>> Fine, I guess I'll have to use getnameinfo()...
> This will not lead to gratuitous or unexpected name lookups using the
> name service switch, possibly even going to the network?

Not if you use NI_NUMERICHOST (and/or NI_NUMERICSERV).  If you use IPv6
and NI_WITHSCOPEID, or if that has been made the default, you may still
get syscalls to map the scope ID into an interface name; itojun's
description didn't include anything like NI_NUMERICSCOPEID....

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