openhands/server/middleware.py

import asyncio
from collections import defaultdict
from datetime import datetime, timedelta
from typing import Callable
from urllib.parse import urlparse

from fastapi import Request, status
from fastapi.middleware.cors import CORSMiddleware
from fastapi.responses import JSONResponse
from starlette.middleware.base import BaseHTTPMiddleware
from starlette.types import ASGIApp

from openhands.server.shared import session_manager
from openhands.server.types import SessionMiddlewareInterface


class LocalhostCORSMiddleware(CORSMiddleware):
    """
    Custom CORS middleware that allows any request from localhost/127.0.0.1 domains,
    while using standard CORS rules for other origins.
    """

    def __init__(self, app: ASGIApp, **kwargs) -> None:
        super().__init__(app, **kwargs)

    def is_allowed_origin(self, origin: str) -> bool:
        if origin:
            parsed = urlparse(origin)
            hostname = parsed.hostname or ''

            # Allow any localhost/127.0.0.1 origin regardless of port
            if hostname in ['localhost', '127.0.0.1']:
                return True

        # For missing origin or other origins, use the parent class's logic
        return super().is_allowed_origin(origin)


class NoCacheMiddleware(BaseHTTPMiddleware):
    """
    Middleware to disable caching for all routes by adding appropriate headers
    """

    async def dispatch(self, request, call_next):
        response = await call_next(request)
        if not request.url.path.startswith('/assets'):
            response.headers['Cache-Control'] = (
                'no-cache, no-store, must-revalidate, max-age=0'
            )
            response.headers['Pragma'] = 'no-cache'
            response.headers['Expires'] = '0'
        return response


class InMemoryRateLimiter:
    history: dict
    requests: int
    seconds: int
    sleep_seconds: int

    def __init__(self, requests: int = 2, seconds: int = 1, sleep_seconds: int = 1):
        self.requests = requests
        self.seconds = seconds
        self.sleep_seconds = sleep_seconds
        self.history = defaultdict(list)
        self.sleep_seconds = sleep_seconds

    def _clean_old_requests(self, key: str) -> None:
        now = datetime.now()
        cutoff = now - timedelta(seconds=self.seconds)
        self.history[key] = [ts for ts in self.history[key] if ts > cutoff]

    async def __call__(self, request: Request) -> bool:
        key = request.client.host
        now = datetime.now()

        self._clean_old_requests(key)

        self.history[key].append(now)

        if len(self.history[key]) > self.requests * 2:
            return False
        elif len(self.history[key]) > self.requests:
            if self.sleep_seconds > 0:
                await asyncio.sleep(self.sleep_seconds)
                return True
            else:
                return False

        return True


class RateLimitMiddleware(BaseHTTPMiddleware):
    def __init__(self, app: ASGIApp, rate_limiter: InMemoryRateLimiter):
        super().__init__(app)
        self.rate_limiter = rate_limiter

    async def dispatch(self, request, call_next):
        ok = await self.rate_limiter(request)
        if not ok:
            return JSONResponse(
                status_code=429,
                content={'message': 'Too many requests'},
                headers={'Retry-After': '1'},
            )
        return await call_next(request)


class AttachConversationMiddleware(SessionMiddlewareInterface):
    def __init__(self, app):
        self.app = app

    def _should_attach(self, request) -> bool:
        """
        Determine if the middleware should attach a session for the given request.
        """
        if request.method == 'OPTIONS':
            return False

        conversation_id = ''
        if request.url.path.startswith('/api/conversation'):
            # FIXME: we should be able to use path_params
            path_parts = request.url.path.split('/')
            if len(path_parts) > 4:
                conversation_id = request.url.path.split('/')[3]
        if not conversation_id:
            return False

        request.state.sid = conversation_id

        return True

    async def _attach_conversation(self, request: Request) -> JSONResponse | None:
        """
        Attach the user's session based on the provided authentication token.
        """
        request.state.conversation = await session_manager.attach_to_conversation(
            request.state.sid
        )
        if not request.state.conversation:
            return JSONResponse(
                status_code=status.HTTP_404_NOT_FOUND,
                content={'error': 'Session not found'},
            )
        return None

    async def _detach_session(self, request: Request) -> None:
        """
        Detach the user's session.
        """
        await session_manager.detach_from_conversation(request.state.conversation)

    async def __call__(self, request: Request, call_next: Callable):
        if not self._should_attach(request):
            return await call_next(request)

        response = await self._attach_conversation(request)
        if response:
            return response

        try:
            # Continue processing the request
            response = await call_next(request)
        finally:
            # Ensure the session is detached
            await self._detach_session(request)

        return response