title: Firebase data validation
body: <p>I'm considering to use Firebase for a project but can't seem to find any informations on server-side data validation.</p>
  
  <p>Lets say i'm making a game and a player deals damage to another player i would like to validate the following: </p>
  
  <ul>
  <li>That the players are actually close to eachother</li>
  <li>That the damage points corresponds to the attack given</li>
  <li>That the data has not been
  tampered from the client to the server</li>
  <li>ETC.</li>
  </ul>
  
  <p>Is it possible to validate this kind of stuff /Adding serverside logic directly with Firebase or do i have to make an intermediate-server, basically smashing the whole point in using Firebase in the first place?</p>
  
  <p>Thanks in advance
  Jonas</p>