Utility classes for correctly parsing
Accept-Encodings
Utility classes for RFC 2616
compliant parsing of the Accept-Encoding, Accept-Charset and Accept-Language header.
Dave Transom's blog post on What's wrong with Request.Headers["Accept-Encoding"].Contains("gzip")?
goes into detail on why parsing Accept-Encoding with String#contains
is a malpractice that has some downsides you should be aware of.
His article also contains some nice utility classes that does what thousand of sites do wrong, which is what I have put up here, along with some bug fixes.
/// load encodings from header
QValueList encodings = new QValueList(Request.Headers["Accept-Encoding"]);
/// get the types we can handle, can be accepted and
/// in the defined client preference
QValue preferred = encodings.FindPreferred("gzip", "deflate", "identity");
/// if none of the preferred values were found, but the
/// client can accept wildcard encodings, we'll default
/// to Gzip.
if (preferred.IsEmpty && encodings.AcceptWildcard && encodings.Find("gzip").IsEmpty)
preferred = new QValue("gzip");
// handle the preferred encoding
switch (preferred.Name)
{
case "gzip":
Response.AppendHeader("Content-Encoding", "gzip");
Response.Filter = new GZipStream(Response.Filter, CompressionMode.Compress);
break;
case "deflate":
Response.AppendHeader("Content-Encoding", "deflate");
Response.Filter = new DeflateStream(Response.Filter, CompressionMode.Compress);
break;
case "identity":
default:
break;
}