Commit a77d4cd5 authored by Dave Grijalva's avatar Dave Grijalva

a useful example app

parent 71c6a65c
.DS_Store
bin
package main
import (
"encoding/json"
"flag"
"fmt"
"io"
"io/ioutil"
"os"
"github.com/dgrijalva/jwt-go"
)
var (
// Options
flagAlg = flag.String("alg", "", "signing algorithm identifier")
flagKey = flag.String("key", "", "path to key file or '-' to read from stdin")
flagPretty = flag.Bool("pretty", true, "output pretty JSON")
// Modes - exactly one of these is required
flagSign = flag.String("sign", "", "path to claims object to sign or '-' to read from stdin")
flagVerify = flag.String("verify", "", "path to JWT token to verify or '-' to read from stdin")
)
func main() {
// Usage message if you ask for -help or if you mess up inputs.
// TODO: make this better
flag.Usage = func() {
fmt.Fprintf(os.Stderr, "Usage of %s:\n", os.Args[0])
fmt.Fprintf(os.Stderr, " One of the following flags is required: sign, verify\n")
flag.PrintDefaults()
}
// Parse command line options
flag.Parse()
// Do the thing. If something goes wrong, print error to stderr
// and exit with a non-zero status code
if err := start(); err != nil {
fmt.Fprintf(os.Stderr, "Error: %v\n", err)
os.Exit(1)
}
}
// Figure out which thing
func start() error {
if *flagSign != "" {
return signToken()
} else if *flagVerify != "" {
return verifyToken()
} else {
flag.Usage()
return fmt.Errorf("None of the required flags are present. What do you want me to do?")
}
}
// Read input from specified file or stdin
func loadData(p string) ([]byte, error) {
if p == "" {
return nil, fmt.Errorf("No path specified")
}
var rdr io.Reader
if p == "-" {
rdr = os.Stdin
} else {
if f, err := os.Open(p); err == nil {
rdr = f
defer f.Close()
} else {
return nil, err
}
}
return ioutil.ReadAll(rdr)
}
// verify a token and output the claims
func verifyToken() error {
// get the token
tokData, err := loadData(*flagVerify)
if err != nil {
return fmt.Errorf("Couldn't read token: %v", err)
}
// Parse the token. Load the key from command line option
token, err := jwt.Parse(string(tokData), func(t *jwt.Token) ([]byte, error) {
return loadData(*flagKey)
})
// Print an error if we can't parse for some reason
if err != nil {
return err
}
// Is token invalid?
if !token.Valid {
return fmt.Errorf("Token is invalid")
}
// Print the token details
// TODO: observe the pretty flag
if out, err := json.MarshalIndent(token.Claims, "", " "); err == nil {
fmt.Println(string(out))
} else {
return fmt.Errorf("Failed to output claims: %v", err)
}
return nil
}
// Create, sign, and output a token
func signToken() error {
// get the token
tokData, err := loadData(*flagSign)
if err != nil {
return fmt.Errorf("Couldn't read token: %v", err)
}
// parse the JSON of the claims
var claims map[string]interface{}
if err := json.Unmarshal(tokData, &claims); err != nil {
return fmt.Errorf("Couldn't parse claims JSON: %v", err)
}
// get the key
keyData, err := loadData(*flagKey)
if err != nil {
return fmt.Errorf("Couldn't read key: %v", err)
}
// get the signing alg
alg := jwt.GetSigningMethod(*flagAlg)
if alg == nil {
return fmt.Errorf("Couldn't find signing method: %v", *flagAlg)
}
// create a new token
token := jwt.New(alg)
token.Claims = claims
if out, err := token.SignedString(keyData); err == nil {
fmt.Println(out)
} else {
return fmt.Errorf("Error signing token: %v", err)
}
return nil
}
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