-sNODERAWSOCKETS DNS resolution, with general readiness#27182
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Move the readiness wait-queue onto FSNode (addListener/notifyListeners) so dup'd fds share one queue, and rewrite the suspending poll() path (readPollfds/writePollfds/pollWait) on top of it. Producers (SOCKFS, PIPEFS) now notify the node on readiness transitions, and close() wakes waiters with POLLNVAL. The stream_ops.poll backend handler signature changes from poll(stream, timeout) to poll(stream) returning the current readiness mask.
Add epoll_create1/epoll_ctl/epoll_wait/epoll_pwait on the legacy (non-WASMFS) JS syscall layer, built on the per-inode readiness wait-queue: level- and edge-triggered modes, EPOLLONESHOT, EPOLLEXCLUSIVE, EPOLLRDHUP, nesting, and blocking waits under PROXY_TO_PTHREAD, ASYNCIFY, and JSPI. Also add emscripten_epoll_set_callback (new experimental <emscripten/epoll.h>), a non-blocking variant that delivers an epoll set's readiness to a JS callback without ASYNCIFY/JSPI.
Under -sNODERAWSOCKETS, getaddrinfo() previously fabricated fake addresses via DNS.lookup_name. This adds real resolution backed by node:dns, plus an async getaddrinfo so names can be resolved without blocking. getaddrinfo() now resolves numeric addresses and /etc/hosts entries (read fresh through emscripten's FS) synchronously, and returns a full addrinfo list (one node per address). For a real hostname: - without JSPI it returns EAI_AGAIN (no synchronous DNS); resolve it via the async API below. - under JSPI it suspends the wasm stack on the node:dns lookup and returns the addresses directly (gated on ASYNCIFY == 2). The async API (available in all builds): - emscripten_dns_lookup_async(node, service, hint) takes the same inputs as getaddrinfo() and returns a pollable fd that becomes readable when resolution completes. - emscripten_dns_lookup_result(fd, struct addrinfo **res) reads the outcome: 0 on success (writing the addrinfo list to *res, freed with freeaddrinfo), or an EAI_* code on failure. The completion fd is a plain pollable descriptor: wait on it with epoll/poll/select. freeaddrinfo now frees the whole ai_next chain; EAI_AGAIN is added to the generated struct info. Tested with test_dns_async, test_dns_callback (completion via emscripten_poll_with_callback), test_dns_async_net, test_dns_async_default, and test_dns_jspi, including PROXY_TO_PTHREAD variants.
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Async DNS, built on top of #27207 for async readiness. Implementation diff is the last commit - b5af97b.
This adds real DNS resolution under
-sNODERAWSOCKETSvianode:dns, along with an async syscall variant ofgetaddrinfofor non-JSPI environments.getaddrinfo()resolves numeric addresses and/etc/hostsentries (read fresh through emscripten's FS) synchronously, and returns a fulladdrinfolist. For a real hostname: without JSPI it returnsEAI_AGAIN(resolve via the async API); under JSPI it suspends the wasm stack on thenode:dnslookup and returns the addresses directly.Async API (available in all builds):
emscripten_dns_lookup_async(node, service, hint)— same inputs asgetaddrinfo(), returns a pollable fd that becomes readable when resolution completes.emscripten_dns_lookup_result(fd, struct addrinfo **res)— reads the outcome:0on success (writing theaddrinfolist to*res, freed withfreeaddrinfo), or anEAI_*code.The original PR in #27162 allowed the async callback for DNS lookup to be registered via
emscripten_set_socket_message_callback. Instead of "hijacking" that mechanism, we can now directly use an epoll'able file descriptor to represent the dns lookup operation. On readiness, the actualemscripten_dns_lookup_result()just gets called again.freeaddrinfonow frees the wholeai_nextchain;EAI_AGAINis added to the generated struct info.Tested with
test_dns_async,test_dns_callback(completion viaemscripten_poll_with_callback),test_dns_async_net,test_dns_async_default, andtest_dns_jspi, includingPROXY_TO_PTHREADvariants.