copilot-swe-agent[bot]
ca27a0b687
- Add RequestSizeLimitMiddleware that checks Content-Length header before request body is read: non-multipart requests capped at MAX_REQUEST_BODY_SIZE (default 1 MB), multipart uploads capped at MAX_UPLOAD_SIZE (default 1 GB). Returns HTTP 413 on violation. - Register middleware in app/main.py - Add max_request_body_size setting to app/config.py - Fix ui_upload in files.py to check Content-Length early and read in 64 KB chunks (bounded memory usage), removing the post-write os.path.getsize check - Document MAX_REQUEST_BODY_SIZE in .env.demo and ConfigurationGuide.md - Mark SECURITY_AUDIT.md item #4 as resolved - Add 9 tests in test_request_size_limit.py - Update test_upload_file_too_large to use patch.object instead of the now-unused os.path.getsize mock Closes #173 Co-authored-by: christianlouis <361235+christianlouis@users.noreply.github.com>
115 lines
4.3 KiB
Python
115 lines
4.3 KiB
Python
#!/usr/bin/env python3
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"""
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Request Size Limit Middleware for DocuElevate.
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This middleware enforces configurable size limits on incoming HTTP request bodies
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to prevent memory exhaustion and Denial-of-Service (DoS) attacks.
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Two independent limits are enforced:
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- ``MAX_REQUEST_BODY_SIZE``: applied to all non-multipart requests (JSON, form data, etc.).
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Default: 1 MB. Configurable via the ``MAX_REQUEST_BODY_SIZE`` environment variable.
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- ``MAX_UPLOAD_SIZE``: applied to multipart/form-data (file upload) requests.
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Default: 1 GB. Configurable via the ``MAX_UPLOAD_SIZE`` environment variable.
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When a request exceeds the applicable limit the middleware immediately returns
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``HTTP 413 Request Entity Too Large`` without reading the full body, which keeps
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memory usage bounded.
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See SECURITY_AUDIT.md – Code Security section for background.
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"""
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import logging
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from fastapi import Request
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from fastapi.responses import JSONResponse
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from starlette.middleware.base import BaseHTTPMiddleware
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logger = logging.getLogger(__name__)
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class RequestSizeLimitMiddleware(BaseHTTPMiddleware):
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"""
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Middleware that rejects requests whose body exceeds a configured size limit.
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File-upload requests (``Content-Type: multipart/form-data``) are checked
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against ``config.max_upload_size``; all other requests are checked against
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``config.max_request_body_size``.
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The check is performed on the ``Content-Length`` header before the body is
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read, so oversized requests are rejected without buffering the payload into
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memory. If the client omits the ``Content-Length`` header the request is
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passed through to the normal handler (where endpoint-level checks still
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apply for file uploads).
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"""
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def __init__(self, app, config):
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"""
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Initialize the middleware.
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Args:
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app: The ASGI application to wrap.
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config: Application settings object with ``max_request_body_size``
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and ``max_upload_size`` attributes.
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"""
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super().__init__(app)
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self.max_body_size = config.max_request_body_size
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self.max_upload_size = config.max_upload_size
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logger.info(
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f"Request size limit middleware enabled – "
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f"body limit: {self.max_body_size} bytes, "
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f"upload limit: {self.max_upload_size} bytes"
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)
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async def dispatch(self, request: Request, call_next):
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"""
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Check the ``Content-Length`` header and reject oversized requests early.
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Args:
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request: Incoming HTTP request.
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call_next: Next middleware or route handler.
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Returns:
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HTTP 413 response if the request is too large, otherwise the
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downstream response.
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"""
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content_length_header = request.headers.get("content-length")
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if content_length_header is not None:
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try:
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content_length = int(content_length_header)
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except ValueError:
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# Malformed header – let downstream handle it
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return await call_next(request)
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content_type = request.headers.get("content-type", "")
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is_multipart = "multipart/form-data" in content_type
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if is_multipart:
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limit = self.max_upload_size
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limit_description = "file upload"
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config_var = "MAX_UPLOAD_SIZE"
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else:
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limit = self.max_body_size
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limit_description = "request body"
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config_var = "MAX_REQUEST_BODY_SIZE"
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if content_length > limit:
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logger.warning(
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f"Rejected oversized {limit_description}: "
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f"{content_length} bytes > {limit} bytes limit "
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f"(configure with {config_var})"
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)
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return JSONResponse(
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status_code=413,
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content={
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"detail": (
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f"Request body too large: {content_length} bytes "
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f"(maximum allowed: {limit} bytes). "
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f"Adjust the {config_var} environment variable to change this limit. "
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f"See SECURITY_AUDIT.md for details."
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)
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},
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)
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return await call_next(request)
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