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From Daniel Shahaf <>
Subject Re: 1.9.4 fix
Date Mon, 02 May 2016 12:05:05 GMT
Stefan Fuhrmann wrote on Mon, May 02, 2016 at 07:19:34 +0200:
> On 30.04.2016 02:47, Daniel Shahaf wrote:
> >Does any third-party tool make that optimization?
> Such a tool would probably ignore checksums altogether
> because there is no point in explicitly ignoring them
> for empty files only.

I thought a reader could, if a "Content-Length: 0" header was present,
hardcode the EXPECTED_MD5 value to d41d8cd98f00b204e9800998ecf8427e
instead of reading it from the Checksum-MD5 header.  It's not possible
to do this optimization for any non-zero Content-Length, and it still
provides the reader with assurance of transport integrity of the payload

What this optimization doesn't provide is assurance against certain bugs
in the dump producer, e.g., against a bug whereby the correct payload
and checksum, but incorrect Content-Length header, would be written,
*and* the payload would look like whatever the dumpstream parser
expects to follow an empty payload.

What's the worst-case failure mode of this optimization, then?
So far, I haven't come up with a failure mode that's both likely and
worse than a parse error on the next node.


(by "payload" I mean the byte string whose md5 and length are in the
dump node headers)

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