From ed50fc346b9c58459bf4e6fe5c45e8d34faac8da Mon Sep 17 00:00:00 2001
From: Damien Arrachequesne <damien.arrachequesne@gmail.com>
Date: Sat, 6 Nov 2021 07:43:40 +0100
Subject: [PATCH] fix: fix payload encoding for v3 clients

The v3 parser (used for compatibility with older clients) was broken
during the migration to TypeScript ([1]).

This was not caught in the test suite because the Node.js client does
not support binary packet in polling mode (packets are base64-encoded).

[1]: https://github.com/socketio/engine.io/commit/c0d6eaa1ba1291946dc8425d5f533d5f721862dd

Backported from 6.0.x branch: https://github.com/socketio/engine.io/commit/3f42262fd27a77a7383cdbb44ede7c6211a9782b
---
 lib/parser-v3/utf8.ts |  2 +-
 test/parser.js        | 22 ++++++++++++++++++++++
 2 files changed, 23 insertions(+), 1 deletion(-)
 create mode 100644 test/parser.js

diff --git a/lib/parser-v3/utf8.ts b/lib/parser-v3/utf8.ts
index 9a9decbd3..b878740ff 100644
--- a/lib/parser-v3/utf8.ts
+++ b/lib/parser-v3/utf8.ts
@@ -203,7 +203,7 @@ function utf8decode(byteString, opts) {
 	return ucs2encode(codePoints);
 }
 
-export default {
+module.exports = {
 	version: '2.1.2',
 	encode: utf8encode,
 	decode: utf8decode
diff --git a/test/parser.js b/test/parser.js
new file mode 100644
index 000000000..3f967e1b7
--- /dev/null
+++ b/test/parser.js
@@ -0,0 +1,22 @@
+const expect = require("expect.js");
+const parser = require("../build/parser-v3/index.js");
+
+describe("parser", () => {
+  it("properly encodes a mixed payload", done => {
+    parser.encodePayload(
+      [
+        { type: "message", data: "€€€€" },
+        { type: "message", data: Buffer.from([1, 2, 3]) }
+      ],
+      true,
+      encoded => {
+        expect(encoded).to.be.a(Buffer);
+
+        parser.decodePayload(encoded, decoded => {
+          expect(decoded.data).to.eql("€€€€");
+          done();
+        });
+      }
+    );
+  });
+});