Exported `NewValidator` (#349)

* Exported `NewValidator`

Previously, we had `newValidator` as a private function. This PR exports this function so that validation can be done independently of parsing the claim.

MIGRATION_GUIDE.md

@@ -17,7 +17,7 @@ and corresponding updates for existing programs.
 
 ## Parsing and Validation Options
 
-Under the hood, a new `validator` struct takes care of validating the claims. A
+Under the hood, a new `Validator` struct takes care of validating the claims. A
 long awaited feature has been the option to fine-tune the validation of tokens.
 This is now possible with several `ParserOption` functions that can be appended
 to most `Parse` functions, such as `ParseWithClaims`. The most important options
@@ -68,6 +68,16 @@ type Claims interface {
 }
 ```
 
+Users that previously directly called the `Valid` function on their claims,
+e.g., to perform validation independently of parsing/verifying a token, can now
+use the `jwt.NewValidator` function to create a `Validator` independently of the
+`Parser`.
+
+```go
+var v = jwt.NewValidator(jwt.WithLeeway(5*time.Second))
+v.Validate(myClaims)
+```
+
 ### Supported Claim Types and Removal of `StandardClaims`
 
 The two standard claim types supported by this library, `MapClaims` and

map_claims_test.go

@@ -62,7 +62,7 @@ func TestVerifyAud(t *testing.T) {
 				opts = append(opts, WithAudience(test.Comparison))
 			}
 
-			validator := newValidator(opts...)
+			validator := NewValidator(opts...)
 			got := validator.Validate(test.MapClaims)
 
 			if (got == nil) != test.Expected {
@@ -77,7 +77,7 @@ func TestMapclaimsVerifyIssuedAtInvalidTypeString(t *testing.T) {
 		"iat": "foo",
 	}
 	want := false
-	got := newValidator(WithIssuedAt()).Validate(mapClaims)
+	got := NewValidator(WithIssuedAt()).Validate(mapClaims)
 	if want != (got == nil) {
 		t.Fatalf("Failed to verify claims, wanted: %v got %v", want, (got == nil))
 	}
@@ -88,7 +88,7 @@ func TestMapclaimsVerifyNotBeforeInvalidTypeString(t *testing.T) {
 		"nbf": "foo",
 	}
 	want := false
-	got := newValidator().Validate(mapClaims)
+	got := NewValidator().Validate(mapClaims)
 	if want != (got == nil) {
 		t.Fatalf("Failed to verify claims, wanted: %v got %v", want, (got == nil))
 	}
@@ -99,7 +99,7 @@ func TestMapclaimsVerifyExpiresAtInvalidTypeString(t *testing.T) {
 		"exp": "foo",
 	}
 	want := false
-	got := newValidator().Validate(mapClaims)
+	got := NewValidator().Validate(mapClaims)
 
 	if want != (got == nil) {
 		t.Fatalf("Failed to verify claims, wanted: %v got %v", want, (got == nil))
@@ -112,14 +112,14 @@ func TestMapClaimsVerifyExpiresAtExpire(t *testing.T) {
 		"exp": float64(exp.Unix()),
 	}
 	want := false
-	got := newValidator(WithTimeFunc(func() time.Time {
+	got := NewValidator(WithTimeFunc(func() time.Time {
 		return exp
 	})).Validate(mapClaims)
 	if want != (got == nil) {
 		t.Fatalf("Failed to verify claims, wanted: %v got %v", want, (got == nil))
 	}
 
-	got = newValidator(WithTimeFunc(func() time.Time {
+	got = NewValidator(WithTimeFunc(func() time.Time {
 		return exp.Add(1 * time.Second)
 	})).Validate(mapClaims)
 	if want != (got == nil) {
@@ -127,7 +127,7 @@ func TestMapClaimsVerifyExpiresAtExpire(t *testing.T) {
 	}
 
 	want = true
-	got = newValidator(WithTimeFunc(func() time.Time {
+	got = NewValidator(WithTimeFunc(func() time.Time {
 		return exp.Add(-1 * time.Second)
 	})).Validate(mapClaims)
 	if want != (got == nil) {

parser.go

@@ -18,7 +18,7 @@ type Parser struct {
 	// Skip claims validation during token parsing.
 	skipClaimsValidation bool
 
-	validator *validator
+	validator *Validator
 
 	decodeStrict bool
 
@@ -28,7 +28,7 @@ type Parser struct {
 // NewParser creates a new Parser with the specified options
 func NewParser(options ...ParserOption) *Parser {
 	p := &Parser{
-		validator: &validator{},
+		validator: &Validator{},
 	}
 
 	// Loop through our parsing options and apply them
@@ -115,7 +115,7 @@ func (p *Parser) ParseWithClaims(tokenString string, claims Claims, keyFunc Keyf
 	if !p.skipClaimsValidation {
 		// Make sure we have at least a default validator
 		if p.validator == nil {
-			p.validator = newValidator()
+			p.validator = NewValidator()
 		}
 
 		if err := p.validator.Validate(claims); err != nil {

validator.go

@@ -28,13 +28,12 @@ type ClaimsValidator interface {
 	Validate() error
 }
 
-// validator is the core of the new Validation API. It is automatically used by
+// Validator is the core of the new Validation API. It is automatically used by
 // a [Parser] during parsing and can be modified with various parser options.
 //
-// Note: This struct is intentionally not exported (yet) as we want to
+// The [NewValidator] function should be used to create an instance of this
-// internally finalize its API. In the future, we might make it publicly
+// struct.
-// available.
+type Validator struct {
-type validator struct {
 	// leeway is an optional leeway that can be provided to account for clock skew.
 	leeway time.Duration
 
@@ -65,16 +64,28 @@ type validator struct {
 	expectedSub string
 }
 
-// newValidator can be used to create a stand-alone validator with the supplied
+// NewValidator can be used to create a stand-alone validator with the supplied
 // options. This validator can then be used to validate already parsed claims.
-func newValidator(opts ...ParserOption) *validator {
+//
+// Note: Under normal circumstances, explicitly creating a validator is not
+// needed and can potentially be dangerous; instead functions of the [Parser]
+// class should be used.
+//
+// The [Validator] is only checking the *validity* of the claims, such as its
+// expiration time, but it does NOT perform *signature verification* of the
+// token.
+func NewValidator(opts ...ParserOption) *Validator {
 	p := NewParser(opts...)
 	return p.validator
 }
 
 // Validate validates the given claims. It will also perform any custom
 // validation if claims implements the [ClaimsValidator] interface.
-func (v *validator) Validate(claims Claims) error {
+//
+// Note: It will NOT perform any *signature verification* on the token that
+// contains the claims and expects that the [Claim] was already successfully
+// verified.
+func (v *Validator) Validate(claims Claims) error {
 	var (
 		now  time.Time
 		errs []error = make([]error, 0, 6)
@@ -153,7 +164,7 @@ func (v *validator) Validate(claims Claims) error {
 //
 // Additionally, if any error occurs while retrieving the claim, e.g., when its
 // the wrong type, an ErrTokenUnverifiable error will be returned.
-func (v *validator) verifyExpiresAt(claims Claims, cmp time.Time, required bool) error {
+func (v *Validator) verifyExpiresAt(claims Claims, cmp time.Time, required bool) error {
 	exp, err := claims.GetExpirationTime()
 	if err != nil {
 		return err
@@ -174,7 +185,7 @@ func (v *validator) verifyExpiresAt(claims Claims, cmp time.Time, required bool)
 //
 // Additionally, if any error occurs while retrieving the claim, e.g., when its
 // the wrong type, an ErrTokenUnverifiable error will be returned.
-func (v *validator) verifyIssuedAt(claims Claims, cmp time.Time, required bool) error {
+func (v *Validator) verifyIssuedAt(claims Claims, cmp time.Time, required bool) error {
 	iat, err := claims.GetIssuedAt()
 	if err != nil {
 		return err
@@ -195,7 +206,7 @@ func (v *validator) verifyIssuedAt(claims Claims, cmp time.Time, required bool)
 //
 // Additionally, if any error occurs while retrieving the claim, e.g., when its
 // the wrong type, an ErrTokenUnverifiable error will be returned.
-func (v *validator) verifyNotBefore(claims Claims, cmp time.Time, required bool) error {
+func (v *Validator) verifyNotBefore(claims Claims, cmp time.Time, required bool) error {
 	nbf, err := claims.GetNotBefore()
 	if err != nil {
 		return err
@@ -215,7 +226,7 @@ func (v *validator) verifyNotBefore(claims Claims, cmp time.Time, required bool)
 //
 // Additionally, if any error occurs while retrieving the claim, e.g., when its
 // the wrong type, an ErrTokenUnverifiable error will be returned.
-func (v *validator) verifyAudience(claims Claims, cmp string, required bool) error {
+func (v *Validator) verifyAudience(claims Claims, cmp string, required bool) error {
 	aud, err := claims.GetAudience()
 	if err != nil {
 		return err
@@ -251,7 +262,7 @@ func (v *validator) verifyAudience(claims Claims, cmp string, required bool) err
 //
 // Additionally, if any error occurs while retrieving the claim, e.g., when its
 // the wrong type, an ErrTokenUnverifiable error will be returned.
-func (v *validator) verifyIssuer(claims Claims, cmp string, required bool) error {
+func (v *Validator) verifyIssuer(claims Claims, cmp string, required bool) error {
 	iss, err := claims.GetIssuer()
 	if err != nil {
 		return err
@@ -271,7 +282,7 @@ func (v *validator) verifyIssuer(claims Claims, cmp string, required bool) error
 //
 // Additionally, if any error occurs while retrieving the claim, e.g., when its
 // the wrong type, an ErrTokenUnverifiable error will be returned.
-func (v *validator) verifySubject(claims Claims, cmp string, required bool) error {
+func (v *Validator) verifySubject(claims Claims, cmp string, required bool) error {
 	sub, err := claims.GetSubject()
 	if err != nil {
 		return err

validator_test.go

@@ -20,7 +20,7 @@ func (m MyCustomClaims) Validate() error {
 	return nil
 }
 
-func Test_validator_Validate(t *testing.T) {
+func Test_Validator_Validate(t *testing.T) {
 	type fields struct {
 		leeway      time.Duration
 		timeFunc    func() time.Time
@@ -71,7 +71,7 @@ func Test_validator_Validate(t *testing.T) {
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			v := &validator{
+			v := &Validator{
 				leeway:      tt.fields.leeway,
 				timeFunc:    tt.fields.timeFunc,
 				verifyIat:   tt.fields.verifyIat,
@@ -86,7 +86,7 @@ func Test_validator_Validate(t *testing.T) {
 	}
 }
 
-func Test_validator_verifyExpiresAt(t *testing.T) {
+func Test_Validator_verifyExpiresAt(t *testing.T) {
 	type fields struct {
 		leeway   time.Duration
 		timeFunc func() time.Time
@@ -117,7 +117,7 @@ func Test_validator_verifyExpiresAt(t *testing.T) {
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			v := &validator{
+			v := &Validator{
 				leeway:   tt.fields.leeway,
 				timeFunc: tt.fields.timeFunc,
 			}
@@ -130,7 +130,7 @@ func Test_validator_verifyExpiresAt(t *testing.T) {
 	}
 }
 
-func Test_validator_verifyIssuer(t *testing.T) {
+func Test_Validator_verifyIssuer(t *testing.T) {
 	type fields struct {
 		expectedIss string
 	}
@@ -160,7 +160,7 @@ func Test_validator_verifyIssuer(t *testing.T) {
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			v := &validator{
+			v := &Validator{
 				expectedIss: tt.fields.expectedIss,
 			}
 			err := v.verifyIssuer(tt.args.claims, tt.args.cmp, tt.args.required)
@@ -171,7 +171,7 @@ func Test_validator_verifyIssuer(t *testing.T) {
 	}
 }
 
-func Test_validator_verifySubject(t *testing.T) {
+func Test_Validator_verifySubject(t *testing.T) {
 	type fields struct {
 		expectedSub string
 	}
@@ -201,7 +201,7 @@ func Test_validator_verifySubject(t *testing.T) {
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			v := &validator{
+			v := &Validator{
 				expectedSub: tt.fields.expectedSub,
 			}
 			err := v.verifySubject(tt.args.claims, tt.args.cmp, tt.args.required)
@@ -212,7 +212,7 @@ func Test_validator_verifySubject(t *testing.T) {
 	}
 }
 
-func Test_validator_verifyIssuedAt(t *testing.T) {
+func Test_Validator_verifyIssuedAt(t *testing.T) {
 	type fields struct {
 		leeway    time.Duration
 		timeFunc  func() time.Time
@@ -248,7 +248,7 @@ func Test_validator_verifyIssuedAt(t *testing.T) {
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			v := &validator{
+			v := &Validator{
 				leeway:    tt.fields.leeway,
 				timeFunc:  tt.fields.timeFunc,
 				verifyIat: tt.fields.verifyIat,