From 9260f576bdf164bc7490320f4499366c5bcc125a Mon Sep 17 00:00:00 2001
From: Joost Jager <joost.jager@gmail.com>
Date: Tue, 17 Jan 2023 13:44:32 +0100
Subject: [PATCH] initialize NewOnionErrorEncrypter with shared secret directly

Allow for more flexible usage of the error encrypter. This is useful when upgrading an
existing legacy error encrypter to fat errors in lnd.
---
 obfuscation.go      | 11 ++---------
 obfuscation_test.go | 16 ++++++----------
 2 files changed, 8 insertions(+), 19 deletions(-)

diff --git a/obfuscation.go b/obfuscation.go
index b8df7cc..14aabbe 100644
--- a/obfuscation.go
+++ b/obfuscation.go
@@ -15,17 +15,10 @@ type OnionErrorEncrypter struct {
 // NewOnionErrorEncrypter creates new instance of the onion encrypter backed by
 // the passed router, with encryption to be doing using the passed
 // ephemeralKey.
-func NewOnionErrorEncrypter(router *Router,
-	ephemeralKey *btcec.PublicKey) (*OnionErrorEncrypter, error) {
-
-	sharedSecret, err := router.generateSharedSecret(ephemeralKey)
-	if err != nil {
-		return nil, err
-	}
-
+func NewOnionErrorEncrypter(sharedSecret Hash256) *OnionErrorEncrypter {
 	return &OnionErrorEncrypter{
 		sharedSecret: sharedSecret,
-	}, nil
+	}
 }
 
 // Encode writes the encrypter's shared secret to the provided io.Writer.
diff --git a/obfuscation_test.go b/obfuscation_test.go
index 665dfa7..5571956 100644
--- a/obfuscation_test.go
+++ b/obfuscation_test.go
@@ -34,9 +34,7 @@ func TestOnionFailure(t *testing.T) {
 	}
 
 	// Emulate creation of the obfuscator on node where error have occurred.
-	obfuscator := &OnionErrorEncrypter{
-		sharedSecret: sharedSecrets[len(errorPath)-1],
-	}
+	obfuscator := NewOnionErrorEncrypter(sharedSecrets[len(errorPath)-1])
 
 	// Emulate the situation when last hop creates the onion failure
 	// message and send it back.
@@ -46,9 +44,7 @@ func TestOnionFailure(t *testing.T) {
 	for i := len(errorPath) - 2; i >= 0; i-- {
 		// Emulate creation of the obfuscator on forwarding node which
 		// propagates the onion failure.
-		obfuscator = &OnionErrorEncrypter{
-			sharedSecret: sharedSecrets[i],
-		}
+		obfuscator = NewOnionErrorEncrypter(sharedSecrets[i])
 		obfuscatedData = obfuscator.EncryptError(false, obfuscatedData)
 	}
 
@@ -207,16 +203,16 @@ func TestOnionFailureSpecVector(t *testing.T) {
 			t.Fatalf("unable to decode spec shared secret: %v",
 				err)
 		}
-		obfuscator := &OnionErrorEncrypter{
-			sharedSecret: sharedSecrets[len(sharedSecrets)-1-i],
-		}
+		obfuscator := NewOnionErrorEncrypter(
+			sharedSecrets[len(sharedSecrets)-1-i],
+		)
 
 		var b bytes.Buffer
 		if err := obfuscator.Encode(&b); err != nil {
 			t.Fatalf("unable to encode obfuscator: %v", err)
 		}
 
-		obfuscator2 := &OnionErrorEncrypter{}
+		obfuscator2 := NewOnionErrorEncrypter(Hash256{})
 		obfuscatorReader := bytes.NewReader(b.Bytes())
 		if err := obfuscator2.Decode(obfuscatorReader); err != nil {
 			t.Fatalf("unable to decode obfuscator: %v", err)