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.

diff --git a/valtz b/valtz
index c68c120e9a96b324a5de4619f3857b418d551e75..eebda76f4b17beb77fce88c1d3b4f5ecb282428f 100644 (file)
--- a/valtz
+++ b/valtz
@@ -202,7 +202,7 @@ my %token_validator = (
         # check all parts
         for my $hostpart (split /\./, $s)
         {
-            return 1005 unless $hostpart =~ /^[-a-z0-9]+$/i;
+            return 1005 unless $hostpart =~ /^_?[-a-z0-9]+$/i;
             return 1006 if $hostpart =~ /^-/;
             return 1007 if $hostpart =~ /-$/;
         }
@@ -268,7 +268,7 @@ my %token_validator = (
         # check all parts
         for (split /\./, $s)
         {
-            return 1005 unless /^[-[a-z0-9]+$/i;
+            return 1005 unless /^_?[-[a-z0-9]+$/i;
             return 1006 if /^-/;
             return 1007 if /-$/;
         }