ddns: store configuation in database (#435)

* ddns: store configuation in database

Co-authored-by: nap0o <144927971+nap0o@users.noreply.github.com>

* feat: split domain with soa lookup

* switch to libdns interface

* ddns: add unit test

* ddns: skip TestSplitDomainSOA on ci

network is not steady

* fix error handling

* fix error handling

---------

Co-authored-by: nap0o <144927971+nap0o@users.noreply.github.com>

pkg/ddns/ddns_test.go

@@ -0,0 +1,44 @@
+package ddns
+
+import (
+	"os"
+	"testing"
+)
+
+type testSt struct {
+	domain string
+	zone   string
+	prefix string
+}
+
+func TestSplitDomainSOA(t *testing.T) {
+	if ci := os.Getenv("CI"); ci != "" { // skip if test on CI
+		return
+	}
+
+	cases := []testSt{
+		{
+			domain: "www.example.co.uk",
+			zone:   "example.co.uk.",
+			prefix: "www",
+		},
+		{
+			domain: "abc.example.com",
+			zone:   "example.com.",
+			prefix: "abc",
+		},
+	}
+
+	for _, c := range cases {
+		prefix, zone, err := splitDomainSOA(c.domain)
+		if err != nil {
+			t.Fatalf("Error: %s", err)
+		}
+		if prefix != c.prefix {
+			t.Fatalf("Expected prefix %s, but got %s", c.prefix, prefix)
+		}
+		if zone != c.zone {
+			t.Fatalf("Expected zone %s, but got %s", c.zone, zone)
+		}
+	}
+}