[PHP] gethostbyname – native DNS resolution in Node.js builds #2988
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adamziel
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[Type] Enhancement
adamziel
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adamziel
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Dec 6, 2025
| */ | ||
| async gethostbyname(hostname: string): Promise<string> { | ||
| const { address } = await lookup(hostname, { | ||
| family: 4, |
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perhaps we could support ipv6 while we're at it. Or merge this as is and add v6 support in a follow-up pr
Resolved conflicts by prioritizing trunk's wasm files and removing syscalls-related code that was removed in trunk.
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Removed all references to SyscallsForNode that were deleted in trunk during the merge. This includes: - Removed SyscallsForNode type from load-runtime.ts - Deleted syscalls-test-worker.ts test file - Removed syscalls field and useSyscalls method from worker classes - Removed syscallsPort parameters from handler functions
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@brandonpayton this may impact your work on the filesystem as it also introduces a central syscalls handler like yours. Let's merge the two. |
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@adamziel sounds good! I plan to account for that in the big rebase I'm doing today. |
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Motivation
Before this PR, the
gethostbyname()PHP function always returns either an internal IP address on success, or an unchanged hostname on failure. That's because Emscripten's default DNS implementation doesn't perform real lookups.This PR enables actual DNS resolution for PHP-WASM running in Node.js via Node's
dnsmodule. When PHP code calls
gethostbyname('wordpress.org'), it now resolves and returnsthe real IP address.
Implementation details
The implementation works similarly to
FileLockManager:phpwasm-emscripten-library-dns-lookup-for-node.jsdefines a new build-time JavaScript library linked with PHP.wasm. It overrides the__emscripten_lookup_nameshipped by Emscripten with a custom callback that callsPHPLoader.syscalls.gethostbyname()to resolve the IP.PHPLoader.syscallsis an object passed toloadNodeRuntime()viaoptions.emscriptenOptions. It's an object that, for now, defines a single method:gethostbyname().Even though you may pass an actual object instance, we create the instance in the parent worker and call
gethostbyname()using a Comlink proxy. This is becauserequire('dns').lookup()is asynchronous in Node. JSPI builds can easilyawaitthe returned value, but Asyncify builds can't. Not without spending a dozen hours tweaking theASYNCIFY_ONLYlist in the PHP compile Dockerfile. Therefore, we use a synchronous Comlink proxy to turn an asynchronousgethostbyname()call into a synchronous one in Asyncify builds.Test plan
CI. See the tests shipped with this PR, confirm they pass and make sense.
cc @bcotrim @fredrikekelund