How to know if a user is logged in from another service - authentication

Question

I have a php/apache service and meteor on the same server. I am using the accounts-ui package.
Is there anyway to know in my php script, that a user is logged in, given the login token (session id?)
This is my original need: upload a profile picture for a logged in user.
Very simple right? But I have not found an answer after hours of googling.
First solution would be using html5 File apis to send data to meteor server and the server save the image. But this solution wont even work for IE9.
Second solution is what I am trying: Using a html form to upload picture to a php script (or whatever script, it can be a nodejs script if needed). This script will save the image like a traditional php script does. The thing is I cannot know if the upload request is authorized, otherwise everybody can change profile picture of anybody. I must add some information in the upload request and verify them in the php code before saving the image. I am thinking about sending a request from php script to meteor server but I need to know which parameters to send and how meteor responses it.
How can I achieve the second solution or if someone has a another solution for my origin problem that would be great.
Thank you.

Answer 1

Meteor uses an a protocol called DDP to communicate between the client and server. But as of now there isn't a PHP ddp client so you would have to use a REST type communication method between your meteor server and your PHP server.
If you feel you could build a PHP client for your meteor client, it would greatly help you as you could do stuff like run Meteor.call from your php scripts and have them subscribe to collections. The full DDP spec (pre1) can be found at : https://github.com/meteor/meteor/blob/master/packages/livedata/DDP.md
To do a REST method you should use Meteor Router to allow you to create server side routes. It is installed via meteorite which helps you access a list of community packages at [atmosphere.meteor.com].1
sever side js
Meteor.Router.add('/checklogin', 'post', function() {
var userId = this.params.userId;
var loginToken = this.params.loginToken;
if(userId && loginToken) {
return (!!Meteor.findOne({_id:userId,"services.resume.loginTokens.token":loginToken}));
}
});
You can then do a POST request with PHP to /checklogin with two params, one is userId which is the userId (found with Meteor.userId() or localStorage.getItem("Meteor.userId"). The other is the login token found via localStorage.getItem("Meteor.loginToken") on your Meteor client.