From: Michael Orlitzky <michael@orlitzky.com>
Date: Thu, 5 Dec 2019 15:34:54 +0000 (-0500)
Subject: Allow underscore characters in FQDNs and pointers.
X-Git-Url: http://gitweb.michael.orlitzky.com/?p=valtz.git;a=commitdiff_plain;h=7c5df8ad5c18a9f8b9440dbd1ae4faacf55b452a;hp=7c5df8ad5c18a9f8b9440dbd1ae4faacf55b452a

Allow underscore characters in FQDNs and pointers.

Modern DNS records can contain underscores for a number of reasons. In
particular, DKIM records involve a "_domainkey" part,

  https://tools.ietf.org/html/rfc6376

that is rejected by the current "fqdn" and "p" validation routines.
Moreover, any SRV records will have a service name prefixed with an
underscore:

  https://tools.ietf.org/html/rfc2782

To recognize these tokens as valid, this commit expands the "fqdn" and
"p" regular expressions to allow underscores as the first character in
each component of an FQDN.
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