2 files changed, 36 insertions(+), 0 deletions(-)

A internal/dns/misc.go
A internal/dns/misc_test.go

@@ 0,0 1,26 @@
+/*
+ * Copyright (C) 2024 Jonni Liljamo <jonni@liljamo.com>
+ *
+ * This file is licensed under AGPL-3.0-or-later, see NOTICE and LICENSE for
+ * more information.
+ */
+
+package dns
+
+import (
+	"log/slog"
+	"strings"
+)
+
+func zoneOf(fqdn string, zone string) bool {
+	// Get the index of the first '.', and compare everything after that to zone.
+	if index := strings.IndexByte(fqdn, '.'); index >= 0 {
+		index++
+		return fqdn[index:] == zone
+	}
+
+	// Probably both fqdn and zone were just '.'. Crossing my fingers and hoping
+	// this can't be reached in correct configuration.
+	slog.Error("Invalid use of zone_of", slog.String("fqdn", fqdn), slog.String("zone", zone))
+	return false
+}

@@ 0,0 1,10 @@
+package dns
+
+import "testing"
+
+func TestZoneOf(t *testing.T) {
+	want := "test.ddns.felu.arpa."
+	if !zoneOf("_acme-challenge.test.ddns.felu.arpa.", want) {
+		t.Error("zoneOf")
+	}
+}