rename payload type to source [squash]

Author: joostjager

attributable_error_crypto.go

@@ -5,6 +5,19 @@ import (
 	"crypto/sha256"
 )
 
+type payloadSource byte
+
+const (
+	// payloadIntermediateNode is a marker to signal that this attributable
+	// error payload is originating from a node between the payer and the error
+	// source.
+	payloadIntermediateNode payloadSource = 0
+
+	// payloadErrorNode is a marker to signal that this attributable error
+	// payload is originating from the error source.
+	payloadErrorNode payloadSource = 1
+)
+
 type AttributableErrorStructure struct {
 	HopCount        int
 	FixedPayloadLen int

attributable_error_decrypt.go

@@ -106,7 +106,7 @@ func (o *OnionAttributableErrorDecrypter) DecryptError(encryptedData []byte) (
 		}
 
 		// Extract the payload and exit with a nil message if it is invalid.
-		payloadType, payload, err := o.extractPayload(payloads)
+		source, payload, err := o.extractPayload(payloads)
 		if sender == 0 {
 			if err != nil {
 				sender = i + 1
@@ -118,7 +118,7 @@ func (o *OnionAttributableErrorDecrypter) DecryptError(encryptedData []byte) (
 
 			// If we are at the node that is the source of the error, we can now
 			// save the message in our return variable.
-			if payloadType == payloadFinal {
+			if source == payloadErrorNode {
 				sender = i + 1
 				msg = message
 			}
@@ -149,11 +149,6 @@ func (o *OnionAttributableErrorDecrypter) DecryptError(encryptedData []byte) (
 	}, nil
 }
 
-const (
-	payloadFinal        = 1
-	payloadIntermediate = 0
-)
-
 func (o *OnionAttributableErrorDecrypter) shiftHmacsLeft(hmacs []byte) {
 	srcIdx := o.maxHops
 	destIdx := 1
@@ -174,21 +169,21 @@ func (o *OnionAttributableErrorDecrypter) shiftPayloadsLeft(payloads []byte) {
 	copy(payloads, payloads[o.payloadLen:o.maxHops*o.payloadLen])
 }
 
-func (o *OnionAttributableErrorDecrypter) extractPayload(payloads []byte) (
-	PayloadType, []byte, error) {
-
-	var payloadType PayloadType
+// extractPayload extracts the payload and payload origin information from the
+// given byte slice.
+func (o *OnionAttributableErrorDecrypter) extractPayload(payloadBytes []byte) (
+	payloadSource, []byte, error) {
 
-	switch payloads[0] {
-	case payloadFinal, payloadIntermediate:
-		payloadType = PayloadType(payloads[0])
+	source := payloadSource(payloadBytes[0])
 
-	default:
-		return 0, nil, errors.New("invalid payload type")
+	// Validate source indicator.
+	if source != payloadErrorNode && source != payloadIntermediateNode {
+		return 0, nil, errors.New("invalid payload source indicator")
 	}
 
+	// Extract payload.
 	payload := make([]byte, o.payloadDataLen)
-	copy(payload, payloads[1:o.payloadLen])
+	copy(payload, payloadBytes[1:o.payloadLen])
 
-	return payloadType, payload, nil
+	return source, payload, nil
 }

attributable_error_encrypt.go

@@ -112,7 +112,7 @@ func (o *OnionAttributableErrorEncrypter) initializePayload(message []byte,
 	_, payloads, _ := o.getMsgComponents(data)
 
 	// Signal final hops in the payload.
-	addPayload(payloads, payloadFinal, payload)
+	addPayload(payloads, payloadErrorNode, payload)
 
 	return data
 }
@@ -127,10 +127,12 @@ func (o *OnionAttributableErrorEncrypter) addIntermediatePayload(data []byte,
 	o.shiftHmacsRight(hmacs)
 
 	// Signal intermediate hop in the payload.
-	addPayload(payloads, payloadIntermediate, payload)
+	addPayload(payloads, payloadIntermediateNode, payload)
 }
 
-func addPayload(payloads []byte, payloadType PayloadType, payload []byte) {
-	payloads[0] = byte(payloadType)
+func addPayload(payloads []byte, source payloadSource,
+	payload []byte) {
+
+	payloads[0] = byte(source)
 	copy(payloads[1:], payload)
 }