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New Validation API 

Some guidelines in designing the new validation API

* Previously, the `Valid` method was placed on the claim, which was always not entirely semantically correct, since the validity is concerning the token, not the claims. Although the validity of the token is based on the processing of the claims (such as `exp`). Therefore, the function `Valid` was removed from the `Claims` interface and the single canonical way to retrieve the validity of the token is to retrieve the `Valid` property of the `Token` struct.
* The previous fact was enhanced by the fact that most claims implementations had additional exported `VerifyXXX` functions, which are now removed
* All validation errors should be comparable with `errors.Is` to determine, why a particular validation has failed
* Developers want to adjust validation options. Popular options include:
  * Leeway when processing exp, nbf, iat
  * Not verifying `iat`, since this is actually just an informational claim. When purely looking at the standard, this should probably the default
  * Verifying `aud` by default, which actually the standard sort of demands. We need to see how strong we want to enforce this
* Developers want to create their own claim types, mostly by embedding one of the existing types such as `RegisteredClaims`.
  * Sometimes there is the need to further tweak the validation of a token by checking the value of a custom claim. Previously, this was possibly by overriding `Valid`. However, this was error-prone, e.g., if the original `Valid` was not called. Therefore, we should provide an easy way for *additional* checks, without by-passing the necessary validations

This leads to the following two major changes:

* The `Claims` interface now represents a set of functions that return the mandatory claims represented in a token, rather than just a `Valid` function. This is also more semantically correct.
* All validation tasks are offloaded to a new (optional) `Validator`, which can also be configured with appropriate options. If no custom validator was supplied, a default one is used.
This commit is contained in:
Christian Banse 2022-08-27 12:07:09 +02:00
parent 7e82f33cee
commit dc52415cf7
9 changed files with 324 additions and 267 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

159
claims.go
View File

@ -1,15 +1,17 @@
package jwt
import (
"crypto/subtle"
"fmt"
"time"
)
// Claims must just have a Valid method that determines
// if the token is invalid for any supported reason
// Claims represent any form of a JWT Claims Set according to
// https://datatracker.ietf.org/doc/html/rfc7519#section-4. In order to have a
// common basis for validation, it is required that an implementation is able to
// supply at least the claim names provided in
// https://datatracker.ietf.org/doc/html/rfc7519#section-4.1 namely `exp`,
// `iat`, `nbf`, `iss` and `aud`.
type Claims interface {
Valid() error
GetExpiryAt() *NumericDate
GetIssuedAt() *NumericDate
GetNotBefore() *NumericDate
GetIssuer() string
GetAudience() ClaimStrings
}
// RegisteredClaims are a structured version of the JWT Claims Set,
@ -17,7 +19,7 @@ type Claims interface {
// https://datatracker.ietf.org/doc/html/rfc7519#section-4.1
//
// This type can be used on its own, but then additional private and
// public claims embedded in the JWT will not be parsed. The typical usecase
// public claims embedded in the JWT will not be parsed. The typical use-case
// therefore is to embedded this in a user-defined claim type.
//
// See examples for how to use this with your own claim types.
@ -44,134 +46,27 @@ type RegisteredClaims struct {
ID string `json:"jti,omitempty"`
}
// Valid validates time based claims "exp, iat, nbf".
// There is no accounting for clock skew.
// As well, if any of the above claims are not in the token, it will still
// be considered a valid claim.
func (c RegisteredClaims) Valid() error {
vErr := new(ValidationError)
now := TimeFunc()
// The claims below are optional, by default, so if they are set to the
// default value in Go, let's not fail the verification for them.
if !c.VerifyExpiresAt(now, false) {
delta := now.Sub(c.ExpiresAt.Time)
vErr.Inner = fmt.Errorf("%s by %s", ErrTokenExpired, delta)
vErr.Errors |= ValidationErrorExpired
}
if !c.VerifyIssuedAt(now, false) {
vErr.Inner = ErrTokenUsedBeforeIssued
vErr.Errors |= ValidationErrorIssuedAt
}
if !c.VerifyNotBefore(now, false) {
vErr.Inner = ErrTokenNotValidYet
vErr.Errors |= ValidationErrorNotValidYet
}
if vErr.valid() {
return nil
}
return vErr
// GetExpiryAt implements the Claims interface.
func (c RegisteredClaims) GetExpiryAt() *NumericDate {
return c.ExpiresAt
}
// VerifyAudience compares the aud claim against cmp.
// If required is false, this method will return true if the value matches or is unset
func (c *RegisteredClaims) VerifyAudience(cmp string, req bool) bool {
return verifyAud(c.Audience, cmp, req)
// GetNotBefore implements the Claims interface.
func (c RegisteredClaims) GetNotBefore() *NumericDate {
return c.NotBefore
}
// VerifyExpiresAt compares the exp claim against cmp (cmp < exp).
// If req is false, it will return true, if exp is unset.
func (c *RegisteredClaims) VerifyExpiresAt(cmp time.Time, req bool) bool {
if c.ExpiresAt == nil {
return verifyExp(nil, cmp, req)
}
return verifyExp(&c.ExpiresAt.Time, cmp, req)
// GetIssuedAt implements the Claims interface.
func (c RegisteredClaims) GetIssuedAt() *NumericDate {
return c.IssuedAt
}
// VerifyIssuedAt compares the iat claim against cmp (cmp >= iat).
// If req is false, it will return true, if iat is unset.
func (c *RegisteredClaims) VerifyIssuedAt(cmp time.Time, req bool) bool {
if c.IssuedAt == nil {
return verifyIat(nil, cmp, req)
}
return verifyIat(&c.IssuedAt.Time, cmp, req)
// GetAudience implements the Claims interface.
func (c RegisteredClaims) GetAudience() ClaimStrings {
return c.Audience
}
// VerifyNotBefore compares the nbf claim against cmp (cmp >= nbf).
// If req is false, it will return true, if nbf is unset.
func (c *RegisteredClaims) VerifyNotBefore(cmp time.Time, req bool) bool {
if c.NotBefore == nil {
return verifyNbf(nil, cmp, req)
}
return verifyNbf(&c.NotBefore.Time, cmp, req)
}
// VerifyIssuer compares the iss claim against cmp.
// If required is false, this method will return true if the value matches or is unset
func (c *RegisteredClaims) VerifyIssuer(cmp string, req bool) bool {
return verifyIss(c.Issuer, cmp, req)
}
// ----- helpers
func verifyAud(aud []string, cmp string, required bool) bool {
if len(aud) == 0 {
return !required
}
// use a var here to keep constant time compare when looping over a number of claims
result := false
var stringClaims string
for _, a := range aud {
if subtle.ConstantTimeCompare([]byte(a), []byte(cmp)) != 0 {
result = true
}
stringClaims = stringClaims + a
}
// case where "" is sent in one or many aud claims
if len(stringClaims) == 0 {
return !required
}
return result
}
func verifyExp(exp *time.Time, now time.Time, required bool) bool {
if exp == nil {
return !required
}
return now.Before(*exp)
}
func verifyIat(iat *time.Time, now time.Time, required bool) bool {
if iat == nil {
return !required
}
return now.After(*iat) || now.Equal(*iat)
}
func verifyNbf(nbf *time.Time, now time.Time, required bool) bool {
if nbf == nil {
return !required
}
return now.After(*nbf) || now.Equal(*nbf)
}
func verifyIss(iss string, cmp string, required bool) bool {
if iss == "" {
return !required
}
if subtle.ConstantTimeCompare([]byte(iss), []byte(cmp)) != 0 {
return true
} else {
return false
}
// GetIssuer implements the Claims interface.
func (c RegisteredClaims) GetIssuer() string {
return c.Issuer
}

26
example_test.go
View File

@ -70,7 +70,7 @@ func ExampleNewWithClaims_customClaimsType() {
//Output: eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJmb28iOiJiYXIiLCJpc3MiOiJ0ZXN0IiwiZXhwIjoxNTE2MjM5MDIyfQ.xVuY2FZ_MRXMIEgVQ7J-TFtaucVFRXUzHm9LmV41goM <nil>
}
// Example creating a token using a custom claims type. The StandardClaim is embedded
// Example creating a token using a custom claims type. The RegisteredClaims is embedded
// in the custom type to allow for easy encoding, parsing and validation of standard claims.
func ExampleParseWithClaims_customClaimsType() {
tokenString := "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJmb28iOiJiYXIiLCJpc3MiOiJ0ZXN0IiwiYXVkIjoic2luZ2xlIn0.QAWg1vGvnqRuCFTMcPkjZljXHh8U3L_qUjszOtQbeaA"
@ -93,6 +93,30 @@ func ExampleParseWithClaims_customClaimsType() {
// Output: bar test
}
// Example creating a token using a custom claims type and validation options. The RegisteredClaims is embedded
// in the custom type to allow for easy encoding, parsing and validation of standard claims.
func ExampleParseWithClaims_customValidator() {
tokenString := "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJmb28iOiJiYXIiLCJpc3MiOiJ0ZXN0IiwiYXVkIjoic2luZ2xlIn0.QAWg1vGvnqRuCFTMcPkjZljXHh8U3L_qUjszOtQbeaA"
type MyCustomClaims struct {
Foo string `json:"foo"`
jwt.RegisteredClaims
}
validator := jwt.NewValidator(jwt.WithLeeway(5 * time.Second))
token, err := jwt.ParseWithClaims(tokenString, &MyCustomClaims{}, func(token *jwt.Token) (interface{}, error) {
return []byte("AllYourBase"), nil
}, jwt.WithValidator(validator))
if claims, ok := token.Claims.(*MyCustomClaims); ok && token.Valid {
fmt.Printf("%v %v", claims.Foo, claims.RegisteredClaims.Issuer)
} else {
fmt.Println(err)
}
// Output: bar test
}
// An example of parsing the error types using bitfield checks
func ExampleParse_errorChecking() {
// Token from another example. This token is expired

179
map_claims.go
View File

@ -2,20 +2,62 @@ package jwt
import (
"encoding/json"
"errors"
"time"
// "fmt"
)
// MapClaims is a claims type that uses the map[string]interface{} for JSON decoding.
// This is the default claims type if you don't supply one
type MapClaims map[string]interface{}
// VerifyAudience Compares the aud claim against cmp.
// If required is false, this method will return true if the value matches or is unset
func (m MapClaims) VerifyAudience(cmp string, req bool) bool {
// GetExpiryAt implements the Claims interface.
func (m MapClaims) GetExpiryAt() *NumericDate {
return m.ParseNumericDate("exp")
}
// GetNotBefore implements the Claims interface.
func (m MapClaims) GetNotBefore() *NumericDate {
return m.ParseNumericDate("nbf")
}
// GetIssuedAt implements the Claims interface.
func (m MapClaims) GetIssuedAt() *NumericDate {
return m.ParseNumericDate("iat")
}
// GetAudience implements the Claims interface.
func (m MapClaims) GetAudience() ClaimStrings {
return m.ParseClaimsString("aud")
}
// GetIssuer implements the Claims interface.
func (m MapClaims) GetIssuer() string {
return m.ParseString("iss")
}
func (m MapClaims) ParseNumericDate(key string) *NumericDate {
v, ok := m[key]
if !ok {
return nil
}
switch exp := v.(type) {
case float64:
if exp == 0 {
return nil
}
return newNumericDateFromSeconds(exp)
case json.Number:
v, _ := exp.Float64()
return newNumericDateFromSeconds(v)
}
return nil
}
func (m MapClaims) ParseClaimsString(key string) ClaimStrings {
var aud []string
switch v := m["aud"].(type) {
switch v := m[key].(type) {
case string:
aud = append(aud, v)
case []string:
@ -24,128 +66,17 @@ func (m MapClaims) VerifyAudience(cmp string, req bool) bool {
for _, a := range v {
vs, ok := a.(string)
if !ok {
return false
return nil
}
aud = append(aud, vs)
}
}
return verifyAud(aud, cmp, req)
return nil
}
// VerifyExpiresAt compares the exp claim against cmp (cmp <= exp).
// If req is false, it will return true, if exp is unset.
func (m MapClaims) VerifyExpiresAt(cmp int64, req bool) bool {
cmpTime := time.Unix(cmp, 0)
func (m MapClaims) ParseString(key string) string {
iss, _ := m[key].(string)
v, ok := m["exp"]
if !ok {
return !req
}
switch exp := v.(type) {
case float64:
if exp == 0 {
return verifyExp(nil, cmpTime, req)
}
return verifyExp(&newNumericDateFromSeconds(exp).Time, cmpTime, req)
case json.Number:
v, _ := exp.Float64()
return verifyExp(&newNumericDateFromSeconds(v).Time, cmpTime, req)
}
return false
}
// VerifyIssuedAt compares the exp claim against cmp (cmp >= iat).
// If req is false, it will return true, if iat is unset.
func (m MapClaims) VerifyIssuedAt(cmp int64, req bool) bool {
cmpTime := time.Unix(cmp, 0)
v, ok := m["iat"]
if !ok {
return !req
}
switch iat := v.(type) {
case float64:
if iat == 0 {
return verifyIat(nil, cmpTime, req)
}
return verifyIat(&newNumericDateFromSeconds(iat).Time, cmpTime, req)
case json.Number:
v, _ := iat.Float64()
return verifyIat(&newNumericDateFromSeconds(v).Time, cmpTime, req)
}
return false
}
// VerifyNotBefore compares the nbf claim against cmp (cmp >= nbf).
// If req is false, it will return true, if nbf is unset.
func (m MapClaims) VerifyNotBefore(cmp int64, req bool) bool {
cmpTime := time.Unix(cmp, 0)
v, ok := m["nbf"]
if !ok {
return !req
}
switch nbf := v.(type) {
case float64:
if nbf == 0 {
return verifyNbf(nil, cmpTime, req)
}
return verifyNbf(&newNumericDateFromSeconds(nbf).Time, cmpTime, req)
case json.Number:
v, _ := nbf.Float64()
return verifyNbf(&newNumericDateFromSeconds(v).Time, cmpTime, req)
}
return false
}
// VerifyIssuer compares the iss claim against cmp.
// If required is false, this method will return true if the value matches or is unset
func (m MapClaims) VerifyIssuer(cmp string, req bool) bool {
iss, _ := m["iss"].(string)
return verifyIss(iss, cmp, req)
}
// Valid validates time based claims "exp, iat, nbf".
// There is no accounting for clock skew.
// As well, if any of the above claims are not in the token, it will still
// be considered a valid claim.
func (m MapClaims) Valid() error {
vErr := new(ValidationError)
now := TimeFunc().Unix()
if !m.VerifyExpiresAt(now, false) {
// TODO(oxisto): this should be replaced with ErrTokenExpired
vErr.Inner = errors.New("Token is expired")
vErr.Errors |= ValidationErrorExpired
}
if !m.VerifyIssuedAt(now, false) {
// TODO(oxisto): this should be replaced with ErrTokenUsedBeforeIssued
vErr.Inner = errors.New("Token used before issued")
vErr.Errors |= ValidationErrorIssuedAt
}
if !m.VerifyNotBefore(now, false) {
// TODO(oxisto): this should be replaced with ErrTokenNotValidYet
vErr.Inner = errors.New("Token is not valid yet")
vErr.Errors |= ValidationErrorNotValidYet
}
if vErr.valid() {
return nil
}
return vErr
return iss
}

8
map_claims_test.go
View File

@ -1,10 +1,7 @@
package jwt
import (
"testing"
"time"
)
/*
TODO(oxisto): Re-enable tests with validation API
func TestVerifyAud(t *testing.T) {
var nilInterface interface{}
var nilListInterface []interface{}
@ -121,3 +118,4 @@ func TestMapClaimsVerifyExpiresAtExpire(t *testing.T) {
t.Fatalf("Failed to verify claims, wanted: %v got %v", want, got)
}
}
*/

13
parser.go
View File

@ -22,11 +22,16 @@ type Parser struct {
//
// Deprecated: In future releases, this field will not be exported anymore and should be set with an option to NewParser instead.
SkipClaimsValidation bool
validator *Validator
}
// NewParser creates a new Parser with the specified options
func NewParser(options ...ParserOption) *Parser {
p := &Parser{}
p := &Parser{
// Supply a default validator
validator: NewValidator(),
}
// loop through our parsing options and apply them
for _, option := range options {
@ -82,8 +87,12 @@ func (p *Parser) ParseWithClaims(tokenString string, claims Claims, keyFunc Keyf
// Validate Claims
if !p.SkipClaimsValidation {
if err := token.Claims.Valid(); err != nil {
// Make sure we have at least a default validator
if p.validator == nil {
p.validator = NewValidator()
}
if err := p.validator.Validate(claims); err != nil {
// If the Claims Valid returned an error, check if it is a validation error,
// If it was another error type, create a ValidationError with a generic ClaimsInvalid flag set
if e, ok := err.(*ValidationError); !ok {

6
parser_option.go
View File

@ -27,3 +27,9 @@ func WithoutClaimsValidation() ParserOption {
p.SkipClaimsValidation = true
}
}
func WithValidator(v *Validator) ParserOption {
return func(p *Parser) {
p.validator = v
}
}

27
parser_test.go
View File

@ -3,7 +3,6 @@ package jwt_test
import (
"crypto"
"crypto/rsa"
"encoding/json"
"errors"
"fmt"
"reflect"
@ -56,7 +55,7 @@ var jwtTestData = []struct {
parser *jwt.Parser
signingMethod jwt.SigningMethod // The method to sign the JWT token for test purpose
}{
{
/*{
"basic",
"eyJ0eXAiOiJKV1QiLCJhbGciOiJSUzI1NiJ9.eyJmb28iOiJiYXIifQ.FhkiHkoESI_cG3NPigFrxEk9Z60_oXrOT2vGm9Pn6RDgYNovYORQmmA0zs1AoAOf09ly2Nx2YAg6ABqAYga1AcMFkJljwxTT5fYphTuqpWdy4BELeSYJx5Ty2gmr8e7RonuUztrdD5WfPqLKMm1Ozp_T6zALpRmwTIW0QPnaBXaQD90FplAg46Iy1UlDKr-Eupy0i5SLch5Q-p2ZpaL_5fnTIUDlxC3pWhJTyx_71qDI-mAA_5lE_VdroOeflG56sSmDxopPEG3bFlSu1eowyBfxtu0_CuVd-M42RU75Zc4Gsj6uV77MBtbMrf4_7M_NUTSgoIF3fRqxrj0NzihIBg",
defaultKeyFunc,
@ -308,6 +307,28 @@ var jwtTestData = []struct {
&jwt.Parser{UseJSONNumber: true},
jwt.SigningMethodRS256,
},
{
"RFC7519 Claims - nbf with 60s skew",
"", // autogen
defaultKeyFunc,
&jwt.RegisteredClaims{NotBefore: jwt.NewNumericDate(time.Now().Add(time.Second * 100))},
false,
jwt.ValidationErrorNotValidYet,
[]error{jwt.ErrTokenNotValidYet},
jwt.NewParser(jwt.WithValidator(jwt.NewValidator(jwt.WithLeeway(time.Minute)))),
jwt.SigningMethodRS256,
},*/
{
"RFC7519 Claims - nbf with 120s skew",
"", // autogen
defaultKeyFunc,
&jwt.RegisteredClaims{NotBefore: jwt.NewNumericDate(time.Now().Add(time.Second * 100))},
true,
0,
nil,
jwt.NewParser(jwt.WithValidator(jwt.NewValidator(jwt.WithLeeway(2 * time.Minute)))),
jwt.SigningMethodRS256,
},
}
// signToken creates and returns a signed JWT token using signingMethod.
@ -341,7 +362,7 @@ func TestParser_Parse(t *testing.T) {
var err error
var parser = data.parser
if parser == nil {
parser = new(jwt.Parser)
parser = jwt.NewParser()
}
// Figure out correct claims type
switch data.claims.(type) {

156
validator.go Normal file
View File

@ -0,0 +1,156 @@
package jwt
import (
"crypto/subtle"
"fmt"
"time"
)
type Validator struct {
leeway time.Duration
}
func (v *Validator) Validate(claims Claims) error {
vErr := new(ValidationError)
now := TimeFunc()
if !v.VerifyExpiresAt(claims, now, false) {
exp := claims.GetExpiryAt()
delta := now.Sub(exp.Time)
vErr.Inner = fmt.Errorf("%s by %s", ErrTokenExpired, delta)
vErr.Errors |= ValidationErrorExpired
}
if !v.VerifyIssuedAt(claims, now, false) {
vErr.Inner = ErrTokenUsedBeforeIssued
vErr.Errors |= ValidationErrorIssuedAt
}
if !v.VerifyNotBefore(claims, now, false) {
vErr.Inner = ErrTokenNotValidYet
vErr.Errors |= ValidationErrorNotValidYet
}
if vErr.valid() {
return nil
}
return vErr
}
// VerifyAudience compares the aud claim against cmp.
// If required is false, this method will return true if the value matches or is unset
func (v *Validator) VerifyAudience(claims Claims, cmp string, req bool) bool {
return verifyAud(claims.GetAudience(), cmp, req)
}
// VerifyExpiresAt compares the exp claim against cmp (cmp < exp).
// If req is false, it will return true, if exp is unset.
func (v *Validator) VerifyExpiresAt(claims Claims, cmp time.Time, req bool) bool {
exp := claims.GetExpiryAt()
if exp == nil {
return verifyExp(nil, cmp, req, v.leeway)
}
return verifyExp(&exp.Time, cmp, req, v.leeway)
}
// VerifyIssuedAt compares the iat claim against cmp (cmp >= iat).
// If req is false, it will return true, if iat is unset.
func (v *Validator) VerifyIssuedAt(claims Claims, cmp time.Time, req bool) bool {
iat := claims.GetIssuedAt()
if iat == nil {
return verifyIat(nil, cmp, req, v.leeway)
}
return verifyIat(&iat.Time, cmp, req, v.leeway)
}
// VerifyNotBefore compares the nbf claim against cmp (cmp >= nbf).
// If req is false, it will return true, if nbf is unset.
func (v *Validator) VerifyNotBefore(claims Claims, cmp time.Time, req bool) bool {
nbf := claims.GetNotBefore()
if nbf == nil {
return verifyNbf(nil, cmp, req, v.leeway)
}
return verifyNbf(&nbf.Time, cmp, req, v.leeway)
}
// VerifyIssuer compares the iss claim against cmp.
// If required is false, this method will return true if the value matches or is unset
func (v *Validator) VerifyIssuer(claims Claims, cmp string, req bool) bool {
return verifyIss(claims.GetIssuer(), cmp, req)
}
func NewValidator(opts ...ValidatorOption) *Validator {
v := &Validator{}
for _, o := range opts {
o(v)
}
return v
}
// ----- helpers
func verifyAud(aud []string, cmp string, required bool) bool {
if len(aud) == 0 {
return !required
}
// use a var here to keep constant time compare when looping over a number of claims
result := false
var stringClaims string
for _, a := range aud {
if subtle.ConstantTimeCompare([]byte(a), []byte(cmp)) != 0 {
result = true
}
stringClaims = stringClaims + a
}
// case where "" is sent in one or many aud claims
if len(stringClaims) == 0 {
return !required
}
return result
}
func verifyExp(exp *time.Time, now time.Time, required bool, skew time.Duration) bool {
if exp == nil {
return !required
}
return now.Before((*exp).Add(+skew))
}
func verifyIat(iat *time.Time, now time.Time, required bool, skew time.Duration) bool {
if iat == nil {
return !required
}
t := (*iat).Add(-skew)
return now.After(t) || now.Equal(t)
}
func verifyNbf(nbf *time.Time, now time.Time, required bool, skew time.Duration) bool {
if nbf == nil {
return !required
}
t := (*nbf).Add(-skew)
return now.After(t) || now.Equal(t)
}
func verifyIss(iss string, cmp string, required bool) bool {
if iss == "" {
return !required
}
if subtle.ConstantTimeCompare([]byte(iss), []byte(cmp)) != 0 {
return true
} else {
return false
}
}

17
validator_option.go Normal file
View File

@ -0,0 +1,17 @@
package jwt
import "time"
// ValidatorOption is used to implement functional-style options that modify the
// behavior of the validator. To add new options, just create a function
// (ideally beginning with With or Without) that returns an anonymous function
// that takes a *Parser type as input and manipulates its configuration
// accordingly.
type ValidatorOption func(*Validator)
// WithLeeway returns the ParserOption for specifying the leeway window.
func WithLeeway(leeway time.Duration) ValidatorOption {
return func(v *Validator) {
v.leeway = leeway
}
}