HTTP Transfer-Encoding and requests

Question

Hi,

the HTTP specification states that the Transfer-Encoding header is allowed for requests - but what error code should a server respond if it doesn't understand that given Transfer-Encoding.

As far as I know the HTTP standard doesn't cover this possibility, but maybe I have just overlooked it.

Answer 1

The RFC is a bit unclear, but IMHO it should be 406 Not Acceptable.

Answer 2

A request with an invalid Transfer-Encoding for the HTTP version is malformed. Therefore, the server should respond with 400 Bad Request.

Answer 3

An unknown transfer-encoding should raise a HTTP error 501 "NOT IMPLEMENTED". That's what Apache does, at least.

Also see http://argray.com/unixfaq/httpd_error_codes.shtml

Edit: pointer to the corresponding RFC section: http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html#sec10.5.2

Answer 4

I agree that the answer to this is non-obvious, and have followed up on the HTTP WG's mailing list.

UPDATE: Björn H. rightfully points out:

Section 3.6 of RFC 2616:

A server which receives an entity-body with a transfer-coding it does not understand SHOULD return 501 (Unimplemented), and close the
connection.

So it does address this already.