Filtering request using OpenAPI spec

.github/workflows/python-linux.yml

@@ -79,3 +79,25 @@ jobs:
           cd docs
           pip install -r doc-requirements.txt
           make html SPHINXOPTS="-W"
+
+  no-tornado-openapi3:
+    runs-on: ${{ matrix.os }}-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu]
+        python-version: ["3.10"]
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+      - name: Base Setup
+        uses: jupyterlab/maintainer-tools/.github/actions/base-setup@v1
+      - name: Install the Python dependencies
+        run: |
+          pip install -e ".[test]"
+          # Remove optional dependency
+          pip uninstall -y tornado-openapi3
+      - name: Run some tests
+        run: |
+          # Use that files as it contains some tests that should pass and other that needs to be skipped
+          pytest -vv jupyter_server/tests/extension/test_launch.py

docs/source/developers/extensions.rst

@@ -306,6 +306,101 @@ To make your extension executable from anywhere on your system, point an entry-p
         }
     )
 
+Filtering requests
+------------------
+
+When launching the ``ExtensionApp`` in standalone mode, you may want to restrict the available endpoints. You can do this by defining
+either ``_allowed_spec`` or ``_blocked_spec`` class attributes as OpenAPI v3 specifications. The allowed paths will blocked any requests
+not matching the specification and the blocked paths will allow any requests except the ones specified.
+
+.. note::
+
+   If both are defined, the blocked paths take precedence on the allowed one; i.e. if a path is allowed and blocked, it will be blocked.
+
+OpenAPI v3 does not support URL path arguments that contains slashes ``/``. For the specification,
+``/api/contents/{path}`` can only be ``/api/contents/[^/]+``. To circumvent this limitation, you can provide a list of regex's through
+the class attributes ``_slash_encoder``. The groups matching one of the encoder will have their slashes encoded (``/`` replaced by ``%2F``).
+This will allow the validation of path through the OpenAPI v3 specification.
+
+Here is an example for the unit tests.
+
+.. code-block:: python
+
+    class MyExtensionApp(ExtensionApp):
+
+        _allowed_spec = {
+            "openapi": "3.0.1",
+            "info": {"title": "Test specs", "version": "0.0.1"},
+            "paths": {
+                "/api/contents/{path}": {
+                    # Will be blocked by _blocked_spec
+                    "get": {
+                        "parameters": [
+                            {
+                                "name": "path",
+                                "in": "path",
+                                "required": True,
+                                "schema": {"type": "string"},
+                            }
+                        ],
+                        "responses": {"200": {"description": ""}},
+                    },
+                },
+                "/api/contents/{path}/checkpoints": {
+                    "post": {
+                        "parameters": [
+                            {
+                                "name": "path",
+                                "in": "path",
+                                "required": True,
+                                "schema": {"type": "string"},
+                            }
+                        ],
+                        "responses": {"201": {"description": ""}},
+                    },
+                },
+                "/api/sessions/{sessionId}": {
+                    "get": {
+                        "parameters": [
+                            {
+                                "name": "sessionId",
+                                "in": "path",
+                                "required": True,
+                                "schema": {"type": "string"},
+                            }
+                        ],
+                        "responses": {"200": {"description": ""}},
+                    },
+                },
+            },
+        }
+
+        _blocked_spec = {
+            "openapi": "3.0.1",
+            "info": {"title": "Test specs", "version": "0.0.1"},
+            "paths": {
+                "/api/contents/{path}": {
+                    "get": {
+                        "parameters": [
+                            {
+                                "name": "path",
+                                "in": "path",
+                                "required": True,
+                                "schema": {"type": "string"},
+                            }
+                        ],
+                        "responses": {"200": {"description": ""}},
+                    },
+                },
+            },
+        }
+
+        _slash_encoder = (
+            r"/api/contents/([^/?]+(?:(?:/[^/]+)*?))/checkpoints$",
+            r"/api/contents/([^/?]+(?:(?:/[^/]+)*?))$",
+        )
+
+
 ``ExtensionApp`` as a classic Notebook server extension
 -------------------------------------------------------
 

jupyter_server/extension/application.py

@@ -1,6 +1,8 @@
 import logging
 import re
 import sys
+from typing import Iterable
+from typing import Optional
 
 from jinja2 import Environment
 from jinja2 import FileSystemLoader
@@ -136,6 +138,13 @@ class method. This method can be set as a entry_point in
         the extensions setup.py
     """
 
+    # Filtering rules to apply on handlers registration
+    # Subclasses can override this list to filter handlers
+    # They will be applied on the ServerApp
+    _allowed_spec: Optional[dict] = None
+    _blocked_spec: Optional[dict] = None
+    _slash_encoder: Optional[Iterable[str]] = None
+
     # Subclasses should override this trait. Tells the server if
     # this extension allows other other extensions to be loaded
     # side-by-side when launched directly.
@@ -180,6 +189,14 @@ def get_extension_package(cls):
     def get_extension_point(cls):
         return cls.__module__
 
+    @classmethod
+    def get_openapi3_spec_rules(cls):
+        return {
+            "allowed": cls._allowed_spec,
+            "blocked": cls._blocked_spec,
+            "slash_encoder": cls._slash_encoder,
+        }
+
     # Extension URL sets the default landing page for this extension.
     extension_url = "/"
 
@@ -495,7 +512,8 @@ def load_classic_server_extension(cls, serverapp):
                     RedirectHandler,
                     {
                         "url": url_path_join(
-                            serverapp.base_url, "static/base/images/favicon-notebook.ico"
+                            serverapp.base_url,
+                            "static/base/images/favicon-notebook.ico",
                         )
                     },
                 ),
@@ -504,7 +522,8 @@ def load_classic_server_extension(cls, serverapp):
                     RedirectHandler,
                     {
                         "url": url_path_join(
-                            serverapp.base_url, "static/base/images/favicon-terminal.ico"
+                            serverapp.base_url,
+                            "static/base/images/favicon-terminal.ico",
                         )
                     },
                 ),

jupyter_server/serverapp.py

@@ -28,6 +28,15 @@
 import urllib
 import webbrowser
 from base64 import encodebytes
+from typing import Iterable
+from typing import Optional
+
+from tornado import httputil
+
+try:
+    from jupyter_server.specvalidator import SpecValidator
+except ImportError:
+    SpecValidator = None
 
 try:
     import resource
@@ -222,7 +231,24 @@ def __init__(
         default_url,
         settings_overrides,
         jinja_env_options,
+        spec_validators=None,
     ):
+        if SpecValidator is None or spec_validators is None:
+
+            class DummyValidator:
+                """Dummy request validator that is always valid."""
+
+                def validate(self, request):
+                    return True
+
+            self.__requestValidator: Optional[SpecValidator] = DummyValidator()
+        else:
+            self.__requestValidator: Optional[SpecValidator] = SpecValidator(
+                base_url,
+                spec_validators.get("allowed"),
+                spec_validators.get("blocked"),
+                spec_validators.get("slash_encoder"),
+            )
 
         settings = self.init_settings(
             jupyter_app,
@@ -433,6 +459,14 @@ def init_handlers(self, default_services, settings):
         new_handlers.append((r"(.*)", Template404))
         return new_handlers
 
+    def find_handler(
+        self, request: httputil.HTTPServerRequest, **kwargs: Any
+    ) -> "web._HandlerDelegate":
+        if self.__requestValidator.validate(request):
+            return super().find_handler(request, **kwargs)
+        else:
+            return self.get_handler_delegate(request, web.ErrorHandler, {"status_code": 403})
+
     def last_activity(self):
         """Get a UTC timestamp for when the server last did something.
 
@@ -756,6 +790,12 @@ class ServerApp(JupyterApp):
         "view",
     )
 
+    # Filtering rules to apply on handlers registration
+    # Subclasses can override this list to filter handlers
+    _allowed_spec: Optional[dict] = None
+    _blocked_spec: Optional[dict] = None
+    _slash_encoder: Optional[Iterable[str]] = None
+
     _log_formatter_cls = LogFormatter
 
     @default("log_level")
@@ -1843,6 +1883,11 @@ def init_webapp(self):
             self.default_url,
             self.tornado_settings,
             self.jinja_environment_options,
+            spec_validators={
+                "allowed": self._allowed_spec,
+                "blocked": self._blocked_spec,
+                "slash_encoder": self._slash_encoder,
+            },
         )
         if self.certfile:
             self.ssl_options["certfile"] = self.certfile
@@ -2316,6 +2361,11 @@ def initialize(
             # Set starter_app property.
             if point.app:
                 self._starter_app = point.app
+                # Apply endpoint filters from the extension app
+                spec_rules = point.app.get_openapi3_spec_rules()
+                self._allowed_spec = spec_rules["allowed"]
+                self._blocked_spec = spec_rules["blocked"]
+                self._slash_encoder = spec_rules["slash_encoder"]
             # Load any configuration that comes from the Extension point.
             self.update_config(Config(point.config))