From d8c62c37a85a2b9e366ce9f9e940537e805f0bcf Mon Sep 17 00:00:00 2001
From: Oliver Gugger <gugger@gmail.com>
Date: Mon, 10 Feb 2020 11:37:44 +0100
Subject: [PATCH] channel_notifier: update backup on pending chan

To fix the discrepancy between getting the channel backups via
RPC where all pending channels are included, we also update the
channel.backup file on disk whenever we get a pending channel
event notification.
---
 channel_notifier.go | 69 ++++++++++++++++++++++++++-------------------
 1 file changed, 40 insertions(+), 29 deletions(-)

diff --git a/channel_notifier.go b/channel_notifier.go
index 36a2224a..960ba0d9 100644
--- a/channel_notifier.go
+++ b/channel_notifier.go
@@ -7,6 +7,7 @@ import (
 	"github.com/btcsuite/btcd/btcec"
 	"github.com/btcsuite/btcd/wire"
 	"github.com/lightningnetwork/lnd/chanbackup"
+	"github.com/lightningnetwork/lnd/channeldb"
 	"github.com/lightningnetwork/lnd/channelnotifier"
 )
 
@@ -51,6 +52,35 @@ func (c *channelNotifier) SubscribeChans(startingChans map[wire.OutPoint]struct{
 	quit := make(chan struct{})
 	chanUpdates := make(chan chanbackup.ChannelEvent, 1)
 
+	// sendChanOpenUpdate is a closure that sends a ChannelEvent to the
+	// chanUpdates channel to inform subscribers about new pending or
+	// confirmed channels.
+	sendChanOpenUpdate := func(newOrPendingChan *channeldb.OpenChannel) {
+		nodeAddrs, err := c.addrs.AddrsForNode(
+			newOrPendingChan.IdentityPub,
+		)
+		if err != nil {
+			pub := newOrPendingChan.IdentityPub
+			ltndLog.Errorf("unable to fetch addrs for %x: %v",
+				pub.SerializeCompressed(), err)
+		}
+
+		chanEvent := chanbackup.ChannelEvent{
+			NewChans: []chanbackup.ChannelWithAddrs{
+				{
+					OpenChannel: newOrPendingChan,
+					Addrs:       nodeAddrs,
+				},
+			},
+		}
+
+		select {
+		case chanUpdates <- chanEvent:
+		case <-quit:
+			return
+		}
+	}
+
 	// In order to adhere to the interface, we'll proxy the events from the
 	// channel notifier to the sub-swapper in a format it understands.
 	go func() {
@@ -74,37 +104,18 @@ func (c *channelNotifier) SubscribeChans(startingChans map[wire.OutPoint]struct{
 				// TODO(roasbeef): batch dispatch ntnfs
 
 				switch event := e.(type) {
-
-				// A new channel has been opened, we'll obtain
-				// the node address, then send to the
+				// A new channel has been opened and is still
+				// pending. We can still create a backup, even
+				// if the final channel ID is not yet available.
+				case channelnotifier.PendingOpenChannelEvent:
+					pendingChan := event.PendingChannel
+					sendChanOpenUpdate(pendingChan)
+
+				// A new channel has been confirmed, we'll
+				// obtain the node address, then send to the
 				// sub-swapper.
 				case channelnotifier.OpenChannelEvent:
-					nodeAddrs, err := c.addrs.AddrsForNode(
-						event.Channel.IdentityPub,
-					)
-					if err != nil {
-						pub := event.Channel.IdentityPub
-						ltndLog.Errorf("unable to "+
-							"fetch addrs for %x: %v",
-							pub.SerializeCompressed(),
-							err)
-					}
-
-					channel := event.Channel
-					chanEvent := chanbackup.ChannelEvent{
-						NewChans: []chanbackup.ChannelWithAddrs{
-							{
-								OpenChannel: channel,
-								Addrs:       nodeAddrs,
-							},
-						},
-					}
-
-					select {
-					case chanUpdates <- chanEvent:
-					case <-quit:
-						return
-					}
+					sendChanOpenUpdate(event.Channel)
 
 				// An existing channel has been closed, we'll
 				// send only the chanPoint of the closed