Resolve the Seafile host over IPv4 only (musl/Alpine ENOTFOUND on IPv6 NXDOMAIN); v2.17.3

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

server/seafile-dns.js

@@ -0,0 +1,30 @@
+import dns from 'node:dns'
+import { SEAFILE_URL } from './config.js'
+
+// Alpine's resolver (musl) fails the whole lookup when a DNS server answers the IPv6 (AAAA)
+// query with "no such name" even though the IPv4 answer is fine, so Node reports ENOTFOUND for
+// a host that resolves. Ask for IPv4 only, and only for the Seafile host.
+export function preferIpv4ForSeafile() {
+  let host = ''
+  try {
+    host = SEAFILE_URL ? new URL(SEAFILE_URL).hostname : ''
+  } catch {
+    return
+  }
+  if (!host) return
+
+  const originalLookup = dns.lookup
+  dns.lookup = function lookup(hostname, options, callback) {
+    if (hostname === host) {
+      if (typeof options === 'function') {
+        callback = options
+        options = {}
+      } else if (typeof options === 'number') {
+        options = { family: options }
+      }
+      if (!options?.family) options = { ...options, family: 4 }
+    }
+    return originalLookup.call(this, hostname, options, callback)
+  }
+  console.log(`[seafile-dns] resolving ${host} over IPv4 only`)
+}