From 012b674f313b628653414c9a8bbbfed79cf76bf6 Mon Sep 17 00:00:00 2001
From: Peter Steinberger <steipete@gmail.com>
Date: Sun, 15 Feb 2026 21:47:51 +0000
Subject: [PATCH] refactor(infra): share isTailnetIPv4 helper

---
 src/infra/bonjour-discovery.ts | 15 +--------------
 src/infra/tailnet.ts           |  2 +-
 2 files changed, 2 insertions(+), 15 deletions(-)

diff --git a/src/infra/bonjour-discovery.ts b/src/infra/bonjour-discovery.ts
index f0ee29615..426d4eb51 100644
--- a/src/infra/bonjour-discovery.ts
+++ b/src/infra/bonjour-discovery.ts
@@ -1,4 +1,5 @@
 import { runCommandWithTimeout } from "../process/exec.js";
+import { isTailnetIPv4 } from "./tailnet.js";
 import { resolveWideAreaDiscoveryDomain } from "./widearea-dns.js";
 
 export type GatewayBonjourBeacon = {
@@ -70,20 +71,6 @@ function decodeDnsSdEscapes(value: string): string {
   return Buffer.from(bytes).toString("utf8");
 }
 
-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
-  const [a, b] = octets;
-  return a === 100 && b >= 64 && b <= 127;
-}
-
 function parseDigShortLines(stdout: string): string[] {
   return stdout
     .split("\n")
diff --git a/src/infra/tailnet.ts b/src/infra/tailnet.ts
index ed666b868..ed2384cfe 100644
--- a/src/infra/tailnet.ts
+++ b/src/infra/tailnet.ts
@@ -5,7 +5,7 @@ export type TailnetAddresses = {
   ipv6: string[];
 };
 
-function isTailnetIPv4(address: string): boolean {
+export function isTailnetIPv4(address: string): boolean {
   const parts = address.split(".");
   if (parts.length !== 4) {
     return false;