measurement-reader: unify TPM & TDX sorting

measurement-reader/internal/sorted/sorted.go

@@ -4,11 +4,67 @@ Copyright (c) Edgeless Systems GmbH
 SPDX-License-Identifier: AGPL-3.0-only
 */
 
-// Type definition for sorted measurements.
+// Package sorted defines a type for print-friendly sorted measurements and allows sorting TPM and TDX measurements.
 package sorted
 
+import (
+	"fmt"
+	"sort"
+
+	"github.com/edgelesssys/constellation/v2/internal/attestation/measurements"
+)
+
 // Measurement wraps a measurement custom index and value.
 type Measurement struct {
 	Index string
 	Value []byte
 }
+
+// MeasurementType are the supported attestation types we can sort.
+type MeasurementType uint32
+
+const (
+	TPM MeasurementType = iota
+	TDX
+)
+
+// SortMeasurements returns the sorted measurements for either TPM or TDX measurements.
+func SortMeasurements(m measurements.M, measurementType MeasurementType) []Measurement {
+	if measurementType != TPM && measurementType != TDX {
+		return nil
+	}
+
+	keys := make([]uint32, 0, len(m))
+	for idx := range m {
+		keys = append(keys, idx)
+	}
+	sort.Slice(keys, func(i, j int) bool {
+		return keys[i] < keys[j]
+	})
+
+	var sortedMeasurements []Measurement
+
+	for _, idx := range keys {
+		var index string
+		switch measurementType {
+		case TPM:
+			index = fmt.Sprintf("PCR[%02d]", idx)
+		case TDX:
+			// idx 0 is MRTD
+			if idx == 0 {
+				index = "MRTD"
+				break
+			}
+			// RTMR 0 starts at idx 1, so we have to subtract by one here.
+			index = fmt.Sprintf("RTMR[%01d]", idx-1)
+		}
+
+		expected := m[idx].Expected
+		sortedMeasurements = append(sortedMeasurements, Measurement{
+			Index: index,
+			Value: expected[:],
+		})
+	}
+
+	return sortedMeasurements
+}