rpc: allow wumbo invoices

In this commit, we remove the restriction surrounding the largest
invoices that we'll allow a user to create. After #3967 has landed,
users will be able to send in _aggregate_ a payment larger than the
current max HTLC size limit in the network. As a result, we can just
treat that value as the system's MTU, and allow users to request
payments it multiples of that MTU value.

A follow up to this PR at a later time will also allow wumbo _channels_.
However, that requires us to tweak the way we scale CSV values, as post
wumbo, there is no true channel size limit, only the
_local_ limit of a given node. We also need to implement a way for nodes
to signal to other nodes their accepted max channel size.

lnrpc/invoicesrpc/addinvoice.go

@@ -37,9 +37,6 @@ type AddInvoiceConfig struct {
 	// that's backed by the identity private key of the running lnd node.
 	NodeSigner *netann.NodeSigner
 
-	// MaxPaymentMSat is the maximum allowed payment.
-	MaxPaymentMSat lnwire.MilliSatoshi
-
 	// DefaultCLTVExpiry is the default invoice expiry if no values is
 	// specified.
 	DefaultCLTVExpiry uint32
@@ -167,15 +164,6 @@ func AddInvoice(ctx context.Context, cfg *AddInvoiceConfig,
 
 	amtMSat := invoice.Value
 
-	// The value of the invoice must also not exceed the current soft-limit
-	// on the largest payment within the network.
-	if amtMSat > cfg.MaxPaymentMSat {
-		return nil, nil, fmt.Errorf("payment of %v is too large, max "+
-			"payment allowed is %v", invoice.Value,
-			cfg.MaxPaymentMSat.ToSatoshis(),
-		)
-	}
-
 	// We also create an encoded payment request which allows the
 	// caller to compactly send the invoice to the payer. We'll create a
 	// list of options to be added to the encoded payment request. For now

lnrpc/invoicesrpc/config_active.go

@@ -40,9 +40,6 @@ type Config struct {
 	// that's backed by the identity private key of the running lnd node.
 	NodeSigner *netann.NodeSigner
 
-	// MaxPaymentMSat is the maximum allowed payment.
-	MaxPaymentMSat lnwire.MilliSatoshi
-
 	// DefaultCLTVExpiry is the default invoice expiry if no values is
 	// specified.
 	DefaultCLTVExpiry uint32

lnrpc/invoicesrpc/invoices_server.go

@@ -250,7 +250,6 @@ func (s *Server) AddHoldInvoice(ctx context.Context,
 		IsChannelActive:    s.cfg.IsChannelActive,
 		ChainParams:        s.cfg.ChainParams,
 		NodeSigner:         s.cfg.NodeSigner,
-		MaxPaymentMSat:     s.cfg.MaxPaymentMSat,
 		DefaultCLTVExpiry:  s.cfg.DefaultCLTVExpiry,
 		ChanDB:             s.cfg.ChanDB,
 		GenInvoiceFeatures: s.cfg.GenInvoiceFeatures,

lnrpc/routerrpc/router_backend.go

@@ -698,18 +698,6 @@ func (r *RouterBackend) extractIntentFromSendRequest(
 		payIntent.DestFeatures = features
 	}
 
-	// Currently, within the bootstrap phase of the network, we limit the
-	// largest payment size allotted to (2^32) - 1 mSAT or 4.29 million
-	// satoshis.
-	if payIntent.Amount > r.MaxPaymentMSat {
-		// In this case, we'll send an error to the caller, but
-		// continue our loop for the next payment.
-		return payIntent, fmt.Errorf("payment of %v is too large, "+
-			"max payment allowed is %v", payIntent.Amount,
-			r.MaxPaymentMSat)
-
-	}
-
 	// Check for disallowed payments to self.
 	if !rpcPayReq.AllowSelfPayment && payIntent.Target == r.SelfNode {
 		return nil, errors.New("self-payments not allowed")

rpcserver.go

@@ -4305,7 +4305,6 @@ func (r *rpcServer) AddInvoice(ctx context.Context,
 		IsChannelActive:   r.server.htlcSwitch.HasActiveLink,
 		ChainParams:       activeNetParams.Params,
 		NodeSigner:        r.server.nodeSigner,
-		MaxPaymentMSat:    MaxPaymentMSat,
 		DefaultCLTVExpiry: defaultDelta,
 		ChanDB:            r.server.chanDB,
 		GenInvoiceFeatures: func() *lnwire.FeatureVector {

subrpcserver_config.go

@@ -202,9 +202,6 @@ func (s *subRPCServerConfigs) PopulateDependencies(cc *chainControl,
 			subCfgValue.FieldByName("NodeSigner").Set(
 				reflect.ValueOf(nodeSigner),
 			)
-			subCfgValue.FieldByName("MaxPaymentMSat").Set(
-				reflect.ValueOf(MaxPaymentMSat),
-			)
 			defaultDelta := cfg.Bitcoin.TimeLockDelta
 			if registeredChains.PrimaryChain() == litecoinChain {
 				defaultDelta = cfg.Litecoin.TimeLockDelta