Re: getaddrinfo(3) on numerical addresses

[Edgar Fuß <ef%math.uni-bonn.de@localhost>]

> I suspect there's some misunderstanding.
Yes. It's about numerical IPv4 addresses being looked up with an AF_INET6 hint.

check_ping tries to figure out whether it needs to call ping6 (suppose 
wer'e on a system where ping6 is different from ping).
Suppose that check_ping is invoked without -4/-6 and with -H 1.2.3.4.
Now check_ping tries to figure out whether the -H argument is a/resolves to 
a IPv6 address. To do so, it checks whether getaddrinfo() on the -H argument 
(which is 1.2.3.4) with an AF_INET6 hint succeeds. But this triggers a DNS 
lookup.
Given this is a monitoring system, who's job it is to detect server failures, 
marking random servers/switches as dead while the resolver is going mad and
so check_ping on their numerical IPv4 times out is not particularily useful.

I guess the point is what you expect getaddrinfo on 1.2.3.4 with a AF_INET6 
hint to do. Well, you could have a search domain of numerical.org and 
1.2.3.4.numerical.org have an AAAA record. How likely is that?