NEW PROVIDER: NETCUP (DNS) (#718)

* Add support for netcup DNS api.
* Add documentation page.
* Update reference to new version path.
* Add OWNERS entry for netcup.
* Add credentials for integration test. Netcup does not support PTRs. Fix parsing/formating of SRV records.
* Skip integration tests that are not supported.
* Use single quotes in JS code.

providers/netcup/netcupProvider.go

@@ -0,0 +1,136 @@
+package netcup
+
+import (
+	"encoding/json"
+	"fmt"
+	"github.com/StackExchange/dnscontrol/v3/models"
+	"github.com/StackExchange/dnscontrol/v3/pkg/diff"
+	"github.com/StackExchange/dnscontrol/v3/providers"
+)
+
+var features = providers.DocumentationNotes{
+	providers.DocCreateDomains:       providers.Cannot(),
+	providers.DocDualHost:            providers.Cannot(),
+	providers.DocOfficiallySupported: providers.Cannot(),
+	providers.CanUsePTR:              providers.Cannot(),
+	providers.CanUseSRV:              providers.Can(),
+	providers.CanUseCAA:              providers.Can(),
+	providers.CanUseTXTMulti:         providers.Can(),
+	providers.CanGetZones:            providers.Cannot(),
+}
+
+func init() {
+	providers.RegisterDomainServiceProviderType("NETCUP", New, features)
+}
+
+func New(settings map[string]string, _ json.RawMessage) (providers.DNSServiceProvider, error) {
+	if settings["api-key"] == "" || settings["api-password"] == "" || settings["customer-number"] == "" {
+		return nil, fmt.Errorf("missing netcup login parameters")
+	}
+
+	api := &api{}
+	err := api.login(settings["api-key"], settings["api-password"], settings["customer-number"])
+	if err != nil {
+		return nil, fmt.Errorf("login to netcup DNS failed, please check your credentials: %v", err)
+	}
+	return api, nil
+}
+
+// GetZoneRecords gets the records of a zone and returns them in RecordConfig format.
+func (api *api) GetZoneRecords(domain string) (models.Records, error) {
+	records, err := api.getRecords(domain)
+	if err != nil {
+		return nil, err
+	}
+	existingRecords := make([]*models.RecordConfig, len(records))
+	for i := range records {
+		existingRecords[i] = toRecordConfig(domain, &records[i])
+	}
+	return existingRecords, nil
+}
+
+// GetNameservers returns the nameservers for a domain.
+// As netcup doesn't support setting nameservers over this API, these are static.
+// Domains not managed by netcup DNS will return an error
+func (api *api) GetNameservers(domain string) ([]*models.Nameserver, error) {
+	return models.ToNameservers([]string{
+		"root-dns.netcup.net",
+		"second-dns.netcup.net",
+		"third-dns.netcup.net",
+	})
+}
+
+// GetDomainCorrections returns the corrections for a domain.
+func (api *api) GetDomainCorrections(dc *models.DomainConfig) ([]*models.Correction, error) {
+	dc, err := dc.Copy()
+	if err != nil {
+		return nil, err
+	}
+
+	dc.Punycode()
+	domain := dc.Name
+
+	// Setting the TTL is not supported for netcup
+	for _, r := range dc.Records {
+		r.TTL = 0
+	}
+
+	// Filter out types we can't modify (like NS)
+	newRecords := models.Records{}
+	for _, r := range dc.Records {
+		if r.Type != "NS" {
+			newRecords = append(newRecords, r)
+		}
+	}
+	dc.Records = newRecords
+
+	// Check existing set
+	existingRecords, err := api.GetZoneRecords(domain)
+	if err != nil {
+		return nil, err
+	}
+
+	// Normalize
+	models.PostProcessRecords(existingRecords)
+	differ := diff.New(dc)
+	_, create, del, modify := differ.IncrementalDiff(existingRecords)
+
+	var corrections []*models.Correction
+
+	// Deletes first so changing type works etc.
+	for _, m := range del {
+		req := m.Existing.Original.(*record)
+		corr := &models.Correction{
+			Msg: fmt.Sprintf("%s, Netcup ID: %s", m.String(), req.Id),
+			F: func() error {
+				return api.deleteRecord(domain, req)
+			},
+		}
+		corrections = append(corrections, corr)
+	}
+
+	for _, m := range create {
+		req := fromRecordConfig(m.Desired)
+		corr := &models.Correction{
+			Msg: m.String(),
+			F: func() error {
+				return api.createRecord(domain, req)
+			},
+		}
+		corrections = append(corrections, corr)
+	}
+	for _, m := range modify {
+		id := m.Existing.Original.(*record).Id
+		req := fromRecordConfig(m.Desired)
+		req.Id = id
+		corr := &models.Correction{
+			Msg: fmt.Sprintf("%s, Netcup ID: %s: ", m.String(), id),
+			F: func() error {
+				return api.modifyRecord(domain, req)
+			},
+		}
+		corrections = append(corrections, corr)
+	}
+
+	return corrections, nil
+}