From 9192c165ffbf485820f309847529d263ed345707 Mon Sep 17 00:00:00 2001
From: Elle Mouton <elle.mouton@gmail.com>
Date: Thu, 4 Jul 2024 14:12:18 +0200
Subject: [PATCH] feature: define new feature bit for bolt11 blinded paths

We need a new feature bit for BOLT11 invoices in order to indicate that
they contain the new blinded path tagged field. Tagged fields pre-date
TLV and so nodes who dont understand them will simply skip them.
Therefore the feature bit helps them to fail fast.
---
 feature/default_sets.go |  3 +++
 feature/deps.go         |  4 ++--
 feature/manager.go      |  4 ++++
 lnwire/features.go      | 26 ++++++++++++++++++--------
 4 files changed, 27 insertions(+), 10 deletions(-)

diff --git a/feature/default_sets.go b/feature/default_sets.go
index cc802fe85..447870b27 100644
--- a/feature/default_sets.go
+++ b/feature/default_sets.go
@@ -92,4 +92,7 @@ var defaultSetDesc = setDesc{
 		SetInit:    {}, // I
 		SetNodeAnn: {}, // N
 	},
+	lnwire.Bolt11BlindedPathsOptional: {
+		SetInvoice: {}, // I
+	},
 }
diff --git a/feature/deps.go b/feature/deps.go
index 350d49acf..64b4f2fc9 100644
--- a/feature/deps.go
+++ b/feature/deps.go
@@ -82,8 +82,8 @@ var deps = depDesc{
 	lnwire.RouteBlindingOptional: {
 		lnwire.TLVOnionPayloadOptional: {},
 	},
-	lnwire.RouteBlindingRequired: {
-		lnwire.TLVOnionPayloadRequired: {},
+	lnwire.Bolt11BlindedPathsOptional: {
+		lnwire.RouteBlindingOptional: {},
 	},
 }
 
diff --git a/feature/manager.go b/feature/manager.go
index c7029e893..0b6653985 100644
--- a/feature/manager.go
+++ b/feature/manager.go
@@ -128,6 +128,8 @@ func newManager(cfg Config, desc setDesc) (*Manager, error) {
 			raw.Unset(lnwire.MPPRequired)
 			raw.Unset(lnwire.RouteBlindingOptional)
 			raw.Unset(lnwire.RouteBlindingRequired)
+			raw.Unset(lnwire.Bolt11BlindedPathsOptional)
+			raw.Unset(lnwire.Bolt11BlindedPathsRequired)
 			raw.Unset(lnwire.AMPOptional)
 			raw.Unset(lnwire.AMPRequired)
 			raw.Unset(lnwire.KeysendOptional)
@@ -187,6 +189,8 @@ func newManager(cfg Config, desc setDesc) (*Manager, error) {
 		if cfg.NoRouteBlinding {
 			raw.Unset(lnwire.RouteBlindingOptional)
 			raw.Unset(lnwire.RouteBlindingRequired)
+			raw.Unset(lnwire.Bolt11BlindedPathsOptional)
+			raw.Unset(lnwire.Bolt11BlindedPathsRequired)
 		}
 		for _, custom := range cfg.CustomFeatures[set] {
 			if custom > set.Maximum() {
diff --git a/lnwire/features.go b/lnwire/features.go
index e4dd7f4f8..db07197e8 100644
--- a/lnwire/features.go
+++ b/lnwire/features.go
@@ -223,7 +223,7 @@ const (
 	// able and willing to accept keysend payments.
 	KeysendOptional = 55
 
-	// ScriptEnforcedLeaseOptional is an optional feature bit that signals
+	// ScriptEnforcedLeaseRequired is a required feature bit that signals
 	// that the node requires channels having zero-fee second-level HTLC
 	// transactions, which also imply anchor commitments, along with an
 	// additional CLTV constraint of a channel lease's expiration height
@@ -241,18 +241,17 @@ const (
 	// TODO: Decide on actual feature bit value.
 	ScriptEnforcedLeaseOptional FeatureBit = 2023
 
-	// SimpleTaprootChannelsRequredFinal is a required bit that indicates
+	// SimpleTaprootChannelsRequiredFinal is a required bit that indicates
 	// the node is able to create taproot-native channels. This is the
 	// final feature bit to be used once the channel type is finalized.
 	SimpleTaprootChannelsRequiredFinal = 80
 
 	// SimpleTaprootChannelsOptionalFinal is an optional bit that indicates
 	// the node is able to create taproot-native channels. This is the
-	// final
-	// feature bit to be used once the channel type is finalized.
+	// final feature bit to be used once the channel type is finalized.
 	SimpleTaprootChannelsOptionalFinal = 81
 
-	// SimpleTaprootChannelsRequredStaging is a required bit that indicates
+	// SimpleTaprootChannelsRequiredStaging is a required bit that indicates
 	// the node is able to create taproot-native channels. This is a
 	// feature bit used in the wild while the channel type is still being
 	// finalized.
@@ -260,11 +259,20 @@ const (
 
 	// SimpleTaprootChannelsOptionalStaging is an optional bit that
 	// indicates the node is able to create taproot-native channels. This
-	// is a feature
-	// bit used in the wild while the channel type is still being
-	// finalized.
+	// is a feature bit used in the wild while the channel type is still
+	// being finalized.
 	SimpleTaprootChannelsOptionalStaging = 181
 
+	// Bolt11BlindedPathsRequired is a required feature bit that indicates
+	// that the node is able to understand the blinded path tagged field in
+	// a BOLT 11 invoice.
+	Bolt11BlindedPathsRequired = 260
+
+	// Bolt11BlindedPathsOptional is an optional feature bit that indicates
+	// that the node is able to understand the blinded path tagged field in
+	// a BOLT 11 invoice.
+	Bolt11BlindedPathsOptional = 261
+
 	// MaxBolt11Feature is the maximum feature bit value allowed in bolt 11
 	// invoices.
 	//
@@ -331,6 +339,8 @@ var Features = map[FeatureBit]string{
 	SimpleTaprootChannelsOptionalFinal:   "simple-taproot-chans",
 	SimpleTaprootChannelsRequiredStaging: "simple-taproot-chans-x",
 	SimpleTaprootChannelsOptionalStaging: "simple-taproot-chans-x",
+	Bolt11BlindedPathsOptional:           "bolt-11-blinded-paths",
+	Bolt11BlindedPathsRequired:           "bolt-11-blinded-paths",
 }
 
 // RawFeatureVector represents a set of feature bits as defined in BOLT-09.  A