From e8f47cf882172d900dbfcddd2fc0d7343c02bf0c Mon Sep 17 00:00:00 2001
From: Andras Banki-Horvath <bhandras@gmail.com>
Date: Mon, 26 Oct 2020 14:14:15 +0100
Subject: [PATCH] invoices: channel graph reference was wrongly retrieved from
 remote db

This commit fixes a bug where we tried to use the graph from the remote
db instance whereas it lives in the local db instance.
---
 lnrpc/invoicesrpc/addinvoice.go | 22 +++++++++-------------
 rpcserver.go                    |  1 +
 2 files changed, 10 insertions(+), 13 deletions(-)

diff --git a/lnrpc/invoicesrpc/addinvoice.go b/lnrpc/invoicesrpc/addinvoice.go
index afa7e708..7628c4ad 100644
--- a/lnrpc/invoicesrpc/addinvoice.go
+++ b/lnrpc/invoicesrpc/addinvoice.go
@@ -47,6 +47,9 @@ type AddInvoiceConfig struct {
 	// channel graph.
 	ChanDB *channeldb.DB
 
+	// Graph holds a reference to the ChannelGraph database.
+	Graph *channeldb.ChannelGraph
+
 	// GenInvoiceFeatures returns a feature containing feature bits that
 	// should be advertised on freshly generated invoices.
 	GenInvoiceFeatures func() *lnwire.FeatureVector
@@ -330,9 +333,8 @@ func AddInvoice(ctx context.Context, cfg *AddInvoiceConfig,
 
 // chanCanBeHopHint returns true if the target channel is eligible to be a hop
 // hint.
-func chanCanBeHopHint(channel *channeldb.OpenChannel,
-	graph *channeldb.ChannelGraph,
-	cfg *AddInvoiceConfig) (*channeldb.ChannelEdgePolicy, bool) {
+func chanCanBeHopHint(channel *channeldb.OpenChannel, cfg *AddInvoiceConfig) (
+	*channeldb.ChannelEdgePolicy, bool) {
 
 	// Since we're only interested in our private channels, we'll skip
 	// public ones.
@@ -359,7 +361,7 @@ func chanCanBeHopHint(channel *channeldb.OpenChannel,
 	// channels.
 	var remotePub [33]byte
 	copy(remotePub[:], channel.IdentityPub.SerializeCompressed())
-	isRemoteNodePublic, err := graph.IsPublicNode(remotePub)
+	isRemoteNodePublic, err := cfg.Graph.IsPublicNode(remotePub)
 	if err != nil {
 		log.Errorf("Unable to determine if node %x "+
 			"is advertised: %v", remotePub, err)
@@ -375,7 +377,7 @@ func chanCanBeHopHint(channel *channeldb.OpenChannel,
 
 	// Fetch the policies for each end of the channel.
 	chanID := channel.ShortChanID().ToUint64()
-	info, p1, p2, err := graph.FetchChannelEdgesByID(chanID)
+	info, p1, p2, err := cfg.Graph.FetchChannelEdgesByID(chanID)
 	if err != nil {
 		log.Errorf("Unable to fetch the routing "+
 			"policies for the edges of the channel "+
@@ -423,8 +425,6 @@ func selectHopHints(amtMSat lnwire.MilliSatoshi, cfg *AddInvoiceConfig,
 	openChannels []*channeldb.OpenChannel,
 	numMaxHophints int) []func(*zpay32.Invoice) {
 
-	graph := cfg.ChanDB.ChannelGraph()
-
 	// We'll add our hop hints in two passes, first we'll add all channels
 	// that are eligible to be hop hints, and also have a local balance
 	// above the payment amount.
@@ -433,9 +433,7 @@ func selectHopHints(amtMSat lnwire.MilliSatoshi, cfg *AddInvoiceConfig,
 	hopHints := make([]func(*zpay32.Invoice), 0, numMaxHophints)
 	for _, channel := range openChannels {
 		// If this channel can't be a hop hint, then skip it.
-		edgePolicy, canBeHopHint := chanCanBeHopHint(
-			channel, graph, cfg,
-		)
+		edgePolicy, canBeHopHint := chanCanBeHopHint(channel, cfg)
 		if edgePolicy == nil || !canBeHopHint {
 			continue
 		}
@@ -485,9 +483,7 @@ func selectHopHints(amtMSat lnwire.MilliSatoshi, cfg *AddInvoiceConfig,
 		// If the channel can't be a hop hint, then we'll skip it.
 		// Otherwise, we'll use the policy information to populate the
 		// hop hint.
-		remotePolicy, canBeHopHint := chanCanBeHopHint(
-			channel, graph, cfg,
-		)
+		remotePolicy, canBeHopHint := chanCanBeHopHint(channel, cfg)
 		if !canBeHopHint || remotePolicy == nil {
 			continue
 		}
diff --git a/rpcserver.go b/rpcserver.go
index 41c57a2f..8d39547f 100644
--- a/rpcserver.go
+++ b/rpcserver.go
@@ -4736,6 +4736,7 @@ func (r *rpcServer) AddInvoice(ctx context.Context,
 		NodeSigner:        r.server.nodeSigner,
 		DefaultCLTVExpiry: defaultDelta,
 		ChanDB:            r.server.remoteChanDB,
+		Graph:             r.server.localChanDB.ChannelGraph(),
 		GenInvoiceFeatures: func() *lnwire.FeatureVector {
 			return r.server.featureMgr.Get(feature.SetInvoice)
 		},