path: root/cmd/swarm/main.go

// Copyright 2016 The go-ethereum Authors
// This file is part of go-ethereum.
//
// go-ethereum is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// go-ethereum is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with go-ethereum. If not, see <http://www.gnu.org/licenses/>.

package main

import (
    "crypto/ecdsa"
    "fmt"
    "io/ioutil"
    "os"
    "os/signal"
    "runtime"
    "sort"
    "strconv"
    "strings"
    "syscall"

    "github.com/ethereum/go-ethereum/accounts"
    "github.com/ethereum/go-ethereum/accounts/keystore"
    "github.com/ethereum/go-ethereum/cmd/utils"
    "github.com/ethereum/go-ethereum/common"
    "github.com/ethereum/go-ethereum/console"
    "github.com/ethereum/go-ethereum/crypto"
    "github.com/ethereum/go-ethereum/internal/debug"
    "github.com/ethereum/go-ethereum/log"
    "github.com/ethereum/go-ethereum/node"
    "github.com/ethereum/go-ethereum/p2p"
    "github.com/ethereum/go-ethereum/p2p/discover"
    "github.com/ethereum/go-ethereum/params"
    "github.com/ethereum/go-ethereum/swarm"
    bzzapi "github.com/ethereum/go-ethereum/swarm/api"
    swarmmetrics "github.com/ethereum/go-ethereum/swarm/metrics"
    "github.com/ethereum/go-ethereum/swarm/tracing"

    "gopkg.in/urfave/cli.v1"
)

const clientIdentifier = "swarm"
const helpTemplate = `NAME:
{{.HelpName}} - {{.Usage}}

USAGE:
{{if .UsageText}}{{.UsageText}}{{else}}{{.HelpName}}{{if .VisibleFlags}} [command options]{{end}} {{if .ArgsUsage}}{{.ArgsUsage}}{{else}}[arguments...]{{end}}{{end}}{{if .Category}}

CATEGORY:
{{.Category}}{{end}}{{if .Description}}

DESCRIPTION:
{{.Description}}{{end}}{{if .VisibleFlags}}

OPTIONS:
{{range .VisibleFlags}}{{.}}
{{end}}{{end}}
`

var (
    gitCommit        string // Git SHA1 commit hash of the release (set via linker flags)
    testbetBootNodes = []string{
        "enode://ec8ae764f7cb0417bdfb009b9d0f18ab3818a3a4e8e7c67dd5f18971a93510a2e6f43cd0b69a27e439a9629457ea804104f37c85e41eed057d3faabbf7744cdf@13.74.157.139:30429",
        "enode://c2e1fceb3bf3be19dff71eec6cccf19f2dbf7567ee017d130240c670be8594bc9163353ca55dd8df7a4f161dd94b36d0615c17418b5a3cdcbb4e9d99dfa4de37@13.74.157.139:30430",
        "enode://fe29b82319b734ce1ec68b84657d57145fee237387e63273989d354486731e59f78858e452ef800a020559da22dcca759536e6aa5517c53930d29ce0b1029286@13.74.157.139:30431",
        "enode://1d7187e7bde45cf0bee489ce9852dd6d1a0d9aa67a33a6b8e6db8a4fbc6fcfa6f0f1a5419343671521b863b187d1c73bad3603bae66421d157ffef357669ddb8@13.74.157.139:30432",
        "enode://0e4cba800f7b1ee73673afa6a4acead4018f0149d2e3216be3f133318fd165b324cd71b81fbe1e80deac8dbf56e57a49db7be67f8b9bc81bd2b7ee496434fb5d@13.74.157.139:30433",
    }
)

var (
    ChequebookAddrFlag = cli.StringFlag{
        Name:   "chequebook",
        Usage:  "chequebook contract address",
        EnvVar: SWARM_ENV_CHEQUEBOOK_ADDR,
    }
    SwarmAccountFlag = cli.StringFlag{
        Name:   "bzzaccount",
        Usage:  "Swarm account key file",
        EnvVar: SWARM_ENV_ACCOUNT,
    }
    SwarmListenAddrFlag = cli.StringFlag{
        Name:   "httpaddr",
        Usage:  "Swarm HTTP API listening interface",
        EnvVar: SWARM_ENV_LISTEN_ADDR,
    }
    SwarmPortFlag = cli.StringFlag{
        Name:   "bzzport",
        Usage:  "Swarm local http api port",
        EnvVar: SWARM_ENV_PORT,
    }
    SwarmNetworkIdFlag = cli.IntFlag{
        Name:   "bzznetworkid",
        Usage:  "Network identifier (integer, default 3=swarm testnet)",
        EnvVar: SWARM_ENV_NETWORK_ID,
    }
    SwarmSwapEnabledFlag = cli.BoolFlag{
        Name:   "swap",
        Usage:  "Swarm SWAP enabled (default false)",
        EnvVar: SWARM_ENV_SWAP_ENABLE,
    }
    SwarmSwapAPIFlag = cli.StringFlag{
        Name:   "swap-api",
        Usage:  "URL of the Ethereum API provider to use to settle SWAP payments",
        EnvVar: SWARM_ENV_SWAP_API,
    }
    SwarmSyncDisabledFlag = cli.BoolTFlag{
        Name:   "nosync",
        Usage:  "Disable swarm syncing",
        EnvVar: SWARM_ENV_SYNC_DISABLE,
    }
    SwarmSyncUpdateDelay = cli.DurationFlag{
        Name:   "sync-update-delay",
        Usage:  "Duration for sync subscriptions update after no new peers are added (default 15s)",
        EnvVar: SWARM_ENV_SYNC_UPDATE_DELAY,
    }
    SwarmDeliverySkipCheckFlag = cli.BoolFlag{
        Name:   "delivery-skip-check",
        Usage:  "Skip chunk delivery check (default false)",
        EnvVar: SWARM_ENV_DELIVERY_SKIP_CHECK,
    }
    EnsAPIFlag = cli.StringSliceFlag{
        Name:   "ens-api",
        Usage:  "ENS API endpoint for a TLD and with contract address, can be repeated, format [tld:][contract-addr@]url",
        EnvVar: SWARM_ENV_ENS_API,
    }
    SwarmApiFlag = cli.StringFlag{
        Name:  "bzzapi",
        Usage: "Swarm HTTP endpoint",
        Value: "http://127.0.0.1:8500",
    }
    SwarmRecursiveFlag = cli.BoolFlag{
        Name:  "recursive",
        Usage: "Upload directories recursively",
    }
    SwarmWantManifestFlag = cli.BoolTFlag{
        Name:  "manifest",
        Usage: "Automatic manifest upload (default true)",
    }
    SwarmUploadDefaultPath = cli.StringFlag{
        Name:  "defaultpath",
        Usage: "path to file served for empty url path (none)",
    }
    SwarmUpFromStdinFlag = cli.BoolFlag{
        Name:  "stdin",
        Usage: "reads data to be uploaded from stdin",
    }
    SwarmUploadMimeType = cli.StringFlag{
        Name:  "mime",
        Usage: "Manually specify MIME type",
    }
    SwarmEncryptedFlag = cli.BoolFlag{
        Name:  "encrypt",
        Usage: "use encrypted upload",
    }
    CorsStringFlag = cli.StringFlag{
        Name:   "corsdomain",
        Usage:  "Domain on which to send Access-Control-Allow-Origin header (multiple domains can be supplied separated by a ',')",
        EnvVar: SWARM_ENV_CORS,
    }
    SwarmStorePath = cli.StringFlag{
        Name:   "store.path",
        Usage:  "Path to leveldb chunk DB (default <$GETH_ENV_DIR>/swarm/bzz-<$BZZ_KEY>/chunks)",
        EnvVar: SWARM_ENV_STORE_PATH,
    }
    SwarmStoreCapacity = cli.Uint64Flag{
        Name:   "store.size",
        Usage:  "Number of chunks (5M is roughly 20-25GB) (default 5000000)",
        EnvVar: SWARM_ENV_STORE_CAPACITY,
    }
    SwarmStoreCacheCapacity = cli.UintFlag{
        Name:   "store.cache.size",
        Usage:  "Number of recent chunks cached in memory (default 5000)",
        EnvVar: SWARM_ENV_STORE_CACHE_CAPACITY,
    }
)

//declare a few constant error messages, useful for later error check comparisons in test
var (
    SWARM_ERR_NO_BZZACCOUNT   = "bzzaccount option is required but not set; check your config file, command line or environment variables"
    SWARM_ERR_SWAP_SET_NO_API = "SWAP is enabled but --swap-api is not set"
)

// this help command gets added to any subcommand that does not define it explicitly
var defaultSubcommandHelp = cli.Command{
    Action:             func(ctx *cli.Context) { cli.ShowCommandHelpAndExit(ctx, "", 1) },
    CustomHelpTemplate: helpTemplate,
    Name:               "help",
    Usage:              "shows this help",
    Hidden:             true,
}

var defaultNodeConfig = node.DefaultConfig

// This init function sets defaults so cmd/swarm can run alongside geth.
func init() {
    defaultNodeConfig.Name = clientIdentifier
    defaultNodeConfig.Version = params.VersionWithCommit(gitCommit)
    defaultNodeConfig.P2P.ListenAddr = ":30399"
    defaultNodeConfig.IPCPath = "bzzd.ipc"
    // Set flag defaults for --help display.
    utils.ListenPortFlag.Value = 30399
}

var app = utils.NewApp(gitCommit, "Ethereum Swarm")

// This init function creates the cli.App.
func init() {
    app.Action = bzzd
    app.HideVersion = true // we have a command to print the version
    app.Copyright = "Copyright 2013-2016 The go-ethereum Authors"
    app.Commands = []cli.Command{
        {
            Action:             version,
            CustomHelpTemplate: helpTemplate,
            Name:               "version",
            Usage:              "Print version numbers",
            Description:        "The output of this command is supposed to be machine-readable",
        },
        {
            Action:             upload,
            CustomHelpTemplate: helpTemplate,
            Name:               "up",
            Usage:              "uploads a file or directory to swarm using the HTTP API",
            ArgsUsage:          "<file>",
            Flags:              []cli.Flag{SwarmEncryptedFlag},
            Description:        "uploads a file or directory to swarm using the HTTP API and prints the root hash",
        },
        {
            Action:             list,
            CustomHelpTemplate: helpTemplate,
            Name:               "ls",
            Usage:              "list files and directories contained in a manifest",
            ArgsUsage:          "<manifest> [<prefix>]",
            Description:        "Lists files and directories contained in a manifest",
        },
        {
            Action:             hash,
            CustomHelpTemplate: helpTemplate,
            Name:               "hash",
            Usage:              "print the swarm hash of a file or directory",
            ArgsUsage:          "<file>",
            Description:        "Prints the swarm hash of file or directory",
        },
        {
            Action:    download,
            Name:      "down",
            Flags:     []cli.Flag{SwarmRecursiveFlag},
            Usage:     "downloads a swarm manifest or a file inside a manifest",
            ArgsUsage: " <uri> [<dir>]",
            Description: `
Downloads a swarm bzz uri to the given dir. When no dir is provided, working directory is assumed. --recursive flag is expected when downloading a manifest with multiple entries.
`,
        },

        {
            Name:               "manifest",
            CustomHelpTemplate: helpTemplate,
            Usage:              "perform operations on swarm manifests",
            ArgsUsage:          "COMMAND",
            Description:        "Updates a MANIFEST by adding/removing/updating the hash of a path.\nCOMMAND could be: add, update, remove",
            Subcommands: []cli.Command{
                {
                    Action:             add,
                    CustomHelpTemplate: helpTemplate,
                    Name:               "add",
                    Usage:              "add a new path to the manifest",
                    ArgsUsage:          "<MANIFEST> <path> <hash> [<content-type>]",
                    Description:        "Adds a new path to the manifest",
                },
                {
                    Action:             update,
                    CustomHelpTemplate: helpTemplate,
                    Name:               "update",
                    Usage:              "update the hash for an already existing path in the manifest",
                    ArgsUsage:          "<MANIFEST> <path> <newhash> [<newcontent-type>]",
                    Description:        "Update the hash for an already existing path in the manifest",
                },
                {
                    Action:             remove,
                    CustomHelpTemplate: helpTemplate,
                    Name:               "remove",
                    Usage:              "removes a path from the manifest",
                    ArgsUsage:          "<MANIFEST> <path>",
                    Description:        "Removes a path from the manifest",
                },
            },
        },
        {
            Name:               "fs",
            CustomHelpTemplate: helpTemplate,
            Usage:              "perform FUSE operations",
            ArgsUsage:          "fs COMMAND",
            Description:        "Performs FUSE operations by mounting/unmounting/listing mount points. This assumes you already have a Swarm node running locally. For all operation you must reference the correct path to bzzd.ipc in order to communicate with the node",
            Subcommands: []cli.Command{
                {
                    Action:             mount,
                    CustomHelpTemplate: helpTemplate,
                    Name:               "mount",
                    Flags:              []cli.Flag{utils.IPCPathFlag},
                    Usage:              "mount a swarm hash to a mount point",
                    ArgsUsage:          "swarm fs mount --ipcpath <path to bzzd.ipc> <manifest hash> <mount point>",
                    Description:        "Mounts a Swarm manifest hash to a given mount point. This assumes you already have a Swarm node running locally. You must reference the correct path to your bzzd.ipc file",
                },
                {
                    Action:             unmount,
                    CustomHelpTemplate: helpTemplate,
                    Name:               "unmount",
                    Flags:              []cli.Flag{utils.IPCPathFlag},
                    Usage:              "unmount a swarmfs mount",
                    ArgsUsage:          "swarm fs unmount --ipcpath <path to bzzd.ipc> <mount point>",
                    Description:        "Unmounts a swarmfs mount residing at <mount point>. This assumes you already have a Swarm node running locally. You must reference the correct path to your bzzd.ipc file",
                },
                {
                    Action:             listMounts,
                    CustomHelpTemplate: helpTemplate,
                    Name:               "list",
                    Flags:              []cli.Flag{utils.IPCPathFlag},
                    Usage:              "list swarmfs mounts",
                    ArgsUsage:          "swarm fs list --ipcpath <path to bzzd.ipc>",
                    Description:        "Lists all mounted swarmfs volumes. This assumes you already have a Swarm node running locally. You must reference the correct path to your bzzd.ipc file",
                },
            },
        },
        {
            Name:               "db",
            CustomHelpTemplate: helpTemplate,
            Usage:              "manage the local chunk database",
            ArgsUsage:          "db COMMAND",
            Description:        "Manage the local chunk database",
            Subcommands: []cli.Command{
                {
                    Action:             dbExport,
                    CustomHelpTemplate: helpTemplate,
                    Name:               "export",
                    Usage:              "export a local chunk database as a tar archive (use - to send to stdout)",
                    ArgsUsage:          "<chunkdb> <file>",
                    Description: `
Export a local chunk database as a tar archive (use - to send to stdout).

    swarm db export ~/.ethereum/swarm/bzz-KEY/chunks chunks.tar

The export may be quite large, consider piping the output through the Unix
pv(1) tool to get a progress bar:

    swarm db export ~/.ethereum/swarm/bzz-KEY/chunks - | pv > chunks.tar
`,
                },
                {
                    Action:             dbImport,
                    CustomHelpTemplate: helpTemplate,
                    Name:               "import",
                    Usage:              "import chunks from a tar archive into a local chunk database (use - to read from stdin)",
                    ArgsUsage:          "<chunkdb> <file>",
                    Description: `
Import chunks from a tar archive into a local chunk database (use - to read from stdin).

    swarm db import ~/.ethereum/swarm/bzz-KEY/chunks chunks.tar

The import may be quite large, consider piping the input through the Unix
pv(1) tool to get a progress bar:

    pv chunks.tar | swarm db import ~/.ethereum/swarm/bzz-KEY/chunks -
`,
                },
                {
                    Action:             dbClean,
                    CustomHelpTemplate: helpTemplate,
                    Name:               "clean",
                    Usage:              "remove corrupt entries from a local chunk database",
                    ArgsUsage:          "<chunkdb>",
                    Description:        "Remove corrupt entries from a local chunk database",
                },
            },
        },

        // See config.go
        DumpConfigCommand,
    }

    // append a hidden help subcommand to all commands that have subcommands
    // if a help command was already defined above, that one will take precedence.
    addDefaultHelpSubcommands(app.Commands)

    sort.Sort(cli.CommandsByName(app.Commands))

    app.Flags = []cli.Flag{
        utils.IdentityFlag,
        utils.DataDirFlag,
        utils.BootnodesFlag,
        utils.KeyStoreDirFlag,
        utils.ListenPortFlag,
        utils.NoDiscoverFlag,
        utils.DiscoveryV5Flag,
        utils.NetrestrictFlag,
        utils.NodeKeyFileFlag,
        utils.NodeKeyHexFlag,
        utils.MaxPeersFlag,
        utils.NATFlag,
        utils.IPCDisabledFlag,
        utils.IPCPathFlag,
        utils.PasswordFileFlag,
        // bzzd-specific flags
        CorsStringFlag,
        EnsAPIFlag,
        SwarmTomlConfigPathFlag,
        SwarmSwapEnabledFlag,
        SwarmSwapAPIFlag,
        SwarmSyncDisabledFlag,
        SwarmSyncUpdateDelay,
        SwarmDeliverySkipCheckFlag,
        SwarmListenAddrFlag,
        SwarmPortFlag,
        SwarmAccountFlag,
        SwarmNetworkIdFlag,
        ChequebookAddrFlag,
        // upload flags
        SwarmApiFlag,
        SwarmRecursiveFlag,
        SwarmWantManifestFlag,
        SwarmUploadDefaultPath,
        SwarmUpFromStdinFlag,
        SwarmUploadMimeType,
        // storage flags
        SwarmStorePath,
        SwarmStoreCapacity,
        SwarmStoreCacheCapacity,
    }
    rpcFlags := []cli.Flag{
        utils.WSEnabledFlag,
        utils.WSListenAddrFlag,
        utils.WSPortFlag,
        utils.WSApiFlag,
        utils.WSAllowedOriginsFlag,
    }
    app.Flags = append(app.Flags, rpcFlags...)
    app.Flags = append(app.Flags, debug.Flags...)
    app.Flags = append(app.Flags, swarmmetrics.Flags...)
    app.Flags = append(app.Flags, tracing.Flags...)
    app.Before = func(ctx *cli.Context) error {
        runtime.GOMAXPROCS(runtime.NumCPU())
        if err := debug.Setup(ctx, ""); err != nil {
            return err
        }
        swarmmetrics.Setup(ctx)
        tracing.Setup(ctx)
        return nil
    }
    app.After = func(ctx *cli.Context) error {
        debug.Exit()
        return nil
    }
}

func main() {
    if err := app.Run(os.Args); err != nil {
        fmt.Fprintln(os.Stderr, err)
        os.Exit(1)
    }
}

func version(ctx *cli.Context) error {
    fmt.Println("Version:", SWARM_VERSION)
    if gitCommit != "" {
        fmt.Println("Git Commit:", gitCommit)
    }
    fmt.Println("Go Version:", runtime.Version())
    fmt.Println("OS:", runtime.GOOS)
    return nil
}

func bzzd(ctx *cli.Context) error {
    //build a valid bzzapi.Config from all available sources:
    //default config, file config, command line and env vars
    bzzconfig, err := buildConfig(ctx)
    if err != nil {
        utils.Fatalf("unable to configure swarm: %v", err)
    }

    cfg := defaultNodeConfig

    //pss operates on ws
    cfg.WSModules = append(cfg.WSModules, "pss")

    //geth only supports --datadir via command line
    //in order to be consistent within swarm, if we pass --datadir via environment variable
    //or via config file, we get the same directory for geth and swarm
    if _, err := os.Stat(bzzconfig.Path); err == nil {
        cfg.DataDir = bzzconfig.Path
    }
    //setup the ethereum node
    utils.SetNodeConfig(ctx, &cfg)
    stack, err := node.New(&cfg)
    if err != nil {
        utils.Fatalf("can't create node: %v", err)
    }
    //a few steps need to be done after the config phase is completed,
    //due to overriding behavior
    initSwarmNode(bzzconfig, stack, ctx)
    //register BZZ as node.Service in the ethereum node
    registerBzzService(bzzconfig, stack)
    //start the node
    utils.StartNode(stack)

    go func() {
        sigc := make(chan os.Signal, 1)
        signal.Notify(sigc, syscall.SIGTERM)
        defer signal.Stop(sigc)
        <-sigc
        log.Info("Got sigterm, shutting swarm down...")
        stack.Stop()
    }()

    // Add bootnodes as initial peers.
    if bzzconfig.BootNodes != "" {
        bootnodes := strings.Split(bzzconfig.BootNodes, ",")
        injectBootnodes(stack.Server(), bootnodes)
    } else {
        if bzzconfig.NetworkID == 3 {
            injectBootnodes(stack.Server(), testbetBootNodes)
        }
    }

    stack.Wait()
    return nil
}

func registerBzzService(bzzconfig *bzzapi.Config, stack *node.Node) {
    //define the swarm service boot function
    boot := func(_ *node.ServiceContext) (node.Service, error) {
        // In production, mockStore must be always nil.
        return swarm.NewSwarm(bzzconfig, nil)
    }
    //register within the ethereum node
    if err := stack.Register(boot); err != nil {
        utils.Fatalf("Failed to register the Swarm service: %v", err)
    }
}

func getAccount(bzzaccount string, ctx *cli.Context, stack *node.Node) *ecdsa.PrivateKey {
    //an account is mandatory
    if bzzaccount == "" {
        utils.Fatalf(SWARM_ERR_NO_BZZACCOUNT)
    }
    // Try to load the arg as a hex key file.
    if key, err := crypto.LoadECDSA(bzzaccount); err == nil {
        log.Info("Swarm account key loaded", "address", crypto.PubkeyToAddress(key.PublicKey))
        return key
    }
    // Otherwise try getting it from the keystore.
    am := stack.AccountManager()
    ks := am.Backends(keystore.KeyStoreType)[0].(*keystore.KeyStore)

    return decryptStoreAccount(ks, bzzaccount, utils.MakePasswordList(ctx))
}

func decryptStoreAccount(ks *keystore.KeyStore, account string, passwords []string) *ecdsa.PrivateKey {
    var a accounts.Account
    var err error
    if common.IsHexAddress(account) {
        a, err = ks.Find(accounts.Account{Address: common.HexToAddress(account)})
    } else if ix, ixerr := strconv.Atoi(account); ixerr == nil && ix > 0 {
        if accounts := ks.Accounts(); len(accounts) > ix {
            a = accounts[ix]
        } else {
            err = fmt.Errorf("index %d higher than number of accounts %d", ix, len(accounts))
        }
    } else {
        utils.Fatalf("Can't find swarm account key %s", account)
    }
    if err != nil {
        utils.Fatalf("Can't find swarm account key: %v - Is the provided bzzaccount(%s) from the right datadir/Path?", err, account)
    }
    keyjson, err := ioutil.ReadFile(a.URL.Path)
    if err != nil {
        utils.Fatalf("Can't load swarm account key: %v", err)
    }
    for i := 0; i < 3; i++ {
        password := getPassPhrase(fmt.Sprintf("Unlocking swarm account %s [%d/3]", a.Address.Hex(), i+1), i, passwords)
        key, err := keystore.DecryptKey(keyjson, password)
        if err == nil {
            return key.PrivateKey
        }
    }
    utils.Fatalf("Can't decrypt swarm account key")
    return nil
}

// getPassPhrase retrieves the password associated with bzz account, either by fetching
// from a list of pre-loaded passwords, or by requesting it interactively from user.
func getPassPhrase(prompt string, i int, passwords []string) string {
    // non-interactive
    if len(passwords) > 0 {
        if i < len(passwords) {
            return passwords[i]
        }
        return passwords[len(passwords)-1]
    }

    // fallback to interactive mode
    if prompt != "" {
        fmt.Println(prompt)
    }
    password, err := console.Stdin.PromptPassword("Passphrase: ")
    if err != nil {
        utils.Fatalf("Failed to read passphrase: %v", err)
    }
    return password
}

func injectBootnodes(srv *p2p.Server, nodes []string) {
    for _, url := range nodes {
        n, err := discover.ParseNode(url)
        if err != nil {
            log.Error("Invalid swarm bootnode", "err", err)
            continue
        }
        srv.AddPeer(n)
    }
}

// addDefaultHelpSubcommand scans through defined CLI commands and adds
// a basic help subcommand to each
// if a help command is already defined, it will take precedence over the default.
func addDefaultHelpSubcommands(commands []cli.Command) {
    for i := range commands {
        cmd := &commands[i]
        if cmd.Subcommands != nil {
            cmd.Subcommands = append(cmd.Subcommands, defaultSubcommandHelp)
            addDefaultHelpSubcommands(cmd.Subcommands)
        }
    }
}