Fixes #23031 - parse server duid's with nested double quotes

[dmitri-d]

No description provided.

[lzap]

It looks like ISC configuration parser treats all strings like that, isn't cleaner to use this in LITERAL constant?

https://github.com/42wim/isc-dhcp/blob/f54a146c7fe88889d60f0c1aa8e6f04707f95223/common/conflex.c#L512

[lzap]

If it won't break our tests, I think we should go with:

LITERAL = /"([^"]|\")*"/.r

Single quotes do not appear to be supported by the parser, if I am looking into the correct place in the codebase. https://lists.isc.org/pipermail/dhcp-users/2011-February/013135.html

[dmitri-d]

I think the ultimate goal should be parsing strings the same way as dhcpd's parser does. Unfortunately, I don't think it is doable using a non-monstrous regex (if at all). The reason I didn't reuse the regex the way you are suggesting is that it will also match comma-separated strings as one string, which breaks the parser.

DUID is an outlier, as majority of the strings are host or option names and values, I think we are pretty safe with the fix in the PR. I'll add extending rsec parser with a custom string parser as a feature to smart-proxy's backlog.

[lzap]

Ok that's good. Thanks.

[mark-wagner]

I think a similar change will be needed for the uid within a lease.

[lzap]

I also think doing this for all strings won't hurt, the ISC parser does seem to work that way.

[alvinstarr]

I believe that literal should be literal = /"([^"]|\\")*"/.r
The patch you suggested is in the version of 1.17 that I have installed but I was still getting duid errors until I added the second .
I am really unfamiliar with ruby so I may well be wrong.

[mark-wagner]

@alvinstarr that regexp doesn't work for. Here is the uid that was tripping me up:

uid "\001X\357h}g\""

http://rubular.com/r/gqxRXXs1YZ

The regexp in https://stackoverflow.com/questions/249791/regex-for-quoted-string-with-escaping-quotes seems to work but may have other problems.

http://rubular.com/r/vRvdrzFYxe

[dmitri-d]

Please see my comment above. Feel free to experiment, but please run tests before proposing a fix. Please also note complicated regular expressions will be rejected.

[alvinstarr]

This may be better
"([^\\"]|\\.)*"
I believe the string consists of:
char - a single character
### - 3 digits 0-7 for octal characters
\char - an escaped character
This of course only works for ASCII characters if my memories of C strings is correct.

[dmitri-d]

I am locking this conversation. If you are seeing this issue, please update the redmine ticket referenced in this PR, or create a new one.

[lzap]

I am not sure if locking was necessary here, "this might be better" is appropriate comment although I do agree some of them can be useless when not properly tried and tested. However, I think leaving those comments "as-is" is probably preferred than locking discussion.