Add filterbackup command

README.md

@@ -7,6 +7,7 @@
 * [Commands](#commands)
   + [dumpbackup](#dumpbackup)
   + [dumpchannels](#dumpchannels)
+  + [filterbackup](#filterbackup)
   + [forceclose](#forceclose)
   + [rescueclosed](#rescueclosed)
   + [showrootkey](#showrootkey)
@@ -54,6 +55,7 @@ Available commands:
   derivekey      Derive a key with a specific derivation path from the BIP32 HD root key.
   dumpbackup     Dump the content of a channel.backup file.
   dumpchannels   Dump all channel information from lnd's channel database.
+  filterbackup   Filter an lnd channel.backup file and remove certain channels.
   forceclose     Force-close the last state that is in the channel.db provided.
   rescueclosed   Try finding the private keys for funds that are in outputs of remotely force-closed channels.
   showrootkey    Extract and show the BIP32 HD root key from the 24 word lnd aezeed.
@@ -126,6 +128,29 @@ Example command:
 chantools dumpchannels --channeldb ~/.lnd/data/graph/mainnet/channel.db
 ```
 
+### filterbackup
+
+```text
+Usage:
+  chantools [OPTIONS] filterbackup [filterbackup-OPTIONS]
+
+[filterbackup command options]
+          --rootkey=     BIP32 HD root key of the wallet that was used to create the backup. Leave empty to prompt for lnd 24 word aezeed.
+          --multi_file=  The lnd channel.backup file to filter.
+          --discard=     A comma separated list of channel funding outpoints (format <fundingTXID>:<index>) to remove from the backup file.
+```
+
+Filter an lnd `channel.backup` file by removing certain channels (identified by
+their funding transaction outpoints). 
+
+Example command:
+
+```bash
+chantools filterbackup --rootkey xprvxxxxxxxxxx \
+  --multi_file ~/.lnd/data/chain/bitcoin/mainnet/channel.backup \
+  --discard 2abcdef2b2bffaaa...db0abadd:1,4abcdef2b2bffaaa...db8abadd:0
+```
+
 ### forceclose
 
 ```text

cmd/chantools/dumpbackup.go

@@ -8,6 +8,7 @@ import (
 	"github.com/guggero/chantools/btc"
 	"github.com/guggero/chantools/dump"
 	"github.com/lightningnetwork/lnd/chanbackup"
+	"github.com/lightningnetwork/lnd/keychain"
 )
 
 type dumpBackupCommand struct {
@@ -40,17 +41,20 @@ func (c *dumpBackupCommand) Execute(_ []string) error {
 		return fmt.Errorf("backup file is required")
 	}
 	multiFile := chanbackup.NewMultiFile(c.MultiFile)
-	multi, err := multiFile.ExtractMulti(&btc.ChannelBackupEncryptionRing{
+	keyRing := &btc.ChannelBackupEncryptionRing{
 		ExtendedKey: extendedKey,
 		ChainParams: chainParams,
-	})
-	if err != nil {
-		return fmt.Errorf("could not extract multi file: %v", err)
 	}
-	return dumpChannelBackup(multi)
+	return dumpChannelBackup(multiFile, keyRing)
 }
 
-func dumpChannelBackup(multi *chanbackup.Multi) error {
+func dumpChannelBackup(multiFile *chanbackup.MultiFile,
+	ring keychain.KeyRing) error {
+
+	multi, err := multiFile.ExtractMulti(ring)
+	if err != nil {
+		return fmt.Errorf("could not extract multi file: %v", err)
+	}
 	dumpSingles := make([]dump.BackupSingle, len(multi.StaticBackups))
 	for idx, single := range multi.StaticBackups {
 		dumpSingles[idx] = dump.BackupSingle{

cmd/chantools/filterbackup.go

@@ -0,0 +1,92 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"strings"
+	"time"
+
+	"github.com/btcsuite/btcutil/hdkeychain"
+	"github.com/guggero/chantools/btc"
+	"github.com/lightningnetwork/lnd/chanbackup"
+	"github.com/lightningnetwork/lnd/keychain"
+)
+
+type filterBackupCommand struct {
+	RootKey   string `long:"rootkey" description:"BIP32 HD root key of the wallet that was used to create the backup. Leave empty to prompt for lnd 24 word aezeed."`
+	MultiFile string `long:"multi_file" description:"The lnd channel.backup file to filter."`
+	Discard   string `long:"discard" description:"A comma separated list of channel funding outpoints (format <fundingTXID>:<index>) to remove from the backup file."`
+}
+
+func (c *filterBackupCommand) Execute(_ []string) error {
+	setupChainParams(cfg)
+
+	var (
+		extendedKey *hdkeychain.ExtendedKey
+		err         error
+	)
+
+	// Check that root key is valid or fall back to console input.
+	switch {
+	case c.RootKey != "":
+		extendedKey, err = hdkeychain.NewKeyFromString(c.RootKey)
+
+	default:
+		extendedKey, err = rootKeyFromConsole()
+	}
+	if err != nil {
+		return fmt.Errorf("error reading root key: %v", err)
+	}
+
+	// Parse discard filter.
+	discard := strings.Split(c.Discard, ",")
+
+	// Check that we have a backup file.
+	if c.MultiFile == "" {
+		return fmt.Errorf("backup file is required")
+	}
+	multiFile := chanbackup.NewMultiFile(c.MultiFile)
+	keyRing := &btc.ChannelBackupEncryptionRing{
+		ExtendedKey: extendedKey,
+		ChainParams: chainParams,
+	}
+	return filterChannelBackup(multiFile, keyRing, discard)
+}
+
+func filterChannelBackup(multiFile *chanbackup.MultiFile, ring keychain.KeyRing,
+	discard []string) error {
+
+	multi, err := multiFile.ExtractMulti(ring)
+	if err != nil {
+		return fmt.Errorf("could not extract multi file: %v", err)
+	}
+
+	keep := make([]chanbackup.Single, 0, len(multi.StaticBackups))
+	for _, single := range multi.StaticBackups {
+		found := false
+		for _, discardChanPoint := range discard {
+			if single.FundingOutpoint.String() == discardChanPoint {
+				found = true
+			}
+		}
+		if found {
+			continue
+		}
+		keep = append(keep, single)
+	}
+	multi.StaticBackups = keep
+
+	fileName := fmt.Sprintf("results/backup-filtered-%s.backup",
+		time.Now().Format("2006-01-02-15-04-05"))
+	log.Infof("Writing result to %s", fileName)
+	f, err := os.OpenFile(fileName, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0644)
+	if err != nil {
+		return err
+	}
+	err = multi.PackToWriter(f, ring)
+	_ = f.Close()
+	if err != nil {
+		return err
+	}
+	return nil
+}

cmd/chantools/main.go

@@ -93,6 +93,10 @@ func runCommandParser() error {
 		"derivekey", "Derive a key with a specific derivation path "+
 			"from the BIP32 HD root key.", "", &deriveKeyCommand{},
 	)
+	_, _ = parser.AddCommand(
+		"filterbackup", "Filter an lnd channel.backup file and " +
+			"remove certain channels.", "", &filterBackupCommand{},
+	)
 
 	_, err := parser.Parse()
 	return err

dataformat/input.go

@@ -61,8 +61,8 @@ func (c *ListChannelsChannel) AsSummaryEntry() *SummaryEntry {
 	return &SummaryEntry{
 		RemotePubkey:   c.RemotePubkey,
 		ChannelPoint:   c.ChannelPoint,
-		FundingTXID:    fundingTXID(c.ChannelPoint),
+		FundingTXID:    FundingTXID(c.ChannelPoint),
-		FundingTXIndex: fundingTXIndex(c.ChannelPoint),
+		FundingTXIndex: FundingTXIndex(c.ChannelPoint),
 		Capacity:       uint64(c.Capacity),
 		Initiator:      c.Initiator,
 		LocalBalance:   uint64(c.LocalBalance),
@@ -115,8 +115,8 @@ func (c *PendingChannelsChannel) AsSummaryEntry() *SummaryEntry {
 	return &SummaryEntry{
 		RemotePubkey:   c.Channel.RemotePubkey,
 		ChannelPoint:   c.Channel.ChannelPoint,
-		FundingTXID:    fundingTXID(c.Channel.ChannelPoint),
+		FundingTXID:    FundingTXID(c.Channel.ChannelPoint),
-		FundingTXIndex: fundingTXIndex(c.Channel.ChannelPoint),
+		FundingTXIndex: FundingTXIndex(c.Channel.ChannelPoint),
 		Capacity:       uint64(c.Channel.Capacity),
 		Initiator:      false,
 		LocalBalance:   uint64(c.Channel.LocalBalance),
@@ -159,7 +159,7 @@ func (f *SummaryEntryFile) AsSummaryEntries() ([]*SummaryEntry, error) {
 	return f.Channels, nil
 }
 
-func fundingTXID(chanPoint string) string {
+func FundingTXID(chanPoint string) string {
 	parts := strings.Split(chanPoint, ":")
 	if len(parts) != 2 {
 		panic(fmt.Errorf("channel point not in format <txid>:<idx>: %s",
@@ -168,7 +168,7 @@ func fundingTXID(chanPoint string) string {
 	return parts[0]
 }
 
-func fundingTXIndex(chanPoint string) uint32 {
+func FundingTXIndex(chanPoint string) uint32 {
 	parts := strings.Split(chanPoint, ":")
 	if len(parts) != 2 {
 		panic(fmt.Errorf("channel point %s not in format <txid>:<idx>",