Re: [PATCH 3/7] pack-protocol.txt: Mark all LFs in push-cert as required

On Wed, Jul 1, 2015 at 1:00 PM, Junio C Hamano [off-list ref] wrote:

Dave Borowitz [off-list ref] writes:

quoted

Signed-off-by: Dave Borowitz <redacted>
---
 Documentation/technical/pack-protocol.txt | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Documentation/technical/pack-protocol.txt

b/Documentation/technical/pack-protocol.txt
index 1386840..2d8b1a1 100644

--- a/Documentation/technical/pack-protocol.txt
+++ b/Documentation/technical/pack-protocol.txt

@@ -534,6 +534,9 @@ A push certificate begins with a set of header

lines.  After the
 header and an empty line, the protocol commands follow, one per
 line.

+Note that (unlike other portions of the protocol), all LFs in the
+`push-cert` specification above MUST be present.
+
 Currently, the following header fields are defined:

 `pusher` ident::

I am moderately negative about this; wouldn't it make the end result
cleaner to fix the implementation?

I'm not sure I understand your suggestion. Are you saying, you would
prefer to make LFs optional in the push cert, for consistency with LFs
being optional elsewhere?

C git servers in the wild already require LFs when extracting the
nonce value from the certificate (see find_header). If we make the LFs
optional, then a conforming client may not send LFs, which will cause
nonce verification to fail when pushing to an unfixed server. That is
why I think we are stuck with this.

(Also, this is probably not insurmountable, but the cert processing
code in receive-pack.c would have to be substantially rewritten if we
loosened this requirement. Currently it concatenates the cert contents
without pkt-line framing into a buffer, and searches around for "\n"
and "\n\n".

If LF is optional, then with that approach you might end up with a
section of that buffer like:
  nonce 1234-abcd0000000000000000000000000000000000000000
deadbeefdeadbeefdeadbeefdeadbeefdeadbeef refs/heads/master
where it is impossible to distinguish between the end of the nonce and
the start of the first command.)