Merge pull request #73 from AzureAD/release-0.3.0

Release 0.3.0

Author: abhidnya13

.github/workflows/codeql.yml

@@ -0,0 +1,46 @@
+name: "Code Scanning - Action"
+
+on:
+  push:
+  schedule:
+    - cron: '0 0 * * 0'
+
+jobs:
+  CodeQL-Build:
+
+    strategy:
+      fail-fast: false
+
+
+    # CodeQL runs on ubuntu-latest, windows-latest, and macos-latest
+    runs-on: ubuntu-latest
+
+    steps:
+    - name: Checkout repository
+      uses: actions/checkout@v2
+
+    # Initializes the CodeQL tools for scanning.
+    - name: Initialize CodeQL
+      uses: github/codeql-action/init@v1
+      # Override language selection by uncommenting this and choosing your languages
+      # with:
+      #   languages: go, javascript, csharp, python, cpp, java
+
+    # Autobuild attempts to build any compiled languages  (C/C++, C#, or Java).
+    # If this step fails, then you should remove it and run the build manually (see below).
+    - name: Autobuild
+      uses: github/codeql-action/autobuild@v1
+
+    # ℹ️ Command-line programs to run using the OS shell.
+    # 📚 https://git.io/JvXDl
+
+    # ✏️ If the Autobuild fails above, remove it and uncomment the following three lines
+    #    and modify them (or add more) to build your code if your project
+    #    uses a compiled language
+
+    #- run: |
+    #   make bootstrap
+    #   make release
+
+    - name: Perform CodeQL Analysis
+      uses: github/codeql-action/analyze@v1

msal_extensions/__init__.py

@@ -1,5 +1,5 @@
 """Provides auxiliary functionality to the `msal` package."""
-__version__ = "0.2.2"
+__version__ = "0.3.0"
 
 import sys
 

msal_extensions/persistence.py

@@ -9,6 +9,7 @@
 import abc
 import os
 import errno
+import logging
 try:
     from pathlib import Path  # Built-in in Python 3
 except:
@@ -21,6 +22,9 @@
     ABC = abc.ABCMeta("ABC", (object,), {"__slots__": ()})  # type: ignore
 
 
+logger = logging.getLogger(__name__)
+
+
 def _mkdir_p(path):
     """Creates a directory, and any necessary parents.
 
@@ -41,6 +45,20 @@ def _mkdir_p(path):
             raise
 
 
+# We do not aim to wrap every os-specific exception.
+# Here we define only the most common one,
+# otherwise caller would need to catch os-specific persistence exceptions.
+class PersistenceNotFound(IOError):  # Use IOError rather than OSError as base,
+        # because historically an IOError was bubbled up and expected.
+        # https://github.com/AzureAD/microsoft-authentication-extensions-for-python/blob/0.2.2/msal_extensions/token_cache.py#L38
+        # Now we want to maintain backward compatibility even when using Python 2.x
+        # It makes no difference in Python 3.3+ where IOError is an alias of OSError.
+    def __init__(
+            self,
+            err_no=errno.ENOENT, message="Persistence not found", location=None):
+        super(PersistenceNotFound, self).__init__(err_no, message, location)
+
+
 class BasePersistence(ABC):
     """An abstract persistence defining the common interface of this family"""
 
@@ -55,12 +73,18 @@ def save(self, content):
     @abc.abstractmethod
     def load(self):
         # type: () -> str
-        """Load content from this persistence"""
+        """Load content from this persistence.
+
+        Could raise PersistenceNotFound if no save() was called before.
+        """
         raise NotImplementedError
 
     @abc.abstractmethod
     def time_last_modified(self):
-        """Get the last time when this persistence has been modified"""
+        """Get the last time when this persistence has been modified.
+
+        Could raise PersistenceNotFound if no save() was called before.
+        """
         raise NotImplementedError
 
     @abc.abstractmethod
@@ -87,11 +111,32 @@ def save(self, content):
     def load(self):
         # type: () -> str
         """Load content from this persistence"""
-        with open(self._location, 'r') as handle:
-            return handle.read()
+        try:
+            with open(self._location, 'r') as handle:
+                return handle.read()
+        except EnvironmentError as exp:  # EnvironmentError in Py 2.7 works across platform
+            if exp.errno == errno.ENOENT:
+                raise PersistenceNotFound(
+                    message=(
+                        "Persistence not initialized. "
+                        "You can recover by calling a save() first."),
+                    location=self._location,
+                    )
+            raise
+
 
     def time_last_modified(self):
-        return os.path.getmtime(self._location)
+        try:
+            return os.path.getmtime(self._location)
+        except EnvironmentError as exp:  # EnvironmentError in Py 2.7 works across platform
+            if exp.errno == errno.ENOENT:
+                raise PersistenceNotFound(
+                    message=(
+                        "Persistence not initialized. "
+                        "You can recover by calling a save() first."),
+                    location=self._location,
+                    )
+            raise
 
     def touch(self):
         """To touch this file-based persistence without writing content into it"""
@@ -115,13 +160,28 @@ def __init__(self, location, entropy=''):
 
     def save(self, content):
         # type: (str) -> None
+        data = self._dp_agent.protect(content)
         with open(self._location, 'wb+') as handle:
-            handle.write(self._dp_agent.protect(content))
+            handle.write(data)
 
     def load(self):
         # type: () -> str
-        with open(self._location, 'rb') as handle:
-            return self._dp_agent.unprotect(handle.read())
+        try:
+            with open(self._location, 'rb') as handle:
+                data = handle.read()
+            return self._dp_agent.unprotect(data)
+        except EnvironmentError as exp:  # EnvironmentError in Py 2.7 works across platform
+            if exp.errno == errno.ENOENT:
+                raise PersistenceNotFound(
+                    message=(
+                        "Persistence not initialized. "
+                        "You can recover by calling a save() first."),
+                    location=self._location,
+                    )
+            logger.exception(
+                "DPAPI error likely caused by file content not previously encrypted. "
+                "App developer should migrate by calling save(plaintext) first.")
+            raise
 
 
 class KeychainPersistence(BasePersistence):
@@ -136,9 +196,10 @@ def __init__(self, signal_location, service_name, account_name):
         """
         if not (service_name and account_name):  # It would hang on OSX
             raise ValueError("service_name and account_name are required")
-        from .osx import Keychain  # pylint: disable=import-outside-toplevel
+        from .osx import Keychain, KeychainError  # pylint: disable=import-outside-toplevel
         self._file_persistence = FilePersistence(signal_location)  # Favor composition
         self._Keychain = Keychain  # pylint: disable=invalid-name
+        self._KeychainError = KeychainError  # pylint: disable=invalid-name
         self._service_name = service_name
         self._account_name = account_name
 
@@ -150,8 +211,21 @@ def save(self, content):
 
     def load(self):
         with self._Keychain() as locker:
-            return locker.get_generic_password(
-                self._service_name, self._account_name)
+            try:
+                return locker.get_generic_password(
+                    self._service_name, self._account_name)
+            except self._KeychainError as ex:
+                if ex.exit_status == self._KeychainError.ITEM_NOT_FOUND:
+                    # This happens when a load() is called before a save().
+                    # We map it into cross-platform error for unified catching.
+                    raise PersistenceNotFound(
+                        location="Service:{} Account:{}".format(
+                            self._service_name, self._account_name),
+                        message=(
+                            "Keychain persistence not initialized. "
+                            "You can recover by call a save() first."),
+                        )
+                raise  # We do not intend to hide any other underlying exceptions
 
     def time_last_modified(self):
         return self._file_persistence.time_last_modified()
@@ -188,7 +262,14 @@ def save(self, content):
             self._file_persistence.touch()  # For time_last_modified()
 
     def load(self):
-        return self._agent.load()
+        data = self._agent.load()
+        if data is None:
+            # Lower level libsecret would return None when found nothing. Here
+            # in persistence layer, we convert it to a unified error for consistence.
+            raise PersistenceNotFound(message=(
+                "Keyring persistence not initialized. "
+                "You can recover by call a save() first."))
+        return data
 
     def time_last_modified(self):
         return self._file_persistence.time_last_modified()

msal_extensions/token_cache.py

@@ -2,14 +2,13 @@
 import os
 import warnings
 import time
-import errno
 import logging
 
 import msal
 
 from .cache_lock import CrossPlatLock
 from .persistence import (
-    _mkdir_p, FilePersistence,
+    _mkdir_p, PersistenceNotFound, FilePersistence,
     FilePersistenceWithDataProtection, KeychainPersistence)
 
 
@@ -35,10 +34,10 @@ def _reload_if_necessary(self):
             if self._last_sync < self._persistence.time_last_modified():
                 self.deserialize(self._persistence.load())
                 self._last_sync = time.time()
-        except IOError as exp:
-            if exp.errno != errno.ENOENT:
-                raise
-            # Otherwise, from cache's perspective, a nonexistent file is a NO-OP
+        except PersistenceNotFound:
+            # From cache's perspective, a nonexistent persistence is a NO-OP.
+            pass
+        # However, existing data unable to be decrypted will still be bubbled up.
 
     def modify(self, credential_type, old_entry, new_key_value_pairs=None):
         with CrossPlatLock(self._lock_location):

tests/cache_file_generator.py

@@ -0,0 +1,43 @@
+"""
+Usage: cache_file_generator.py cache_file_path sleep_interval
+
+This is a console application which is to be used for cross-platform lock performance testing.
+The app will acquire lock for the cache file, log the process id and then release the lock.
+
+It takes in two arguments - cache file path and the sleep interval.
+The cache file path is the path of cache file.
+The sleep interval is the time in seconds for which the lock is held by a process.
+"""
+
+import logging
+import os
+import sys
+import time
+
+from portalocker import exceptions
+
+from msal_extensions import FilePersistence, CrossPlatLock
+
+
+def _acquire_lock_and_write_to_cache(cache_location, sleep_interval):
+    cache_accessor = FilePersistence(cache_location)
+    lock_file_path = cache_accessor.get_location() + ".lockfile"
+    try:
+        with CrossPlatLock(lock_file_path):
+            data = cache_accessor.load()
+            if data is None:
+                data = ""
+            data += "< " + str(os.getpid()) + "\n"
+            time.sleep(sleep_interval)
+            data += "> " + str(os.getpid()) + "\n"
+            cache_accessor.save(data)
+    except exceptions.LockException as e:
+        logging.warning("Unable to acquire lock %s", e)
+
+
+if __name__ == "__main__":
+    if len(sys.argv) < 3:
+        print(__doc__)
+        sys.exit(0)
+    _acquire_lock_and_write_to_cache(sys.argv[1], float(sys.argv[2]))
+

tests/test_agnostic_backend.py

@@ -44,3 +44,8 @@ def test_current_platform_cache_roundtrip_with_alias_class(temp_location):
 def test_persisted_token_cache(temp_location):
     _test_token_cache_roundtrip(PersistedTokenCache(FilePersistence(temp_location)))
 
+def test_file_not_found_error_is_not_raised():
+    persistence = FilePersistence('non_existing_file')
+    cache = PersistedTokenCache(persistence=persistence)
+    # An exception raised here will fail the test case as it is supposed to be a NO-OP
+    cache.find('')

tests/test_cache_lock_file_perf.py

@@ -0,0 +1,75 @@
+import multiprocessing
+import os
+import shutil
+import tempfile
+
+import pytest
+
+from cache_file_generator import _acquire_lock_and_write_to_cache
+
+
+@pytest.fixture
+def temp_location():
+    test_folder = tempfile.mkdtemp(prefix="test_persistence_roundtrip")
+    yield os.path.join(test_folder, 'persistence.bin')
+    shutil.rmtree(test_folder, ignore_errors=True)
+
+
+def _validate_result_in_cache(cache_location):
+    with open(cache_location) as handle:
+        data = handle.read()
+    prev_process_id = None
+    count = 0
+    for line in data.split("\n"):
+        if line:
+            count += 1
+            tag, process_id = line.split(" ")
+            if prev_process_id is not None:
+                assert process_id == prev_process_id, "Process overlap found"
+                assert tag == '>', "Process overlap_found"
+                prev_process_id = None
+            else:
+                assert tag == '<', "Opening bracket not found"
+                prev_process_id = process_id
+    return count
+
+
+def _run_multiple_processes(no_of_processes, cache_location, sleep_interval):
+    open(cache_location, "w+")
+    processes = []
+    for i in range(no_of_processes):
+        process = multiprocessing.Process(
+            target=_acquire_lock_and_write_to_cache,
+            args=(cache_location, sleep_interval))
+        processes.append(process)
+
+    for process in processes:
+        process.start()
+
+    for process in processes:
+        process.join()
+
+
+def test_lock_for_normal_workload(temp_location):
+    num_of_processes = 4
+    sleep_interval = 0.1
+    _run_multiple_processes(num_of_processes, temp_location, sleep_interval)
+    count = _validate_result_in_cache(temp_location)
+    assert count == num_of_processes * 2, "Should not observe starvation"
+
+
+def test_lock_for_high_workload(temp_location):
+    num_of_processes = 80
+    sleep_interval = 0
+    _run_multiple_processes(num_of_processes, temp_location, sleep_interval)
+    count = _validate_result_in_cache(temp_location)
+    assert count <= num_of_processes * 2, "Starvation or not, we should not observe garbled payload"
+
+
+def test_lock_for_timeout(temp_location):
+    num_of_processes = 10
+    sleep_interval = 1
+    _run_multiple_processes(num_of_processes, temp_location, sleep_interval)
+    count = _validate_result_in_cache(temp_location)
+    assert count < num_of_processes * 2, "Should observe starvation"
+