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A hostname router can read a TLS ClientHello with MSG_PEEK, pick the
server for that hostname, and pass the descriptor on (SCM_RIGHTS) so it
leaves the path. node:http can take such a socket through
emit("connection"); Bun.serve had no way to.
server.adopt(fd) registers an already-connected socket on the server's
listener exactly as if the listener had accepted it (same group, TLS
context and open callback) and reads at once, so the ClientHello still
in the kernel buffer is handled by the normal path. The accept loop and
adopt share one helper in uSockets.
IPC: a NODE_HANDLE message with type "fd" delivers the raw descriptor
to process.on("message") without wrapping it in a net.Socket, which
would start reading and consume the ClientHello.
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WalkthroughThe change adds ChangesSocket adoption and descriptor IPC
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The title clearly and concisely identifies the main change: adding server.adopt(fd) to serve connections accepted elsewhere. |
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Actionable comments posted: 5
- 🪄 Fix CodeRabbit comments on this PR
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Inline comments:
Review comments at @src/js/builtins/Ipc.ts:
- Around line 80-81: Update the IPC message delivery path around emit(target,
serialized.msg, fd) to close the descriptor when Process__emitMessageEvent finds
no matching listener. Preserve ownership transfer by leaving the descriptor open
when a listener receives it.
Review comments at @src/runtime/server/server_body.rs:
- Around line 1534-1537: Validate arguments[0] as a finite, non-negative integer
within the supported descriptor range before calling to_int32, and reject
invalid values instead of converting them; only pass an exact descriptor to
adopt_fd.
- Around line 1538-1539: Update the no-listener branch in the
accepted-descriptor handling path to explicitly close the accepted descriptor
before returning false, preserving the ownership contract and preventing the raw
descriptor from leaking.
Review comments at @test/js/bun/http/serve.test.ts:
- Around line 5609-5611: Replace the fixed Bun.sleep delay in the test with an
observable wait confirming the fetch client has established its TCP connection
before calling raw.accept(). Keep the HTTP and TLS assertions on the adopted
socket.
- Around line 5573-5574: Move the dlopen and ptr imports from the socket test’s
local require to a module-scope import from bun:ffi, keeping the existing FFI
usage unchanged.
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packages/bun-types/serve.d.tspackages/bun-usockets/src/libusockets.hpackages/bun-usockets/src/loop.csrc/js/builtins/Ipc.tssrc/runtime/server/server.classes.tssrc/runtime/server/server_body.rssrc/uws_sys/App.rssrc/uws_sys/ListenSocket.rstest/js/bun/http/serve.test.ts
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adopt() now takes fd through validateInt32 (an integer >= 0), so NaN, fractions, negatives and values past int32 throw instead of being coerced to another descriptor. With no listener it closes the descriptor before returning false, as documented. An IPC fd that arrives with no "message" listener is closed rather than leaked. The test imports bun:ffi at module scope and waits for a pending connection with poll() instead of a sleep.
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- 🪄 Fix CodeRabbit comments on this PR
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Inline comments:
Review comments at @src/js/builtins/Ipc.ts:
- Around line 77-87: Update #emitIpcMessage to close numeric file descriptors
when emitting an IPC message finds no listener. Preserve the existing event
selection and message arguments, and leave non-numeric handles unchanged.
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src/js/builtins/Ipc.tssrc/runtime/server/server_body.rstest/js/bun/http/serve.test.ts
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A parent that receives a raw descriptor (NODE_HANDLE type "fd") from a forked child with no "message" listener now closes it, as the child side already does. Tests send the descriptor the way a router does (a JSON line with SCM_RIGHTS over the channel) in both directions and check the receiver closed it. Both fail without the close.
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- 🪄 Fix CodeRabbit comments on this PR
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Inline comments:
Review comments at @test/js/bun/http/serve.test.ts:
- Around line 5650-5656: Convert the parameterized validation test from
`it.each()` into a `describe.each()` suite with one `it()` assertion per case,
keeping the existing fd inputs and expected error codes.
- Line 5608: Update the readiness loop around libc.poll so it calls accept only
after poll reports readable readiness; retry interrupted polls and fail on other
poll errors instead of treating -1 as ready. Preserve the existing wait behavior
while ensuring accept cannot block when no connection is pending.
- Line 5647: Update the stopped-server adoption test near the server.adopt
assertion to also pass a valid owned descriptor and verify it is closed when
adoption returns false. Retain the existing invalid-descriptor assertion.
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test/js/bun/http/serve.test.ts
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…ped server, describe.each Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
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@alii Can you please review this PR. |
# Conflicts: # packages/bun-usockets/src/loop.c
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What does this PR do?
Adds
server.adopt(fd)to the serverBun.serve()returns. It takes a TCP connection that some other process accepted (for example a hostname router that read the TLS ClientHello withMSG_PEEKand passed the descriptor on withSCM_RIGHTS) and serves it exactly as if the server's own listener had accepted it.Why: running several apps on one IP:443 needs something to route by hostname. Today, for
Bun.serveapps, that router has to stay in the path and copy every byte, becauseBun.servecannot take a connection it didn't accept. node:http can (server.emit("connection", socket)), but in Bun that means giving up Bun.serve's native HTTP stack. #44015 notes the same limit for cluster: a Bun HTTP server "cannot take connections that the primary accepted". #17247 is a hand-off proxy blocked on Bun for the same reason. #44013 (Bun.serve({ fd })) covers a listening socket and rejects a connected one, so this is complementary.Changes:
us_listen_socket_adopt_fd(listener, fd)uses it, so an adopted socket gets the same group, kind, ext size, TLS context and open callback as an accepted one, then reads at once (the ClientHello is already in the kernel buffer). The accept loop's behavior is unchanged.server.adopt(fd): boolean: returnsfalseif the server has no listener (for example, it has stopped) or the descriptor can't be registered. In that case the descriptor is closed.NODE_HANDLEmessage withtype: "fd"hands the raw descriptor toprocess.on("message", (msg, fd) => …)without wrapping it in anet.Socket, which would start reading and consume the ClientHello. Happy to split this into its own PR if you prefer.serve.d.ts.How did you verify your code works?
test/js/bun/http/serve.test.ts: a connection accepted with raw libc calls is adopted and served, over plain HTTP and over TLS.adoptreturnsfalseafterstop(). They fail on main and pass with this change.serve.test.ts,node-net-server.test.ts,node-tls-server.test.ts,cluster.test.tsandnode-http.test.tswith a release build of main and with this branch. The failing tests are identical in both, apart from the three new tests. The remaining failures come from my environment: no IPv6, andbun:internal-for-testingis absent in release builds.type: "fd", to twoBun.serveTLS + HTTP/2 workers. Requests reached the right app,requestIP()showed the real client address, and the router held no connections afterwards.server.adoptOn open connections an adopted socket is the same as a directly accepted one. The extra cost per new connection is the router's accept, peek and sendmsg plus the IPC message.