v1.0.21

src/lib/server/dns-dispatcher.ts

@@ -0,0 +1,91 @@
+import { setGlobalDispatcher, Agent } from 'undici';
+import dns from 'node:dns';
+import net from 'node:net';
+
+const origLookup = dns.lookup.bind(dns);
+
+// DNS cache: hostname → { address, family, expiresAt } (positive)
+// DNS negative cache: hostname → { error, expiresAt } (failed lookups)
+const dnsCache = new Map<string, { address: string; family: number; expiresAt: number }>();
+const dnsNegCache = new Map<string, { error: Error; expiresAt: number }>();
+const DNS_TTL_MS = 30_000;
+const DNS_NEG_TTL_MS = 10_000; // Cache failures for 10s to prevent DNS server storms
+
+// In-flight deduplication: hostname → pending Promise<{address, family}>
+const inFlight = new Map<string, Promise<{ address: string; family: number }>>();
+
+function lookupWithCache(hostname: string): Promise<{ address: string; family: number }> {
+	// Positive cache hit
+	const cached = dnsCache.get(hostname);
+	if (cached) {
+		if (cached.expiresAt > Date.now()) {
+			return Promise.resolve({ address: cached.address, family: cached.family });
+		}
+		dnsCache.delete(hostname); // evict stale entry
+	}
+
+	// Negative cache hit — don't hammer DNS for recently-failed hostnames
+	const negCached = dnsNegCache.get(hostname);
+	if (negCached) {
+		if (negCached.expiresAt > Date.now()) {
+			return Promise.reject(negCached.error);
+		}
+		dnsNegCache.delete(hostname);
+	}
+
+	// In-flight deduplication
+	const pending = inFlight.get(hostname);
+	if (pending) return pending;
+
+	// Use getaddrinfo (libc) as primary — works through Docker's embedded DNS (127.0.0.11)
+	// and respects --dns-result-order=ipv4first from entrypoint. This matches Bun's native
+	// behavior which worked reliably on NAS environments where c-ares failed (#676).
+	const promise = new Promise<{ address: string; family: number }>((resolve, reject) => {
+		origLookup(hostname, { all: false }, (err, address, family) => {
+			if (err) {
+				// Cache the failure so parallel/subsequent requests don't all hammer DNS
+				dnsNegCache.set(hostname, { error: err, expiresAt: Date.now() + DNS_NEG_TTL_MS });
+				reject(err);
+			} else {
+				const result = { address: address as string, family: family as number };
+				dnsCache.set(hostname, { ...result, expiresAt: Date.now() + DNS_TTL_MS });
+				resolve(result);
+			}
+		});
+	}).finally(() => {
+		inFlight.delete(hostname);
+	});
+
+	inFlight.set(hostname, promise);
+	return promise;
+}
+
+setGlobalDispatcher(
+	new Agent({
+		connect: {
+			// Undici default is 10s. Increase to 30s for NAS environments with slow NAT/firewalls (#676).
+			timeout: 30_000,
+			lookup(hostname: string, opts: any, cb: any) {
+				if (typeof opts === 'function') {
+					cb = opts;
+					opts = {};
+				}
+
+				// IP addresses / localhost → no DNS needed
+				if (net.isIP(hostname) || hostname === 'localhost') {
+					return origLookup(hostname, opts, cb);
+				}
+
+				lookupWithCache(hostname)
+					.then(({ address, family }) => {
+						if (opts.all) {
+							cb(null, [{ address, family }]);
+						} else {
+							cb(null, address, family);
+						}
+					})
+					.catch((err) => cb(err));
+			}
+		}
+	})
+);