Bug expires at (#783)

* verify that expires_at is an int before casting it as such.

* casting expires_at as int within try catch with test.

Co-authored-by: Scott Gifford <sgifford@activecampaign.com>

oauthlib/oauth2/rfc6749/clients/base.py

@@ -513,7 +513,10 @@ def populate_token_attributes(self, response):
             self._expires_at = time.time() + int(self.expires_in)
 
         if 'expires_at' in response:
-            self._expires_at = int(response.get('expires_at'))
+            try:
+                self._expires_at = int(response.get('expires_at'))
+            except:
+                self._expires_at = None
 
         if 'mac_key' in response:
             self.mac_key = response.get('mac_key')

tests/oauth2/rfc6749/clients/test_base.py

@@ -301,3 +301,27 @@ def test_prepare_refresh_token_request(self):
         self.assertEqual(u, url)
         self.assertEqual(h, {'Content-Type': 'application/x-www-form-urlencoded'})
         self.assertFormBodyEqual(b, 'grant_type=refresh_token&scope={}&refresh_token={}'.format(scope, token))
+
+    def test_parse_token_response_invalid_expires_at(self):
+        token_json = ('{   "access_token":"2YotnFZFEjr1zCsicMWpAA",'
+                      '    "token_type":"example",'
+                      '    "expires_at":"2006-01-02T15:04:05Z",'
+                      '    "scope":"/profile",'
+                      '    "example_parameter":"example_value"}')
+        token = {
+            "access_token": "2YotnFZFEjr1zCsicMWpAA",
+            "token_type": "example",
+            "expires_at": "2006-01-02T15:04:05Z",
+            "scope": ["/profile"],
+            "example_parameter": "example_value"
+        }
+
+        client = Client(self.client_id)
+
+        # Parse code and state
+        response = client.parse_request_body_response(token_json, scope=["/profile"])
+        self.assertEqual(response, token)
+        self.assertEqual(None, client._expires_at)
+        self.assertEqual(client.access_token, response.get("access_token"))
+        self.assertEqual(client.refresh_token, response.get("refresh_token"))
+        self.assertEqual(client.token_type, response.get("token_type"))