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"
@@ -223,6 +224,8 @@ type Config struct {
 
 	AuxTrafficShaper *tapchannel.AuxTrafficShaper
 
+	AuxChanNegotiator *tapfeatures.AuxChannelNegotiator
+
 	AuxInvoiceManager *tapchannel.AuxInvoiceManager
 
 	AuxChanCloser *tapchannel.AuxChanCloser

server.go

@@ -1284,3 +1284,91 @@ 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) {
+	srvrLog.Tracef("GetInitFeatures called, peer=%s", peer)
+
+	if err := s.waitForReady(); err != nil {
+		return nil, err
+	}
+
+	// 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 {
+
+	srvrLog.Tracef("ProcessInitFeatures called, peer=%s", peer)
+
+	if err := s.waitForReady(); err != nil {
+		return err
+	}
+
+	// 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(cid lnwire.ChannelID,
+	auxChanBlob tlv.Blob) (tlv.Blob, error) {
+
+	srvrLog.Tracef("GetReestablishFeatures called, cid=%s", cid.String())
+
+	if err := s.waitForReady(); err != nil {
+		return nil, err
+	}
+
+	// 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(
+		cid, 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(cid lnwire.ChannelID,
+	features tlv.Blob, auxChanBlob tlv.Blob) error {
+
+	srvrLog.Tracef("ProcessReestablishFeatures called, cid=%s",
+		cid.String())
+
+	if err := s.waitForReady(); err != nil {
+		return err
+	}
+
+	// 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(
+		cid, features, auxChanBlob,
+	)
+}
+
+// ProcessChannelReady handles the event of marking a channel identified by its
+// channel ID as ready to use. We also provide the peer the channel was
+// established with.
+func (s *Server) ProcessChannelReady(cid lnwire.ChannelID, peer route.Vertex) {
+	srvrLog.Tracef("ProcessChannelReady called, cid=%s, peer=%s", cid, peer)
+
+	if err := s.waitForReady(); err != nil {
+		srvrLog.Errorf("ProcessChannelReady got error while waiting " +
+			"for server ready")
+
+		return
+	}
+
+	s.cfg.AuxChanNegotiator.ProcessChannelReady(cid, peer)
+}

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"
@@ -470,6 +471,9 @@ 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,
@@ -478,6 +482,7 @@ func genServerConfig(cfg *Config, cfgLogger btclog.Logger,
 		PriceOracle:               priceOracle,
 		ChannelLister:             lndServices.Client,
 		GroupLookup:               tapdbAddrBook,
+		AuxChanNegotiator:         auxChanNegotiator,
 		AliasManager:              lndRouterClient,
 		AcceptPriceDeviationPpm:   rfqCfg.AcceptPriceDeviationPpm,
 		SkipAcceptQuotePriceCheck: rfqCfg.SkipAcceptQuotePriceCheck,
@@ -588,9 +593,10 @@ 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(
@@ -704,6 +710,7 @@ func genServerConfig(cfg *Config, cfgLogger btclog.Logger,
 		AuxFundingController:     auxFundingController,
 		AuxChanCloser:            auxChanCloser,
 		AuxTrafficShaper:         auxTrafficShaper,
+		AuxChanNegotiator:        auxChanNegotiator,
 		AuxInvoiceManager:        auxInvoiceManager,
 		AuxSweeper:               auxSweeper,
 		LogWriter:                cfg.LogWriter,