multi: add new dropgraphzombies command

README.md

@@ -414,6 +414,7 @@ Available Commands:
   derivekey           Derive a key with a specific derivation path
   doublespendinputs   Tries to double spend the given inputs by deriving the private for the address and sweeping the funds to the given address. This can only be used with inputs that belong to an lnd wallet.
   dropchannelgraph    Remove all graph related data from a channel DB
+  dropgraphzombies    Remove all channels identified as zombies from the graph to force a re-sync of the graph
   dumpbackup          Dump the content of a channel.backup file
   dumpchannels        Dump all channel information from an lnd channel database
   fakechanbackup      Fake a channel backup file to attempt fund recovery
@@ -471,6 +472,7 @@ Legend:
 | [derivekey](doc/chantools_derivekey.md)                     | :pencil: Derive a single private/public key from `lnd`'s seed, use to test seed                                                          |
 | [doublespendinputs](doc/chantools_doublespendinputs.md)     | :pencil: Tries to double spend the given inputs by deriving the private for the address and sweeping the funds to the given address      |
 | [dropchannelgraph](doc/chantools_dropchannelgraph.md)       | (:warning:) Completely drop the channel graph from a `channel.db` to force re-sync                                                       |
+| [dropgraphzombies](doc/chantools_dropgraphzombies.md)       | Drop all zombie channels from a `channel.db` to force a graph re-sync                                                                    |
 | [dumpbackup](doc/chantools_dumpbackup.md)                   | :pencil: Show the content of a `channel.backup` file as text                                                                             |
 | [dumpchannels](doc/chantools_dumpchannels.md)               | Show the content of a `channel.db` file as text                                                                                          |
 | [fakechanbackup](doc/chantools_fakechanbackup.md)           | :pencil: Create a fake `channel.backup` file from public information                                                                     |

cmd/chantools/dropchannelgraph.go

@@ -58,7 +58,7 @@ chantools dropchannelgraph \
 		RunE: cc.Execute,
 	}
 	cc.cmd.Flags().StringVar(
-		&cc.ChannelDB, "channeldb", "", "lnd channel.db file to dump "+
+		&cc.ChannelDB, "channeldb", "", "lnd channel.db file to drop "+
 			"channels from",
 	)
 	cc.cmd.Flags().Uint64Var(

cmd/chantools/dropgraphzombies.go

@@ -0,0 +1,88 @@
+package main
+
+import (
+	"fmt"
+
+	"github.com/lightninglabs/chantools/lnd"
+	"github.com/lightningnetwork/lnd/channeldb"
+	"github.com/spf13/cobra"
+)
+
+var (
+	zombieBucket = []byte("zombie-index")
+)
+
+type dropGraphZombiesCommand struct {
+	ChannelDB       string
+	NodeIdentityKey string
+	FixOnly         bool
+
+	SingleChannel uint64
+
+	cmd *cobra.Command
+}
+
+func newDropGraphZombiesCommand() *cobra.Command {
+	cc := &dropGraphZombiesCommand{}
+	cc.cmd = &cobra.Command{
+		Use: "dropgraphzombies",
+		Short: "Remove all channels identified as zombies from the " +
+			"graph to force a re-sync of the graph",
+		Long: `This command removes all channels that were identified as
+zombies from the local graph.
+
+This will cause lnd to re-download all those channels from the network and can
+be helpful to fix a graph that is out of sync with the network.
+
+CAUTION: Running this command will make it impossible to use the channel DB
+with an older version of lnd. Downgrading is not possible and you'll need to
+run lnd ` + lndVersion + ` or later after using this command!'`,
+		Example: `chantools dropgraphzombies \
+	--channeldb ~/.lnd/data/graph/mainnet/channel.db`,
+		RunE: cc.Execute,
+	}
+	cc.cmd.Flags().StringVar(
+		&cc.ChannelDB, "channeldb", "", "lnd channel.db file to drop "+
+			"zombies from",
+	)
+
+	return cc.cmd
+}
+
+func (c *dropGraphZombiesCommand) Execute(_ *cobra.Command, _ []string) error {
+	// 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 rescue DB: %w", err)
+	}
+	defer func() { _ = db.Close() }()
+
+	log.Infof("Dropping zombie channel bucket")
+
+	rwTx, err := db.BeginReadWriteTx()
+	if err != nil {
+		return err
+	}
+
+	success := false
+	defer func() {
+		if !success {
+			_ = rwTx.Rollback()
+		}
+	}()
+
+	edges := rwTx.ReadWriteBucket(edgeBucket)
+	if edges == nil {
+		return channeldb.ErrGraphNoEdgesFound
+	}
+
+	if err := edges.DeleteNestedBucket(zombieBucket); err != nil {
+		return err
+	}
+
+	success = true
+	return rwTx.Commit()
+}

cmd/chantools/root.go

@@ -103,6 +103,7 @@ func main() {
 		newDeriveKeyCommand(),
 		newDoubleSpendInputsCommand(),
 		newDropChannelGraphCommand(),
+		newDropGraphZombiesCommand(),
 		newDumpBackupCommand(),
 		newDumpChannelsCommand(),
 		newDocCommand(),

doc/chantools.md

@@ -26,6 +26,7 @@ Complete documentation is available at https://github.com/lightninglabs/chantool
 * [chantools derivekey](chantools_derivekey.md)	 - Derive a key with a specific derivation path
 * [chantools doublespendinputs](chantools_doublespendinputs.md)	 - Tries to double spend the given inputs by deriving the private for the address and sweeping the funds to the given address. This can only be used with inputs that belong to an lnd wallet.
 * [chantools dropchannelgraph](chantools_dropchannelgraph.md)	 - Remove all graph related data from a channel DB
+* [chantools dropgraphzombies](chantools_dropgraphzombies.md)	 - Remove all channels identified as zombies from the graph to force a re-sync of the graph
 * [chantools dumpbackup](chantools_dumpbackup.md)	 - Dump the content of a channel.backup file
 * [chantools dumpchannels](chantools_dumpchannels.md)	 - Dump all channel information from an lnd channel database
 * [chantools fakechanbackup](chantools_fakechanbackup.md)	 - Fake a channel backup file to attempt fund recovery

doc/chantools_dropchannelgraph.md

@@ -34,7 +34,7 @@ chantools dropchannelgraph \
 ### Options
 
 ```
-      --channeldb string           lnd channel.db file to dump channels from
+      --channeldb string           lnd channel.db file to drop channels from
       --fix_only                   fix an already empty graph by re-adding the own node's channels
   -h, --help                       help for dropchannelgraph
       --node_identity_key string   your node's identity public key

doc/chantools_dropgraphzombies.md

@@ -0,0 +1,46 @@
+## chantools dropgraphzombies
+
+Remove all channels identified as zombies from the graph to force a re-sync of the graph
+
+### Synopsis
+
+This command removes all channels that were identified as
+zombies from the local graph.
+
+This will cause lnd to re-download all those channels from the network and can
+be helpful to fix a graph that is out of sync with the network.
+
+CAUTION: Running this command will make it impossible to use the channel DB
+with an older version of lnd. Downgrading is not possible and you'll need to
+run lnd v0.16.0-beta or later after using this command!'
+
+```
+chantools dropgraphzombies [flags]
+```
+
+### Examples
+
+```
+chantools dropgraphzombies \
+	--channeldb ~/.lnd/data/graph/mainnet/channel.db
+```
+
+### Options
+
+```
+      --channeldb string   lnd channel.db file to drop zombies from
+  -h, --help               help for dropgraphzombies
+```
+
+### Options inherited from parent commands
+
+```
+  -r, --regtest   Indicates if regtest parameters should be used
+  -s, --signet    Indicates if the public signet parameters should be used
+  -t, --testnet   Indicates if testnet parameters should be used
+```
+
+### SEE ALSO
+
+* [chantools](chantools.md)	 - Chantools helps recover funds from lightning channels
+