks on the synchronous proxy. Payloads are already copied out of wasm memory before being handed to node, so a SharedArrayBuffer heap is safe. - run the TCP client, TCP server, UDP and connected-UDP tests in a second '-pthread -sPROXY_TO_PTHREAD' configuration to prove the proxied path - document the threading behavior on the NODERAWSOCKETS setting and backend
The weak native stubs for __syscall_setsockopt and __syscall_shutdown were removed from emscripten_syscall_stubs.c in favor of JS implementations in libsyscall.js, but libsyscall.js is not linked under WASMFS, leaving the symbols undefined. Stub them out in WASMFS alongside the other socket syscalls.
__syscall_setsockopt and __syscall_shutdown move from native wasm exports to JS library imports in hello_dylink_all.
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This adds a new
-sNODERAWSOCKETSsetting that for supporting direct full sockets on Node.js via thenode:netfor TCP andnode:dgramfor UDP modules, without needingws, an external proxy process, or pthreads.It is layered into four separate commits:
node:netAPIsprocess.binding('tcp_wrap')API to get the raw socket handle, which is also supported on other runtimes like Deno.UDP without JSPI cannot support bindSync so errors will not be well-defined in Node.js. The async errors will be surfaced after the original bind call instead. I've included in this PR the usage of
socket.bindSyncbased on this being supported in the next Node.js release via nodejs/node#63838.For comprehensive
setsockoptssupport I also posted nodejs/node#63825 as well, which closes the loop on all options being supported in latest Node.js 26 and these patterns are effectively used in a backwards compatible way here despite not landing yet.Note: AI was used to create this PR, under my review.