- From: John Franks <john@math.nwu.edu>
- Date: Tue, 9 Dec 1997 22:24:59 -0600 (CST)
- To: Dave Kristol <dmk@bell-labs.com>
- Cc: Paul Leach <paulle@microsoft.com>, Jim Gettys <jg@pa.dec.com>, Eric_Houston/CAM/Lotus@lotus.com, Scott Lawrence <lawrence@agranat.com>, fielding@kiwi.ics.uci.edu, http-wg%cuckoo.hpl.hp.com@hplb.hpl.hp.com
On Tue, 9 Dec 1997, Dave Kristol wrote: > > I like Benjamin Franz's suggestion of a fixed date that means "this is > not a date" as a placeholder. Yes, this makes sense. > Content-length is another matter. If the client sends the entity with > chunked encoding, it probably does not know the content length, although > it may calculate an entity-digest on the fly (and add it as a > trailer?). But the proxy may coalesce the entity and add a > Content-length header. Now what? The entity-digest as calculated by > the two parties will be different because of the Content-length. > I believe that entity headers like Content-MD5, Content-Length, etc. refer to the entity after any Content-encoding has been applied, but before any hop-by-hop Transfer-encoding has been applied. The specification is pretty explicit about this: "Entity-header fields define optional metainformation about the entity-body..." "The entity-body is obtained from the message-body by decoding any Transfer-Encoding that may have been applied to ensure safe and proper transfer of the message." This is important as it would be impossible to put Content-MD5 in a chunked trailer, if the MD5 hash was calculated on the chunked entity. Likewise Authentication-Info is explicitly allowed in a chunked trailer and it depends on the Content-Length. In any case, it seems the Content-length of an entity is the length before any chunking. Thus if a proxy removes chunking and adds a Contact-Length header that should not introduce any errors in entity-digest calculation. Am I missing something? John Franks john@math.nwu.edu
Received on Tuesday, 9 December 1997 20:12:49 UTC