Preparation:

Server-side deployment with nodejs and socket.io

Directly on the code, simply:

app.js :

//http class
//var http = require('http');
//var socketIO = require('socket.io');
//var app = http.createServer();
//var PORT = 8081;
//app.listen(PORT);
//var io = socketIO.listen(app);

 //https class
var http = require('http');
 / / file operation class
var fs = require('fs');
 / / Read the key and signing certificate
var options = {
  key: fs.readFileSync('keys/server.key'),
  cert: fs.readFileSync('keys/server.crt')
}
 //socket.io class
var socketIO = require('socket.io');

 / / Build http server
var apps = http.createServer(options);
 //Listen port
var SSL_PORT = 8443;
apps.listen(SSL_PORT);

 / / Build Sock.io server
var io = socketIO.listen(apps);
 //Socket connection listener
io.sockets.on('connection', function (socket) {
     //socket closed
  socket.on('disconnect', function(reason){
    //room
    // var room = Object.keys(socket.rooms)[1];
    // //socket id
    // var socketId = socket.id;
    // var message = {};
    // message.from = socketId;
    // message.room = room;
    // console.log('disconnect: ' + socketId + ' reason:' + reason +' message: ' + JSON.stringify(message));
         // //Close the connection
    // socket.leave(room);
         // //Get the room
    // var clientsInRoom = io.sockets.adapter.rooms[room];
    // if (clientsInRoom) {
    //   var otherSocketIds = Object.keys(clientsInRoom.sockets);
    //   for (var i = 0; i < otherSocketIds.length; i++) {
         // // Forward [exit] message to other clients
    //     var otherSocket = io.sockets.connected[otherSocketIds[i]];
    //     otherSocket.emit('exit', message);
    //   }
    // }
    var socketId = socket.id;
    console.log('disconnect: ' + socketId + ' reason:' + reason );
    var message = {};
    message.from = socketId;
    message.room = '';
    socket.broadcast.emit('exit', message);
   });

     /** client->server signaling set*/
     //[createAndJoinRoom] Create and join the Room [room]
  socket.on('createAndJoinRoom', function (message) {
    var room = message.room;
    console.log('Received createAndJoinRoom：' + room);
         / / Determine if the room exists
    var clientsInRoom = io.sockets.adapter.rooms[room];
    var numClients = clientsInRoom ? Object.keys(clientsInRoom.sockets).length : 0;
    console.log('Room ' + room + ' now has ' + numClients + ' client(s)');
    if (clientsInRoom) {
      console.log(Object.keys(clientsInRoom.sockets));
    }
    if (numClients === 0) {
             /** room does not exist Create (socket.join)*/ if it does not exist
             //Join and create a room
      socket.join(room);
      console.log('Client ID ' + socket.id + ' created room ' + room);

             / / Send [created] message to the client [id, room, peers]
      var data = {};
      //socket id
      data.id = socket.id;
      //room id
      data.room = room;
             //Other connections are empty
      data.peers = [];
             //send
      socket.emit('created', data);
    } else {
             /** room exists */
             //Send [joined] message to other clients in the room [id,room]
      var data = {};
      //socket id
      data.id = socket.id;
      //room id
      data.room = room;
             //Send other clients in the room
      io.sockets.in(room).emit('joined', data);


             / / Send [created] message to the client [id, room, peers]
      var data = {};
      //socket id
      data.id = socket.id;
      //room id
      data.room = room;
             //Other connections
      var peers = new Array();
      var otherSocketIds = Object.keys(clientsInRoom.sockets);
      console.log('Socket length ' + otherSocketIds.length);
      for (var i = 0; i < otherSocketIds.length; i++) {
        var peer = {};
        peer.id = otherSocketIds[i];
        peers.push(peer);
      }
      data.peers = peers;
             //send
      socket.emit('created', data);

             //Join the room
      socket.join(room);
      console.log('Client ID ' + socket.id + ' joined room ' + room);
    }

  });

     //[offer] forwards the offer message to the other clients in the room [from,to,room,sdp]
  socket.on('offer', function (message) {
    var room = Object.keys(socket.rooms)[1];
    console.log('Received offer: ' + message.from + ' room:' + room + ' message: ' + JSON.stringify(message) );
         / / Forward [offer] message to other clients
         / / Find the corresponding connection according to the id
    var otherClient = io.sockets.connected[message.to];
    if (!otherClient) {
      return;
    }
    otherClient.emit('offer', message);

  });

     //[answer] Forward answer message to room other clients [from,to,room,sdp]
  socket.on('answer', function (message) {
    var room = Object.keys(socket.rooms)[1];
    console.log('Received answer: ' + message.from + ' room:' + room + ' message: ' + JSON.stringify(message));
         / / Forward [answer] message to other clients
         / / Find the corresponding connection according to the id
    var otherClient = io.sockets.connected[message.to];
    if (!otherClient) {
      return;
    }
    otherClient.emit('answer', message);
  });

     //[candidate] forwards the candidate message to the other clients in the room [from,to,room,candidate[sdpMid,sdpMLineIndex,sdp]]
  socket.on('candidate', function (message) {
    console.log('Received candidate: ' + message.from + ' message: ' + JSON.stringify(message));
         / / Forward [candidate] message to other clients
         / / Find the corresponding connection according to the id
    var otherClient = io.sockets.connected[message.to];
    if (!otherClient) {
      return;
    }
    otherClient.emit('candidate', message);
  });

     //[exit] close the connection and forward the exit message to the other clients in the room [from,room]
  socket.on('exit', function (message) {
    console.log('Received exit: ' + message.from + ' message: ' + JSON.stringify(message));
    var room = message.room;
         / / Close the connection
    socket.leave(room);
         //Get the room
    var clientsInRoom = io.sockets.adapter.rooms[room];
    if (clientsInRoom) {
      var otherSocketIds = Object.keys(clientsInRoom.sockets);
      for (var i = 0; i < otherSocketIds.length; i++) {
                 / / Forward [exit] message to other clients
        var otherSocket = io.sockets.connected[otherSocketIds[i]];
        otherSocket.emit('exit', message);
      }
    }
  });

});



 /** Build html page */
var express = require("express");
var htmlApp = express();
htmlApp.use(express.static("htmlTest")).listen(8080)
var httpsServer = http.createServer(options,htmlApp);
httpsServer.listen(8441);

 // //http static route
htmlApp.use(express.static("htmlTest")).listen(8080);

Js script file

socket.io.js:

webRtc.html: webRtc.html

Two mobile phones open hotspots, under Firefox browser, to achieve functions

Demo download link: