openhands/server/middleware.py

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

from fastapi import Request
from fastapi.middleware.cors import CORSMiddleware
from fastapi.responses import JSONResponse
from starlette.middleware.base import BaseHTTPMiddleware, RequestResponseEndpoint
from starlette.requests import Request as StarletteRequest
from starlette.responses import Response
from starlette.types import ASGIApp


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) -> None:
        allow_origins_str = os.getenv('PERMITTED_CORS_ORIGINS')
        if allow_origins_str:
            allow_origins = tuple(
                origin.strip() for origin in allow_origins_str.split(',')
            )
        else:
            allow_origins = ()
        super().__init__(
            app,
            allow_origins=allow_origins,
            allow_credentials=True,
            allow_methods=['*'],
            allow_headers=['*'],
        )

    def is_allowed_origin(self, origin: str) -> bool:
        if origin and not self.allow_origins and not self.allow_origin_regex:
            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
        result: bool = super().is_allowed_origin(origin)
        return result


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

    async def dispatch(
        self, request: Request, call_next: RequestResponseEndpoint
    ) -> Response:
        response = await call_next(request)
        if request.url.path.startswith('/assets'):
            # The content of the assets directory has fingerprinted file names so we cache aggressively
            response.headers['Cache-Control'] = 'public, max-age=2592000, immutable'
        else:
            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[str, list[datetime]]
    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: Request, call_next: RequestResponseEndpoint
    ) -> Response:
        if not self.is_rate_limited_request(request):
            return await call_next(request)
        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)

    def is_rate_limited_request(self, request: StarletteRequest) -> bool:
        if request.url.path.startswith('/assets'):
            return False
        # Put Other non rate limited checks here
        return True