Gateway: wide-area Bonjour via clawdis.internal

src/infra/tailnet.ts

@@ -0,0 +1,52 @@
+import os from "node:os";
+
+export type TailnetAddresses = {
+  ipv4: string[];
+  ipv6: string[];
+};
+
+function isTailnetIPv4(address: string): boolean {
+  const parts = address.split(".");
+  if (parts.length !== 4) return false;
+  const octets = parts.map((p) => Number.parseInt(p, 10));
+  if (octets.some((n) => !Number.isFinite(n) || n < 0 || n > 255)) return false;
+
+  // Tailscale IPv4 range: 100.64.0.0/10
+  // https://tailscale.com/kb/1015/100.x-addresses
+  const [a, b] = octets;
+  return a === 100 && b >= 64 && b <= 127;
+}
+
+function isTailnetIPv6(address: string): boolean {
+  // Tailscale IPv6 ULA prefix: fd7a:115c:a1e0::/48
+  // (stable across tailnets; nodes get per-device suffixes)
+  const normalized = address.trim().toLowerCase();
+  return normalized.startsWith("fd7a:115c:a1e0:");
+}
+
+export function listTailnetAddresses(): TailnetAddresses {
+  const ipv4: string[] = [];
+  const ipv6: string[] = [];
+
+  const ifaces = os.networkInterfaces();
+  for (const entries of Object.values(ifaces)) {
+    if (!entries) continue;
+    for (const e of entries) {
+      if (!e || e.internal) continue;
+      const address = e.address?.trim();
+      if (!address) continue;
+      if (isTailnetIPv4(address)) ipv4.push(address);
+      if (isTailnetIPv6(address)) ipv6.push(address);
+    }
+  }
+
+  return { ipv4: [...new Set(ipv4)], ipv6: [...new Set(ipv6)] };
+}
+
+export function pickPrimaryTailnetIPv4(): string | undefined {
+  return listTailnetAddresses().ipv4[0];
+}
+
+export function pickPrimaryTailnetIPv6(): string | undefined {
+  return listTailnetAddresses().ipv6[0];
+}