How to find out the recipient id when sending via socket.broadcast?

Question

Node.js

How to find out/get/specify the client id when sending him a message using the socket.broadcast method?
An example of code in which the server forwards an incoming message to other clients.

socket.on('set_data', function (data) {		// обработчик входящего сообщения
  socket.broadcast.emit('set_data', {
    from: socket.id,		// от этого клиента пришло сообщение
    to: ?,				// этому клиенту пересылаем сообщение
    data: data
  });
});

Thanks in advance.
UPD I will clarify that the message should be sent to everyone, and Everyone should send His own id on the server.

Answer 1

Well, as I understand it, this does not fit into the logic of socket.broadcast

Answer 2

broadcast means sending a message to ALL. If I need to send to a specific socket, I write this: io.sockets.socket("required socket.id here").json.send(data); I work with json for this. In your case, I think it will be like this: io.sockets.socket("required socket.id here").emit(...)
UPD: I just saw your UPD =) Why not send users their id when they first connect?