[ntp:questions] ntp client ipv6 support

Danny Mayer mayer at ntp.org
Sat Jun 18 03:00:55 UTC 2011


On 6/17/2011 7:44 PM, Rick Jones wrote:
> John Hasler <jhasler at newsguy.com> wrote:
>> Rick Jones wrote:
>>> Netperf has been passing IPs to getaddrinfo() without setting any
>>> special flags.
> 
>> Chuck Swiger writes:
>>> Maybe there are broken implementations of getaddrinfo() floating
>>> around?
> 
>> On Linux you must set a flag to tell it not to consider the possibility
>> that what you are passing it is not a numeric address:
> 
>>        node specifies either a numerical network address (for IPv4,
>>        numbers-and-dots notation as supported by inet_aton(3); for IPv6,
>>        hexadecimal string format as supported by inet_pton(3)), or a
>>        network hostname, whose network addresses are looked up and
>>        resolved.  If hints.ai_flags contains the AI_NUMERICHOST flag
>>        then node must be a numerical network address.  The
>>        AI_NUMERICHOST flag suppresses any potentially lengthy network
>>        host address lookups.
> 
>>        CONFORMING TO
>>        POSIX.1-2001.  The getaddrinfo() function is documented in RFC 2553.
> 
> I may be parsing your sentence incorrectly, but my reading of the
> manpage is that one may set AI_NUMERICHOST, in which case node must be
> an IP address, but that is not the same thing as saying that if node
> is an IP address that AI_NUMERICHOST must be set.

I think you are misreading it. As I recall, if you don't provide it with
hints, it defaults and does a lookup on the string provided. You have to
set the AI_NUMERICHOST to prevent that.

Can you look at HP's source code for getaddrinfo() on various platforms
and see what it does? I did look at this in considerable detail at the
time that I was working on this one. I don't however remember a lot of
the details.

Danny




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