From 23ce82f4e37d22171a8be79ee5a72999125e97db Mon Sep 17 00:00:00 2001
From: "Johan T. Halseth" <johanth@gmail.com>
Date: Tue, 4 Dec 2018 14:58:39 +0100
Subject: [PATCH] routing/router: don't apply channel policy updates for
 unknown channels

---
 routing/router.go | 41 +++++++++--------------------------------
 1 file changed, 9 insertions(+), 32 deletions(-)

diff --git a/routing/router.go b/routing/router.go
index c33f3ff1..cdb8d53a 100644
--- a/routing/router.go
+++ b/routing/router.go
@@ -1125,8 +1125,6 @@ func (r *ChannelRouter) processUpdate(msg interface{}) error {
 		}
 		r.rejectMtx.RUnlock()
 
-		channelID := lnwire.NewShortChanIDFromInt(msg.ChannelID)
-
 		// We make sure to hold the mutex for this channel ID,
 		// such that no other goroutine is concurrently doing
 		// database accesses for the same channel ID.
@@ -1142,6 +1140,15 @@ func (r *ChannelRouter) processUpdate(msg interface{}) error {
 
 		}
 
+		// If the channel doesn't exist in our database, we cannot
+		// apply the updated policy.
+		if !exists {
+			return newErrf(ErrIgnored, "Ignoring update "+
+				"(flags=%v|%v) for unknown chan_id=%v",
+				msg.MessageFlags, msg.ChannelFlags,
+				msg.ChannelID)
+		}
+
 		// As edges are directional edge node has a unique policy for
 		// the direction of the edge they control. Therefore we first
 		// check if we already have the most up to date information for
@@ -1174,36 +1181,6 @@ func (r *ChannelRouter) processUpdate(msg interface{}) error {
 			}
 		}
 
-		if !exists && !r.cfg.AssumeChannelValid {
-			// Before we can update the channel information, we'll
-			// ensure that the target channel is still open by
-			// querying the utxo-set for its existence.
-			chanPoint, fundingTxOut, err := r.fetchChanPoint(
-				&channelID,
-			)
-			if err != nil {
-				r.rejectMtx.Lock()
-				r.rejectCache[msg.ChannelID] = struct{}{}
-				r.rejectMtx.Unlock()
-
-				return errors.Errorf("unable to fetch chan "+
-					"point for chan_id=%v: %v",
-					msg.ChannelID, err)
-			}
-			_, err = r.cfg.Chain.GetUtxo(
-				chanPoint, fundingTxOut.PkScript,
-				channelID.BlockHeight,
-			)
-			if err != nil {
-				r.rejectMtx.Lock()
-				r.rejectCache[msg.ChannelID] = struct{}{}
-				r.rejectMtx.Unlock()
-
-				return errors.Errorf("unable to fetch utxo for "+
-					"chan_id=%v: %v", msg.ChannelID, err)
-			}
-		}
-
 		// Now that we know this isn't a stale update, we'll apply the
 		// new edge policy to the proper directional edge within the
 		// channel graph.