config.go

package main

import (
	"fmt"
	"os"
	"path/filepath"
	"sort"
	"strings"

	"github.com/btcsuite/go-flags"
	"github.com/decred/dcrutil"
)

const (
	defaultConfigFilename = "gominer.conf"
	defaultLogLevel       = "info"
	defaultDataDirname    = "data"
	defaultLogDirname     = "logs"
	defaultLogFilename    = "gominer.log"
)

var (
	homeDir            = dcrutil.AppDataDir("dcrd", false)
	defaultConfigFile  = filepath.Join(homeDir, defaultConfigFilename)
	defaultDataDir     = filepath.Join(homeDir, defaultDataDirname)
	defaultRPCKeyFile  = filepath.Join(homeDir, "rpc.key")
	defaultRPCCertFile = filepath.Join(homeDir, "rpc.cert")
	defaultLogDir      = filepath.Join(homeDir, defaultLogDirname)
)

type config struct {
	ShowVersion bool `short:"V" long:"version" description:"Display version information and exit"`

	// Config / log options
	ConfigFile string `short:"C" long:"configfile" description:"Path to configuration file"`
	DataDir    string `short:"b" long:"datadir" description:"Directory to store wallets and transactions"`
	LogDir     string `long:"logdir" description:"Directory to log output."`
	DebugLevel string `short:"d" long:"debuglevel" description:"Logging level for all subsystems {trace, debug, info, warn, error, critical} -- You may also specify <subsystem>=<level>,<subsystem2>=<level>,... to set the log level for individual subsystems -- Use show to list available subsystems"`

	// Debugging options
	Profile    string `long:"profile" description:"Enable HTTP profiling on given port -- NOTE port must be between 1024 and 65536"`
	CPUProfile string `long:"cpuprofile" description:"Write CPU profile to the specified file"`
	MemProfile string `long:"memprofile" description:"Write mem profile to the specified file"`

	// RPC connection options
	RPCConnect string `short:"c" long:"rpcconnect" description:"Hostname/IP and port of dcrd RPC server to connect to (default localhost:19109, mainnet: localhost:9109, simnet: localhost:19556)"`
	Username   string `short:"u" long:"username" description:"Username for client and dcrd authorization"`
	Password   string `short:"P" long:"password" default-mask:"-" description:"Password for client and dcrd authorization"`
	CAFile     string `long:"cafile" description:"File containing root certificates to authenticate a TLS connections with dcrd"`
	RPCCert    string `long:"rpccert" description:"File containing the certificate file"`
	RPCKey     string `long:"rpckey" description:"File containing the certificate key"`
	DisableTLS bool   `long:"notls" description:"Disable TLS for the RPC client -- NOTE: This is only allowed if the RPC client is connecting to localhost"`
	Benchmark  bool   `short:"B" long:"benchmark" description:"Run in benchmark mode."`
}

// filesExists reports whether the named file or directory exists.
func fileExists(name string) bool {
	if _, err := os.Stat(name); err != nil {
		if os.IsNotExist(err) {
			return false
		}
	}
	return true
}

// validLogLevel returns whether or not logLevel is a valid debug log level.
func validLogLevel(logLevel string) bool {
	switch logLevel {
	case "trace":
		fallthrough
	case "debug":
		fallthrough
	case "info":
		fallthrough
	case "warn":
		fallthrough
	case "error":
		fallthrough
	case "critical":
		return true
	}
	return false
}

// 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 btcd 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() (*config, []string, error) {
	// Default config.
	cfg := config{
		ConfigFile: defaultConfigFile,
		DebugLevel: defaultLogLevel,
		DataDir:    defaultDataDir,
		LogDir:     defaultLogDir,
		RPCKey:     defaultRPCKeyFile,
		RPCCert:    defaultRPCCertFile,
	}

	// A config file in the current directory takes precedence.
	if fileExists(defaultConfigFilename) {
		cfg.ConfigFile = defaultConfigFile
	}

	// 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 {
		if e, ok := err.(*flags.Error); !ok || e.Type != flags.ErrHelp {
			preParser.WriteHelp(os.Stderr)
		}
		return nil, nil, 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.Println(appName, "version", version())
		os.Exit(0)
	}

	// Load additional config from file.
	var configFileError error
	parser := flags.NewParser(&cfg, flags.Default)
	err = flags.NewIniParser(parser).ParseFile(preCfg.ConfigFile)
	if err != nil {
		if _, ok := err.(*os.PathError); !ok {
			fmt.Fprintln(os.Stderr, err)
			parser.WriteHelp(os.Stderr)
			return nil, nil, 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 nil, nil, 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.DataDir != defaultDataDir {
		if cfg.RPCKey == defaultRPCKeyFile {
			cfg.RPCKey = filepath.Join(cfg.DataDir, "rpc.key")
		}
		if cfg.RPCCert == defaultRPCCertFile {
			cfg.RPCCert = filepath.Join(cfg.DataDir, "rpc.cert")
		}
	}

	// Create the home directory if it doesn't already exist.
	err = os.MkdirAll(homeDir, 0700)
	if err != nil {
		// Show a nicer error message if it's because a symlink is
		// linked to a directory that does not exist (probably because
		// it's not mounted).
		if e, ok := err.(*os.PathError); ok && os.IsExist(err) {
			if link, lerr := os.Readlink(e.Path); lerr == nil {
				str := "is symlink %s -> %s mounted?"
				err = fmt.Errorf(str, e.Path, link)
			}
		}

		str := "%s: Failed to create home directory: %v"
		err := fmt.Errorf(str, funcName, err)
		fmt.Fprintln(os.Stderr, err)
		return nil, nil, err
	}

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

	// Initialize logging at the default logging level.
	initSeelogLogger(filepath.Join(cfg.LogDir, defaultLogFilename))
	setLogLevels(defaultLogLevel)

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

	if cfg.RPCConnect == "" {
		cfg.RPCConnect = "http://localhost:9109"
	}

	// Warn about missing config file only after all other configuration is
	// done.  This prevents the warning on help messages and invalid
	// options.  Note this should go directly before the return.
	if configFileError != nil {
		mainLog.Warnf("%v", configFileError)
	}

	return &cfg, remainingArgs, nil
}