[erlang-questions] : : Broken ipv6 behavior?

Fredrik Thulin <>
Thu Apr 10 08:45:14 CEST 2008


Raimo Niskanen wrote:
...
> In this particular case there has to be an investigation
> in if the test suites are wrong or the implementation,
> or the test site (DNS vs NIS).
> 
> Would it be acceptable that there are no hostent aliases
> on getaddrinfo hosts but there are on getipnodebyname
> hosts?

It sounds icky to have different results based on what the libc you are 
using supports, but NIS is as far as I'm concerned totally irrelevant 
(today) - the world runs on DNS! ;)

So to put it differently - I'd rather have working IPv6 hostname 
resolving, than support for struct hostent aliases at all.

> Or since there is alias information in DNS,
> should the inet_gethost_native code be able to
> find alias information also on getaddrinfo hosts?
> And how?

How do you mean? In DNS, aliases are CNAMEs, DNAMEs (not very widely 
used) or if you stretch the definition a bit - multiple A records 
pointing at the same IP address.

There is no way to ask DNS "what is all the aliases for host 
www.example.com?" or "what is all the names for IP 192.0.2.2?". The 
reason for this? There is no central place to ask, so you can't know if 
someone far far away has created an alias pointing at you.

To illustrate - you have a CNAME pointing www3.erlang.org at 
erlang.mirrors.su.se (which in turn happens to be an alias for 
afs-ftp1.it.su.se). There can be aliases to one of _my_ hosts in _any_ 
domain on the internet.

/Fredrik



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