title: CORS request immediately canceled chrome
body: <p>I'm trying to send a file to rackspace via AJAX. This is my first time looking at CORS. I see in the documentation the option to send a preflight request, however since I personally set the header and know that my origin is valid I'm trying to forgo, these are the headers from my upload endpoint:</p>
  
  <pre><code>HTTP/1.1 204 No Content
  Content-Length: 0
  X-Container-Object-Count: 2
  Accept-Ranges: bytes
  X-Container-Meta-Access-Log-Delivery: false
  X-Container-Meta-Access-Control-Expose-Headers: etag location x-timestamp x-trans-id
  X-Timestamp: 1401852621.29287
  X-Container-Meta-Access-Control-Allow-Origin: h ttp://localhost:8080**&lt;-- (manually added the space after "h" so stackoverflow would let me submit) 
  X-Container-Bytes-Used: 5572910
  Content-Type: text/plain; charset=utf-8
  X-Trans-Id: txfc64055cb1114b6fb0ef6-0053a77a46ord1
  Date: Mon, 23 Jun 2014 00:52:22 GMT
  </code></pre>
  
  <p>However, whenever I try to send the request it immediate fails in chrome with the following message:</p>
  
  <pre><code>XMLHttpRequest cannot load [**I'm redacting my actual endpoint**]. No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'h ttp://localhost:8080' is therefore not allowed access. 
  </code></pre>
  
  <p>Here are my request headers:</p>
  
  <pre><code>Content-Type:multipart/form-data; boundary=----WebKitFormBoundaryZSg4nEq8EDaXQQBu
  Origin:h ttp://localhost:8080
  Referer:h ttp://localhost:8080/tools/artwork
  &lt;-- (manually added the space after "h" so stackoverflow would let me submit) 
  User-Agent:Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/33.0.1750.152 Safari/537.36
  </code></pre>
  
  <p>What am I missing? Is preflight request required even if you know origin is permitted? I never see a packet come back to seems like Chrome isn't sending?</p>