BUG: Some DNS zones are downloaded twice (#2120)

Signed-off-by: Amelia Aronsohn <squirrel@wearing.black>
Co-authored-by: Tom Limoncelli <tal@whatexit.org>
Co-authored-by: Grégoire Henry <hnrgrgr@users.noreply.github.com>
Co-authored-by: Amelia Aronsohn <squirrel@wearing.black>
Co-authored-by: Kai Schwarz <kschwarz@hexonet.net>
Co-authored-by: Asif Nawaz <asif.nawaz@centralnic.com>
Co-authored-by: imlonghao <git@imlonghao.com>
Co-authored-by: Will Power <1619102+willpower232@users.noreply.github.com>

pkg/zonerecs/zonerecords.go

@@ -0,0 +1,34 @@
+package zonerecs
+
+import (
+	"github.com/StackExchange/dnscontrol/v3/models"
+)
+
+// CorrectZoneRecords calls both GetZoneRecords, does any
+// post-processing, and then calls GetZoneRecordsCorrections.  The
+// name sucks because all the good names were taken.
+func CorrectZoneRecords(driver models.DNSProvider, dc *models.DomainConfig) ([]*models.Correction, error) {
+	existingRecords, err := driver.GetZoneRecords(dc.Name)
+	if err != nil {
+		return nil, err
+	}
+
+	// downcase
+	models.Downcase(existingRecords)
+
+	// Copy dc so that any corrections code that wants to
+	// modify the records may. For example, if the provider only
+	// supports certain TTL values, it will adjust the ones in
+	// dc.Records.
+	dc, err = dc.Copy()
+	if err != nil {
+		return nil, err
+	}
+
+	// punycode
+	dc.Punycode()
+	// FIXME(tlim) It is a waste to PunyCode every iteration.
+	// This should be moved to where the JavaScript is processed.
+
+	return driver.GetZoneRecordsCorrections(dc, existingRecords)
+}