Hi,
On Fri, Feb 19, 2010 at 03:21:34PM +0100, JuanJo Ciarlante wrote:
> > JJO's patch does more than that, he does DNS lookups to print the
> > DNS name for the IPv6 address in question.
>
> Wrong.
> From getaddrinfo(3):
> """
> If hints.ai_flags contains the AI_NUMERICHOST flag then the node
> parameter must be a numerical network address.
> The AI_NUMERICHOST flag suppresses any potentially lengthy
> network host address lookups.
> """
Ah! Learned something new today. So what's the specific advantage of
using getnameinfo() instead of inet_ntop() instead?
(I've only ever used getnameinfo() if I really wanted to do DNS lookups).
> > Now we enter religious
> > territory - *I* think that this is not a good thing.
>
> I can't more eagerly _agree_ on tossing out any reverse
> DNS lookups at this level.
OK, good. Glad that this was just a misreading of the code.
> > The existing
> > code doesn't do reverse DNS lookups for IPv4 mroute printing, and so
> > the IPv6 code should behave similar to the IPv4 code, and not do DNS
> > either (also, depending on DNS lookup in this place might lead to
> > weird delays in unexpected situations). But this is partly religious,
> > partly "follow the coding style of the existing code" stuff.
>
> IMO we should void using inet_ntop() and friends, personally
> I don't like locking around their lack of multi-threading.
Mmmh, ok. I wasn't aware that inet_ntop() is not thread-safe. (Looking
at the FreeBSD implementation, at least that one *is* thread-safe - no
static buffers, etc.).
If it is not thread-safe, it won't break anything in my code, though
(lucky me :-) ) - my use of it in print_in6_addr() is mutex-locked anyway,
due to the use of a static buffer there.
Is getnameinfo() *guaranteed* to be thread-safe?
Do you have a reference that documents that inet_ntop() and inet_pton()
are unsave to be used in a threaded context?
gert
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