fix: report IMPORT_TRANSFORM of a non-existent domain instead of crashing

pkg/normalize/importTransform_test.go

@@ -1,6 +1,7 @@
 package normalize
 
 import (
+	"strings"
 	"testing"
 
 	dnsv2 "codeberg.org/miekg/dns"
@@ -46,3 +47,36 @@ func TestImportTransform(t *testing.T) {
 		t.Fatalf("Expected 3 records in internal, but got %d", len(d.Records))
 	}
 }
+
+// An IMPORT_TRANSFORM that names a domain that is not in the config must be
+// reported as an error. It must not crash.
+func TestImportTransformMissingDomain(t *testing.T) {
+	const transformSingle = "0.0.0.0~1.1.1.1~~8.0.0.0"
+
+	dc := models.MustNewDomainConfig("internal")
+	dc.AddRecordConfig(dc.MustNewRecordConfig("www", 0, dnsv2.TypeA, "0.0.3.3"))
+	dc.AddRecordConfig(dc.MustNewRecordConfig("@", 0, privatetypes.TypeIMPORTTRANSFORM, transformSingle, 299, "com.internal", "missing.example"))
+
+	cfg := &models.DNSConfig{}
+	cfg.Domains = append(cfg.Domains, dc)
+	if err := cfg.PostProcess(); err != nil {
+		t.Fatal(err)
+	}
+
+	var errs []error
+	func() {
+		defer func() {
+			if r := recover(); r != nil {
+				t.Fatalf("ValidateAndNormalizeConfig panicked: %v", r)
+			}
+		}()
+		errs = ValidateAndNormalizeConfig(cfg)
+	}()
+
+	for _, err := range errs {
+		if strings.Contains(err.Error(), `IMPORT_TRANSFORM mentions non-existent domain "missing.example"`) {
+			return
+		}
+	}
+	t.Errorf("expected an error about the non-existent domain, got %v", errs)
+}

pkg/normalize/validate.go

@@ -530,6 +530,7 @@ func ValidateAndNormalizeConfig(config *models.DNSConfig) (errs []error) {
 				if c == nil {
 					err = fmt.Errorf("IMPORT_TRANSFORM mentions non-existent domain %q", targetDomain)
 					errs = append(errs, err)
+					continue
 				}
 				err = importTransform(c, domain, table, ttl, suffixstrip)
 				if err != nil {