dcrd/cmd/checkdevpremine/config.go

// Copyright (c) 2016 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 (
	"fmt"
	"net"
	"os"
	"path/filepath"
	"strings"

	"github.com/decred/dcrd/dcrutil"

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

var (
	dcrdHomeDir        = dcrutil.AppDataDir("dcrd", false)
	appHomeDir         = dcrutil.AppDataDir("checkdevpremine", false)
	defaultConfigFile  = filepath.Join(appHomeDir, "checkdevpremine.conf")
	defaultRPCServer   = "localhost"
	defaultRPCCertFile = filepath.Join(dcrdHomeDir, "rpc.cert")
)

// config defines the configuration options for dcrctl.
//
// See loadConfig for details on the configuration load process.
type config struct {
	ConfigFile  string `short:"C" long:"configfile" description:"Path to configuration file"`
	RPCUser     string `short:"u" long:"rpcuser" description:"RPC username"`
	RPCPassword string `short:"P" long:"rpcpass" default-mask:"-" description:"RPC password"`
	RPCServer   string `short:"s" long:"rpcserver" description:"RPC server to connect to"`
	RPCCert     string `short:"c" long:"rpccert" description:"RPC server certificate chain for validation"`
	NoTLS       bool   `long:"notls" description:"Disable TLS"`
	Quiet       bool   `long:"quiet" description:"Do not print any found outpoints which can be useful if only relying on the return code"`
}

// normalizeAddress returns addr with the default port appended if there is not
// already a port specified.
func normalizeAddress(addr string) string {
	_, _, err := net.SplitHostPort(addr)
	if err != nil {
		return net.JoinHostPort(addr, "9109")
	}
	return addr
}

// cleanAndExpandPath expands environement variables and leading ~ in the
// passed path, cleans the result, and returns it.
func cleanAndExpandPath(path string) string {
	// Expand initial ~ to OS specific home directory.
	if strings.HasPrefix(path, "~") {
		homeDir := filepath.Dir(appHomeDir)
		path = strings.Replace(path, "~", homeDir, 1)
	}

	// NOTE: The os.ExpandEnv doesn't work with Windows-style %VARIABLE%,
	// but they variables can still be expanded via POSIX-style $VARIABLE.
	return filepath.Clean(os.ExpandEnv(path))
}

// 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 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,
		RPCServer:  defaultRPCServer,
		RPCCert:    defaultRPCCertFile,
	}

	// Create the home directory if it doesn't already exist.
	err := os.MkdirAll(dcrdHomeDir, 0700)
	if err != nil {
		fmt.Fprintf(os.Stderr, "%v\n", err)
		os.Exit(-1)
	}

	// Pre-parse the command line options to see if an alternative config
	// file, the version flag, or the list commands flag was specified.  Any
	// errors aside from the help message error can be ignored here since
	// they will be caught by the final parse below.
	preCfg := cfg
	preParser := flags.NewParser(&preCfg, flags.HelpFlag)
	_, err = preParser.Parse()
	if err != nil {
		if e, ok := err.(*flags.Error); ok && e.Type == flags.ErrHelp {
			fmt.Fprintln(os.Stderr, err)
			fmt.Fprintln(os.Stderr, "")
			fmt.Fprintln(os.Stderr, "The special parameter `-` "+
				"indicates that a parameter should be read "+
				"from the\nnext unread line from standard "+
				"input.")
			return nil, nil, err
		}
	}

	// Load additional config from file.
	appName := filepath.Base(os.Args[0])
	appName = strings.TrimSuffix(appName, filepath.Ext(appName))
	usageMessage := fmt.Sprintf("Use %s -h to show options", appName)
	parser := flags.NewParser(&cfg, flags.Default)
	err = flags.NewIniParser(parser).ParseFile(preCfg.ConfigFile)
	if err != nil {
		if _, ok := err.(*os.PathError); !ok {
			fmt.Fprintf(os.Stderr, "Error parsing config file: %v\n",
				err)
			fmt.Fprintln(os.Stderr, usageMessage)
			return nil, nil, 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 {
			fmt.Fprintln(os.Stderr, usageMessage)
		}
		return nil, nil, err
	}

	// Handle environment variable expansion in the RPC certificate path.
	cfg.RPCCert = cleanAndExpandPath(cfg.RPCCert)

	// Add default port to RPC server if needed.
	cfg.RPCServer = normalizeAddress(cfg.RPCServer)

	return &cfg, remainingArgs, nil
}