Volatile not working from server to client with binary data

[sergmister]

Describe the bug
Sending a volatile event from the client (Chrome) to Node with binary data works fine. Sending a volatile event from Node to the client with binary data does not work. Sending binary data without volatile works, sending non binary data with volatile works.

To Reproduce

Socket.IO server version: 4.1.1

Server

import { createServer } from "http";
import { Server, Socket } from "socket.io";

const httpServer = createServer({});

const io = new Server(httpServer, {
  cors: {
    origin: "http://localhost:8080",
    methods: ["GET", "POST"],
  },
});

io.on("connection", (socket) => {
  socket.on("some event", (data) => {
    console.log(data);
  });

  setTimeout(() => {
    socket.volatile.emit("some event", "hello");
    // socket.volatile.emit("some event", new ArrayBuffer(10));
  }, 1000);
});

httpServer.listen(3000);

Socket.IO client version: 4.1.1

Client

import { io } from "socket.io-client";

this.socket = io("http://localhost:3000");

    this.socket.on("some event", (data) => {
      console.log(data);
    });

    setTimeout(() => {
      this.socket.volatile.emit("some event", new ArrayBuffer(10));
    }, 1000);

works fine, changing the server code:

  setTimeout(() => {
    // socket.volatile.emit("some event", "hello");
    socket.volatile.emit("some event", new ArrayBuffer(10));
  }, 1000);

and the client receives nothing

Expected behavior
The client receives the binary data.

Platform:

• OS: Linux 5.10
• Node 15.14.0

[BrendanAnnable]

I can confirm this bug, and just encountered it when upgrading from socket.io v2 to v4.

It appears to send non-binary data just fine, and it will even send the non-binary parts of the same message just fine, including binary placeholder objects. But the binary packets which correspond to those placeholder objects appear to be never sent.

[lemonad]

I also ran into this problem when trying to use volatile. I'm using socket.io version 4.2.0.

[darrachequesne]

I could indeed reproduce the issue. We will publish a fix as soon as possible.

[refeed]

I just upgraded my app's socketio to the latest version (4.3.1) and still having this issue

[alexfrs69]

Same issue here, tested with Uint8Array (protobuf), and Buffer.from (same as unit test) server to client volatile.emit() is still broken.

[darrachequesne]

This should be fixed by dc81fcf, included in socket.io@4.3.1.

@refeed I cannot reproduce: https://github.com/socketio/socket.io-fiddle/tree/issues/socket.io/3919, could you please check?

[brako]

Thanks, the problem occurs when we send volatile data directly with the server (working fine with the socket )

setInterval(() => {
    io.volatile.emit("test", Buffer.from([1,2,3]));
  }, 1000);

You won't receive the data with the client.

[darrachequesne]

@brako zut, you are right. This should be finally fixed by socketio/socket.io-adapter@88eee59, included in socket.io-adapter@2.3.3 (which should be included by latest socket.io by transitivity).

I added a test case here, to prevent any regression in the future.

Please reopen if needed.