Re: IPv6 address parsing

On Thu, Dec 7, 2017 at 1:21 PM, Michael Powell <[email protected]> wrote:
> Again, I am moving beyond IPv4 into IPv6. Do I need to re-post that
> grammar attempt? Maybe I do at this point.
>
> _dot = ".";
> _col = char_(':');
> _col_x2 = _col >> _col;
>
> // _dec_octet = uint_parser<std::uint8_t, 10, 1, 3>();
>
> qi::rule<Iterator> _dec_octet = ... ; // Approach TBD; probably
> running with the IPv4 proposal discussed in earlier thread(s).
>
> qi::rule<Iterator> _ipv4_addr = _dec_octet >> repeat(3)[_dot >> _dec_octet];
> // or, qi::rule<Iterator> _ipv4_addr = raw[_dec_octet >> _dot >>
> _dec_octet >> _dot >> _dec_octet >> _dot >> _dec_octet];
>
> qi::rule<Iterator> _h16 = raw[repeat(1, 4)[hex]];
> // Or (?): _h16 = hex >> -(hex >> -(hex >> -hex));
> qi::rule<Iterator> _h16_col = _h16 >> _col;
> qi::rule<Iterator> _ls32 = _h16_col >> _h16 | _ipv4_addr;
>
> qi::rule<Iterator, std::string()> _ipv6_addr
>     = repeat(6)[_h16_col] >> _ls32
>     | _col_x2 >> repeat(5)[_h16_col] >> _ls32
>     | -(_h16) >> _col_x2 >> repeat(4)[_h16_col] >> _ls32
>     | -(_h16_col >> _h16) >> _col_x2 >> repeat(3)[_h16_col] >> _ls32
>     | -(repeat(1, 2)[_h16_col] >> _h16) >> _col_x2 >>
> repeat(2)[_h16_col] >> _ls32
>     | -(repeat(1, 3)[_h16_col] >> _h16) >> _col_x2 >> _h16_col >> _ls32
>     | -(repeat(1, 4)[_h16_col] >> _h16) >> _col_x2 >> _ls32
>     | -(repeat(1, 5)[_h16_col] >> _h16) >> _col_x2 >> _h16
>     | -(repeat(1, 6)[_h16_col] >> _h16) >> _col_x2
>     ;

I am testing the grammar now, and it seems like to me that the
optional and/or repeat are not working correctly.

For test case: prefix = pf_max_4|pf_count_1, suffix = pf_none,
appendix = bo_hex_2, which yields address: "6a80:9024::c7e3:4150".

Should be matching the alternative, from the RFC grammar:
  / [*4(h16 ":") h16] "::"            ls32

Or from the Qi grammar:
     | -(repeat(1, 4)[_h16_col] >> _h16) >> _col_x2 >> _ls32

But gets rejected. Did not parse, or rejected the entire string.

Perhaps repeat does not work quite as advertised?

Thoughts? Suggestions?

Thank you!

> qi::rule<Iterator> _start = _ipv6_addr >> eoi;
>
> Q: Notwithstanding concern over raw IPv4, does the overall Qi-based
> IPv6 grammar look reasonable? If not, why not?
>
> I'd like to land in a Fusion data structure something like (string >>
> uint16_t >> eoi), but if I can land here, that's acceptable, too:
> (string >> -(uint8_t >> uint8_t >>
> uint8_t >> uint8_t) >> uint16_t >> eoi).
>
> From what I can determine, then, raw[...] is the difference between
> parsed types like uint8_t and string?
>
> ref: http://www.ietf.org/rfc/rfc5954.txt, section 4.1 Resolution for
> Extra Colon in IPv4-Mapped IPv6 Address
>
> Constructive feedback appreciated.
>
> Untested ATM, to be fair.
>
> On Thu, Dec 7, 2017 at 1:09 PM, Seth <[email protected]> wrote:
>> On 07-12-17 18:21, Michael Powell wrote:
>>> Well, you remembered incorrectly.
>>
>> I was asking.
>>
>>> If there's a doable intermediate step of parsed individual octets, so
>>> be it; no problem.
>>
>> Please per-use all the parts of my answer.
>>
>> On 07-12-17 17:13, Seth wrote:
>>> Maybe you'll be more convinced when it's demonstrated (I think I did
>>> this before):
>>>
>>> https://wandbox.org/permlink/M12U5PEYcB8vnxIs
>>>
>>> It's really just ~3 lines of code changed:
>>>
>>>     using ipv4_address = std::string; // much less useful representation
>>>     // ....
>>>     addr_  = raw[ octet_ >> '.' >> octet_ >> '.' >> octet_ >> '.' >>
>>> octet_ ];
>>>
>>> Note now that test fails:
>>
>> It's all there.
>>

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