invoicesrpc: move blinded path config to AddInvoiceData

since `AddInvoiceData` is config _per invoice_ where as `AddInvoiceConfig`
is config for the invoice server itself and so pretty much should stay
the same for the lifetime of LND. This change sets us up for moving some
of the blinded path config options to be changeable per AddInvoice call
rather that having fixed config values in the config file.

Author: ellemouton

lnrpc/invoicesrpc/addinvoice.go

@@ -96,28 +96,6 @@ type AddInvoiceConfig struct {
 	// QueryBlindedRoutes can be used to generate a few routes to this node
 	// that can then be used in the construction of a blinded payment path.
 	QueryBlindedRoutes func(lnwire.MilliSatoshi) ([]*route.Route, error)
-
-	// BlindedRoutePolicyIncrMultiplier is the amount by which policy values
-	// for hops in a blinded route will be bumped to avoid easy probing. For
-	// example, a multiplier of 1.1 will bump all appropriate the values
-	// (base fee, fee rate, CLTV delta and min HLTC) by 10%.
-	BlindedRoutePolicyIncrMultiplier float64
-
-	// BlindedRoutePolicyDecrMultiplier is the amount by which appropriate
-	// policy values for hops in a blinded route will be decreased to avoid
-	// easy probing. For example, a multiplier of 0.9 will reduce
-	// appropriate values (like maximum HTLC) by 10%.
-	BlindedRoutePolicyDecrMultiplier float64
-
-	// MinNumBlindedPathHops is the minimum number of hops that a blinded
-	// path should be. Dummy hops will be used to pad any route with a
-	// length less than this.
-	MinNumBlindedPathHops uint8
-
-	// DefaultDummyHopPolicy holds the default policy values to use for
-	// dummy hops in a blinded path in the case where they cant be derived
-	// through other means.
-	DefaultDummyHopPolicy *blindedpath.BlindedHopPolicy
 }
 
 // AddInvoiceData contains the required data to create a new invoice.
@@ -168,16 +146,44 @@ type AddInvoiceData struct {
 	// NOTE: Preimage should always be set to nil when this value is true.
 	Amp bool
 
-	// Blind signals that this invoice should disguise the location of the
-	// recipient by adding blinded payment paths to the invoice instead of
-	// revealing the destination node's real pub key.
-	Blind bool
+	// BlindedPathCfg holds the config values to use when constructing
+	// blinded paths to add to the invoice. A non-nil BlindedPathCfg signals
+	// that this invoice should disguise the location of the recipient by
+	// adding blinded payment paths to the invoice instead of revealing the
+	// destination node's real pub key.
+	BlindedPathCfg *BlindedPathConfig
 
 	// RouteHints are optional route hints that can each be individually
 	// used to assist in reaching the invoice's destination.
 	RouteHints [][]zpay32.HopHint
 }
 
+// BlindedPathConfig holds the configuration values required for blinded path
+// generation for invoices.
+type BlindedPathConfig struct {
+	// RoutePolicyIncrMultiplier is the amount by which policy values for
+	// hops in a blinded route will be bumped to avoid easy probing. For
+	// example, a multiplier of 1.1 will bump all appropriate the values
+	// (base fee, fee rate, CLTV delta and min HLTC) by 10%.
+	RoutePolicyIncrMultiplier float64
+
+	// RoutePolicyDecrMultiplier is the amount by which appropriate policy
+	// values for hops in a blinded route will be decreased to avoid easy
+	// probing. For example, a multiplier of 0.9 will reduce appropriate
+	// values (like maximum HTLC) by 10%.
+	RoutePolicyDecrMultiplier float64
+
+	// MinNumPathHops is the minimum number of hops that a blinded path
+	// should be. Dummy hops will be used to pad any route with a length
+	// less than this.
+	MinNumPathHops uint8
+
+	// DefaultDummyHopPolicy holds the default policy values to use for
+	// dummy hops in a blinded path in the case where they cant be derived
+	// through other means.
+	DefaultDummyHopPolicy *blindedpath.BlindedHopPolicy
+}
+
 // paymentHashAndPreimage returns the payment hash and preimage for this invoice
 // depending on the configuration.
 //
@@ -277,7 +283,9 @@ func (d *AddInvoiceData) mppPaymentHashAndPreimage() (*lntypes.Preimage,
 func AddInvoice(ctx context.Context, cfg *AddInvoiceConfig,
 	invoice *AddInvoiceData) (*lntypes.Hash, *invoices.Invoice, error) {
 
-	if invoice.Amp && invoice.Blind {
+	blind := invoice.BlindedPathCfg != nil
+
+	if invoice.Amp && blind {
 		return nil, nil, fmt.Errorf("AMP invoices with blinded paths " +
 			"are not yet supported")
 	}
@@ -420,7 +428,7 @@ func AddInvoice(ctx context.Context, cfg *AddInvoiceConfig,
 	// Only include a final CLTV expiry delta if this is not a blinded
 	// invoice. In a blinded invoice, this value will be added to the total
 	// blinded route CLTV delta value
-	if !invoice.Blind {
+	if !blind {
 		options = append(options, zpay32.CLTVExpiry(cltvExpiryDelta))
 	}
 
@@ -433,7 +441,7 @@ func AddInvoice(ctx context.Context, cfg *AddInvoiceConfig,
 
 	// Include route hints if needed.
 	if len(invoice.RouteHints) > 0 || invoice.Private {
-		if invoice.Blind {
+		if blind {
 			return nil, nil, fmt.Errorf("can't set both hop " +
 				"hints and add blinded payment paths")
 		}
@@ -492,7 +500,9 @@ func AddInvoice(ctx context.Context, cfg *AddInvoiceConfig,
 		return nil, nil, err
 	}
 
-	if invoice.Blind {
+	if blind {
+		blindCfg := invoice.BlindedPathCfg
+
 		// Use the 10-min-per-block assumption to get a rough estimate
 		// of the number of blocks until the invoice expires. We want
 		// to make sure that the blinded path definitely does not expire
@@ -525,12 +535,12 @@ func AddInvoice(ctx context.Context, cfg *AddInvoiceConfig,
 
 					//nolint:lll
 					return blindedpath.AddPolicyBuffer(
-						p, cfg.BlindedRoutePolicyIncrMultiplier,
-						cfg.BlindedRoutePolicyDecrMultiplier,
+						p, blindCfg.RoutePolicyIncrMultiplier,
+						blindCfg.RoutePolicyDecrMultiplier,
 					)
 				},
-				MinNumHops:            cfg.MinNumBlindedPathHops,
-				DefaultDummyHopPolicy: cfg.DefaultDummyHopPolicy,
+				MinNumHops:            blindCfg.MinNumPathHops,
+				DefaultDummyHopPolicy: blindCfg.DefaultDummyHopPolicy,
 			},
 		)
 		if err != nil {
@@ -560,7 +570,7 @@ func AddInvoice(ctx context.Context, cfg *AddInvoiceConfig,
 			// For an invoice without a blinded path, the main node
 			// key is used to sign the invoice so that the sender
 			// can derive the true pub key of the recipient.
-			if !invoice.Blind {
+			if !blind {
 				return cfg.NodeSigner.SignMessageCompact(
 					msg, false,
 				)

rpcserver.go

@@ -5820,10 +5820,6 @@ func (r *rpcServer) AddInvoice(ctx context.Context,
 		},
 		GetAlias:   r.server.aliasMgr.GetPeerAlias,
 		BestHeight: r.server.cc.BestBlockTracker.BestHeight,
-		BlindedRoutePolicyIncrMultiplier: r.server.cfg.Routing.
-			BlindedPaths.PolicyIncreaseMultiplier,
-		BlindedRoutePolicyDecrMultiplier: r.server.cfg.Routing.
-			BlindedPaths.PolicyDecreaseMultiplier,
 		QueryBlindedRoutes: func(amt lnwire.MilliSatoshi) (
 			[]*route.Route, error) {
 
@@ -5833,18 +5829,6 @@ func (r *rpcServer) AddInvoice(ctx context.Context,
 				blindingRestrictions,
 			)
 		},
-		MinNumBlindedPathHops: r.server.cfg.Routing.BlindedPaths.
-			NumHops,
-		DefaultDummyHopPolicy: &blindedpath.BlindedHopPolicy{
-			CLTVExpiryDelta: uint16(defaultDelta),
-			FeeRate:         uint32(r.server.cfg.Bitcoin.FeeRate),
-			BaseFee:         r.server.cfg.Bitcoin.BaseFee,
-			MinHTLCMsat:     r.server.cfg.Bitcoin.MinHTLCIn,
-
-			// MaxHTLCMsat will be calculated on the fly by using
-			// the introduction node's channel's capacities.
-			MaxHTLCMsat: 0,
-		},
 	}
 
 	value, err := lnrpc.UnmarshallAmt(invoice.Value, invoice.ValueMsat)
@@ -5857,6 +5841,34 @@ func (r *rpcServer) AddInvoice(ctx context.Context,
 	if err != nil {
 		return nil, err
 	}
+
+	var blindedPathCfg *invoicesrpc.BlindedPathConfig
+	if invoice.Blind {
+		bpConfig := r.server.cfg.Routing.BlindedPaths
+
+		blindedPathCfg = &invoicesrpc.BlindedPathConfig{
+			RoutePolicyIncrMultiplier: bpConfig.
+				PolicyIncreaseMultiplier,
+			RoutePolicyDecrMultiplier: bpConfig.
+				PolicyDecreaseMultiplier,
+			DefaultDummyHopPolicy: &blindedpath.BlindedHopPolicy{
+				CLTVExpiryDelta: uint16(defaultDelta),
+				FeeRate: uint32(
+					r.server.cfg.Bitcoin.FeeRate,
+				),
+				BaseFee:     r.server.cfg.Bitcoin.BaseFee,
+				MinHTLCMsat: r.server.cfg.Bitcoin.MinHTLCIn,
+
+				// MaxHTLCMsat will be calculated on the fly by
+				// using the introduction node's channel's
+				// capacities.
+				MaxHTLCMsat: 0,
+			},
+			MinNumPathHops: r.server.cfg.Routing.BlindedPaths.
+				NumHops,
+		}
+	}
+
 	addInvoiceData := &invoicesrpc.AddInvoiceData{
 		Memo:            invoice.Memo,
 		Value:           value,
@@ -5867,7 +5879,7 @@ func (r *rpcServer) AddInvoice(ctx context.Context,
 		Private:         invoice.Private,
 		RouteHints:      routeHints,
 		Amp:             invoice.IsAmp,
-		Blind:           invoice.Blind,
+		BlindedPathCfg:  blindedPathCfg,
 	}
 
 	if invoice.RPreimage != nil {