[bugfix] Punycode fixes (#1743)

Co-authored-by: kim <grufwub@gmail.com>
Co-authored-by: kim <89579420+NyaaaWhatsUpDoc@users.noreply.github.com>

1 files changed, 44 insertions, 0 deletions

diff --git a/internal/util/punycode.go b/internal/util/punycode.go
new file mode 100644
index 000000000..4a595a281
--- /dev/null
+++ b/internal/util/punycode.go
@@ -0,0 +1,44 @@
+// GoToSocial
+// Copyright (C) GoToSocial Authors admin@gotosocial.org
+// SPDX-License-Identifier: AGPL-3.0-or-later
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package util
+
+import (
+	"strings"
+
+	"golang.org/x/net/idna"
+)
+
+// Punify converts the given domain to lowercase
+// then to punycode (for international domain names).
+//
+// Returns the resulting domain or an error if the
+// punycode conversion fails.
+func Punify(domain string) (string, error) {
+	domain = strings.ToLower(domain)
+	return idna.ToASCII(domain)
+}
+
+// DePunify converts the given punycode string
+// to its original unicode representation (lowercased).
+// Noop if the domain is (already) not puny.
+//
+// Returns an error if conversion fails.
+func DePunify(domain string) (string, error) {
+	out, err := idna.ToUnicode(domain)
+	return strings.ToLower(out), err
+}