Re: [netmod] 6991bis: host

Ladislav Lhotka <lhotka@nic.cz> Mon, 22 July 2019 21:05 UTC

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From: Ladislav Lhotka <lhotka@nic.cz>
To: Juergen Schoenwaelder <j.schoenwaelder@jacobs-university.de>
Cc: NETMOD WG <netmod@ietf.org>
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Date: Mon, 22 Jul 2019 17:05:44 -0400
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Subject: Re: [netmod] 6991bis: host
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Juergen Schoenwaelder <j.schoenwaelder@jacobs-university.de> 
writes:

> Lada, 
> 
> the definition of inet:domain-name already has text that 
> Internet host names have a stricter syntax. Perhaps we should 
> simply state explicitely in the definition of host that the 
> stricter rules apply? 
> 
> I understand that you want to capture more in the definition 
> itself.  Perhaps this makes sense and is backwards compatible 
> (for implementations that followed the advice in the descriptin 
> of inet:domain-name).

Yes. In this case the constraint is easy to express it in a 
"pattern" statement, which is of course considerably more useful 
than having it only in the description.

Lada 
> 
> /js 
> 
> On Fri, Mar 29, 2019 at 03:29:05PM +0100, Ladislav Lhotka wrote: 
>> Hi,  the inet:host type should not use the inet:domain-name as 
>> its member because the latter type doesn't satisfy the 
>> requirements of RFC 952 and 1123 on host names.  For example, 
>> the type now permits a single dot (".") as the value or the 
>> underscore character.   I propose to change the "host" type as 
>> follows:  OLD  
>>     typedef host { 
>>       type union { 
>>         type inet:ip-address; type inet:domain-name; 
>>       } ... 
>>     } 
>>  NEW  
>>     typedef host { 
>>       type union { 
>>         type inet:ip-address; type inet:host-name; 
>>       } ... 
>>     } 
>>  A reasonable definition of "host-name" is IMO a domain name 
>> whose labels are NR- LDH (non-registered letter-digit-hyphen 
>> label) [RFC 5890]:  
>>     typedef host-name { 
>>       type string { 
>>         pattern 
>>           '((([a-zA-Z0-9]([a-zA-Z0-9\-]){0,61})?[a-zA-Z0-9]\.)*' 
>>         + '([a-zA-Z0-9]([a-zA-Z0-9\-]){0,61})?[a-zA-Z0-9]\.?)'; 
>>         pattern '(.*\.)?..\-\-.*' { 
>>           modifier invert-match; 
>>         } length "2..253"; ... 
>>       } 
>>     } 
>>  Lada  --  Ladislav Lhotka Head, CZ.NIC Labs PGP Key ID: 
>> 0xB8F92B08A9F76C67 
>> _______________________________________________ netmod mailing 
>> list netmod@ietf.org 
>> https://www.ietf.org/mailman/listinfo/netmod 
> 
> --  Juergen Schoenwaelder           Jacobs University Bremen 
> gGmbH Phone: +49 421 200 3587         Campus Ring 1 | 28759 
> Bremen | Germany Fax:   +49 421 200 3103 
> <https://www.jacobs-university.de/> 

-- 
Ladislav Lhotka
Head, CZ.NIC Labs
PGP Key ID: 0xB8F92B08A9F76C67