feat: mvp (#1)

MVP including features:
* Detect IP change
* Configurable/generic external IP provider
* Configurable/generic DNS provider
* Impl. of plain external IP provider
* Impl. of Ionos DNS provider

Reviewed-on: #1
Co-authored-by: Timo Behrendt <t.behrendt@t00n.de>
Co-committed-by: Timo Behrendt <t.behrendt@t00n.de>

pkg/changeDetector/changeDetector.go

@@ -0,0 +1,53 @@
+package changeDetector
+
+import (
+	"realdnydns/pkg/config"
+	"realdnydns/pkg/dnsProvider"
+	"realdnydns/pkg/externalIpProvider"
+)
+
+type ChangeDetector struct {
+	externalIpProvider externalIpProvider.ExternalIpProvider
+	dnsProvider        dnsProvider.DNSProvider
+	domains            []config.DomainConfig
+}
+
+func New(
+	externalIpProvider externalIpProvider.ExternalIpProvider,
+	dnsProvider dnsProvider.DNSProvider,
+	domains []config.DomainConfig,
+) ChangeDetector {
+	return ChangeDetector{
+		externalIpProvider: externalIpProvider,
+		dnsProvider:        dnsProvider,
+		domains:            domains,
+	}
+}
+
+func (c *ChangeDetector) DetectAndApplyChanges() (int, error) {
+	externalIp, err := c.externalIpProvider.GetExternalIp()
+	if err != nil {
+		return 0, err
+	}
+
+	var numberUpdated int
+
+	for _, domain := range c.domains {
+		for _, subdomain := range domain.Subdomains {
+			currentRecord, err := c.dnsProvider.GetRecord(domain.TLD, subdomain)
+			if err != nil {
+				return numberUpdated, err
+			}
+
+			if currentRecord.IP != externalIp.String() {
+				_, err = c.dnsProvider.UpdateRecord(domain.TLD, subdomain, externalIp, currentRecord.TTL, currentRecord.Prio, currentRecord.Disabled)
+				numberUpdated++
+				if err != nil {
+					return numberUpdated, err
+				}
+			}
+		}
+	}
+
+	return numberUpdated, nil
+}

pkg/changeDetector/changeDetector_test.go

@@ -0,0 +1,105 @@
+package changeDetector
+
+import (
+	"net"
+	"realdnydns/model/common"
+	"realdnydns/pkg/config"
+	"testing"
+)
+
+type MockExternalIpProvider struct {
+	ExternalIp string
+}
+
+func (m *MockExternalIpProvider) GetExternalIp() (net.IP, error) {
+	return net.ParseIP(m.ExternalIp), nil
+}
+
+type MockDNSProvider interface {
+	UpdateRecord(tld string, subdomain string, ip net.IP, ttl int, prio int, disabled bool) (*common.ARecord, error)
+	GetRecord(tld string, subdomain string) (*common.ARecord, error)
+}
+
+type MockDNSProviderImpl struct {
+	GetRecordIpResponse    string
+	UpdateRecordIpResponse string
+}
+
+func (m *MockDNSProviderImpl) GetRecord(tld string, subdomain string) (*common.ARecord, error) {
+	return &common.ARecord{
+		IP:       m.GetRecordIpResponse,
+		TTL:      10,
+		Prio:     20,
+		Disabled: false,
+	}, nil
+}
+
+func (m *MockDNSProviderImpl) UpdateRecord(tld string, subdomain string, ip net.IP, ttl int, prio int, disabled bool) (*common.ARecord, error) {
+	return &common.ARecord{
+		IP:       m.UpdateRecordIpResponse,
+		TTL:      10,
+		Prio:     20,
+		Disabled: false,
+	}, nil
+}
+
+func TestDetectAndApplyChanges(t *testing.T) {
+	t.Run("with changes", testDetectAndApplyChangesWithChanges())
+	t.Run("without changes", testDetectAndApplyChangesWithoutChanges())
+}
+
+func testDetectAndApplyChangesWithChanges() func(t *testing.T) {
+	return func(t *testing.T) {
+		changeDetector := New(&MockExternalIpProvider{
+			ExternalIp: "127.0.0.1",
+		}, &MockDNSProviderImpl{
+			GetRecordIpResponse:    "127.0.0.2",
+			UpdateRecordIpResponse: "127.0.0.1",
+		}, []config.DomainConfig{
+			{
+				TLD: "example.com",
+				Subdomains: []string{
+					"test",
+					"@",
+				},
+			},
+		})
+
+		numberUpdated, err := changeDetector.DetectAndApplyChanges()
+		if err != nil {
+			t.Errorf("expected no error, got %v", err)
+		}
+
+		if numberUpdated != 2 {
+			t.Errorf("expected numberUpdated to be 2, got %v", numberUpdated)
+		}
+	}
+}
+
+func testDetectAndApplyChangesWithoutChanges() func(t *testing.T) {
+	return func(t *testing.T) {
+		changeDetector := New(&MockExternalIpProvider{
+			ExternalIp: "127.0.0.1",
+		}, &MockDNSProviderImpl{
+			GetRecordIpResponse:    "127.0.0.1",
+			UpdateRecordIpResponse: "127.0.0.1",
+		}, []config.DomainConfig{
+			{
+				TLD: "example.com",
+				Subdomains: []string{
+					"test",
+					"@",
+				},
+			},
+		})
+
+		numberUpdated, err := changeDetector.DetectAndApplyChanges()
+		if err != nil {
+			t.Errorf("expected no error, got %v", err)
+		}
+
+		if numberUpdated != 0 {
+			t.Errorf("expected numberUpdated to be 0, got %v", numberUpdated)
+		}
+	}
+}