hack-house/cmd_chat/server/helpers.py
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harden(ft,auth,net): cap transfers/frames, evict stale SRP, distrust XFF
M1: enforce the declared transfer size (clamped to MAX_SIZE) on chunk
receipt in both the Rust and Python clients — a malicious sender can no
longer grow the receive buffer unboundedly.
M2: only honor X-Forwarded-For when TRUST_PROXY is set, so a direct
client can't spoof a source IP to dodge the per-IP rate limiter.
M3: evict unverified SRP sessions after a 60s TTL on each new handshake,
preventing half-finished auths from exhausting memory.
M4: drop WS frames larger than 256 KB before they hit the store or
broadcast, bounding per-message memory and flood blast radius.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
2026-06-05 06:59:16 -07:00

57 lines
1.7 KiB
Python

import os
import time
from collections import defaultdict
from datetime import datetime, timezone
from dataclasses import asdict
import json
from sanic import Request, Sanic, Websocket
def utcnow() -> datetime:
return datetime.now(timezone.utc)
# Only honor X-Forwarded-For when explicitly told we sit behind a trusted proxy
# (TRUST_PROXY=1). Otherwise a direct client can spoof the header to forge a
# source IP and dodge the per-IP rate limiter, so we use the real peer address.
_TRUST_PROXY = os.environ.get("TRUST_PROXY", "").lower() in ("1", "true", "yes")
def get_client_ip(request: Request) -> str:
if _TRUST_PROXY:
if forwarded := request.headers.get("x-forwarded-for"):
return forwarded.split(",")[0].strip()
return request.ip
async def send_state(ws: Websocket, app: Sanic) -> None:
messages = app.ctx.message_store.get_all()
users = app.ctx.session_store.get_all()
await ws.send(
json.dumps(
{
"type": "init",
"messages": [asdict(m) for m in messages],
"users": [
{"user_id": u.user_id, "username": u.username} for u in users
],
}
)
)
class RateLimiter:
def __init__(self, max_requests: int = 10, window_seconds: int = 60):
self.max_requests = max_requests
self.window = window_seconds
self._requests: dict[str, list[float]] = defaultdict(list)
def is_allowed(self, key: str) -> bool:
now = time.monotonic()
timestamps = self._requests[key]
timestamps[:] = [t for t in timestamps if now - t < self.window]
if len(timestamps) >= self.max_requests:
return False
timestamps.append(now)
return True