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refactor: code style improvements and formatting cleanup (#1962)

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Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>
This commit is contained in:
Marcelo Trylesinski 2026-01-27 13:48:52 +01:00 • committed by GitHub
commit 6f0e8e7851
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GPG key ID: B5690EEEBB952194
7 changed files with 30 additions and 91 deletions
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5
src/mcp/client/stdio.py
View file

@ -177,10 +177,7 @@ async def stdio_client(server: StdioServerParameters, errlog: TextIO = sys.stder
except anyio.ClosedResourceError: # pragma: no cover
await anyio.lowlevel.checkpoint()
async with (
anyio.create_task_group() as tg,
process,
):
async with anyio.create_task_group() as tg, process:
tg.start_soon(stdout_reader)
tg.start_soon(stdin_writer)
try:

2
src/mcp/server/lowlevel/server.py
View file

@ -825,7 +825,7 @@ class Server(Generic[LifespanResultT, RequestT]):
host: str = "127.0.0.1",
auth: AuthSettings | None = None,
token_verifier: TokenVerifier | None = None,
auth_server_provider: (OAuthAuthorizationServerProvider[Any, Any, Any] | None) = None,
auth_server_provider: OAuthAuthorizationServerProvider[Any, Any, Any] | None = None,
custom_starlette_routes: list[Route] | None = None,
debug: bool = False,
) -> Starlette:

5
src/mcp/server/models.py
View file

@ -4,10 +4,7 @@ and tools.
from pydantic import BaseModel
from mcp.types import (
Icon,
ServerCapabilities,
)
from mcp.types import Icon, ServerCapabilities
class InitializationOptions(BaseModel):

5
src/mcp/server/stdio.py
View file

@ -30,10 +30,7 @@ from mcp.shared.message import SessionMessage
@asynccontextmanager
async def stdio_server(
stdin: anyio.AsyncFile[str] | None = None,
stdout: anyio.AsyncFile[str] | None = None,
):
async def stdio_server(stdin: anyio.AsyncFile[str] | None = None, stdout: anyio.AsyncFile[str] | None = None):
"""Server transport for stdio: this communicates with an MCP client by reading
from the current process' stdin and writing to stdout.
"""

52
src/mcp/server/streamable_http_manager.py
View file

@ -124,20 +124,10 @@ class StreamableHTTPSessionManager:
# Clear any remaining server instances
self._server_instances.clear()
async def handle_request(
self,
scope: Scope,
receive: Receive,
send: Send,
) -> None:
async def handle_request(self, scope: Scope, receive: Receive, send: Send) -> None:
"""Process ASGI request with proper session handling and transport setup.
Dispatches to the appropriate handler based on stateless mode.
Args:
scope: ASGI scope
receive: ASGI receive function
send: ASGI send function
"""
if self._task_group is None:
raise RuntimeError("Task group is not initialized. Make sure to use run().")
@ -148,19 +138,8 @@ class StreamableHTTPSessionManager:
else:
await self._handle_stateful_request(scope, receive, send)
async def _handle_stateless_request(
self,
scope: Scope,
receive: Receive,
send: Send,
) -> None:
"""Process request in stateless mode - creating a new transport for each request.
Args:
scope: ASGI scope
receive: ASGI receive function
send: ASGI send function
"""
async def _handle_stateless_request(self, scope: Scope, receive: Receive, send: Send) -> None:
"""Process request in stateless mode - creating a new transport for each request."""
logger.debug("Stateless mode: Creating new transport for this request")
# No session ID needed in stateless mode
http_transport = StreamableHTTPServerTransport(
@ -196,19 +175,8 @@ class StreamableHTTPSessionManager:
# Terminate the transport after the request is handled
await http_transport.terminate()
async def _handle_stateful_request(
self,
scope: Scope,
receive: Receive,
send: Send,
) -> None:
"""Process request in stateful mode - maintaining session state between requests.
Args:
scope: ASGI scope
receive: ASGI receive function
send: ASGI send function
"""
async def _handle_stateful_request(self, scope: Scope, receive: Receive, send: Send) -> None:
"""Process request in stateful mode - maintaining session state between requests."""
request = Request(scope, receive)
request_mcp_session_id = request.headers.get(MCP_SESSION_ID_HEADER)
@ -248,11 +216,8 @@ class StreamableHTTPSessionManager:
self.app.create_initialization_options(),
stateless=False, # Stateful mode
)
except Exception as e:
logger.error(
f"Session {http_transport.mcp_session_id} crashed: {e}",
exc_info=True,
)
except Exception:
logger.exception(f"Session {http_transport.mcp_session_id} crashed")
finally:
# Only remove from instances if not terminated
if ( # pragma: no branch
@ -262,8 +227,7 @@ class StreamableHTTPSessionManager:
):
logger.info(
"Cleaning up crashed session "
f"{http_transport.mcp_session_id} from "
"active instances."
f"{http_transport.mcp_session_id} from active instances."
)
del self._server_instances[http_transport.mcp_session_id]

45
src/mcp/server/transport_security.py
View file

@ -9,37 +9,35 @@ from starlette.responses import Response
logger = logging.getLogger(__name__)
# TODO(Marcelo): We should flatten these settings. To be fair, I don't think we should even have this middleware.
class TransportSecuritySettings(BaseModel):
"""Settings for MCP transport security features.
These settings help protect against DNS rebinding attacks by validating
incoming request headers.
These settings help protect against DNS rebinding attacks by validating incoming request headers.
"""
enable_dns_rebinding_protection: bool = Field(
default=True,
description="Enable DNS rebinding protection (recommended for production)",
)
enable_dns_rebinding_protection: bool = True
"""Enable DNS rebinding protection (recommended for production)."""
allowed_hosts: list[str] = Field(
default=[],
description="List of allowed Host header values. Only applies when "
+ "enable_dns_rebinding_protection is True.",
)
allowed_hosts: list[str] = Field(default_factory=list)
"""List of allowed Host header values.
allowed_origins: list[str] = Field(
default=[],
description="List of allowed Origin header values. Only applies when "
+ "enable_dns_rebinding_protection is True.",
)
Only applies when `enable_dns_rebinding_protection` is `True`.
"""
allowed_origins: list[str] = Field(default_factory=list)
"""List of allowed Origin header values.
Only applies when `enable_dns_rebinding_protection` is `True`.
"""
# TODO(Marcelo): This should be a proper ASGI middleware. I'm sad to see this.
class TransportSecurityMiddleware:
"""Middleware to enforce DNS rebinding protection for MCP transport endpoints."""
def __init__(self, settings: TransportSecuritySettings | None = None):
# If not specified, disable DNS rebinding protection by default
# for backwards compatibility
# If not specified, disable DNS rebinding protection by default for backwards compatibility
self.settings = settings or TransportSecuritySettings(enable_dns_rebinding_protection=False)
def _validate_host(self, host: str | None) -> bool: # pragma: no cover
@ -88,16 +86,7 @@ class TransportSecurityMiddleware:
def _validate_content_type(self, content_type: str | None) -> bool:
"""Validate the Content-Type header for POST requests."""
if not content_type: # pragma: lax no cover
logger.warning("Missing Content-Type header in POST request")
return False
# Content-Type must start with application/json
if not content_type.lower().startswith("application/json"):
logger.warning(f"Invalid Content-Type header: {content_type}")
return False
return True
return content_type is not None and content_type.lower().startswith("application/json")
async def validate_request(self, request: Request, is_post: bool = False) -> Response | None:
"""Validate request headers for DNS rebinding protection.

7
src/mcp/shared/memory.py
View file

@ -28,10 +28,5 @@ async def create_client_server_memory_streams() -> AsyncGenerator[tuple[MessageS
client_streams = (server_to_client_receive, client_to_server_send)
server_streams = (client_to_server_receive, server_to_client_send)
async with (
server_to_client_receive,
client_to_server_send,
client_to_server_receive,
server_to_client_send,
):
async with server_to_client_receive, client_to_server_send, client_to_server_receive, server_to_client_send:
yield client_streams, server_streams