Motivation

This is a test project to illustrate the issue with Play 2.6 with request headers when certain Content-Encoding is used in the request.

Issue summary

Most of request headers are dropped when Content-Encoding header with values gzip or deflate is sent with the request.

Details

With a default Play 2.6.6 setup, most of the request headers are not available in the actual play.api.mvc.RequestHeader.headers instance inside the controller when the compressed Content-Encoding header is sent. Here's an example:

When the controller looks like this:

@Singleton
class HomeController @Inject()(cc: ControllerComponents) extends AbstractController(cc) {
  def testGzip() = Action { implicit request: Request[AnyContent] =>
    Ok(request.headers.toString)
  }
}

And the following curl command is executed against a Play instance running at http://localhost:9000:

curl -X POST http://localhost:9000 \
-H 'Content-Encoding: gzip' \
-H 'Authorization: Bearer 123' \
-H 'X-Custom-Header: 123' -vvv
* Rebuilt URL to: http://localhost:9000/
*   Trying ::1...
* TCP_NODELAY set
* Connected to localhost (::1) port 9000 (#0)
> POST / HTTP/1.1
> Host: localhost:9000
> User-Agent: curl/7.54.0
> Accept: */*
> Authorization: Bearer 123
> Content-Encoding: gzip
> X-Custom-Header: 123
>
< HTTP/1.1 200 OK
< Referrer-Policy: origin-when-cross-origin, strict-origin-when-cross-origin
< X-Frame-Options: DENY
< X-XSS-Protection: 1; mode=block
< X-Content-Type-Options: nosniff
< Content-Security-Policy: default-src 'self'
< X-Permitted-Cross-Domain-Policies: master-only
< Date: Tue, 10 Oct 2017 12:02:09 GMT
< Content-Type: text/plain; charset=UTF-8
< Content-Length: 84
<
* Connection #0 to host localhost left intact
List((Transfer-Encoding,chunked), (Content-Type,none/none), (Content-Encoding,gzip))

Then you can see that headers Authorization and X-Custom-Header are missing from the request object.

To be clear, when the Content-Encoding: gzip is specified, no matter if the body of the request actually include something gzipped, the situation with headers remain the same. It also doesn't matter if the Content-Type is correctly specified or not. Also to be clear, Play can decompress the gzipped content when this Content-Encoding is specified, so that part is fine. The problem is that headers are missing.

P.S. also worth noting that Transfer-Encoding: chunked is somehow inferred by Play, even though it is not sent by the client.