[Freeipa-devel] [PATCH 0070] Normalization check only for IDNA domains

[Petr Spacek]

On 27.6.2014 11:21, Jan Cholasta wrote:
> On 27.6.2014 10:58, Alexander Bokovoy wrote:
>> On Fri, 27 Jun 2014, Jan Cholasta wrote:
>>> On 27.6.2014 10:29, Alexander Bokovoy wrote:
>>>> On Fri, 27 Jun 2014, Jan Cholasta wrote:
>>>>> On 27.6.2014 10:15, Alexander Bokovoy wrote:
>>>>>> On Fri, 20 Jun 2014, Martin Basti wrote:
>>>>>>> On Fri, 2014-06-20 at 10:32 +0200, Jan Cholasta wrote:
>>>>>>>> On 18.6.2014 16:49, Martin Basti wrote:
>>>>>>>>> Due to compability with older versions, only IDNA domains should be
>>>>>>>>> checked
>>>>>>>>> Patch attached.
>>>>>>>>
>>>>>>>> I'm not particularly happy about the u'\xdf' special case. Isn't
>>>>>>>> there a
>>>>>>>> better way to do this check?
>>>>>>> I cant find better way. u'\xdf' is mapped to ss, and ss is not IDN
>>>>>>> string.
>>>>>>>
>>>>>>> Or just remove this validation.
>>>>>>>
>>>>>>>> (BTW I really think this should be a warning, not an error, but that
>>>>>>>> would require larger amount of work, so I guess it's OK for now.)
>>>>>>> (More pain than gain)
>>>>>> Main thing in this patch is that the check should not be done against
>>>>>> non-IDN strings. I want this version of the patch to go in for that
>>>>>> reason as currently you cannot even complete ipa-adtrust-install
>>>>>> run due
>>>>>> to IDN normalisation check being applied to non-IDN domains.
>>>>>
>>>>> On non-IDN domains, the only effect of IDN normalization is that it
>>>>> lower-cases the names (right?), so the check should compare
>>>>> lower-cased original name with the normalized name, instead of
>>>>> special-casing certain characters etc.
>>>> .. what's the reason to do such comparison then? lower-cased non-IDN
>>>> name will be equal to lower-cased normalized non-IDN name by definition,
>>>> so the check is not needed in this case, at all.
>>>
>>> The point is that it works for both IDN and non-IDN, without
>>> u'\xdf'-style hacks.
>> No, your proposal of comparing low-cased value and normalized value is
>> not going to work because low-cased value is in general not equal to
>> normalized value for IDN names, only for non-IDN ones, due to the fact
>> that lower case for non-ASCII Unicode character may map to a completely
>> different character than in normalization situation. Take, for example,
>> Turkish alphabet where there are six letters with different case rules
>> (uppercase dotted i, dottless lowercase i, upper- and lowercase G with
>> breve accent, and upper- and lowercase S with cedilla), which will break
>> your generalized check.
>> So you'll anyway will need to split these cases.
>>
>
> I see.
>
> I'm still not comfortable with carrying the bit of knowledge about u'\xdf' in
> this particular spot. Can we check that a name is IDN some other way than
> "domain_name.is_idn() or u'\xdf' in value"?

Why can't we simply fix string constants in ipa-adtrust-install and avoid 
adding hacks for it?

-- 
Petr^2 Spacek