Drop every second socket error that has no listener

test/bin-store-ping.test.ts

@@ -100,24 +100,40 @@ describe("mongo bin store ping", () => {
 		}
 	});
 
-	it("keeps a second socket proxy error inside the process", () => {
+	it("still throws the first socket error that has no listener", () => {
+		installSocketProxyGuard();
+		const socket = new net.Socket();
+		expect(() => {
+			socket.emit("error", new Error("first failure"));
+		}).toThrow(/first failure/);
+		socket.destroy();
+	});
+
+	it("drops a second socket error that has no listener", () => {
 		installSocketProxyGuard();
 		const socket = new net.Socket();
 		const proxy = new Error(
 			"proxy request failed, cannot connect to the specified address",
 		);
+		const seen: unknown[] = [];
+		socket.once("error", (error: unknown) => {
+			seen.push(error);
+		});
+		expect(socket.emit("error", proxy)).toBe(true);
 		expect(() => {
 			socket.emit("error", proxy);
 		}).not.toThrow();
 		expect(() => {
-			socket.emit("error", new Error("other failure"));
-		}).toThrow(/other failure/);
-		const seen: unknown[] = [];
+			socket.emit("error", new Error("TLS handshake failed"));
+		}).not.toThrow();
+		expect(seen).toEqual([proxy]);
+		const later: unknown[] = [];
 		socket.on("error", (error: unknown) => {
-			seen.push(error);
+			later.push(error);
 		});
-		socket.emit("error", proxy);
-		expect(seen).toEqual([proxy]);
+		const again = new Error("later failure");
+		expect(socket.emit("error", again)).toBe(true);
+		expect(later).toEqual([again]);
 		socket.destroy();
 	});
 });

worker/bin-store.ts

@@ -15,13 +15,16 @@ import type { MockHttpBinsOptions } from "../src/mock-http-bins.js";
 
 export const BIN_STORE_PING_TIMEOUT_MS = 2_000;
 
-const SOCKET_PROXY_FAILURE = "proxy request failed";
 let socketProxyGuardInstalled = false;
+const socketsWithError = new WeakSet<object>();
 
 /**
- * workerd reports a refused socket twice. The driver handles the first emit.
- * The second emit has no listener, so the isolate aborts.
- * Keep that second emit inside the process.
+ * workerd `node:net` emits `error` twice for one failed socket.
+ * `cleanupAfterDestroy` emits the first time. The stream `destroy` callback emits again.
+ * The driver listens with `once`, so the second emit has no listener and the isolate aborts.
+ * The message differs for a proxy failure, a TLS failure, or a reset.
+ * Drop a later `error` that has no listener. The first `error` still uses Node behavior.
+ * `tls.TLSSocket` uses this `emit`.
  */
 export function installSocketProxyGuard(): void {
 	if (socketProxyGuardInstalled) {
@@ -37,22 +40,17 @@ export function installSocketProxyGuard(): void {
 		event: string | symbol,
 		...args: unknown[]
 	) {
-		if (
-			event === "error" &&
-			this.listenerCount("error") === 0 &&
-			isSocketProxyFailure(args[0])
-		) {
-			return false;
+		if (event === "error") {
+			const repeat = socketsWithError.has(this);
+			socketsWithError.add(this);
+			if (repeat && this.listenerCount("error") === 0) {
+				return false;
+			}
 		}
 		return emit.call(this, event, ...args);
 	};
 }
 
-function isSocketProxyFailure(error: unknown): boolean {
-	const message = error instanceof Error ? error.message : String(error ?? "");
-	return message.includes(SOCKET_PROXY_FAILURE);
-}
-
 installSocketProxyGuard();
 
 const workerBinMongoOptions = {