Tore Anderson 2ad52c57f8 Use IPv6 sockets when querying IPv4 nameservers ...

This works around a bug in Net::DNS (or arguably in IO::Socket::IP)
which causes it to refuse to send queries to IPv4 nameservers (even
localhost), when running on IPv6-only hosts. Since IPv6-only hosts are
the primary use case for clatd, and most modern Linux distributions are
shipping with systemd-resolved listening on 127.0.0.53 by default, this
prevents PLAT prefix discovery from working correctly out of the box.

Forcing Net::DNS to use an IPv6 socket, by simply substituting all IPv4
addresses in the name server as IPv4-mapped IPv6 addreses, successfully
works around this problem.

This bug has been present in Net::DNS since version 1.03 (more
specifically since SVN r1406, dated 2015-10-05). This version started
defaulting to using IO::Socket::IP for all sockets, so it is no longer
necessary to require it explicitly in clatd.

For more info:

https://rt.cpan.org/Public/Bug/Display.html?id=158714 (Net::DNS)
https://rt.cpan.org/Public/Bug/Display.html?id=132760 (IO::Socket::IP)

2025-02-09 10:53:17 +01:00

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