lnwire+feature: new zero-conf, scid-alias feature bit + chantypes

This defines the zero-conf feature bit, the scid-alias feature bit,
the zero-conf channel type, and the scid-alias channel type. It also
defines the dependency "tree" that exists for the feature bits.

The scid-alias feature bit signals that the node requires an alias
short channel id to be sent in funding_locked. The scid-alias channel
type requires that the channel is private, in addition to some other
forwarding-related privacy measures.

feature/default_sets.go

@@ -71,4 +71,12 @@ var defaultSetDesc = setDesc{
 		SetInit:    {}, // I
 		SetNodeAnn: {}, // N
 	},
+	lnwire.ScidAliasOptional: {
+		SetInit:    {}, // I
+		SetNodeAnn: {}, // N
+	},
+	lnwire.ZeroConfOptional: {
+		SetInit:    {}, // I
+		SetNodeAnn: {}, // N
+	},
 }

feature/deps.go

@@ -72,6 +72,12 @@ var deps = depDesc{
 	lnwire.KeysendOptional: {
 		lnwire.TLVOnionPayloadOptional: {},
 	},
+	lnwire.ScidAliasOptional: {
+		lnwire.ExplicitChannelTypeOptional: {},
+	},
+	lnwire.ZeroConfOptional: {
+		lnwire.ScidAliasOptional: {},
+	},
 }
 
 // ValidateDeps asserts that a feature vector sets all features and their

feature/manager.go

@@ -31,6 +31,15 @@ type Config struct {
 	// NoKeysend unsets any bits signaling support for accepting keysend
 	// payments.
 	NoKeysend bool
+
+	// NoOptionScidAlias unsets any bits signalling support for
+	// option_scid_alias. This also implicitly disables zero-conf channels.
+	NoOptionScidAlias bool
+
+	// NoZeroConf unsets any bits signalling support for zero-conf
+	// channels. This should be used instead of NoOptionScidAlias to still
+	// keep option-scid-alias support.
+	NoZeroConf bool
 }
 
 // Manager is responsible for generating feature vectors for different requested
@@ -125,6 +134,14 @@ func newManager(cfg Config, desc setDesc) (*Manager, error) {
 			raw.Unset(lnwire.KeysendOptional)
 			raw.Unset(lnwire.KeysendRequired)
 		}
+		if cfg.NoOptionScidAlias {
+			raw.Unset(lnwire.ScidAliasOptional)
+			raw.Unset(lnwire.ScidAliasRequired)
+		}
+		if cfg.NoZeroConf {
+			raw.Unset(lnwire.ZeroConfOptional)
+			raw.Unset(lnwire.ZeroConfRequired)
+		}
 
 		// Ensure that all of our feature sets properly set any
 		// dependent features.

lnwire/features.go

@@ -155,6 +155,16 @@ const (
 	// TODO: Decide on actual feature bit value.
 	ExplicitChannelTypeOptional = 45
 
+	// ScidAliasRequired is a required feature bit that signals that the
+	// node requires understanding of ShortChannelID aliases in the TLV
+	// segment of the funding_locked message.
+	ScidAliasRequired FeatureBit = 46
+
+	// ScidAliasOptional is an optional feature bit that signals that the
+	// node understands ShortChannelID aliases in the TLV segment of the
+	// funding_locked message.
+	ScidAliasOptional FeatureBit = 47
+
 	// PaymentMetadataRequired is a required bit that denotes that if an
 	// invoice contains metadata, it must be passed along with the payment
 	// htlc(s).
@@ -165,6 +175,14 @@ const (
 	// htlc(s).
 	PaymentMetadataOptional = 49
 
+	// ZeroConfRequired is a required feature bit that signals that the
+	// node requires understanding of the zero-conf channel_type.
+	ZeroConfRequired FeatureBit = 50
+
+	// ZeroConfOptional is an optional feature bit that signals that the
+	// node understands the zero-conf channel type.
+	ZeroConfOptional FeatureBit = 51
+
 	// KeysendRequired is a required bit that indicates that the node is
 	// able and willing to accept keysend payments.
 	KeysendRequired = 54
@@ -173,7 +191,7 @@ const (
 	// able and willing to accept keysend payments.
 	KeysendOptional = 55
 
-	// ScriptEnforcedLeaseRequired is a required feature bit that signals
+	// ScriptEnforcedLeaseOptional is an optional 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
@@ -244,6 +262,10 @@ var Features = map[FeatureBit]string{
 	KeysendRequired:               "keysend",
 	ScriptEnforcedLeaseRequired:   "script-enforced-lease",
 	ScriptEnforcedLeaseOptional:   "script-enforced-lease",
+	ScidAliasRequired:             "scid-alias",
+	ScidAliasOptional:             "scid-alias",
+	ZeroConfRequired:              "zero-conf",
+	ZeroConfOptional:              "zero-conf",
 }
 
 // RawFeatureVector represents a set of feature bits as defined in BOLT-09.  A