"Content decoding has failed" error when download files using GZIP compression - http

Question

My web app generates a CSV file on the fly, but whenever I use GZIP compression, the download fails:
HTTP/1.1 200 OK
Cache-Control: private, s-maxage=0,no-store, no-cache
Transfer-Encoding: chunked
Content-Type: text/csv;charset=utf-8
Content-Encoding: gzip
Vary: Accept-Encoding
Server: Microsoft-IIS/7.5
X-AspNetMvc-Version: 3.0
Content-Disposition: attachment;filename="filename.csv"
X-AspNet-Version: 4.0.30319
X-Powered-By: ASP.NET
p3p: CP="CAO PSA OUR"
Date: Fri, 03 Feb 2012 11:27:27 GMT
The download appears as "Interrupted" in Google Chrome, and in Internet Explorer appears an error that says "Content decoding has failed" .
HTTP/1.1 200 OK
Cache-Control: private, s-maxage=0,no-store, no-cache
Transfer-Encoding: chunked
Content-Type: text/csv;charset=utf-8
Server: Microsoft-IIS/7.5
X-AspNetMvc-Version: 3.0
Content-Disposition: attachment;filename="filename.csv"
X-AspNet-Version: 4.0.30319
X-Powered-By: ASP.NET
p3p: CP="CAO PSA OUR"
Date: Fri, 03 Feb 2012 11:23:30 GMT
The solution is disabling compression on that action, but... why does this happen?
Cheers.
UPDATE: The compression filter that I use:
public class EnableCompressionAttribute : ActionFilterAttribute
{
const CompressionMode compress = CompressionMode.Compress;
public override void OnActionExecuting(ActionExecutingContext filterContext)
{
if (filterContext.IsChildAction)
return;
var actionAttributes = filterContext.ActionDescriptor.GetCustomAttributes(true);
if (actionAttributes != null && actionAttributes.Any(attr => attr is SkipCompressionAttribute))
return;
HttpRequestBase request = filterContext.HttpContext.Request;
HttpResponseBase response = filterContext.HttpContext.Response;
String acceptEncoding = request.Headers["Accept-Encoding"];
if (acceptEncoding == null || response.Filter == null)
return;
if (acceptEncoding.ToLower().Contains("gzip"))
{
response.Filter = new GZipStream(response.Filter, compress);
response.AppendHeader("Content-Encoding", "gzip");
response.AppendHeader("Vary", "Accept-Encoding");
}
else if (acceptEncoding.ToLower().Contains("deflate"))
{
response.Filter = new DeflateStream(response.Filter, compress);
response.AppendHeader("Content-Encoding", "deflate");
response.AppendHeader("Vary", "Accept-Encoding");
}
}
}

Answer 1

Try:
Response.Headers.Remove("Content-Encoding");
Response.AppendHeader("Content-Encoding", "gzip");
Another problem may be the caching: what if a client accepts compressed content, but the next client doesn't, and the server cached the compressed data? what the second client will get? A cached compressed page that won't decode!
To fix that, add another method:
public override string GetVaryByCustomString(HttpContext context, string custom)
{
if (custom == "GZIP")
{
string acceptEncoding = HttpContext.Current.Response.Headers["Content-Encoding"];
if (string.IsNullOrEmpty(acceptEncoding))
return "";
else if (acceptEncoding.Contains("gzip"))
return "GZIP";
else if (acceptEncoding.Contains("deflate"))
return "DEFLATE";
return "";
}
return base.GetVaryByCustomString(context, custom);
}