fix: check the format of the event name

darrachequesne · darrachequesne · commit 3b78117bf6ba · 2023-05-22T08:25:33.000+02:00
A packet like '2[{"toString":"foo"}]' was decoded as: { type: EVENT, data: [ { "toString": "foo" } ] } Which would then throw an error when passed to the EventEmitter class: > TypeError: Cannot convert object to primitive value > at Socket.emit (node:events:507:25) > at .../node_modules/socket.io/lib/socket.js:531:14 History of the isPayloadValid() method: - added in [78f9fc2](78f9fc2) (v4.0.1, socket.io@3.0.0) - updated in [1c220dd](1c220dd) (v4.0.4, socket.io@3.1.0)
diff --git a/lib/index.ts b/lib/index.ts
@@ -275,7 +275,10 @@ export class Decoder extends Emitter<{}, {}, DecoderReservedEvents> {
         return typeof payload === "string" || typeof payload === "object";
       case PacketType.EVENT:
       case PacketType.BINARY_EVENT:
-        return Array.isArray(payload) && payload.length > 0;
+        return (
+          Array.isArray(payload) &&
+          (typeof payload[0] === "string" || typeof payload[0] === "number")
+        );
       case PacketType.ACK:
       case PacketType.BINARY_ACK:
         return Array.isArray(payload);
diff --git a/test/parser.js b/test/parser.js
@@ -118,6 +118,9 @@ describe("socket.io-parser", () => {
     isInvalidPayload("1/admin,{}");
     isInvalidPayload('2/admin,"invalid');
     isInvalidPayload("2/admin,{}");
+    isInvalidPayload('2[{"toString":"foo"}]');
+    isInvalidPayload('2[true,"foo"]');
+    isInvalidPayload('2[null,"bar"]');
 
     expect(() => new Decoder().add("999")).to.throwException(
       /^unknown packet type 9$/
