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feat(crd): Support MX record with trailing dot #6163

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feat(crd): Support MX record with trailing dot #6163

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16 changes: 13 additions & 3 deletions source/crd.go
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Original file line number Diff line number Diff line change
Expand Up @@ -197,13 +197,23 @@ func (cs *crdSource) Endpoints(ctx context.Context) ([]*endpoint.Endpoint, error
}
isNAPTR := ep.RecordType == endpoint.RecordTypeNAPTR
isTXT := ep.RecordType == endpoint.RecordTypeTXT
isMx := ep.RecordType == endpoint.RecordTypeMX
illegalTarget := false
for _, target := range ep.Targets {
hasDot := strings.HasSuffix(target, ".")
// Skip dot validation for TXT records as they can contain arbitrary text
if !isTXT && ((isNAPTR && !hasDot) || (!isNAPTR && hasDot)) {
illegalTarget = true
break
if !isTXT {
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@ivankatliarchuk ivankatliarchuk Feb 3, 2026

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nesting if is not a great idea

consider something like

for _, target := range ep.Targets {
	hasDot := strings.HasSuffix(target, ".")

	// TXT can contain arbitrary text, skip dot validation.
	if isTXT {
		continue
	}

	// Records that require a trailing dot (hostnames).
	requiresDot := isNAPTR || isMx

	if requiresDot && !hasDot {
		illegalTarget = true
		break
	}

	if !requiresDot && hasDot {
		illegalTarget = true
		break
	}
}

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@ivankatliarchuk ivankatliarchuk Feb 3, 2026

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Or we could avoid growing list of boolean variables entiretly

illegalTarget := false
for _, target := range ep.Targets {
	hasDot := strings.HasSuffix(target, ".")

	switch ep.RecordType {
	case endpoint.RecordTypeTXT:
		 continue // TXT records allow arbitrary text, skip validation
	case endpoint.RecordTypeNAPTR, endpoint.RecordTypeMX:
		illegalTarget = !hasDot // Must have trailing dot
	default:
		illegalTarget = hasDot // Must NOT have trailing dot
	}

	if illegalTarget {
		break
	}
}

// Allow trailing dots if record is NAPTR OR MX.
// Otherwise, if it's NOT NAPTR and NOT MX, a dot is illegal.
if isNAPTR || isMx {
if !hasDot {
illegalTarget = true
break
}
} else if hasDot {
illegalTarget = true
break
}
}
}
if illegalTarget {
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21 changes: 21 additions & 0 deletions source/crd_test.go
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Expand Up @@ -518,6 +518,27 @@ func testCRDSourceEndpoints(t *testing.T) {
expectEndpoints: false,
expectError: false,
},
{
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@ivankatliarchuk ivankatliarchuk Feb 3, 2026

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can we have test without trailing dot as well

title: "MX Record allowing trailing dot in target",
registeredAPIVersion: apiv1alpha1.GroupVersion.String(),
apiVersion: apiv1alpha1.GroupVersion.String(),
registeredKind: apiv1alpha1.DNSEndpointKind,
kind: apiv1alpha1.DNSEndpointKind,
namespace: "foo",
registeredNamespace: "foo",
labels: map[string]string{"test": "that"},
labelFilter: "test=that",
endpoints: []*endpoint.Endpoint{
{
DNSName: "example.org",
Targets: endpoint.Targets{"example.com."},
RecordType: endpoint.RecordTypeMX,
RecordTTL: 180,
},
},
expectEndpoints: true,
expectError: false,
},
} {
t.Run(ti.title, func(t *testing.T) {
t.Parallel()
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