maddy

 1/*
 2Maddy Mail Server - Composable all-in-one email server.
 3Copyright © 2019-2020 Max Mazurov <fox.cpp@disroot.org>, Maddy Mail Server contributors
 4
 5This program is free software: you can redistribute it and/or modify
 6it under the terms of the GNU General Public License as published by
 7the Free Software Foundation, either version 3 of the License, or
 8(at your option) any later version.
 9
10This program is distributed in the hope that it will be useful,
11but WITHOUT ANY WARRANTY; without even the implied warranty of
12MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13GNU General Public License for more details.
14
15You should have received a copy of the GNU General Public License
16along with this program.  If not, see <https://www.gnu.org/licenses/>.
17*/
18
19package dns
20
21import (
22	"golang.org/x/net/idna"
23	"golang.org/x/text/unicode/norm"
24)
25
26// SelectIDNA is a convenience function for encoding to/from Punycode.
27//
28// If ulabel is true, it returns U-label encoded domain in the Unicode NFC
29// form.
30// If ulabel is false, it returns A-label encoded domain.
31func SelectIDNA(ulabel bool, domain string) (string, error) {
32	if ulabel {
33		uDomain, err := idna.ToUnicode(domain)
34		return norm.NFC.String(uDomain), err
35	}
36	return idna.ToASCII(domain)
37}