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Re: chunking and trailers

From: Jeffrey Mogul <mogul@pa.dec.com>
Date: Tue, 21 Jul 98 13:42:06 MDT
Message-Id: <9807212042.AA18983@acetes.pa.dec.com>
To: Richard Gray <rlgray@us.ibm.com>
Cc: http-wg@cuckoo.hpl.hp.com
Richard L. Gray wrote:
    Since the spec does not appear to anywhere specify that clients
    MUST honour header fields found in chunked trailers, nor that
    proxies MUST NOT remove and discard header fields found in chunked
    trailers, I think that it would be a bad idea for a server to
    place, in a chunked trailer, a header field that it did not want to
    risk loss of.
    
Your premise is wrong.  Section 13.5.1 (End-to-end and Hop-by-hop
Headers) defines:

       End-to-end headers, which must be transmitted to the ultimate
       recipient of a request or response.

(that "must" should be a MUST; see issue-list MMS_AUDIT_ITEM_110).
and says:

	All other headers defined by HTTP/1.1 are end-to-end headers.

after a short list of specifically hop-by-hop headers.  Thus, proxies
MUST forward all but a specific and small set of headers.

There is no exception here for header fields carried in the
trailer of a chunked encoding; this encoding is hop-by-hop
and so one clearly can't use it as an excuse to delete a header
that would otherwise have to be sent end-to-end.

-Jeff
Received on Thursday, 23 July 1998 03:38:33 EDT

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