[wrangler] fix: listen on loopback for wrangler dev port check and login

The `wrangler dev` port availability check triggers a firewall prompt on
macOS while it briefly opens and closes listeners. The OAuth callback
server from `wrangler login` has the same issue.

Fix both cases by listening on the loopback address only.

Relates to cloudflare#4430

.changeset/smart-owls-jog.md

@@ -0,0 +1,10 @@
+---
+"wrangler": patch
+---
+
+fix: listen on loopback for wrangler dev port check and login
+
+Avoid listening on the wildcard address to reduce the attacker's surface and
+avoid firewall prompts on macOS.
+
+Relates to #4430.

packages/wrangler/src/dev.tsx

@@ -626,12 +626,17 @@ export async function startApiDev(args: StartDevOptions) {
 	};
 }
 /**
+ * Get an available TCP port number.
+ *
  * Avoiding calling `getPort()` multiple times by memoizing the first result.
  */
 function memoizeGetPort(defaultPort?: number) {
 	let portValue: number;
 	return async () => {
-		return portValue || (portValue = await getPort({ port: defaultPort }));
+		// Check a specific host to avoid probing all local addresses.
+		portValue =
+			portValue ?? (await getPort({ port: defaultPort, host: "localhost" }));
+		return portValue;
 	};
 }
 /**

packages/wrangler/src/dev/proxy.ts

@@ -686,7 +686,7 @@ export async function waitForPortToBeAvailable(
 					doReject(err);
 				}
 			});
-			server.listen(port, () =>
+			server.listen(port, "localhost", () =>
 				terminator
 					.terminate()
 					.then(doResolve, () =>

packages/wrangler/src/user/user.ts

@@ -1014,7 +1014,7 @@ export async function login(
 			}
 		});
 
-		server.listen(8976);
+		server.listen(8976, "localhost");
 	});
 	if (props?.browser) {
 		logger.log(`Opening a link in your default browser: ${urlToOpen}`);