From eb4413154d219766a8a7a4d94b60abe229c9d6bc Mon Sep 17 00:00:00 2001
From: Wilmer Paulino <wilmer.paulino@gmail.com>
Date: Thu, 29 Apr 2021 15:45:06 -0700
Subject: [PATCH] routing: return err on validation failure of network update

This ensures the waiting receiving channel always receives an error to
prevent a deadlock when processing a network update that fails due to
the validation barrier.

On commit d5aedbcbd9db510c974c9f7be5ab177ad6546994:

1000 @ 0x43a285 0x44a38f 0xc42e86 0xc80fda 0xc8682d 0xc976c9 0x46fce1
github.com/lightningnetwork/lnd/routing.(*ChannelRouter).AddNode+0x245                      github.com/lightningnetwork/lnd/routing/router.go:2218
github.com/lightningnetwork/lnd/discovery.(*AuthenticatedGossiper).addNode+0x3b9            github.com/lightningnetwork/lnd/discovery/gossiper.go:1510
github.com/lightningnetwork/lnd/discovery.(*AuthenticatedGossiper).processNetworkAnnouncement+0x574c github.com/lightningnetwork/lnd/discovery/gossiper.go:1554
github.com/lightningnetwork/lnd/discovery.(*AuthenticatedGossiper).networkHandler.func1+0x24github.com/lightningnetwork/lnd/discovery/gossiper.go:1043
---
 routing/router.go | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/routing/router.go b/routing/router.go
index 20f7ee0c..a609bff3 100644
--- a/routing/router.go
+++ b/routing/router.go
@@ -1038,12 +1038,19 @@ func (r *ChannelRouter) networkHandler() {
 					update.msg,
 				)
 				if err != nil {
-					if err != ErrVBarrierShuttingDown &&
-						err != ErrParentValidationFailed {
+					switch err {
+					case ErrVBarrierShuttingDown:
+						update.err <- err
+					case ErrParentValidationFailed:
+						update.err <- newErrf(
+							ErrIgnored, err.Error(),
+						)
+					default:
 						log.Warnf("unexpected error "+
 							"during validation "+
 							"barrier shutdown: %v",
 							err)
+						update.err <- err
 					}
 					return
 				}