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package middleware
import (
"errors"
"fmt"
"net/http"
"reflect"
"strings"
"github.com/dgrijalva/jwt-go"
"github.com/labstack/echo"
)
type (
// JWTConfig defines the config for JWT middleware.
JWTConfig struct {
// Skipper defines a function to skip middleware.
Skipper Skipper
// Signing key to validate token.
// Required.
SigningKey interface{}
// Signing method, used to check token signing method.
// Optional. Default value HS256.
SigningMethod string
// Context key to store user information from the token into context.
// Optional. Default value "user".
ContextKey string
// Claims are extendable claims data defining token content.
// Optional. Default value jwt.MapClaims
Claims jwt.Claims
// TokenLookup is a string in the form of "<source>:<name>" that is used
// to extract token from the request.
// Optional. Default value "header:Authorization".
// Possible values:
// - "header:<name>"
// - "query:<name>"
// - "cookie:<name>"
TokenLookup string
// AuthScheme to be used in the Authorization header.
// Optional. Default value "Bearer".
AuthScheme string
keyFunc jwt.Keyfunc
}
jwtExtractor func(echo.Context) (string, error)
)
// Algorithms
const (
AlgorithmHS256 = "HS256"
)
var (
// DefaultJWTConfig is the default JWT auth middleware config.
DefaultJWTConfig = JWTConfig{
Skipper: DefaultSkipper,
SigningMethod: AlgorithmHS256,
ContextKey: "user",
TokenLookup: "header:" + echo.HeaderAuthorization,
AuthScheme: "Bearer",
Claims: jwt.MapClaims{},
}
)
// JWT returns a JSON Web Token (JWT) auth middleware.
//
// For valid token, it sets the user in context and calls next handler.
// For invalid token, it returns "401 - Unauthorized" error.
// For missing token, it returns "400 - Bad Request" error.
//
// See: https://jwt.io/introduction
// See `JWTConfig.TokenLookup`
func JWT(key []byte) echo.MiddlewareFunc {
c := DefaultJWTConfig
c.SigningKey = key
return JWTWithConfig(c)
}
// JWTWithConfig returns a JWT auth middleware with config.
// See: `JWT()`.
func JWTWithConfig(config JWTConfig) echo.MiddlewareFunc {
// Defaults
if config.Skipper == nil {
config.Skipper = DefaultJWTConfig.Skipper
}
if config.SigningKey == nil {
panic("jwt middleware requires signing key")
}
if config.SigningMethod == "" {
config.SigningMethod = DefaultJWTConfig.SigningMethod
}
if config.ContextKey == "" {
config.ContextKey = DefaultJWTConfig.ContextKey
}
if config.Claims == nil {
config.Claims = DefaultJWTConfig.Claims
}
if config.TokenLookup == "" {
config.TokenLookup = DefaultJWTConfig.TokenLookup
}
if config.AuthScheme == "" {
config.AuthScheme = DefaultJWTConfig.AuthScheme
}
config.keyFunc = func(t *jwt.Token) (interface{}, error) {
// Check the signing method
if t.Method.Alg() != config.SigningMethod {
return nil, fmt.Errorf("Unexpected jwt signing method=%v", t.Header["alg"])
}
return config.SigningKey, nil
}
// Initialize
parts := strings.Split(config.TokenLookup, ":")
extractor := jwtFromHeader(parts[1], config.AuthScheme)
switch parts[0] {
case "query":
extractor = jwtFromQuery(parts[1])
case "cookie":
extractor = jwtFromCookie(parts[1])
}
return func(next echo.HandlerFunc) echo.HandlerFunc {
return func(c echo.Context) error {
if config.Skipper(c) {
return next(c)
}
auth, err := extractor(c)
if err != nil {
return echo.NewHTTPError(http.StatusBadRequest, err.Error())
}
token := new(jwt.Token)
// Issue #647, #656
if _, ok := config.Claims.(jwt.MapClaims); ok {
token, err = jwt.Parse(auth, config.keyFunc)
} else {
claims := reflect.ValueOf(config.Claims).Interface().(jwt.Claims)
token, err = jwt.ParseWithClaims(auth, claims, config.keyFunc)
}
if err == nil && token.Valid {
// Store user information from token into context.
c.Set(config.ContextKey, token)
return next(c)
}
return echo.ErrUnauthorized
}
}
}
// jwtFromHeader returns a `jwtExtractor` that extracts token from the request header.
func jwtFromHeader(header string, authScheme string) jwtExtractor {
return func(c echo.Context) (string, error) {
auth := c.Request().Header.Get(header)
l := len(authScheme)
if len(auth) > l+1 && auth[:l] == authScheme {
return auth[l+1:], nil
}
return "", errors.New("Missing or invalid jwt in the request header")
}
}
// jwtFromQuery returns a `jwtExtractor` that extracts token from the query string.
func jwtFromQuery(param string) jwtExtractor {
return func(c echo.Context) (string, error) {
token := c.QueryParam(param)
if token == "" {
return "", errors.New("Missing jwt in the query string")
}
return token, nil
}
}
// jwtFromCookie returns a `jwtExtractor` that extracts token from the named cookie.
func jwtFromCookie(name string) jwtExtractor {
return func(c echo.Context) (string, error) {
cookie, err := c.Cookie(name)
if err != nil {
return "", errors.New("Missing jwt in the cookie")
}
return cookie.Value, nil
}
}
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