tapfeatures: add aux feature bits

Author: GeorgeTsagk

tapfeatures/aux_feature_bits.go

@@ -0,0 +1,51 @@
+package tapfeatures
+
+import "github.com/lightningnetwork/lnd/lnwire"
+
+const (
+	// NoOpHTLCsRequired is a feature bit that declares the noop-htlcs as a
+	// required feature.
+	NoOpHTLCsRequired lnwire.FeatureBit = 0
+
+	// NoOpHTLCsOptional is a feature bit that declares the noop-htlcs as an
+	// optional feature.
+	NoOpHTLCsOptional lnwire.FeatureBit = 1
+
+	// STXORequired is a feature bit that declares STXO proofs as a required
+	// feature.
+	STXORequired lnwire.FeatureBit = 2
+
+	// STXOOptional is a feature bit that declares the STXO proofs as an
+	// optional feature.
+	STXOOptional lnwire.FeatureBit = 3
+)
+
+// featureNames keeps track of the string description of known features.
+var featureNames = map[lnwire.FeatureBit]string{
+	NoOpHTLCsRequired: "noop-htlcs",
+	NoOpHTLCsOptional: "noop-htlcs",
+	STXORequired:      "stxo-proofs",
+	STXOOptional:      "stxo-proofs",
+}
+
+// ourFeatures returns a slice containing all of the locally supported features.
+func ourFeatures() []lnwire.FeatureBit {
+	// TODO(george): instead of hosting the supported features in the
+	// following slice we could make something more explicit / modular.
+	return []lnwire.FeatureBit{
+		NoOpHTLCsOptional,
+		STXOOptional,
+	}
+}
+
+// getLocalFeatureVec returns the feature vector of the currently supported
+// features. This set of features may change between different versions of tapd,
+// and that exactly is its purpose. This feature vector denotes which features
+// of tap channels are currently supported, in order to maintain compatibility
+// with our peers.
+func getLocalFeatureVec() *lnwire.RawFeatureVector {
+	ourFeatures := ourFeatures()
+	return lnwire.NewRawFeatureVector(
+		ourFeatures...,
+	)
+}