Fix schema validation (#175)

* Fix schema validation

Stop using the global schema in pure functions. Also now properly allows
custom schema validators.

Next step for fixing schema validation is #166

* Remove unused "validate" function

jsonrpcserver/dispatcher.py

@@ -11,7 +11,6 @@
 from typing import Any, Callable, Dict, List, Union
 
 from apply_defaults import apply_config  # type: ignore
-from jsonschema import ValidationError  # type: ignore
 from jsonschema.validators import validator_for  # type: ignore
 from pkg_resources import resource_string  # type: ignore
 
@@ -28,11 +27,14 @@
 )
 from .result import InvalidParams, InternalError, Result
 
-# Prepare the jsonschema validator
-global_schema = json.loads(resource_string(__name__, "request-schema.json"))
-klass = validator_for(global_schema)
-klass.check_schema(global_schema)
-validator = klass(global_schema)
+default_deserializer = json.loads
+
+# Prepare the jsonschema validator. This is global so it loads only once, not every
+# time dispatch is called.
+schema = json.loads(resource_string(__name__, "request-schema.json"))
+klass = validator_for(schema)
+klass.check_schema(schema)
+default_schema_validator = klass(schema).validate
 
 # Read configuration file
 config = ConfigParser(default_section="dispatch")
@@ -140,27 +142,13 @@ def create_requests(requests: Union[Dict, List[Dict]]) -> Union[Request, List[Re
     )
 
 
-def validate(request: Union[Dict, List]) -> Union[Dict, List]:
-    """
-    Wraps jsonschema.validate, returning the same object passed in if successful.
-
-    Raises an exception if invalid.
-
-    Args:
-        request: The deserialized-from-json request.
-
-    Returns:
-        The same object passed in.
-
-    Raises:
-        jsonschema.ValidationError
-    """
-    validator.validate(request)
-    return request
-
-
 def dispatch_to_response_pure(
-    *, methods: Methods, context: Any, deserializer: Callable, request: str
+    *,
+    methods: Methods,
+    context: Any,
+    schema_validator: Callable,
+    deserializer: Callable,
+    request: str,
 ) -> Union[Response, List[Response], None]:
     """
     Dispatch a JSON-serialized request string to methods.
@@ -186,9 +174,12 @@ def dispatch_to_response_pure(
         # will be raised is unknown. Any exception is a parse error.
         except Exception as exc:
             return ParseErrorResponse(str(exc))
+        # As above, we don't know which validator will be used, so the specific
+        # exception that will be raised is unknown. Any exception is an invalid request
+        # error.
         try:
-            validate(deserialized)
-        except ValidationError as exc:
+            schema_validator(deserialized)
+        except Exception as exc:
             return InvalidRequestResponse("The request failed schema validation")
         return dispatch_requests(
             methods=methods, context=context, requests=create_requests(deserialized)
@@ -204,7 +195,8 @@ def dispatch_to_response(
     methods: Methods = None,
     *,
     context: Any = None,
-    deserializer: Callable = json.loads,
+    schema_validator: Callable = default_schema_validator,
+    deserializer: Callable = default_deserializer,
 ) -> Union[Response, List[Response], None]:
     """
     Dispatch a JSON-serialized request to methods.
@@ -218,9 +210,10 @@ def dispatch_to_response(
         request: The JSON-RPC request string.
         methods: Collection of methods that can be called. If not passed, uses the
             internal methods object.
-        request: The incoming request string.
         context: Will be passed to methods as the first param if not None.
+        schema_validator:
         deserialize: Function that is used to deserialize data.
+        request: The incoming request string.
 
     Returns:
         A Response, list of Responses or None.
@@ -231,13 +224,16 @@ def dispatch_to_response(
     return dispatch_to_response_pure(
         methods=global_methods if methods is None else methods,
         context=context,
+        schema_validator=schema_validator,
         deserializer=deserializer,
         request=request,
     )
 
 
 def dispatch_to_json(
-    *args: Any, serializer: Callable = json.dumps, **kwargs: Any
+    *args: Any,
+    serializer: Callable = json.dumps,
+    **kwargs: Any,
 ) -> str:
     """
     This is the main public method, it goes through the entire JSON-RPC process

tests/test_dispatcher.py

@@ -6,6 +6,8 @@
 from jsonrpcserver import status
 from jsonrpcserver.dispatcher import (
     create_requests,
+    default_deserializer,
+    default_schema_validator,
     dispatch_request,
     dispatch_to_response,
     dispatch_to_response_pure,
@@ -117,7 +119,8 @@ def test_dispatch_to_response_pure():
     response = dispatch_to_response_pure(
         methods=Methods(ping),
         context=None,
-        deserializer=json.loads,
+        schema_validator=default_schema_validator,
+        deserializer=default_deserializer,
         request='{"jsonrpc": "2.0", "method": "ping", "id": 1}',
     )
     assert isinstance(response, SuccessResponse)
@@ -129,7 +132,8 @@ def test_dispatch_to_response_pure_notification():
     response = dispatch_to_response_pure(
         methods=Methods(ping),
         context=None,
-        deserializer=json.loads,
+        schema_validator=default_schema_validator,
+        deserializer=default_deserializer,
         request='{"jsonrpc": "2.0", "method": "ping"}',
     )
     assert response is None
@@ -139,7 +143,8 @@ def test_dispatch_to_response_pure_notification_invalid_jsonrpc():
     response = dispatch_to_response_pure(
         methods=Methods(ping),
         context=None,
-        deserializer=json.loads,
+        schema_validator=default_schema_validator,
+        deserializer=default_deserializer,
         request='{"jsonrpc": "0", "method": "notify"}',
     )
     assert isinstance(response, ErrorResponse)
@@ -148,15 +153,23 @@ def test_dispatch_to_response_pure_notification_invalid_jsonrpc():
 def test_dispatch_to_response_pure_invalid_json():
     """Unable to parse, must return an error"""
     response = dispatch_to_response_pure(
-        methods=Methods(ping), context=None, deserializer=json.loads, request="{"
+        methods=Methods(ping),
+        context=None,
+        schema_validator=default_schema_validator,
+        deserializer=default_deserializer,
+        request="{",
     )
     assert isinstance(response, ErrorResponse)
 
 
 def test_dispatch_to_response_pure_invalid_jsonrpc():
     """Invalid JSON-RPC, must return an error. (impossible to determine if notification)"""
     response = dispatch_to_response_pure(
-        methods=Methods(ping), context=None, deserializer=json.loads, request="{}"
+        methods=Methods(ping),
+        context=None,
+        schema_validator=default_schema_validator,
+        deserializer=default_deserializer,
+        request="{}",
     )
     assert isinstance(response, ErrorResponse)
 
@@ -169,7 +182,8 @@ def foo(colour: str) -> Result:
     response = dispatch_to_response_pure(
         methods=Methods(foo),
         context=None,
-        deserializer=json.loads,
+        schema_validator=default_schema_validator,
+        deserializer=default_deserializer,
         request='{"jsonrpc": "2.0", "method": "foo", "params": ["blue"], "id": 1}',
     )
     assert isinstance(response, ErrorResponse)
@@ -182,7 +196,8 @@ def foo(colour: str, size: str):
     response = dispatch_to_response_pure(
         methods=Methods(foo),
         context=None,
-        deserializer=json.loads,
+        schema_validator=default_schema_validator,
+        deserializer=default_deserializer,
         request='{"jsonrpc": "2.0", "method": "foo", "params": {"colour":"blue"}, "id": 1}',
     )
     assert isinstance(response, ErrorResponse)
@@ -216,7 +231,8 @@ def subtract(minuend, subtrahend):
     response = dispatch_to_response_pure(
         methods=Methods(subtract),
         context=None,
-        deserializer=json.loads,
+        schema_validator=default_schema_validator,
+        deserializer=default_deserializer,
         request='{"jsonrpc": "2.0", "method": "subtract", "params": [42, 23], "id": 1}',
     )
     assert isinstance(response, SuccessResponse)
@@ -226,7 +242,8 @@ def subtract(minuend, subtrahend):
     response = dispatch_to_response_pure(
         methods=Methods(subtract),
         context=None,
-        deserializer=json.loads,
+        schema_validator=default_schema_validator,
+        deserializer=default_deserializer,
         request='{"jsonrpc": "2.0", "method": "subtract", "params": [23, 42], "id": 2}',
     )
     assert isinstance(response, SuccessResponse)
@@ -240,7 +257,8 @@ def subtract(**kwargs):
     response = dispatch_to_response_pure(
         methods=Methods(subtract),
         context=None,
-        deserializer=json.loads,
+        schema_validator=default_schema_validator,
+        deserializer=default_deserializer,
         request='{"jsonrpc": "2.0", "method": "subtract", "params": {"subtrahend": 23, "minuend": 42}, "id": 3}',
     )
     assert isinstance(response, SuccessResponse)
@@ -250,7 +268,8 @@ def subtract(**kwargs):
     response = dispatch_to_response_pure(
         methods=Methods(subtract),
         context=None,
-        deserializer=json.loads,
+        schema_validator=default_schema_validator,
+        deserializer=default_deserializer,
         request='{"jsonrpc": "2.0", "method": "subtract", "params": {"minuend": 42, "subtrahend": 23}, "id": 4}',
     )
     assert isinstance(response, SuccessResponse)
@@ -261,7 +280,8 @@ def test_examples_notification():
     response = dispatch_to_response_pure(
         methods=Methods(update=lambda: None, foobar=lambda: None),
         context=None,
-        deserializer=json.loads,
+        schema_validator=default_schema_validator,
+        deserializer=default_deserializer,
         request='{"jsonrpc": "2.0", "method": "update", "params": [1, 2, 3, 4, 5]}',
     )
     assert response is None
@@ -270,7 +290,8 @@ def test_examples_notification():
     response = dispatch_to_response_pure(
         methods=Methods(update=lambda: None, foobar=lambda: None),
         context=None,
-        deserializer=json.loads,
+        schema_validator=default_schema_validator,
+        deserializer=default_deserializer,
         request='{"jsonrpc": "2.0", "method": "foobar"}',
     )
     assert response is None
@@ -280,7 +301,8 @@ def test_examples_invalid_json():
     response = dispatch_to_response_pure(
         methods=Methods(ping),
         context=None,
-        deserializer=json.loads,
+        schema_validator=default_schema_validator,
+        deserializer=default_deserializer,
         request='[{"jsonrpc": "2.0", "method": "sum", "params": [1,2,4], "id": "1"}, {"jsonrpc": "2.0", "method"]',
     )
     assert isinstance(response, ErrorResponse)
@@ -293,7 +315,8 @@ def test_examples_empty_array():
         request="[]",
         methods=Methods(ping),
         context=None,
-        deserializer=json.loads,
+        schema_validator=default_schema_validator,
+        deserializer=default_deserializer,
     )
     assert isinstance(response, ErrorResponse)
     assert response.code == status.JSONRPC_INVALID_REQUEST_CODE
@@ -305,7 +328,11 @@ def test_examples_invalid_jsonrpc_batch():
     The examples are expecting a batch response full of error responses.
     """
     response = dispatch_to_response_pure(
-        methods=Methods(ping), context=None, deserializer=json.loads, request="[1]"
+        methods=Methods(ping),
+        context=None,
+        schema_validator=default_schema_validator,
+        deserializer=default_deserializer,
+        request="[1]",
     )
     assert isinstance(response, ErrorResponse)
     assert response.code == status.JSONRPC_INVALID_REQUEST_CODE
@@ -319,7 +346,8 @@ def test_examples_multiple_invalid_jsonrpc():
     response = dispatch_to_response_pure(
         methods=Methods(ping),
         context=None,
-        deserializer=json.loads,
+        schema_validator=default_schema_validator,
+        deserializer=default_deserializer,
         request="[1, 2, 3]",
     )
     assert isinstance(response, ErrorResponse)
@@ -357,7 +385,11 @@ def test_examples_mixed_requests_and_notifications():
         ]
     )
     response = dispatch_to_response_pure(
-        methods=methods, context=None, deserializer=json.loads, request=requests
+        methods=methods,
+        context=None,
+        schema_validator=default_schema_validator,
+        deserializer=default_deserializer,
+        request=requests,
     )
     expected = [
         SuccessResponse(