Super basic socket.io v3 signaling server

signal-server.js

// (C)opyright 2021 Dirk Holtwick, holtwick.it. All rights reserved.

import helmet from "helmet"
import cors from "cors"

const config = {
  host: process.env.HOST || undefined,
  port: process.env.PORT || 3000,
  message: {
    announce: "announce",
    publish: "publish",
    signal: "signal",
  },
}

async function run() {
  const app = require("express")()
  app.use(helmet())
  app.use(cors())

  const http = require("http").createServer(app)
  const io = require("socket.io")(http, {
    cors: true,
  })

  io.on("connection", (socket) => {
    let activeRoom
    const connSocketID = socket.id

    // Subscribe to {room} and announce to others, such they can signal us
    socket.on(config.message.publish, (msg) => {
      try {
        const { room, data } = msg
        activeRoom = room
        socket.join(room)
        socket.to(room).emit(config.message.announce, {
          id: connSocketID,
          room,
          data,
        })
        io.to(room)
          .allSockets()
          .then((ids) => {})
      } catch (error) {
        console.error(config.message.publish, error, msg)
      }
    })

    // Send {id, data} to socket.id === id
    socket.on(config.message.signal, (msg) => {
      try {
        const toSocket = io.of("/").sockets.get(msg.id)
        if (toSocket) {
          toSocket.emit(config.message.signal, msg)
        }
      } catch (error) {
        console.error(config.message.signal, error, msg)
      }
    })
  })

  http.listen(
    {
      host: config.host,
      port: config.port,
    },
    () => {
      const { port, family, address } = http.address()
      console.info(`Listening on ${address}:${port} (${family})`)
    }
  )
}

run()