The Tor Browser / file revision

 const CC = Components.Constructor;

 const BinaryInputStream = CC("@mozilla.org/binaryinputstream;1",

                              "nsIBinaryInputStream",

                              "setInputStream");

 // Simply sending back the same data that is received

 function handleRequest(request, response)

 {

   var body = "";

   var bodyStream = new BinaryInputStream(request.bodyInputStream);

   var bytes = [], avail = 0;

   while ((avail = bodyStream.available()) > 0)

     body += String.fromCharCode.apply(String, bodyStream.readByteArray(avail));

   response.setHeader("Content-Type", "application/octet-stream", false);

   response.write(body);

 }