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fix: use lax IDNA profile to support underscores in domains #145

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Merged
natesales merged 1 commit into from
Dec 8, 2025
Merged

fix: use lax IDNA profile to support underscores in domains #145

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14 changes: 10 additions & 4 deletions main.go
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Original file line number Diff line number Diff line change
Expand Up @@ -328,13 +328,19 @@ All long form (--) flags can be toggled with the dig-standard +[no]flag notation
// Skip if already an in-addr.arpa or ip6.arpa name
lowerName := strings.ToLower(opts.Name)
if !strings.HasSuffix(lowerName, ".in-addr.arpa") && !strings.HasSuffix(lowerName, ".ip6.arpa") {
// Allow underscores during IDNA conversion
_asciiName := strings.ReplaceAll(opts.Name, "_", "..")
asciiName, err := idna.Lookup.ToASCII(_asciiName)
// Use a custom IDNA profile to allow underscores (non-LDH characters).
// Standard IDNA Lookup enforces STD3 rules which forbid underscores,
// but they are valid in DNS records (e.g. TXT, SRV).
p := idna.New(
idna.MapForLookup(),
idna.StrictDomainName(false),
)

asciiName, err := p.ToASCII(opts.Name)
if err != nil {
return fmt.Errorf("idna toascii: %s", err)
}
opts.Name = strings.ReplaceAll(asciiName, "..", "_")
opts.Name = asciiName
}
}

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