feat(pdns): add validation for MX and SRV records

endpoint/endpoint.go

@@ -20,6 +20,7 @@ import (
 	"fmt"
 	"net/netip"
 	"sort"
+	"strconv"
 	"strings"
 
 	log "github.com/sirupsen/logrus"
@@ -396,3 +397,41 @@ func RemoveDuplicates(endpoints []*Endpoint) []*Endpoint {
 
 	return result
 }
+
+// Check endpoint if is it properly formatted according to RFC standards
+func CheckEndpoint(endpoint Endpoint) bool {
+	switch recordType := endpoint.RecordType; recordType {
+	case "MX":
+		for _, target := range endpoint.Targets {
+			// MX records must have a preference value to indicate priority, e.g. "10 example.com"
+			// as per https://www.rfc-editor.org/rfc/rfc974.txt
+			targetParts := strings.Fields(strings.TrimSpace(target))
+			if len(targetParts) != 2 {
+				return false
+			}
+
+			preferenceRaw := targetParts[0]
+			_, err := strconv.ParseInt(preferenceRaw, 10, 32)
+			if err != nil {
+				return false
+			}
+		}
+	case "SRV":
+		for _, target := range endpoint.Targets {
+			// SRV records must have a priority, weight, and port value, e.g. "10 5 5060 example.com"
+			// as per https://www.rfc-editor.org/rfc/rfc2782.txt
+			targetParts := strings.Fields(strings.TrimSpace(target))
+			if len(targetParts) != 4 {
+				return false
+			}
+
+			for _, part := range targetParts[:3] {
+				_, err := strconv.ParseInt(part, 10, 32)
+				if err != nil {
+					return false
+				}
+			}
+		}
+	}
+	return true
+}

endpoint/endpoint_test.go

@@ -19,6 +19,8 @@ package endpoint
 import (
 	"reflect"
 	"testing"
+
+	"github.com/stretchr/testify/assert"
 )
 
 func TestNewEndpoint(t *testing.T) {
@@ -441,3 +443,98 @@ func TestDuplicatedEndpointsWithOverlappingZones(t *testing.T) {
 		})
 	}
 }
+
+func TestPDNScheckEndpoint(t *testing.T) {
+	tests := []struct {
+		description string
+		endpoint    Endpoint
+		expected    bool
+	}{
+		{
+			description: "Valid MX record target",
+			endpoint: Endpoint{
+				DNSName:    "example.com",
+				RecordType: RecordTypeMX,
+				Targets:    Targets{"10 example.com"},
+			},
+			expected: true,
+		},
+		{
+			description: "Valid MX record with multiple targets",
+			endpoint: Endpoint{
+				DNSName:    "example.com",
+				RecordType: RecordTypeMX,
+				Targets:    Targets{"10 example.com", "20 backup.example.com"},
+			},
+			expected: true,
+		},
+		{
+			description: "MX record with valid and invalid targets",
+			endpoint: Endpoint{
+				DNSName:    "example.com",
+				RecordType: RecordTypeMX,
+				Targets:    Targets{"example.com", "backup.example.com"},
+			},
+			expected: false,
+		},
+		{
+			description: "Invalid MX record with missing priority value",
+			endpoint: Endpoint{
+				DNSName:    "example.com",
+				RecordType: RecordTypeMX,
+				Targets:    Targets{"example.com"},
+			},
+			expected: false,
+		},
+		{
+			description: "Invalid MX record with too many arguments",
+			endpoint: Endpoint{
+				DNSName:    "example.com",
+				RecordType: RecordTypeMX,
+				Targets:    Targets{"10 example.com abc"},
+			},
+			expected: false,
+		},
+		{
+			description: "Invalid MX record with non-integer priority",
+			endpoint: Endpoint{
+				DNSName:    "example.com",
+				RecordType: RecordTypeMX,
+				Targets:    Targets{"abc example.com"},
+			},
+			expected: false,
+		},
+		{
+			description: "Valid SRV record target",
+			endpoint: Endpoint{
+				DNSName:    "_service._tls.example.com",
+				RecordType: RecordTypeSRV,
+				Targets:    Targets{"10 20 5060 service.example.com"},
+			},
+			expected: true,
+		},
+		{
+			description: "Invalid SRV record with missing part",
+			endpoint: Endpoint{
+				DNSName:    "_service._tls.example.com",
+				RecordType: RecordTypeSRV,
+				Targets:    Targets{"10 20 5060"},
+			},
+			expected: false,
+		},
+		{
+			description: "Invalid SRV record with non-integer part",
+			endpoint: Endpoint{
+				DNSName:    "_service._tls.example.com",
+				RecordType: RecordTypeSRV,
+				Targets:    Targets{"10 20 abc service.example.com"},
+			},
+			expected: false,
+		},
+	}
+
+	for _, tt := range tests {
+		actual := CheckEndpoint(tt.endpoint)
+		assert.Equal(t, tt.expected, actual)
+	}
+}

provider/pdns/pdns.go

@@ -433,6 +433,19 @@ func (p *PDNSProvider) Records(ctx context.Context) (endpoints []*endpoint.Endpo
 	return endpoints, nil
 }
 
+// AdjustEndpoints performs checks on the provided endpoints and will skip any potentially failing changes.
+func (p *PDNSProvider) AdjustEndpoints(endpoints []*endpoint.Endpoint) ([]*endpoint.Endpoint, error) {
+	var validEndpoints []*endpoint.Endpoint
+	for i := 0; i < len(endpoints); i++ {
+		if !endpoint.CheckEndpoint(*endpoints[i]) {
+			log.Warnf("Ignoring Endpoint because of invalid %v record formatting: {Target: '%v'}", endpoints[i].RecordType, endpoints[i].Targets)
+			continue
+		}
+		validEndpoints = append(validEndpoints, endpoints[i])
+	}
+	return validEndpoints, nil
+}
+
 // ApplyChanges takes a list of changes (endpoints) and updates the PDNS server
 // by sending the correct HTTP PATCH requests to a matching zone
 func (p *PDNSProvider) ApplyChanges(ctx context.Context, changes *plan.Changes) error {

provider/pdns/pdns_test.go

@@ -161,6 +161,24 @@ var (
 		endpoint.NewEndpointWithTTL("example.com", endpoint.RecordTypeA, endpoint.TTL(300), "8.8.8.8", "8.8.4.4", "4.4.4.4"),
 	}
 
+	endpointsMXRecord = []*endpoint.Endpoint{
+		endpoint.NewEndpointWithTTL("mail.example.com", endpoint.RecordTypeMX, endpoint.TTL(300), "10 example.com"),
+	}
+
+	endpointsMXRecordInvalidFormatTooManyArgs = []*endpoint.Endpoint{
+		endpoint.NewEndpointWithTTL("mail.example.com", endpoint.RecordTypeMX, endpoint.TTL(300), "10 example.com abc"),
+	}
+
+	endpointsMultipleMXRecordsWithSingleInvalid = []*endpoint.Endpoint{
+		endpoint.NewEndpointWithTTL("mail.example.com", endpoint.RecordTypeMX, endpoint.TTL(300), "abc example.com"),
+		endpoint.NewEndpointWithTTL("mail.example.com", endpoint.RecordTypeMX, endpoint.TTL(300), "20 backup.example.com"),
+	}
+
+	endpointsMultipleInvalidMXRecords = []*endpoint.Endpoint{
+		endpoint.NewEndpointWithTTL("mail.example.com", endpoint.RecordTypeMX, endpoint.TTL(300), "example.com"),
+		endpoint.NewEndpointWithTTL("mail.example.com", endpoint.RecordTypeMX, endpoint.TTL(300), "backup.example.com"),
+	}
+
 	endpointsMixedRecords = []*endpoint.Endpoint{
 		endpoint.NewEndpointWithTTL("cname.example.com", endpoint.RecordTypeCNAME, endpoint.TTL(300), "example.com"),
 		endpoint.NewEndpointWithTTL("example.com", endpoint.RecordTypeTXT, endpoint.TTL(300), "'would smell as sweet'"),
@@ -1116,6 +1134,51 @@ func (suite *NewPDNSProviderTestSuite) TestPDNSClientPartitionZones() {
 	assert.Equal(suite.T(), partitionResultResidualSingleFilter, residualZones)
 }
 
+// Validate whether invalid endpoints are removed by AdjustEndpoints
+func (suite *NewPDNSProviderTestSuite) TestPDNSAdjustEndpoints() {
+	// Function definition: AdjustEndpoints(endpoints []*endpoint.Endpoint) []*endpoint.Endpoint
+
+	// Create a new provider to run tests against
+	p := &PDNSProvider{}
+
+	tests := []struct {
+		description string
+		endpoints   []*endpoint.Endpoint
+		expected    []*endpoint.Endpoint
+	}{
+		{
+			description: "Valid MX endpoint is not removed",
+			endpoints:   endpointsMXRecord,
+			expected: []*endpoint.Endpoint{
+				endpoint.NewEndpointWithTTL("mail.example.com", endpoint.RecordTypeMX, endpoint.TTL(300), "10 example.com"),
+			},
+		},
+		{
+			description: "Invalid MX endpoint with too many arguments is removed",
+			endpoints:   endpointsMXRecordInvalidFormatTooManyArgs,
+			expected:    []*endpoint.Endpoint([]*endpoint.Endpoint(nil)),
+		},
+		{
+			description: "Invalid MX endpoint is removed among valid endpoints",
+			endpoints:   endpointsMultipleMXRecordsWithSingleInvalid,
+			expected: []*endpoint.Endpoint{
+				endpoint.NewEndpointWithTTL("mail.example.com", endpoint.RecordTypeMX, endpoint.TTL(300), "20 backup.example.com"),
+			},
+		},
+		{
+			description: "Multiple invalid MX endpoints are removed",
+			endpoints:   endpointsMultipleInvalidMXRecords,
+			expected:    []*endpoint.Endpoint([]*endpoint.Endpoint(nil)),
+		},
+	}
+
+	for _, tt := range tests {
+		actual, err := p.AdjustEndpoints(tt.endpoints)
+		assert.Nil(suite.T(), err)
+		assert.Equal(suite.T(), tt.expected, actual)
+	}
+}
+
 func TestNewPDNSProviderTestSuite(t *testing.T) {
 	suite.Run(t, new(NewPDNSProviderTestSuite))
 }