server+tapcfg: implement AuxChannelNegotiator

Author: GeorgeTsagk

config.go

@@ -15,6 +15,7 @@ import (
 	"github.com/lightninglabs/taproot-assets/rfq"
 	"github.com/lightninglabs/taproot-assets/tapchannel"
 	"github.com/lightninglabs/taproot-assets/tapdb"
+	"github.com/lightninglabs/taproot-assets/tapfeatures"
 	"github.com/lightninglabs/taproot-assets/tapfreighter"
 	"github.com/lightninglabs/taproot-assets/tapgarden"
 	"github.com/lightninglabs/taproot-assets/universe"
@@ -219,6 +220,8 @@ type Config struct {
 
 	AuxTrafficShaper *tapchannel.AuxTrafficShaper
 
+	AuxChanNegotiator *tapfeatures.AuxChannelNegotiator
+
 	AuxInvoiceManager *tapchannel.AuxInvoiceManager
 
 	AuxChanCloser *tapchannel.AuxChanCloser

server.go

@@ -1279,3 +1279,50 @@ func (s *Server) NotifyBroadcast(req *sweep.BumpRequest,
 
 	return s.cfg.AuxSweeper.NotifyBroadcast(req, tx, fee, outpointToTxIndex)
 }
+
+// GetInitFeatures is called when sending an init message to a peer. It returns
+// custom feature bits to include in the init message TLVs. The implementation
+// can decide which features to advertise based on the peer's identity.
+func (s *Server) GetInitFeatures(peer route.Vertex) (tlv.Blob, error) {
+	// There's no need to wait for the server to be ready, this action acts
+	// only within the aux chan negotiator instance.
+	return s.cfg.AuxChanNegotiator.GetInitFeatures(peer)
+}
+
+// ProcessInitFeatures handles received init feature TLVs from a peer. The
+// implementation can store state internally to affect future channel operations
+// with this peer.
+func (s *Server) ProcessInitFeatures(peer route.Vertex,
+	features tlv.Blob) error {
+
+	// There's no need to wait for the server to be ready, this action acts
+	// only within the aux chan negotiator instance.
+	return s.cfg.AuxChanNegotiator.ProcessInitFeatures(peer, features)
+}
+
+// GetReestablishFeatures is called when sending a channel_reestablish message.
+// It returns feature bits based on the specific channel identified by its
+// funding outpoint and aux channel blob.
+func (s *Server) GetReestablishFeatures(fundingPoint wire.OutPoint,
+	auxChanBlob tlv.Blob) (tlv.Blob, error) {
+
+	// There's no need to wait for the server to be ready, this action acts
+	// only within the aux chan negotiator instance.
+	return s.cfg.AuxChanNegotiator.GetReestablishFeatures(
+		fundingPoint, auxChanBlob,
+	)
+}
+
+// ProcessReestablishFeatures handles received channel_reestablish feature TLVs.
+// This is a blocking call - the channel link will wait for this method to
+// complete before continuing channel operations. The implementation can modify
+// aux channel behavior based on the negotiated features.
+func (s *Server) ProcessReestablishFeatures(fundingPoint wire.OutPoint,
+	features tlv.Blob, auxChanBlob tlv.Blob) error {
+
+	// There's no need to wait for the server to be ready, this action acts
+	// only within the aux chan negotiator instance.
+	return s.cfg.AuxChanNegotiator.ProcessReestablishFeatures(
+		fundingPoint, features, auxChanBlob,
+	)
+}

tapcfg/server.go

@@ -20,6 +20,7 @@ import (
 	"github.com/lightninglabs/taproot-assets/tapchannel"
 	"github.com/lightninglabs/taproot-assets/tapdb"
 	"github.com/lightninglabs/taproot-assets/tapdb/sqlc"
+	"github.com/lightninglabs/taproot-assets/tapfeatures"
 	"github.com/lightninglabs/taproot-assets/tapfreighter"
 	"github.com/lightninglabs/taproot-assets/tapgarden"
 	"github.com/lightninglabs/taproot-assets/tapscript"
@@ -455,16 +456,20 @@ func genServerConfig(cfg *Config, cfgLogger btclog.Logger,
 		}
 	}
 
+	// Construct the AuxChannelNegotiator.
+	auxChanNegotiator := tapfeatures.NewAuxChannelNegotiator()
+
 	// Construct the RFQ manager.
 	rfqManager, err := rfq.NewManager(
 		rfq.ManagerCfg{
-			PeerMessenger:   msgTransportClient,
-			HtlcInterceptor: lndRouterClient,
-			HtlcSubscriber:  lndRouterClient,
-			PriceOracle:     priceOracle,
-			ChannelLister:   lndServices.Client,
-			GroupLookup:     tapdbAddrBook,
-			AliasManager:    lndRouterClient,
+			PeerMessenger:     msgTransportClient,
+			HtlcInterceptor:   lndRouterClient,
+			HtlcSubscriber:    lndRouterClient,
+			PriceOracle:       priceOracle,
+			ChannelLister:     lndServices.Client,
+			GroupLookup:       tapdbAddrBook,
+			AliasManager:      lndRouterClient,
+			AuxChanNegotiator: auxChanNegotiator,
 			// nolint: lll
 			AcceptPriceDeviationPpm: rfqCfg.AcceptPriceDeviationPpm,
 			// nolint: lll
@@ -538,9 +543,10 @@ func genServerConfig(cfg *Config, cfgLogger btclog.Logger,
 	)
 	auxTrafficShaper := tapchannel.NewAuxTrafficShaper(
 		&tapchannel.TrafficShaperConfig{
-			ChainParams: &tapChainParams,
-			RfqManager:  rfqManager,
-			NoopHTLCs:   cfg.Channel.NoopHTLCs,
+			ChainParams:       &tapChainParams,
+			RfqManager:        rfqManager,
+			NoopHTLCs:         cfg.Channel.NoopHTLCs,
+			AuxChanNegotiator: auxChanNegotiator,
 		},
 	)
 	auxInvoiceManager := tapchannel.NewAuxInvoiceManager(
@@ -694,6 +700,7 @@ func genServerConfig(cfg *Config, cfgLogger btclog.Logger,
 		AuxFundingController:     auxFundingController,
 		AuxChanCloser:            auxChanCloser,
 		AuxTrafficShaper:         auxTrafficShaper,
+		AuxChanNegotiator:        auxChanNegotiator,
 		AuxInvoiceManager:        auxInvoiceManager,
 		AuxSweeper:               auxSweeper,
 		LogWriter:                cfg.LogWriter,