Code review request, 8020842 IDN do not throw IAE when hostname ends with a trailing dot

[Xuelei Fan]

On 8/9/2013 7:31 PM, Michael McMahon wrote:
> I don't see how this fixes the original problem as the SNIHostName spec
> still doesn't like hostnames with a trailing '.'
> 
The bug description did not reflect the IDN specification correctly.  If
"com." is a valid IDN, SNIHostName should accept it an an valid
hostname.  The host name in SNIHostName is nothing more or less than an
standard IDN.

I added a comment in the bug: "com." and "." are valid IDN according the
IDN and domain name specifications.  I will contact the bug reporter
about this point.

Xuelei

> I'd prefer to check first where that requirement is coming from, if it is
> actually necessary, and if not consider removing it from SNIHostName.
> If it is necessary, then the check should be implemented in SNIHostName.
> 
> Michael
> 
> On 09/08/13 05:28, Xuelei Fan wrote:
>> Thanks for your feedback and suggestions.
>>
>> Here is the new webrev:
>>     http://cr.openjdk.java.net/~xuelei/8020842/webrev.02/
>>
>> "." is regarded as valid IDN in this update.
>>
>> Thanks,
>> Xuelei
>>
>> On 8/9/2013 10:50 AM, Xuelei Fan wrote:
>>> On 8/9/2013 10:14 AM, Weijun Wang wrote:
>>>>
>>>> On 8/9/13 9:37 AM, Xuelei Fan wrote:
>>>>> On 8/9/2013 9:22 AM, Weijun Wang wrote:
>>>>>> I tried nslookup. Those with ".." inside are illegal,
>>>>>>
>>>>>> $ nslookup com..
>>>>>> nslookup: 'com..' is not a legal name (empty label)
>>>>>>
>>>>>> but
>>>>>>
>>>>>> $ nslookup .
>>>>>> Server:        192.168.10.1
>>>>>> Address:    192.168.10.1#53
>>>>>>
>>>>>> Non-authoritative answer:
>>>>>> *** Can't find .: No answer
>>>>>>
>>>>> Thanks for the testing.  The behaviors are the same as this fix now.
>>>> No exactly. It seems nslookup still regards "." legal but just cannot
>>>> find an IP for it.
>>>>
>>> I'm not sure whether a root domain name can be stand alone.  Root label
>>> is not considered as a label in IDN.  I think it is safe to regard that
>>> "." is not a valid IDN as it contains no label.  Anyway, it is a corner
>>> case.
>>>
>>> There are many online IDN conversion web services, some of them can
>>> convert ".", some of the cannot.  In the present implementation, we
>>> cannot recognize ".", and IDN.toASCII(".") throws
>>> StringIndexOutOfBoundsException.  With this fix, I was wondering IAE is
>>> a better exception for IDN.toASCII(".").
>>>
>>>>> Learn something new today to use nslookup.
>>>>>
>>>>>> Also, since this bug was originally about SNIHostName, do you need to
>>>>>> add some extra restriction there to reject "oracle.com." things?
>>>>>>
>>>>> No, we cannot restrict the format of IDN in SNIHostName more than in
>>>>> IDN. However, we may need to rethink about the comparing of two
>>>>> IDN, for
>>>>> example, "example.com." should equal to "example.com".  I want to
>>>>> consider it in another bug.
>>>> Not sure. Does the spec say IDN and SNIHostName are equivalent sets?
>>>> And
>>>> it's not one is another's subset?
>>>>
>>> Per TLS specification, host name in SNI is an IDN.  The spec of
>>> SNIHostname says, "hostname is not a valid Internationalized Domain Name
>>> (IDN) compliant with the RFC 3490 specification". The spec in
>>> SNIHostName has the same means as IDN.  I won't want to add additional
>>> restrict beyond the specification of an IDN.
>>>
>>> Xuelei
>>>
>>>>> Can I push the changeset?
>>>> I think it's better to ask someone in the networking team to make the
>>>> suggestion. From what I read Michael in this thread, he does not seem
>>>> totally agreed with your code changes (at least not the 00 version).
>>>>
>>>> Thanks
>>>> Max
>>>>
>>>>> Thanks,
>>>>> Xuelei
>>>>>
>>>>>> Thanks
>>>>>> Max
>>>>>>
>>>>>> On 8/9/13 8:41 AM, Xuelei Fan wrote:
>>>>>>> Ping.
>>>>>>>
>>>>>>> Thanks,
>>>>>>> Xuelei
>>>>>>>
>>>>>>> On 8/7/2013 11:17 PM, Xuelei Fan wrote:
>>>>>>>> Please review the new update:
>>>>>>>>
>>>>>>>> http://cr.openjdk.java.net./~xuelei/8020842/webrev.01/
>>>>>>>>
>>>>>>>> With this update, "com." is valid (return "com."); "." and
>>>>>>>> "example..com" are invalid.  And IAE will be thrown for invalid
>>>>>>>> IDN.
>>>>>>>>
>>>>>>>> Thanks,
>>>>>>>> Xuelei
>>>>>>>>
>