re-read files automatically if changed (files checked every cache_time seconds)

Author: jschlyter

src/cryptojwt/key_bundle.py

@@ -180,6 +180,7 @@ def __init__(self, keys=None, source="", cache_time=300, verify_ssl=True,
 
         self._keys = []
         self.remote = False
+        self.local = False
         self.cache_time = cache_time
         self.time_out = 0
         self.etag = ""
@@ -189,7 +190,8 @@ def __init__(self, keys=None, source="", cache_time=300, verify_ssl=True,
         self.keyusage = keyusage
         self.imp_jwks = None
         self.last_updated = 0
-        self.last_remote = None
+        self.last_remote = None  # HTTP Date of last remote update
+        self.last_local = None   # UNIX timestamp of last local update
 
         if httpc:
             self.httpc = httpc
@@ -209,13 +211,13 @@ def __init__(self, keys=None, source="", cache_time=300, verify_ssl=True,
                 self.do_keys(keys)
         else:
             self._set_source(source, fileformat)
-
-            if not self.remote and self.source:  # local file
+            if self.local:
                 self._do_local(kid)
 
     def _set_source(self, source, fileformat):
         if source.startswith("file://"):
             self.source = source[7:]
+            self.local = True
         elif source.startswith("http://") or source.startswith("https://"):
             self.source = source
             self.remote = True
@@ -225,6 +227,7 @@ def _set_source(self, source, fileformat):
             if fileformat.lower() in ['rsa', 'der', 'jwks']:
                 if os.path.isfile(source):
                     self.source = source
+                    self.local = True
                 else:
                     raise ImportError('No such file')
             else:
@@ -236,6 +239,16 @@ def _do_local(self, kid):
         elif self.fileformat == "der":
             self.do_local_der(self.source, self.keytype, self.keyusage, kid)
 
+    def _local_update_required(self) -> bool:
+        stat = os.stat(self.source)
+        if self.last_local and stat.st_mtime < self.last_local:
+            LOGGER.debug("%s not modfied", self.source)
+            return False
+        else:
+            LOGGER.debug("%s modfied", self.source)
+            self.last_local = stat.st_mtime
+            return True
+
     def do_keys(self, keys):
         """
         Go from JWK description to binary keys
@@ -291,12 +304,15 @@ def do_local_jwk(self, filename):
 
         :param filename: Name of the file from which the JWKS should be loaded
         """
+        LOGGER.debug("Reading JWKS from %s", filename)
         with open(filename) as input_file:
             _info = json.load(input_file)
         if 'keys' in _info:
             self.do_keys(_info["keys"])
         else:
             self.do_keys([_info])
+        self.last_local = time.time()
+        self.time_out = self.last_local + self.cache_time
 
     def do_local_der(self, filename, keytype, keyusage=None, kid=''):
         """
@@ -306,6 +322,7 @@ def do_local_der(self, filename, keytype, keyusage=None, kid=''):
         :param keytype: Presently 'rsa' and 'ec' supported
         :param keyusage: encryption ('enc') or signing ('sig') or both
         """
+        LOGGER.debug("Reading DER from %s", filename)
         key_args = {}
         _kty = keytype.lower()
         if _kty in ['rsa', 'ec']:
@@ -325,6 +342,8 @@ def do_local_der(self, filename, keytype, keyusage=None, kid=''):
             key_args['kid'] = kid
 
         self.do_keys([key_args])
+        self.last_local = time.time()
+        self.time_out = self.last_local + self.cache_time
 
     def do_remote(self):
         """
@@ -400,14 +419,12 @@ def _parse_remote_response(self, response):
 
     def _uptodate(self):
         res = False
-        if not self._keys:
-            if self.remote:  # verify that it's not to old
-                if time.time() > self.time_out:
-                    if self.update():
-                        res = True
-        elif self.remote:
-            if self.update():
-                res = True
+        if self.remote or self.local:
+            if time.time() > self.time_out:
+                if self.local and not self._local_update_required():
+                    res = True
+                elif self.update():
+                    res = True
         return res
 
     def update(self):
@@ -425,13 +442,13 @@ def update(self):
             self._keys = []
 
             try:
-                if self.remote is False:
+                if self.local:
                     if self.fileformat in ["jwks", "jwk"]:
                         self.do_local_jwk(self.source)
                     elif self.fileformat == "der":
                         self.do_local_der(self.source, self.keytype,
                                           self.keyusage)
-                else:
+                elif self.remote:
                     res = self.do_remote()
             except Exception as err:
                 LOGGER.error('Key bundle update failed: %s', err)
@@ -674,8 +691,11 @@ def dump(self):
             "keys": _keys,
             "fileformat": self.fileformat,
             "last_updated": self.last_updated,
+            "last_remote": self.last_remote,
+            "last_local": self.last_local,
             "httpc_params": self.httpc_params,
             "remote": self.remote,
+            "local": self.local,
             "imp_jwks": self.imp_jwks,
             "time_out": self.time_out,
             "cache_time": self.cache_time
@@ -693,7 +713,10 @@ def load(self, spec):
         self.source = spec.get("source", None)
         self.fileformat = spec.get("fileformat", "jwks")
         self.last_updated = spec.get("last_updated", 0)
+        self.last_remote = spec.get("last_remote", None)
+        self.last_local = spec.get("last_local", None)
         self.remote = spec.get("remote", False)
+        self.local = spec.get("local", False)
         self.imp_jwks = spec.get('imp_jwks', None)
         self.time_out = spec.get('time_out', 0)
         self.cache_time = spec.get('cache_time', 0)

tests/test_03_key_bundle.py

@@ -938,7 +938,10 @@ def test_export_inactive():
                                'imp_jwks',
                                'keys',
                                'last_updated',
+                               'last_remote',
+                               'last_local',
                                'remote',
+                               'local',
                                'time_out'}
 
     kb2 = KeyBundle().load(res)