title: Why doesn't base64_decode return false on invalid input?
body: <pre><code>echo base64_decode("http://www.domain.com/en/messages/list?all=1");
  </code></pre>
  
  <p>this gives the result:</p>
  
  <pre><code>†Ыiяь0БЪ&amp;j)ЬўoЮџщћІЖ zПеЉЛZ–]
  </code></pre>
  
  <p>How to check if <code>string</code> is <code>base64_encoded</code> ?</p>
  
  <p>Shouldn't it return <code>false</code> if it's not valid base64 encoded string? </p>
  
  <p>I have some urls base64_encoded comming from emails and some simple urls.</p>