Add removechannel command

Author: guggero

README.md

@@ -16,6 +16,7 @@
   + [fixoldbackup](#fixoldbackup)
   + [genimportscript](#genimportscript)
   + [forceclose](#forceclose)
+  + [removechannel](#removechannel)
   + [rescueclosed](#rescueclosed)
   + [rescuefunding](#rescuefunding)
   + [showrootkey](#showrootkey)
@@ -267,6 +268,7 @@ Available commands:
   fixoldbackup         Fixes an old channel.backup file that is affected by the lnd issue #3881 (unable to derive shachain root key).
   forceclose           Force-close the last state that is in the channel.db provided.
   genimportscript      Generate a script containing the on-chain keys of an lnd wallet that can be imported into other software like bitcoind.
+  removechannel        Remove a single channel from the given channel DB.
   rescueclosed         Try finding the private keys for funds that are in outputs of remotely force-closed channels.
   rescuefunding        Rescue funds locked in a funding multisig output that never resulted in a proper channel. This is the command the initiator of the channel needs to run.
   showrootkey          Extract and show the BIP32 HD root key from the 24 word lnd aezeed.
@@ -505,6 +507,26 @@ Example command:
 chantools genimportscript --format bitcoin-cli --recoverywindow 5000
 ```
 
+### removechannel
+
+```text
+Usage:
+  chantools [OPTIONS] removechannel [removechannel-OPTIONS]
+
+[removechannel command options]
+          --channeldb=   The lnd channel.db file to remove the channel from.
+          --channel=     The channel to remove from the DB file, identified by its channel point (<txid>:<txindex>).
+```
+
+Removes a single channel from the given channel DB.
+
+Example command:
+
+```bash
+chantools --channeldb ~/.lnd/data/graph/mainnet/channel.db \
+  --channel 3149764effbe82718b280de425277e5e7b245a4573aa4a0203ac12cee1c37816:0
+```
+
 ### rescueclosed
 
 ```text

cmd/chantools/main.go

@@ -156,6 +156,10 @@ func runCommandParser() error {
 			"-initiator) of the channel needs to run.", "",
 		&signRescueFundingCommand{},
 	)
+	_, _ = parser.AddCommand(
+		"removechannel", "Remove a single channel from the given "+
+			"channel DB.", "", &removeChannelCommand{},
+	)
 
 	_, err := parser.Parse()
 	return err

cmd/chantools/removechannel.go

@@ -0,0 +1,71 @@
+package main
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+
+	"github.com/btcsuite/btcd/chaincfg/chainhash"
+	"github.com/btcsuite/btcd/wire"
+	"github.com/guggero/chantools/lnd"
+	"github.com/lightningnetwork/lnd/channeldb"
+)
+
+type removeChannelCommand struct {
+	ChannelDB string `long:"channeldb" description:"The lnd channel.db file to remove the channel from."`
+	Channel   string `long:"channel" description:"The channel to remove from the DB file, identified by its channel point (<txid>:<txindex>)."`
+}
+
+func (c *removeChannelCommand) Execute(_ []string) error {
+	setupChainParams(cfg)
+
+	// Check that we have a channel DB.
+	if c.ChannelDB == "" {
+		return fmt.Errorf("channel DB is required")
+	}
+	db, err := lnd.OpenDB(c.ChannelDB, false)
+	if err != nil {
+		return fmt.Errorf("error opening channel DB: %v", err)
+	}
+	defer func() {
+		if err := db.Close(); err != nil {
+			log.Errorf("Error closing DB: %v", err)
+		}
+	}()
+
+	parts := strings.Split(c.Channel, ":")
+	if len(parts) != 2 {
+		return fmt.Errorf("invalid channel point format: %v", c.Channel)
+	}
+	hash, err := chainhash.NewHashFromStr(parts[0])
+	if err != nil {
+		return err
+	}
+	index, err := strconv.ParseUint(parts[1], 10, 64)
+	if err != nil {
+		return err
+	}
+
+	return removeChannel(db, &wire.OutPoint{
+		Hash:  *hash,
+		Index: uint32(index),
+	})
+}
+
+func removeChannel(db *channeldb.DB, chanPoint *wire.OutPoint) error {
+	dbChan, err := db.FetchChannel(*chanPoint)
+	if err != nil {
+		return err
+	}
+
+	if err := dbChan.MarkBorked(); err != nil {
+		return err
+	}
+
+	// Abandoning a channel is a three step process: remove from the open
+	// channel state, remove from the graph, remove from the contract
+	// court. Between any step it's possible that the users restarts the
+	// process all over again. As a result, each of the steps below are
+	// intended to be idempotent.
+	return db.AbandonChannel(chanPoint, uint32(100000))
+}