socket rooms doesn't work

I'm trying to create a private tchat room using the concept of socket.io rooms. When the user clicks on a name of another user, a comparaison will start,if there is a room which contains both users, then it will join the room, otherwise a new room with both users will be created. When a message arrives, the message is sent to the corrsponding room, but my code doesn't work: the comparaison is done, the corresponding ids are found, but the messages are send for everyone connected to the tchat.

Here is the code of the server

var express = require('express');
var app = express();
var server = require('http').createServer(app);
var io = require('socket.io').listen(server);

var port = process.env.PORT || 8080;

var cookieParser = require('cookie-parser');
var session = require('express-session');
var morgan = require('morgan');
var mongoose = require('mongoose');
var bodyParser = require('body-parser');
var passport = require('passport');
var flash = require('connect-flash');

//session-store
//pour eviter dactualiser le login apres que le serveur soit 'tombe'

var MongoStore = require('connect-mongo')(session);

var configDB = require('./config/database.js');
mongoose.connect(configDB.url);
require('./config/passport')(passport);


var Room = require('./app/models/room');
var User = require('./app/models/user');

//session
var sessionMiddleware = session({secret: 'anystringoftext',
                                 saveUninitialized: true,
                                 resave: true,
         store: new MongoStore({mongooseConnection: mongoose.connection}),
                        //session expire, par defaut c 15js
                                 ttl: 2 * 24 * 60 * 60
                         });
//fonction btoa
var btoa = require('btoa');
var atob = require('atob');

//session with socket.io
        io .use(function(socket, next){
                         sessionMiddleware(socket.request, {}, next);
        });

        io.on('connection', function(socket) {

     socket.on('startchat', function(name){

                            //my id
           var idUser = socket.request.session.passport.user;
           //search for my name
           User.findById(idUser, function(err, user){
               if(err) throw err;
               if(user){
                                                                  //my name
                 nameUser = user.local.username;


                                                                 if(name < nameUser){
                                                                         var users = name +','+ nameUser;
                                                                         }
                                                                         else{
                                                                                  var users = nameUser +','+ name;
                                                                         }
                 //encrypt the string
                                                                 var roomid = btoa(users);

                                                                 //searching fo ra corresponding id
                  Room.find(function(err, room){
                    if(err) throw err;
                    if(room){
                        var dRoom = '';
                      room.forEach(function(room){ /


                        var idRoom = atob(room.id).split(',');
                                                                                        //comparaison

                        if((idRoom[0] == nameUser && idRoom[1] == name)||(idRoom[0] == name && idRoom[1] == nameUser)){
                          dRoom = room.id;
                          console.log(idRoom, room.id);
                                                                                                        //join the room
                                                                                                        socket.join(dRoom);
                        }
                      });

                    if(dRoom == ''){
                                                                                                //we didn't find an id which corresponds so we create a room with this id
                                                                                                 dRoom = roomid;
                        var newroom = new Room({id:roomid});
                        newroom.save();
                        console.log('created');
                                                                                                console.log(atob(roomid).split(','));
                                                                                                console.log(roomid);
                                                                                                //join the room
                                                                                                socket.join(roomid);
                      }

                    }

                                                                 //when msg is emitted
                                                                                socket.on('message', function(msg){
                                                                                        console.log('message', dRoom);
                                                                                        //emit the msgs to this room
                                                                                  io.sockets.in(dRoom).emit('msg', msg);
                                                                                });
                  });

               }

             });


     });





        });

app.use(express.static('public'));

app.use(morgan('dev'));
app.use(cookieParser());
app.use(bodyParser.urlencoded({extended: false}));
app.use(sessionMiddleware);
//passport and sessions

app.use(passport.initialize());
app.use(passport.session()); // persistent login sessions
app.use(flash()); // use connect-flash for flash messages stored in session


app.set('view engine', 'ejs');

require('./app/routes.js')(app, passport);

server.listen(port, function(){
        console.log('Server running on port: ' + port);
});

the client.js

$(document).ready(function(){
  var socket = io();

  socket.on('connect', function() {
   // Connected, let's sign-up for to receive messages for this room
   $('#chat').hide();

   var start;
   window.start = function (id,name){
     $('#chat').show();
     $('#chatHeader').html(name);
     socket.emit('startchat', name);
  }


  $('#send').submit(function(event){
    event.preventDefault(); //empeche la page de se recharger
    var msg = $('#message').val();
     if(msg !== ''){
      socket.emit('message', msg);
         }
   $('#message').val('');

   });
  });

  socket.on('msg', function(msg){
    $('.messages').append('<div>'+ msg + '</div>');
  });





 });

via Meli