refactor: export a function to validate the format of a packet

socketio · May 31, 2023 · 7c1632f · 7c1632f
1 parent d9db473
commit 7c1632f
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Showing 2 changed files with 71 additions and 3 deletions.
diff --git a/lib/index.ts b/lib/index.ts
@@ -280,11 +280,11 @@ export class Decoder extends Emitter<{}, {}, DecoderReservedEvents> {
   private static isPayloadValid(type: PacketType, payload: any): boolean {
     switch (type) {
       case PacketType.CONNECT:
-        return typeof payload === "object";
+        return isObject(payload);
       case PacketType.DISCONNECT:
         return payload === undefined;
       case PacketType.CONNECT_ERROR:
-        return typeof payload === "string" || typeof payload === "object";
+        return typeof payload === "string" || isObject(payload);
       case PacketType.EVENT:
       case PacketType.BINARY_EVENT:
         return (
@@ -354,3 +354,46 @@ class BinaryReconstructor {
     this.buffers = [];
   }
 }
+
+export function isPacketValid(packet: Packet): boolean {
+  return (
+    isNamespaceValid(packet) &&
+    isAckIdValid(packet) &&
+    isPayloadValid(packet.type, packet.data)
+  );
+}
+
+function isNamespaceValid(packet: Packet): boolean {
+  return typeof packet.nsp === "string";
+}
+
+function isAckIdValid(packet: Packet) {
+  return packet.id === undefined || Number.isInteger(packet.id);
+}
+
+// see https://stackoverflow.com/questions/8511281/check-if-a-value-is-an-object-in-javascript
+function isObject(value: any): boolean {
+  return Object.prototype.toString.call(value) === "[object Object]";
+}
+
+function isPayloadValid(type: PacketType, payload: any): boolean {
+  switch (type) {
+    case PacketType.CONNECT:
+      return payload === undefined || isObject(payload);
+    case PacketType.DISCONNECT:
+      return payload === undefined;
+    case PacketType.EVENT:
+      return (
+        Array.isArray(payload) &&
+        (typeof payload[0] === "number" ||
+          (typeof payload[0] === "string" &&
+            RESERVED_EVENTS.indexOf(payload[0]) === -1))
+      );
+    case PacketType.ACK:
+      return Array.isArray(payload);
+    case PacketType.CONNECT_ERROR:
+      return typeof payload === "string" || isObject(payload);
+    default:
+      return false;
+  }
+}
diff --git a/test/parser.js b/test/parser.js
@@ -1,4 +1,9 @@
-const { PacketType, Decoder, Encoder } = require("..");
+const {
+  PacketType,
+  Decoder,
+  Encoder,
+  isPacketValid,
+} = require("..");
 const expect = require("expect.js");
 const helpers = require("./helpers.js");
 
@@ -147,4 +152,24 @@ describe("socket.io-parser", () => {
       decoder.add('2["hello"]');
     });
   });
+
+  it("should ensure that a packet is valid", () => {
+    expect(isPacketValid({ type: 0, nsp: "/" })).to.eql(true);
+    expect(isPacketValid({ type: 0, nsp: "/", data: { foo: "bar" } })).to.eql(true);
+    expect(isPacketValid({ type: 1, nsp: "/" })).to.eql(true);
+    expect(isPacketValid({ type: 2, nsp: "/", data: ["foo"] })).to.eql(true);
+    expect(isPacketValid({ type: 2, nsp: "/", data: [1] })).to.eql(true);
+    expect(isPacketValid({ type: 3, nsp: "/", id: 1, data: ["foo"] })).to.eql(true);
+    expect(isPacketValid({ type: 4, nsp: "/", data: "foo" })).to.eql(true);
+    expect(isPacketValid({ type: 4, nsp: "/", data: { foo: "bar" } })).to.eql(true);
+
+    expect(isPacketValid({ type: 9, nsp: "/" })).to.eql(false);
+    expect(isPacketValid({ type: 0 })).to.eql(false);
+    expect(isPacketValid({ type: 0, nsp: 1 })).to.eql(false);
+    expect(isPacketValid({ type: 0, nsp: "/", data: ["foo"] })).to.eql(false);
+    expect(isPacketValid({ type: 1, nsp: "/", data: ["foo"] })).to.eql(false);
+    expect(isPacketValid({ type: 2, nsp: "/", data: { foo: "bar" } })).to.eql(false);
+    expect(isPacketValid({ type: 3, nsp: "/", id: "1", data: ["foo"] })).to.eql(false);
+    expect(isPacketValid({ type: 4, nsp: "/" })).to.eql(false);
+  });
 });