add fastapi app middleware

buckler_fastapi.py

@@ -0,0 +1,74 @@
+#!/usr/bin/env python3
+"""
+Session interface middlewares to integrate the fastapi app with Buckler.
+"""
+import json
+from datetime import datetime
+
+import httpx
+from fastapi import FastAPI, Request
+from fastapi.responses import RedirectResponse
+from starlette.middleware.base import BaseHTTPMiddleware
+
+import config
+
+
+class BucklerSessionMiddleware(BaseHTTPMiddleware):
+	"""
+	Verifies the user with the configured Buckler app and retrieves any
+	session data they may have. Redirects them to the login page otherwise.
+	"""
+	def __init__(self, app):
+		super().__init__(app)
+
+	async def dispatch(self, request: Request, call_next):
+		user_id = request.cookies.get('userid', '')
+		user_sid = request.cookies.get('session', '')
+
+		url = config.buckler['url'] + '/get_session'
+		params = {
+			'app_id': config.buckler['app_id'],
+			'app_key': config.buckler['app_key'],
+			'userid': user_id,
+			'session': user_sid }
+
+		async with httpx.AsyncClient() as client:
+			resp = await client.get(url, params=params)
+			data = resp.json()
+
+		if data.get('error'): # user not logged in
+			response = RedirectResponse(config.buckler['login_url'])
+			response.set_cookie('redirect', config.server_homepage)
+			return response
+
+		request.state.session = data.get('session_data')
+		request.state.meta = data.get('meta')
+		response = await call_next(request)
+
+		if request.state.session != data['session_data']: # session data modified
+			url = config.buckler['url'] + '/set_session'
+			data = json.dumps(request.state.session)
+			async with httpx.AsyncClient() as client:
+				await client.post(url, params=params, data=data)
+
+		last_used = datetime.fromisoformat(request.state.meta['last_used'])
+		now = datetime.now(last_used.tzinfo)
+		delta = now - last_used
+		if delta.seconds > 600:
+			response.set_cookie(
+				'userid',
+				user_id,
+				domain=config.server_domain,
+				max_age=30*24*60*60,
+				secure=True,
+				httponly=True,
+				samesite='strict')
+			response.set_cookie(
+				'session',
+				user_sid,
+				domain=config.server_domain,
+				max_age=30*24*60*60,
+				secure=True,
+				httponly=True,
+				samesite='strict')
+		return response