RFC 8490: Implement DSO type registry

Signed-off-by: Miek Gieben <[email protected]>

Author: miekg

reverse.go

@@ -23,9 +23,12 @@ var StringToAlgorithm = reverseInt8(AlgorithmToString)
 // StringToHash is a map of names to hash IDs.
 var StringToHash = reverseInt8(HashToString)
 
-// StringToCertType is the reverseof CertTypeToString.
+// StringToCertType is the reverse of CertTypeToString.
 var StringToCertType = reverseInt16(CertTypeToString)
 
+// StringToStatefulType is the reverse of StatefulTypeToString.
+var StringToStatefulType = reverseInt16(StatefulTypeToString)
+
 // Reverse a map
 func reverseInt8(m map[uint8]string) map[string]uint8 {
 	n := make(map[string]uint8, len(m))

types.go

@@ -181,6 +181,19 @@ const (
 	AMTRELAYHost = IPSECGatewayHost
 )
 
+// Stateful types as defined in RFC 8490.
+const (
+	StatefulTypeKeepAlive uint16 = iota + 1
+	StatefulTypeRetryDelay
+	StatefulTypeEncryptionPadding
+)
+
+var StatefulTypeToString = map[uint16]string{
+	StatefulTypeKeepAlive:         "KeepAlive",
+	StatefulTypeRetryDelay:        "RetryDelay",
+	StatefulTypeEncryptionPadding: "EncryptionPadding",
+}
+
 // Header is the wire format for the DNS packet header.
 type Header struct {
 	Id                                 uint16