# -*- coding: utf-8 -*-
"""Location: ./mcpgateway/validation/jsonrpc.py
Copyright 2025
SPDX-License-Identifier: Apache-2.0
Authors: Mihai Criveti
JSON-RPC Validation.
This module provides validation functions for JSON-RPC 2.0 requests and responses
according to the specification at https://www.jsonrpc.org/specification.
Includes:
- Request validation
- Response validation
- Standard error codes
- Error message formatting
Examples:
>>> from mcpgateway.validation.jsonrpc import JSONRPCError, validate_request
>>> error = JSONRPCError(-32600, "Invalid Request")
>>> error.code
-32600
>>> error.message
'Invalid Request'
>>> validate_request({'jsonrpc': '2.0', 'method': 'test', 'id': 1})
>>> validate_request({'jsonrpc': '2.0', 'method': 'test'}) # notification
>>> try:
... validate_request({'method': 'test'}) # missing jsonrpc
... except JSONRPCError as e:
... e.code
-32600
"""
# Standard
from typing import Any, Dict, Optional, Union
class JSONRPCError(Exception):
"""JSON-RPC protocol error."""
def __init__(
self,
code: int,
message: str,
data: Optional[Any] = None,
request_id: Optional[Union[str, int]] = None,
):
"""Initialize JSON-RPC error.
Args:
code: Error code
message: Error message
data: Optional error data
request_id: Optional request ID
"""
self.code = code
self.message = message
self.data = data
self.request_id = request_id
super().__init__(message)
def to_dict(self) -> Dict[str, Any]:
"""Convert error to JSON-RPC error response dict.
Returns:
Error response dictionary
Examples:
Basic error without data:
>>> error = JSONRPCError(-32600, "Invalid Request", request_id=1)
>>> error.to_dict()
{'jsonrpc': '2.0', 'error': {'code': -32600, 'message': 'Invalid Request'}, 'request_id': 1}
Error with additional data:
>>> error = JSONRPCError(-32602, "Invalid params", data={"param": "value"}, request_id="abc")
>>> error.to_dict()
{'jsonrpc': '2.0', 'error': {'code': -32602, 'message': 'Invalid params', 'data': {'param': 'value'}}, 'request_id': 'abc'}
Error without request ID (for parse errors):
>>> error = JSONRPCError(-32700, "Parse error", data="Unexpected EOF")
>>> error.to_dict()
{'jsonrpc': '2.0', 'error': {'code': -32700, 'message': 'Parse error', 'data': 'Unexpected EOF'}, 'request_id': None}
Error with complex data:
>>> error = JSONRPCError(-32603, "Internal error", data={"details": ["error1", "error2"], "timestamp": 123456}, request_id=42)
>>> sorted(error.to_dict()['error']['data']['details'])
['error1', 'error2']
"""
error = {"code": self.code, "message": self.message}
if self.data is not None:
error["data"] = self.data
return {"jsonrpc": "2.0", "error": error, "request_id": self.request_id}
# Standard JSON-RPC error codes
PARSE_ERROR = -32700 #: Invalid JSON
INVALID_REQUEST = -32600 #: Invalid Request object
METHOD_NOT_FOUND = -32601 #: Method not found
INVALID_PARAMS = -32602 #: Invalid method parameters
INTERNAL_ERROR = -32603 #: Internal JSON-RPC error
SERVER_ERROR_START = -32000 #: Start of server error codes
SERVER_ERROR_END = -32099 #: End of server error codes
def validate_request(request: Dict[str, Any]) -> None:
"""Validate JSON-RPC request.
Args:
request: Request dictionary to validate
Raises:
JSONRPCError: If request is invalid
Examples:
Valid request:
>>> validate_request({"jsonrpc": "2.0", "method": "ping", "id": 1})
Valid notification (no id):
>>> validate_request({"jsonrpc": "2.0", "method": "notify"})
Valid request with params:
>>> validate_request({"jsonrpc": "2.0", "method": "add", "params": [1, 2], "id": 1})
>>> validate_request({"jsonrpc": "2.0", "method": "add", "params": {"a": 1, "b": 2}, "id": 1})
Invalid version:
>>> validate_request({"jsonrpc": "1.0", "method": "ping", "id": 1}) # doctest: +ELLIPSIS
Traceback (most recent call last):
...
mcpgateway.validation.jsonrpc.JSONRPCError: Invalid JSON-RPC version
Missing method:
>>> validate_request({"jsonrpc": "2.0", "id": 1}) # doctest: +ELLIPSIS
Traceback (most recent call last):
...
mcpgateway.validation.jsonrpc.JSONRPCError: Invalid or missing method
Empty method:
>>> validate_request({"jsonrpc": "2.0", "method": "", "id": 1}) # doctest: +ELLIPSIS
Traceback (most recent call last):
...
mcpgateway.validation.jsonrpc.JSONRPCError: Invalid or missing method
Invalid params type:
>>> validate_request({"jsonrpc": "2.0", "method": "test", "params": "invalid", "id": 1}) # doctest: +ELLIPSIS
Traceback (most recent call last):
...
mcpgateway.validation.jsonrpc.JSONRPCError: Invalid params type
Invalid ID type:
>>> validate_request({"jsonrpc": "2.0", "method": "test", "id": True}) # doctest: +ELLIPSIS
Traceback (most recent call last):
...
mcpgateway.validation.jsonrpc.JSONRPCError: Invalid request ID type
""" # doctest: +ELLIPSIS
# Check jsonrpc version
if request.get("jsonrpc") != "2.0":
raise JSONRPCError(INVALID_REQUEST, "Invalid JSON-RPC version", request_id=request.get("id"))
# Check method
method = request.get("method")
if not isinstance(method, str) or not method:
raise JSONRPCError(INVALID_REQUEST, "Invalid or missing method", request_id=request.get("id"))
# Check ID for requests (not notifications)
if "id" in request:
request_id = request["id"]
if not isinstance(request_id, (str, int)) or isinstance(request_id, bool):
raise JSONRPCError(INVALID_REQUEST, "Invalid request ID type", request_id=None)
# Check params if present
params = request.get("params")
if params is not None:
if not isinstance(params, (dict, list)):
raise JSONRPCError(INVALID_REQUEST, "Invalid params type", request_id=request.get("id"))
def validate_response(response: Dict[str, Any]) -> None:
"""Validate JSON-RPC response.
Args:
response: Response dictionary to validate
Raises:
JSONRPCError: If response is invalid
Examples:
Valid success response:
>>> validate_response({"jsonrpc": "2.0", "result": 42, "id": 1})
Valid error response:
>>> validate_response({"jsonrpc": "2.0", "error": {"code": -32601, "message": "Method not found"}, "id": 1})
Valid response with null result:
>>> validate_response({"jsonrpc": "2.0", "result": None, "id": 1})
Valid response with null id (for errors during id parsing):
>>> validate_response({"jsonrpc": "2.0", "error": {"code": -32700, "message": "Parse error"}, "id": None})
Invalid version:
>>> validate_response({"jsonrpc": "1.0", "result": 42, "id": 1}) # doctest: +ELLIPSIS
Traceback (most recent call last):
...
mcpgateway.validation.jsonrpc.JSONRPCError: Invalid JSON-RPC version
Missing ID:
>>> validate_response({"jsonrpc": "2.0", "result": 42}) # doctest: +ELLIPSIS
Traceback (most recent call last):
...
mcpgateway.validation.jsonrpc.JSONRPCError: Missing response ID
Invalid ID type (boolean):
>>> validate_response({"jsonrpc": "2.0", "result": 42, "id": True}) # doctest: +ELLIPSIS
Traceback (most recent call last):
...
mcpgateway.validation.jsonrpc.JSONRPCError: Invalid response ID type
Invalid ID type (list):
>>> validate_response({"jsonrpc": "2.0", "result": 42, "id": [1, 2]}) # doctest: +ELLIPSIS
Traceback (most recent call last):
...
mcpgateway.validation.jsonrpc.JSONRPCError: Invalid response ID type
Missing both result and error:
>>> validate_response({"jsonrpc": "2.0", "id": 1}) # doctest: +ELLIPSIS
Traceback (most recent call last):
...
mcpgateway.validation.jsonrpc.JSONRPCError: Response must contain either result or error
Both result and error present:
>>> validate_response({"jsonrpc": "2.0", "result": 42, "error": {"code": -1, "message": "Error"}, "id": 1}) # doctest: +ELLIPSIS
Traceback (most recent call last):
...
mcpgateway.validation.jsonrpc.JSONRPCError: Response cannot contain both result and error
Invalid error object type:
>>> validate_response({"jsonrpc": "2.0", "error": "Invalid error", "id": 1}) # doctest: +ELLIPSIS
Traceback (most recent call last):
...
mcpgateway.validation.jsonrpc.JSONRPCError: Invalid error object type
Error missing code:
>>> validate_response({"jsonrpc": "2.0", "error": {"message": "Error"}, "id": 1}) # doctest: +ELLIPSIS
Traceback (most recent call last):
...
mcpgateway.validation.jsonrpc.JSONRPCError: Error must contain code and message
Error missing message:
>>> validate_response({"jsonrpc": "2.0", "error": {"code": -32601}, "id": 1}) # doctest: +ELLIPSIS
Traceback (most recent call last):
...
mcpgateway.validation.jsonrpc.JSONRPCError: Error must contain code and message
Invalid error code type:
>>> validate_response({"jsonrpc": "2.0", "error": {"code": "invalid", "message": "Error"}, "id": 1}) # doctest: +ELLIPSIS
Traceback (most recent call last):
...
mcpgateway.validation.jsonrpc.JSONRPCError: Error code must be integer
Invalid error message type:
>>> validate_response({"jsonrpc": "2.0", "error": {"code": -32601, "message": 123}, "id": 1}) # doctest: +ELLIPSIS
Traceback (most recent call last):
...
mcpgateway.validation.jsonrpc.JSONRPCError: Error message must be string
Valid error with additional data:
>>> validate_response({"jsonrpc": "2.0", "error": {"code": -32602, "message": "Invalid params", "data": {"param": "name"}}, "id": 1})
"""
# Check jsonrpc version
if response.get("jsonrpc") != "2.0":
raise JSONRPCError(INVALID_REQUEST, "Invalid JSON-RPC version", request_id=response.get("id"))
# Check ID
if "id" not in response:
raise JSONRPCError(INVALID_REQUEST, "Missing response ID", request_id=None)
response_id = response["id"]
if not isinstance(response_id, (str, int, type(None))) or isinstance(response_id, bool):
raise JSONRPCError(INVALID_REQUEST, "Invalid response ID type", request_id=None)
# Check result XOR error
has_result = "result" in response
has_error = "error" in response
if not has_result and not has_error:
raise JSONRPCError(INVALID_REQUEST, "Response must contain either result or error", request_id=id)
if has_result and has_error:
raise JSONRPCError(INVALID_REQUEST, "Response cannot contain both result and error", request_id=id)
# Validate error object
if has_error:
error = response["error"]
if not isinstance(error, dict):
raise JSONRPCError(INVALID_REQUEST, "Invalid error object type", request_id=id)
if "code" not in error or "message" not in error:
raise JSONRPCError(INVALID_REQUEST, "Error must contain code and message", request_id=id)
if not isinstance(error["code"], int):
raise JSONRPCError(INVALID_REQUEST, "Error code must be integer", request_id=id)
if not isinstance(error["message"], str):
raise JSONRPCError(INVALID_REQUEST, "Error message must be string", request_id=id)
