configure.go

package cmd

import (
	"encoding/hex"
	"fmt"
	"io/ioutil"
	"net/http"
	"path"
	"strings"

	homedir "github.com/mitchellh/go-homedir"
	"github.com/spf13/cobra"
	"github.com/spf13/viper"
	"golang.org/x/crypto/sha3"
)

// The NATS URL passed in from command-line
var natsURL string

// The NATS cluster ID passed in from command-line
var natsClusterID string

// Path to CA certificate path (useful for self-signed CAs)
var natsCaCert string

// The URL or filepath to file
var keyFile string

// A known fingerprint in hex format
var knownFingerprint string

// Whether standard uuid format channel names should be used instead of the short names
var useLongName bool

// Whether the current config file should be overwritten
var forceWrite bool

// Shake256MinBytesRequired is our minimum bytes required for input to SHAKE-256
const Shake256MinBytesRequired = 64

func generateFingerprint(keyFile string) string {
	hash := make([]byte, FingerprintByteLength)
	var inputBytes []byte
	var err error
	if keyFile == "" {
		return ""
	}
	if strings.HasPrefix(keyFile, "http://") || strings.HasPrefix(keyFile, "https://") {
		// Read keyfile from url
		resp, err := http.Get(keyFile)
		if err != nil {
			errorExit(err.Error())
		}
		if resp.StatusCode != http.StatusOK {
			errMsg := fmt.Sprintf("Keyfile url not OK - Status code %d was returned from GET %s", resp.StatusCode, keyFile)
			errorExit(errMsg)
		}
		defer resp.Body.Close()
		inputBytes, err = ioutil.ReadAll(resp.Body)
		if err != nil {
			errorExit(err.Error())
		}
	} else {
		// Read keyfile from local file
		inputBytes, err = ioutil.ReadFile(keyFile)
		if err != nil {
			errorExit(err.Error())
		}
	}

	// Generate the fingerprint
	inputBytesLen := len(inputBytes)
	if inputBytesLen < Shake256MinBytesRequired {
		errMsg := fmt.Sprintf("Bad keyfile provided - At least %d bytes required but got %d byte(s).", Shake256MinBytesRequired, inputBytesLen)
		errorExit(errMsg)
	}
	sha3.ShakeSum256(hash, inputBytes)
	return hex.EncodeToString(hash)
}

func init() {
	rootCmd.AddCommand(configureCmd)
	configureCmd.PersistentFlags().StringVar(&natsURL, "nats-url", "", "(advanced) NATS server url")
	configureCmd.PersistentFlags().StringVar(&natsClusterID, "nats-cluster", "", "(advanced) NATS cluster id")
	configureCmd.PersistentFlags().StringVar(&natsCaCert, "nats-cacert", "", "(advanced) Local path to CA certificate used by NATS server")
	configureCmd.PersistentFlags().StringVar(&keyFile, "keyfile", "", "URL or local path to keyfile (at least 64 bytes is required)")
	configureCmd.PersistentFlags().StringVar(&knownFingerprint, "fingerprint", "", "(advanced) If you know the fingerprint you want to use (SHAKE-256 hex), you can set it directly instead of using --keyfile")
	configureCmd.PersistentFlags().BoolVar(&useLongName, "long-names", false, "Use standard uuid format for channel names ")
	configureCmd.PersistentFlags().BoolVar(&forceWrite, "overwrite", false, "Overwrite current configuration")
}

var configureCmd = &cobra.Command{
	Use:   "configure",
	Short: "Configure Convey",
	Run:   ConfigureCommandFunc,
}

// ConfigureCommandFunc is a handler for the configure command
func ConfigureCommandFunc(cmd *cobra.Command, args []string) {
	var fingerprint string
	if knownFingerprint != "" {
		if keyFile != "" {
			errorExit("Specify either --fingerprint OR --keyfile, not both.")
		}
		if IsValidFingerprint(knownFingerprint) {
			fingerprint = knownFingerprint
		} else {
			errorExit(InvalidFingerprintMsg)
		}
	} else {
		fingerprint = generateFingerprint(keyFile)
	}

	// Set config passed on the arguments passed in
	viper.Set(configKeyFingerprint, fingerprint)
	viper.Set(configKeyNatsURL, natsURL)
	viper.Set(configKeyNatsClusterID, natsClusterID)
	viper.Set(configKeyUseLongName, useLongName)
	viper.Set(configKeyNatsCACert, natsCaCert)

	// If a config file is found, read it in.
	configFileExists := false
	if err := viper.ReadInConfig(); err == nil {
		configFileExists = true
	}

	// If config file doesn't exist and it hasn't been set in viper, set it
	if !configFileExists && viper.ConfigFileUsed() == "" {
		home, err := homedir.Dir()
		if err != nil {
			errorExit(err.Error())
		}
		viper.SetConfigFile(path.Join(home, ".convey.yaml"))
	}

	configFilePath := viper.ConfigFileUsed()

	if forceWrite || !configFileExists {
		err := viper.WriteConfigAs(configFilePath)
		if err != nil {
			errorExit(err.Error())
		}
	} else {
		msg := fmt.Sprintf("Config file exists. Use --overwrite to overwrite the config file at %s", configFilePath)
		errorExit(msg)
	}
}