[Freeipa-devel] [PATCH] ipv6 compatible way to check the hostname

[Rob Crittenden]

Simo Sorce wrote:
> Rob Crittenden wrote:
>> Simo Sorce wrote:
>>> This change checks the machine can resolve address using nsswitch 
>>> host name resolution, this means we are also checking that /etc/hosts 
>>> is not broken.
>>>
>>> It uses IPv6 aware system functions, so this should make it also IPv6 
>>> compatible.
>>>
>>> It does not force to have a DNS set up correctly, but that's 
>>> intentional as we might want to install DNS as part of the 
>>> installation (--setup-bind) and checking DNS before installing it 
>>> wouldn't really work :-)
>>>
>>> It still do try to check the DNS but currently it just exists 
>>> silently if DNS is not configured. I am not sure how to raise a 
>>> warning without throwing an exception that would make the install 
>>> script abort in this case.
>>>
>>> It does error out if DNS is setup incorrectly.
>>>
>>
>> +
>> +    rev = None
>> +    for rsn in rs:
>> +        if rsn.dns_type == dnsclient.DNS_T_A:
>> +            rev = rsn
>> +            break
>> +
>> +    if rev == None:
>> +        raise RuntimeError("Cannot find PTR record for %s" % addr)
>> +
>> +    reverse = rev.rdata.ptrdname
>>
>> Should you be looking for DNS_T_PTR here instead? If you have an A 
>> record you won't have a ptrdname.
>>
>> You need to add a try/except around socket.getaddrinfo() to catch 
>> errors if the hostname isn't found so a more useful error message can 
>> be returned than 'Name or service not known'
>>
>> gethostbyaddr may need a try/except around it too.
>>
>> rob
>>
> 
> 
> 
> Good points, new patch attached.

I have just a couple more comments (sorry, should have included these in 
the first patch):

- We should say why 127.0.0.1/::1 is an Invalid IP address. Or rather, 
just say that the hostname needs to resolve to a real address or something.
- When are you planning on filling in the #TODO raise a warning? What 
happens if the hostname is a CNAME, will it work? It kinda looks like it 
will still be accepted.

rob
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