Finish functional implementation of jwt signature verification. Closes …

…#6

cmd/jwt/jwt.go

@@ -21,20 +21,23 @@
 package jwt
 
 import (
+	"bytes"
 	"encoding/base64"
 	"encoding/json"
 	"errors"
 	"fmt"
 	"github.com/chclaus/dt/cmd"
+	"github.com/chclaus/dt/config"
 	"github.com/chclaus/dt/utils"
+	"github.com/dgrijalva/jwt-go"
+	"github.com/fatih/color"
 	"github.com/hokaccha/go-prettyjson"
 	"github.com/spf13/cobra"
+	"github.com/spf13/viper"
+	"io/ioutil"
 	"log"
+	"os"
 	"strings"
-	"github.com/spf13/viper"
-	"github.com/dgrijalva/jwt-go"
-	"github.com/fatih/color"
-	"github.com/chclaus/dt/config"
 )
 
 // jwtCmd represents the jwt command
@@ -50,20 +53,27 @@ var jwtCmd = &cobra.Command{
 	},
 	Long: "Allows decoding of a jwt.",
 	Run: func(cmd *cobra.Command, args []string) {
-		parts := strings.Split(args[0], ".")
+		jwtString := args[0]
+		parts := strings.Split(jwtString, ".")
 		if len(parts) != 3 {
 			log.Fatal("Invalid JWT. It must has a JOSE Header, JWS Payload and JWS Signature")
 		}
 
 		printJWT(parts)
 
-		if config.Cfg.JWT.Secret != "" {
-			_, err := jwt.Parse(args[0], func(token *jwt.Token) (interface{}, error) {
-				return []byte(config.Cfg.JWT.Secret), nil
+		secret, err := determineSecret()
+		if err != nil {
+			log.Fatal(err)
+		}
+
+		if secret != nil {
+			_, err := jwt.Parse(jwtString, func(token *jwt.Token) (interface{}, error) {
+				return []byte(secret), nil
 			})
 			if err != nil {
 				red := color.New(color.FgRed)
 				red.Printf("\nOh no! %s.\n", err)
+				fmt.Printf("Your chosen secret is: '%s'\n", secret)
 			} else {
 				green := color.New(color.FgGreen)
 				green.Printf("\ntoken signature is valid.\n")
@@ -75,6 +85,38 @@ var jwtCmd = &cobra.Command{
 dt jwt eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3MiOiJmb28iLCJzdWIiOiJiYXIifQ.UxyRHFY_BpuDQ1Qp9MVvbn5uAlaoWCUKUIeq1qQIcCw -s foobar`,
 }
 
+func determineSecret() ([]byte, error) {
+	jwtCfg := config.Cfg.JWT
+
+	if jwtCfg.Secret != "" {
+		if jwtCfg.Base64Secret {
+			return []byte(utils.DecodeBase64(base64.StdEncoding, jwtCfg.Secret)), nil
+		}
+
+		return []byte(jwtCfg.Secret), nil
+	}
+
+	if jwtCfg.SecretFile != "" {
+		if _, err := os.Stat(jwtCfg.SecretFile); err != nil {
+			return nil, fmt.Errorf("secret file doesn't exist: %s", err)
+		}
+
+		b, err := ioutil.ReadFile(jwtCfg.SecretFile)
+		if err != nil {
+			return nil, fmt.Errorf("error reading secret file: %s", err)
+		}
+
+		b = bytes.TrimSpace(b)
+		if jwtCfg.Base64Secret {
+			return []byte(utils.DecodeBase64(base64.StdEncoding, string(b))), nil
+		}
+
+		return b, nil
+	}
+
+	return nil, nil
+}
+
 func printJWT(parts []string) {
 	fmt.Println("JOSE Header:")
 	fmt.Println(prettifyPart(parts[0]))
@@ -96,5 +138,9 @@ func init() {
 	cmd.RootCmd.AddCommand(jwtCmd)
 
 	jwtCmd.Flags().StringP("secret", "s", "", "the secret to validate the token signature")
+	jwtCmd.Flags().StringP("secretFile", "f", "", "a file of the secret to validate the token signature")
+	jwtCmd.Flags().BoolP("base64Secret", "b", false, "set to true if the secret is base64 encoded")
 	viper.BindPFlag("jwt.secret", jwtCmd.Flags().Lookup("secret"))
+	viper.BindPFlag("jwt.secretFile", jwtCmd.Flags().Lookup("secretFile"))
+	viper.BindPFlag("jwt.base64Secret", jwtCmd.Flags().Lookup("base64Secret"))
 }

config/config.go

@@ -49,7 +49,9 @@ type HashConfig struct {
 
 // JWTConfig allows configuration settings of the jwt cmd
 type JWTConfig struct {
-	Secret string
+	Secret       string
+	SecretFile   string
+	Base64Secret bool
 }
 
 // Cfg the root object of the configuration