config.go

// Copyright (c) 2013-2016 The btcsuite developers
// Copyright (c) 2015-2017 The Decred developers
// Use of this source code is governed by an ISC
// license that can be found in the LICENSE file.

package main

import (
	"context"
	"fmt"
	"net"
	"os"
	"os/user"
	"path/filepath"
	"runtime"
	"sort"
	"strings"

	"github.com/btcsuite/btclog"
	"github.com/decred/dcrd/dcrutil"
	"github.com/decred/tumblebit/internal/cfgutil"
	"github.com/decred/tumblebit/netparams"
	"github.com/decred/tumblebit/tumbler"
	"github.com/decred/tumblebit/version"

	flags "github.com/jessevdk/go-flags"
)

const (
	defaultCAFilename     = "dcrwallet.cert"
	defaultConfigFilename = "tumblebit.conf"
	defaultLogLevel       = "info"
	defaultLogDirname     = "logs"
	defaultLogFilename    = "tumblebit.log"
)

var (
	walletDefaultCAFile = filepath.Join(dcrutil.AppDataDir("dcrwallet", false), "rpc.cert")
	defaultAppDataDir   = dcrutil.AppDataDir("tumblebit", false)
	defaultConfigFile   = filepath.Join(defaultAppDataDir, defaultConfigFilename)
	defaultRPCKeyFile   = filepath.Join(defaultAppDataDir, "rpc.key")
	defaultRPCCertFile  = filepath.Join(defaultAppDataDir, "rpc.cert")
	defaultLogDir       = filepath.Join(defaultAppDataDir, defaultLogDirname)
)

type config struct {
	// General application behavior
	ConfigFile  *cfgutil.ExplicitString `short:"C" long:"configfile" description:"Path to configuration file"`
	ShowVersion bool                    `short:"V" long:"version" description:"Display version information and exit"`
	AppDataDir  *cfgutil.ExplicitString `short:"A" long:"appdata" description:"Application data directory for tumblebit config, databases and logs"`
	TestNet     bool                    `long:"testnet" description:"Use the test network"`
	SimNet      bool                    `long:"simnet" description:"Use the simulation test network"`
	DebugLevel  string                  `short:"d" long:"debuglevel" description:"Logging level {trace, debug, info, warn, error, critical}"`
	LogDir      *cfgutil.ExplicitString `long:"logdir" description:"Directory to log output."`
	MemProfile  string                  `long:"memprofile" description:"Write mem profile to the specified file"`

	// RPC client options
	RPCConnect       string                  `short:"c" long:"rpcconnect" description:"Hostname/IP and port of dcrwallet RPC server to connect to"`
	CAFile           *cfgutil.ExplicitString `long:"cafile" description:"File containing root certificates to authenticate a TLS connections with dcrwallet"`
	DisableClientTLS bool                    `long:"noclienttls" description:"Disable TLS for the RPC client -- NOTE: This is only allowed if the RPC client is connecting to localhost"`
	WalletPassword   string                  `long:"walletpassword" default-mask:"-" description:"The private passphrase to unlock the wallet"`
	Account          uint32                  `long:"account" description:"BIP0044 account number to use for transactions"`
	AccountName      string                  `long:"accountname" description:"Name of the account to use for transactions -- NOTE: This takes precedence over the numeric specification"`

	// RPC server options
	RPCCert          *cfgutil.ExplicitString `long:"rpccert" description:"File containing the certificate file"`
	RPCKey           *cfgutil.ExplicitString `long:"rpckey" description:"File containing the certificate key"`
	TLSCurve         *cfgutil.CurveFlag      `long:"tlscurve" description:"Curve to use when generating TLS keypairs"`
	OneTimeTLSKey    bool                    `long:"onetimetlskey" description:"Generate a new TLS certpair at startup, but only write the certificate to disk"`
	DisableServerTLS bool                    `long:"noservertls" description:"Disable TLS for the RPC servers -- NOTE: This is only allowed if the RPC server is bound to localhost"`
	GRPCListeners    []string                `long:"grpclisten" description:"Listen for gRPC connections on this interface/port"`

	// TumbleBit specific options
	EpochDuration    int32 `long:"epochduration" description:"Duration of a single epoch and a TumbleBit escrow"`
	EpochRenewal     int32 `long:"epochrenewal" description:"Interval between two consecutive epochs"`
	PuzzleDifficulty int   `long:"puzzledifficulty" description:"TumbleBit puzzle difficulty"`
}

// cleanAndExpandPath expands environement variables and leading ~ in the
// passed path, cleans the result, and returns it.
func cleanAndExpandPath(path string) string {
	// NOTE: The os.ExpandEnv doesn't work with Windows cmd.exe-style
	// %VARIABLE%, but they variables can still be expanded via POSIX-style
	// $VARIABLE.
	path = os.ExpandEnv(path)

	if !strings.HasPrefix(path, "~") {
		return filepath.Clean(path)
	}

	// Expand initial ~ to the current user's home directory, or ~otheruser
	// to otheruser's home directory.  On Windows, both forward and backward
	// slashes can be used.
	path = path[1:]

	var pathSeparators string
	if runtime.GOOS == "windows" {
		pathSeparators = string(os.PathSeparator) + "/"
	} else {
		pathSeparators = string(os.PathSeparator)
	}

	userName := ""
	if i := strings.IndexAny(path, pathSeparators); i != -1 {
		userName = path[:i]
		path = path[i:]
	}

	homeDir := ""
	var u *user.User
	var err error
	if userName == "" {
		u, err = user.Current()
	} else {
		u, err = user.Lookup(userName)
	}
	if err == nil {
		homeDir = u.HomeDir
	}
	// Fallback to CWD if user lookup fails or user has no home directory.
	if homeDir == "" {
		homeDir = "."
	}

	return filepath.Join(homeDir, path)
}

// validLogLevel returns whether or not logLevel is a valid debug log level.
func validLogLevel(logLevel string) bool {
	_, ok := btclog.LevelFromString(logLevel)
	return ok
}

// supportedSubsystems returns a sorted slice of the supported subsystems for
// logging purposes.
func supportedSubsystems() []string {
	// Convert the subsystemLoggers map keys to a slice.
	subsystems := make([]string, 0, len(subsystemLoggers))
	for subsysID := range subsystemLoggers {
		subsystems = append(subsystems, subsysID)
	}

	// Sort the subsytems for stable display.
	sort.Strings(subsystems)
	return subsystems
}

// parseAndSetDebugLevels attempts to parse the specified debug level and set
// the levels accordingly.  An appropriate error is returned if anything is
// invalid.
func parseAndSetDebugLevels(debugLevel string) error {
	// When the specified string doesn't have any delimters, treat it as
	// the log level for all subsystems.
	if !strings.Contains(debugLevel, ",") && !strings.Contains(debugLevel, "=") {
		// Validate debug log level.
		if !validLogLevel(debugLevel) {
			str := "The specified debug level [%v] is invalid"
			return fmt.Errorf(str, debugLevel)
		}

		// Change the logging level for all subsystems.
		setLogLevels(debugLevel)

		return nil
	}

	// Split the specified string into subsystem/level pairs while detecting
	// issues and update the log levels accordingly.
	for _, logLevelPair := range strings.Split(debugLevel, ",") {
		if !strings.Contains(logLevelPair, "=") {
			str := "The specified debug level contains an invalid " +
				"subsystem/level pair [%v]"
			return fmt.Errorf(str, logLevelPair)
		}

		// Extract the specified subsystem and log level.
		fields := strings.Split(logLevelPair, "=")
		subsysID, logLevel := fields[0], fields[1]

		// Validate subsystem.
		if _, exists := subsystemLoggers[subsysID]; !exists {
			str := "The specified subsystem [%v] is invalid -- " +
				"supported subsytems %v"
			return fmt.Errorf(str, subsysID, supportedSubsystems())
		}

		// Validate log level.
		if !validLogLevel(logLevel) {
			str := "The specified debug level [%v] is invalid"
			return fmt.Errorf(str, logLevel)
		}

		setLogLevel(subsysID, logLevel)
	}

	return nil
}

// loadConfig initializes and parses the config using a config file and command
// line options.
//
// The configuration proceeds as follows:
//      1) Start with a default config with sane settings
//      2) Pre-parse the command line to check for an alternative config file
//      3) Load configuration file overwriting defaults with any specified options
//      4) Parse CLI options and overwrite/add any specified options
//
// The above results in tumblebit functioning properly without any config
// settings while still allowing the user to override settings with config files
// and command line options.  Command line options always take precedence.
func loadConfig(ctx context.Context) (*config, []string, error) {
	loadConfigError := func(err error) (*config, []string, error) {
		return nil, nil, err
	}

	// Default config.
	cfg := config{
		DebugLevel: defaultLogLevel,
		ConfigFile: cfgutil.NewExplicitString(defaultConfigFile),
		AppDataDir: cfgutil.NewExplicitString(defaultAppDataDir),
		LogDir:     cfgutil.NewExplicitString(defaultLogDir),
		CAFile:     cfgutil.NewExplicitString(""),
		RPCKey:     cfgutil.NewExplicitString(defaultRPCKeyFile),
		RPCCert:    cfgutil.NewExplicitString(defaultRPCCertFile),
		TLSCurve:   cfgutil.NewCurveFlag(cfgutil.CurveP521),
	}

	// Pre-parse the command line options to see if an alternative config
	// file or the version flag was specified.
	preCfg := cfg
	preParser := flags.NewParser(&preCfg, flags.Default)
	_, err := preParser.Parse()
	if err != nil {
		e, ok := err.(*flags.Error)
		if ok && e.Type == flags.ErrHelp {
			os.Exit(0)
		}
		preParser.WriteHelp(os.Stderr)
		return loadConfigError(err)
	}

	// Show the version and exit if the version flag was specified.
	funcName := "loadConfig"
	appName := filepath.Base(os.Args[0])
	appName = strings.TrimSuffix(appName, filepath.Ext(appName))
	usageMessage := fmt.Sprintf("Use %s -h to show usage", appName)
	if preCfg.ShowVersion {
		fmt.Printf("%s version %s (Go version %s)\n", appName, version.String(), runtime.Version())
		os.Exit(0)
	}

	// Load additional config from file.
	var configFileError error
	parser := flags.NewParser(&cfg, flags.Default)
	configFilePath := preCfg.ConfigFile.Value
	if preCfg.ConfigFile.ExplicitlySet() {
		configFilePath = cleanAndExpandPath(configFilePath)
	} else {
		appDataDir := preCfg.AppDataDir.Value
		if appDataDir != defaultAppDataDir {
			configFilePath = filepath.Join(appDataDir, defaultConfigFilename)
		}
	}
	err = flags.NewIniParser(parser).ParseFile(configFilePath)
	if err != nil {
		if _, ok := err.(*os.PathError); !ok {
			fmt.Fprintln(os.Stderr, err)
			parser.WriteHelp(os.Stderr)
			return loadConfigError(err)
		}
		configFileError = err
	}

	// Parse command line options again to ensure they take precedence.
	remainingArgs, err := parser.Parse()
	if err != nil {
		if e, ok := err.(*flags.Error); !ok || e.Type != flags.ErrHelp {
			parser.WriteHelp(os.Stderr)
		}
		return loadConfigError(err)
	}

	// If an alternate data directory was specified, and paths with defaults
	// relative to the data dir are unchanged, modify each path to be
	// relative to the new data dir.
	if cfg.AppDataDir.ExplicitlySet() {
		cfg.AppDataDir.Value = cleanAndExpandPath(cfg.AppDataDir.Value)
		if !cfg.RPCKey.ExplicitlySet() {
			cfg.RPCKey.Value = filepath.Join(cfg.AppDataDir.Value, "rpc.key")
		}
		if !cfg.RPCCert.ExplicitlySet() {
			cfg.RPCCert.Value = filepath.Join(cfg.AppDataDir.Value, "rpc.cert")
		}
		if !cfg.LogDir.ExplicitlySet() {
			cfg.LogDir.Value = filepath.Join(cfg.AppDataDir.Value, defaultLogDirname)
		}
	}

	// Choose the active network params based on the selected network.
	// Multiple networks can't be selected simultaneously.
	numNets := 0
	if cfg.TestNet {
		activeNet = &netparams.TestNet2Params
		numNets++
	}
	if cfg.SimNet {
		activeNet = &netparams.SimNetParams
		numNets++
	}
	if numNets > 1 {
		str := "%s: The testnet and simnet params can't be used " +
			"together -- choose one"
		err := fmt.Errorf(str, "loadConfig")
		fmt.Fprintln(os.Stderr, err)
		return loadConfigError(err)
	}

	// Append the network type to the log directory so it is "namespaced"
	// per network.
	cfg.LogDir.Value = cleanAndExpandPath(cfg.LogDir.Value)
	cfg.LogDir.Value = filepath.Join(cfg.LogDir.Value, activeNet.Params.Name)

	// Special show command to list supported subsystems and exit.
	if cfg.DebugLevel == "show" {
		fmt.Println("Supported subsystems", supportedSubsystems())
		os.Exit(0)
	}

	// Initialize log rotation.  After log rotation has been initialized, the
	// logger variables may be used.
	initLogRotator(filepath.Join(cfg.LogDir.Value, defaultLogFilename))

	// Parse, validate, and set debug log level(s).
	if err := parseAndSetDebugLevels(cfg.DebugLevel); err != nil {
		err := fmt.Errorf("%s: %v", "loadConfig", err.Error())
		fmt.Fprintln(os.Stderr, err)
		parser.WriteHelp(os.Stderr)
		return loadConfigError(err)
	}

	// Error and shutdown if config file is specified on the command line
	// but cannot be found.
	if configFileError != nil && cfg.ConfigFile.ExplicitlySet() {
		if preCfg.ConfigFile.ExplicitlySet() || cfg.ConfigFile.ExplicitlySet() {
			log.Errorf("%v", configFileError)
			return loadConfigError(configFileError)
		}
	}

	// Warn about missing config file after the final command line parse
	// succeeds.  This prevents the warning on help messages and invalid
	// options.
	if configFileError != nil {
		log.Warnf("%v", configFileError)
	}

	if cfg.RPCConnect == "" {
		cfg.RPCConnect = net.JoinHostPort("localhost", activeNet.WalletClientPort)
	}

	// Add default port to connect flag if missing.
	cfg.RPCConnect, err = cfgutil.NormalizeAddress(cfg.RPCConnect,
		activeNet.WalletClientPort)
	if err != nil {
		fmt.Fprintf(os.Stderr,
			"Invalid rpcconnect network address: %v\n", err)
		return loadConfigError(err)
	}

	localhostListeners := map[string]struct{}{
		"localhost": {},
		"127.0.0.1": {},
		"::1":       {},
	}
	RPCHost, _, err := net.SplitHostPort(cfg.RPCConnect)
	if err != nil {
		return loadConfigError(err)
	}
	if cfg.DisableClientTLS {
		if _, ok := localhostListeners[RPCHost]; !ok {
			str := "%s: the --noclienttls option may not be used " +
				"when connecting RPC to non localhost " +
				"addresses: %s"
			err := fmt.Errorf(str, funcName, cfg.RPCConnect)
			fmt.Fprintln(os.Stderr, err)
			fmt.Fprintln(os.Stderr, usageMessage)
			return loadConfigError(err)
		}
	} else {
		// If CAFile is unset, choose either the copy or local dcrwallet cert.
		if !cfg.CAFile.ExplicitlySet() {
			cfg.CAFile.Value = filepath.Join(cfg.AppDataDir.Value, defaultCAFilename)

			// If the CA copy does not exist, check if we're connecting to
			// a local dcrwallet and switch to its RPC cert if it exists.
			certExists, err := cfgutil.FileExists(cfg.CAFile.Value)
			if err != nil {
				fmt.Fprintln(os.Stderr, err)
				return loadConfigError(err)
			}
			if !certExists {
				if _, ok := localhostListeners[RPCHost]; ok {
					walletCertExists, err := cfgutil.FileExists(
						walletDefaultCAFile)
					if err != nil {
						fmt.Fprintln(os.Stderr, err)
						return loadConfigError(err)
					}
					if walletCertExists {
						cfg.CAFile.Value = walletDefaultCAFile
					}
				}
			}
		}
	}

	// Default to localhost listen addresses if no listeners were manually
	// specified.  When the RPC server is configured to be disabled, remove all
	// listeners so it is not started.
	localhostAddrs, err := net.LookupHost("localhost")
	if err != nil {
		return loadConfigError(err)
	}
	if len(cfg.GRPCListeners) == 0 {
		cfg.GRPCListeners = make([]string, 0, len(localhostAddrs))
		for _, addr := range localhostAddrs {
			cfg.GRPCListeners = append(cfg.GRPCListeners,
				net.JoinHostPort(addr, activeNet.TumblerServerPort))
		}
	}

	// Add default port to all rpc listener addresses if needed and remove
	// duplicate addresses.
	cfg.GRPCListeners, err = cfgutil.NormalizeAddresses(
		cfg.GRPCListeners, activeNet.TumblerServerPort)
	if err != nil {
		fmt.Fprintf(os.Stderr,
			"Invalid network address in RPC listeners: %v\n", err)
		return loadConfigError(err)
	}

	// Only allow server TLS to be disabled if the RPC server is bound to
	// localhost addresses.
	if cfg.DisableServerTLS {
		for _, addr := range cfg.GRPCListeners {
			host, _, err := net.SplitHostPort(addr)
			if err != nil {
				str := "%s: RPC listen interface '%s' is " +
					"invalid: %v"
				err := fmt.Errorf(str, funcName, addr, err)
				fmt.Fprintln(os.Stderr, err)
				fmt.Fprintln(os.Stderr, usageMessage)
				return loadConfigError(err)
			}
			if _, ok := localhostListeners[host]; !ok {
				str := "%s: the --noservertls option may not be used " +
					"when binding RPC to non localhost " +
					"addresses: %s"
				err := fmt.Errorf(str, funcName, addr)
				fmt.Fprintln(os.Stderr, err)
				fmt.Fprintln(os.Stderr, usageMessage)
				return loadConfigError(err)
			}
		}
	}

	// Expand environment variable and leading ~ for filepaths.
	cfg.CAFile.Value = cleanAndExpandPath(cfg.CAFile.Value)
	cfg.RPCCert.Value = cleanAndExpandPath(cfg.RPCCert.Value)
	cfg.RPCKey.Value = cleanAndExpandPath(cfg.RPCKey.Value)

	// TumbleBit defaults
	if cfg.PuzzleDifficulty == 0 {
		cfg.PuzzleDifficulty = tumbler.PuzzleDifficulty
	}
	if cfg.EpochDuration == 0 {
		cfg.EpochDuration = tumbler.EpochDuration
	}
	if cfg.EpochRenewal == 0 {
		cfg.EpochRenewal = tumbler.EpochRenewal
	}

	return &cfg, remainingArgs, nil
}