Add specific "token expired" exceptions (#830)

* Add a specific backend exception for expired tokens

To later allow specific handling for this case in the layers above.

* Add a separate TokenError subclass for expired tokens

To allow the caller to handle expired tokens separately from invalid ones
without resorting to string matching.

Author: vainu-arto

rest_framework_simplejwt/backends.py

@@ -5,9 +5,14 @@
 
 import jwt
 from django.utils.translation import gettext_lazy as _
-from jwt import InvalidAlgorithmError, InvalidTokenError, algorithms
-
-from .exceptions import TokenBackendError
+from jwt import (
+    ExpiredSignatureError,
+    InvalidAlgorithmError,
+    InvalidTokenError,
+    algorithms,
+)
+
+from .exceptions import TokenBackendError, TokenBackendExpiredToken
 from .tokens import Token
 from .utils import format_lazy
 
@@ -101,7 +106,7 @@ def get_verifying_key(self, token: Token) -> Optional[str]:
             try:
                 return self.jwks_client.get_signing_key_from_jwt(token).key
             except PyJWKClientError as ex:
-                raise TokenBackendError(_("Token is invalid or expired")) from ex
+                raise TokenBackendError(_("Token is invalid")) from ex
 
         return self.verifying_key
 
@@ -150,5 +155,7 @@ def decode(self, token: Token, verify: bool = True) -> Dict[str, Any]:
             )
         except InvalidAlgorithmError as ex:
             raise TokenBackendError(_("Invalid algorithm specified")) from ex
+        except ExpiredSignatureError as ex:
+            raise TokenBackendExpiredToken(_("Token is expired")) from ex
         except InvalidTokenError as ex:
-            raise TokenBackendError(_("Token is invalid or expired")) from ex
+            raise TokenBackendError(_("Token is invalid")) from ex

rest_framework_simplejwt/exceptions.py

@@ -8,10 +8,18 @@ class TokenError(Exception):
     pass
 
 
+class ExpiredTokenError(TokenError):
+    pass
+
+
 class TokenBackendError(Exception):
     pass
 
 
+class TokenBackendExpiredToken(TokenBackendError):
+    pass
+
+
 class DetailDictMixin:
     default_detail: str
     default_code: str

rest_framework_simplejwt/tokens.py

@@ -7,7 +7,12 @@
 from django.utils.module_loading import import_string
 from django.utils.translation import gettext_lazy as _
 
-from .exceptions import TokenBackendError, TokenError
+from .exceptions import (
+    ExpiredTokenError,
+    TokenBackendError,
+    TokenBackendExpiredToken,
+    TokenError,
+)
 from .models import TokenUser
 from .settings import api_settings
 from .token_blacklist.models import BlacklistedToken, OutstandingToken
@@ -56,8 +61,10 @@ def __init__(self, token: Optional["Token"] = None, verify: bool = True) -> None
             # Decode token
             try:
                 self.payload = token_backend.decode(token, verify=verify)
+            except TokenBackendExpiredToken:
+                raise ExpiredTokenError(_("Token is expired"))
             except TokenBackendError:
-                raise TokenError(_("Token is invalid or expired"))
+                raise TokenError(_("Token is invalid"))
 
             if verify:
                 self.verify()

tests/test_backends.py

@@ -14,7 +14,10 @@
 from jwt import algorithms
 
 from rest_framework_simplejwt.backends import JWK_CLIENT_AVAILABLE, TokenBackend
-from rest_framework_simplejwt.exceptions import TokenBackendError
+from rest_framework_simplejwt.exceptions import (
+    TokenBackendError,
+    TokenBackendExpiredToken,
+)
 from rest_framework_simplejwt.utils import aware_utcnow, datetime_to_epoch, make_utc
 from tests.keys import (
     ES256_PRIVATE_KEY,
@@ -191,7 +194,7 @@ def test_decode_with_expiry(self):
                     self.payload, backend.signing_key, algorithm=backend.algorithm
                 )
 
-                with self.assertRaises(TokenBackendError):
+                with self.assertRaises(TokenBackendExpiredToken):
                     backend.decode(expired_token)
 
     def test_decode_with_invalid_sig(self):
@@ -346,9 +349,7 @@ def test_decode_jwk_missing_key_raises_tokenbackenderror(self):
                 "RS256", PRIVATE_KEY, PUBLIC_KEY, AUDIENCE, ISSUER, JWK_URL
             )
 
-            with self.assertRaisesRegex(
-                TokenBackendError, "Token is invalid or expired"
-            ):
+            with self.assertRaisesRegex(TokenBackendError, "Token is invalid"):
                 jwk_token_backend.decode(token)
 
     def test_decode_when_algorithm_not_available(self):

tests/test_serializers.py

@@ -206,7 +206,7 @@ def test_it_should_not_validate_if_token_invalid(self):
         with self.assertRaises(TokenError) as e:
             s.is_valid()
 
-        self.assertIn("invalid or expired", e.exception.args[0])
+        self.assertIn("expired", e.exception.args[0])
 
     def test_it_should_raise_token_error_if_token_has_no_refresh_exp_claim(self):
         token = SlidingToken()
@@ -337,7 +337,7 @@ def test_it_should_raise_token_error_if_token_invalid(self):
         with self.assertRaises(TokenError) as e:
             s.is_valid()
 
-        self.assertIn("invalid or expired", e.exception.args[0])
+        self.assertIn("expired", e.exception.args[0])
 
     def test_it_should_raise_token_error_if_token_has_wrong_type(self):
         token = RefreshToken()
@@ -503,7 +503,7 @@ def test_it_should_raise_token_error_if_token_invalid(self):
         with self.assertRaises(TokenError) as e:
             s.is_valid()
 
-        self.assertIn("invalid or expired", e.exception.args[0])
+        self.assertIn("expired", e.exception.args[0])
 
     def test_it_should_not_raise_token_error_if_token_has_wrong_type(self):
         token = RefreshToken()
@@ -548,7 +548,7 @@ def test_it_should_raise_token_error_if_token_invalid(self):
         with self.assertRaises(TokenError) as e:
             s.is_valid()
 
-        self.assertIn("invalid or expired", e.exception.args[0])
+        self.assertIn("expired", e.exception.args[0])
 
     def test_it_should_raise_token_error_if_token_has_wrong_type(self):
         token = RefreshToken()

tests/test_tokens.py

@@ -6,7 +6,11 @@
 from django.test import TestCase
 from jose import jwt
 
-from rest_framework_simplejwt.exceptions import TokenBackendError, TokenError
+from rest_framework_simplejwt.exceptions import (
+    ExpiredTokenError,
+    TokenBackendError,
+    TokenError,
+)
 from rest_framework_simplejwt.settings import api_settings
 from rest_framework_simplejwt.state import token_backend
 from rest_framework_simplejwt.tokens import (
@@ -157,7 +161,7 @@ def test_init_expired_token_given(self):
         t = MyToken()
         t.set_exp(lifetime=-timedelta(seconds=1))
 
-        with self.assertRaises(TokenError):
+        with self.assertRaises(ExpiredTokenError):
             MyToken(str(t))
 
     def test_init_no_type_token_given(self):