Repository: mlcommons/medperf (python)

Issue:
Check Refresh token expiration on the client
Some users are experiencing an "Unknown or Invalid refresh token" error. This may be caused when a user leaves the MedPerf client for a month, since the refresh token lifetime is 1 month, and the error above could happen when the refresh token is expired.

For a better user experience, the MedPerf client should keep track of the refresh token lifetime and instruct the user to login again if the existing refresh token has expired.

One TODO before this: check whether the 1 month lifetime is relative to the last login timestamp, or relative to the last refresh request. (Since we use Refresh token rotation). It's not clear from the Auth0 docs, so we may test this manually with small lifetimes using the development tenant.

Pull request description:
Check for refresh token absolute expiration time
This PR implements some logic that handles cases where an user hasn't logged in for longer than Auth0's absolute expiration time (30 days). Currently, if that happens the user encounters an error without much explanation of what happened or how to work through it. This PR checks if the error is related to expiration time, and if that's the case it explains to the user the problem and that they have to re-authenticate. It also automatically logs out the user.

Closes #583.

Patch:
diff --git a/cli/medperf/account_management/account_management.py b/cli/medperf/account_management/account_management.py
index d19cf8c..f8ea4e8 100644
--- a/cli/medperf/account_management/account_management.py
+++ b/cli/medperf/account_management/account_management.py
@@ -19,16 +19,29 @@ def set_credentials(
     id_token_payload,
     token_issued_at,
     token_expires_in,
+    login_event=False,
 ):
     email = id_token_payload["email"]
     TokenStore().set_tokens(email, access_token, refresh_token)
+    config_p = read_config()
+
+    if login_event:
+        # Set the time the user logged in, so that we can track the lifetime of
+        # the refresh token
+        logged_in_at = token_issued_at
+    else:
+        # This means this is a refresh event. Preserve the logged_in_at timestamp.
+        logged_in_at = config_p.active_profile[config.credentials_keyword][
+            "logged_in_at"
+        ]
 
     account_info = {
         "email": email,
         "token_issued_at": token_issued_at,
         "token_expires_in": token_expires_in,
+        "logged_in_at": logged_in_at,
     }
-    config_p = read_config()
+
     config_p.active_profile[config.credentials_keyword] = account_info
     write_config(config_p)
 
diff --git a/cli/medperf/comms/auth/auth0.py b/cli/medperf/comms/auth/auth0.py
index 3da6eca..60a052b 100644
--- a/cli/medperf/comms/auth/auth0.py
+++ b/cli/medperf/comms/auth/auth0.py
@@ -4,7 +4,7 @@ import threading
 import sqlite3
 from medperf.comms.auth.interface import Auth
 from medperf.comms.auth.token_verifier import verify_token
-from medperf.exceptions import CommunicationError
+from medperf.exceptions import CommunicationError, AuthenticationError
 import requests
 import medperf.config as config
 from medperf.utils import log_response_error
@@ -66,6 +66,7 @@ class Auth0(Auth):
             id_token_payload,
             token_issued_at,
             token_expires_in,
+            login_event=True,
         )
 
     def __request_device_code(self):
@@ -191,11 +192,35 @@ class Auth0(Auth):
         refresh_token = creds["refresh_token"]
         token_expires_in = creds["token_expires_in"]
         token_issued_at = creds["token_issued_at"]
-        if (
-            time.time()
-            > token_issued_at + token_expires_in - config.token_expiration_leeway
-        ):
-            access_token = self.__refresh_access_token(refresh_token)
+        logged_in_at = creds["logged_in_at"]
+
+        # token_issued_at and expires_in are for the access token
+        sliding_expiration_time = (
+            token_issued_at + token_expires_in - config.token_expiration_leeway
+        )
+        absolute_expiration_time = (
+            logged_in_at
+            + config.token_absolute_expiry
+            - config.refresh_token_expiration_leeway
+        )
+        current_time = time.time()
+
+        if current_time < sliding_expiration_time:
+            # Access token not expired. No need to refresh.
+            return access_token
+
+        # So we need to refresh.
+        if current_time > absolute_expiration_time:
+            # Expired refresh token. Force logout and ask the user to re-authenticate
+            logging.debug(
+                f"Refresh token expired: {absolute_expiration_time=} <> {current_time=}"
+            )
+            self.logout()
+            raise AuthenticationError("Token expired. Please re-authenticate")
+
+        # Expired access token and not expired refresh token. Refresh.
+        access_token = self.__refresh_access_token(refresh_token)
+
         return access_token
 
     def __refresh_access_token(self, refresh_token):
diff --git a/cli/medperf/comms/auth/local.py b/cli/medperf/comms/auth/local.py
index 1c12ba1..a597d4c 100644
--- a/cli/medperf/comms/auth/local.py
+++ b/cli/medperf/comms/auth/local.py
@@ -39,6 +39,7 @@ class Local(Auth):
             id_token_payload,
             token_issued_at,
             token_expires_in,
+            login_event=True,
         )
 
     def logout(self):
diff --git a/cli/medperf/config.py b/cli/medperf/config.py
index f43af8f..2c5b520 100644
--- a/cli/medperf/config.py
+++ b/cli/medperf/config.py
@@ -37,6 +37,8 @@ auth_dev_audience = "https://localhost-dev/"
 auth_jwks_cache_ttl = 600  # fetch jwks every 10 mins. Default value in auth0 python SDK
 
 token_expiration_leeway = 10  # Refresh tokens 10 seconds before expiration
+refresh_token_expiration_leeway = 10  # Logout users 10 seconds before absolute token expiration.
+token_absolute_expiry = 2592000  # Refresh token absolute expiration time (seconds). This value is set on auth0's configuration
 access_token_storage_id = "medperf_access_token"
 refresh_token_storage_id = "medperf_refresh_token"
 
diff --git a/cli/medperf/exceptions.py b/cli/medperf/exceptions.py
index 6844f28..68e858c 100644
--- a/cli/medperf/exceptions.py
+++ b/cli/medperf/exceptions.py
@@ -30,6 +30,10 @@ class ExecutionError(MedperfException):
     """Raised when an execution component fails"""
 
 
+class AuthenticationError(MedperfException):
+    """Raised when authentication can't be processed"""
+
+
 class CleanExit(MedperfException):
     """Raised when Medperf needs to stop for non erroneous reasons"""
 
diff --git a/cli/medperf/storage/__init__.py b/cli/medperf/storage/__init__.py
index acebb6f..74e4e79 100644
--- a/cli/medperf/storage/__init__.py
+++ b/cli/medperf/storage/__init__.py
@@ -1,5 +1,6 @@
 import os
 import shutil
+import time
 
 from medperf import config
 from medperf.config_management import read_config, write_config
@@ -25,6 +26,7 @@ def apply_configuration_migrations():
 
     config_p = read_config()
 
+    # Migration for moving the logs folder to a new location
     if "logs_folder" not in config_p.storage:
         return
 
@@ -35,4 +37,16 @@ def apply_configuration_migrations():
 
     del config_p.storage["logs_folder"]
 
+    # Migration for tracking the login timestamp (i.e., refresh token issuance timestamp)
+    if config.credentials_keyword in config_p.active_profile:
+        # So the user is logged in
+        if "logged_in_at" not in config_p.active_profile[config.credentials_keyword]:
+            # Apply migration. We will set it to the current time, since this
+            # will make sure they will not be logged out before the actual refresh
+            # token expiration (for a better user experience). However, currently logged
+            # in users will still face a confusing error when the refresh token expires.
+            config_p.active_profile[config.credentials_keyword][
+                "logged_in_at"
+            ] = time.time()
+
     write_config(config_p)


Test patch:
diff --git a/cli/medperf/tests/comms/test_auth0.py b/cli/medperf/tests/comms/test_auth0.py
index 313f4f6..9eadd96 100644
--- a/cli/medperf/tests/comms/test_auth0.py
+++ b/cli/medperf/tests/comms/test_auth0.py
@@ -2,9 +2,12 @@ import time
 from unittest.mock import ANY
 from medperf.tests.mocks import MockResponse
 from medperf.comms.auth.auth0 import Auth0
+from medperf import config
+from medperf.exceptions import AuthenticationError
 import sqlite3
 import pytest
 
+
 PATCH_AUTH = "medperf.comms.auth.auth0.{}"
 
 
@@ -35,6 +38,7 @@ def test_token_is_not_refreshed_if_not_expired(mocker, setup):
         "access_token": "",
         "token_expires_in": 900,
         "token_issued_at": time.time(),
+        "logged_in_at": time.time(),
     }
     mocker.patch(PATCH_AUTH.format("read_credentials"), return_value=creds)
     spy = mocker.patch(PATCH_AUTH.format("Auth0._Auth0__refresh_access_token"))
@@ -48,11 +52,14 @@ def test_token_is_not_refreshed_if_not_expired(mocker, setup):
 
 def test_token_is_refreshed_if_expired(mocker, setup):
     # Arrange
+    expiration_time = 900
+    mocked_issued_at = time.time() - expiration_time
     creds = {
         "refresh_token": "",
         "access_token": "",
-        "token_expires_in": 900,
-        "token_issued_at": time.time() - 1000,
+        "token_expires_in": expiration_time,
+        "token_issued_at": mocked_issued_at,
+        "logged_in_at": time.time(),
     }
     mocker.patch(PATCH_AUTH.format("read_credentials"), return_value=creds)
     spy = mocker.patch(PATCH_AUTH.format("Auth0._Auth0__refresh_access_token"))
@@ -64,6 +71,30 @@ def test_token_is_refreshed_if_expired(mocker, setup):
     spy.assert_called_once()
 
 
+def test_logs_out_if_session_reaches_token_absolute_expiration_time(mocker, setup):
+    # Arrange
+    expiration_time = 900
+    absolute_expiration_time = config.token_absolute_expiry
+    mocked_logged_in_at = time.time() - absolute_expiration_time
+    mocked_issued_at = time.time() - expiration_time
+    creds = {
+        "refresh_token": "",
+        "access_token": "",
+        "token_expires_in": expiration_time,
+        "token_issued_at": mocked_issued_at,
+        "logged_in_at": mocked_logged_in_at,
+    }
+    mocker.patch(PATCH_AUTH.format("read_credentials"), return_value=creds)
+    spy = mocker.patch(PATCH_AUTH.format("Auth0.logout"))
+
+    # Act
+    with pytest.raises(AuthenticationError):
+        Auth0().access_token
+
+    # Assert
+    spy.assert_called_once()
+
+
 def test_refresh_token_sets_new_tokens(mocker, setup):
     # Arrange
     access_token = "access_token"