Files
quiz/app/routes_student.py
ameer 9ea0a8b039 feat: anti-cheat + presence panel + projector view
Refinement pass on top of the validated v1.2 base.

Hardening / quick fixes
- Caddyfile.tpl: CSP / HSTS / X-Frame / Referrer-Policy / Permissions-Policy,
  1 MiB request body cap, X-Forwarded-For pass-through; stock-Caddy compatible.
- auth.py: STUDENT_MAX_AGE 1y -> 30d.
- bootstrap.sh: stage 5 prepends `git config --add safe.directory` so the
  re-bootstrap path no longer 'detected dubious ownership' faults.
- admin.js: drop the misleading `closedPayload?.state || session.state`
  shim; state derives from session only.

Anti-cheat
- New `student_events` audit table; new POST /api/session/{sid}/event for
  blur / visibility_hidden / focus / visibility_visible. quiz.js debounces
  events at 1.5s and uses sendBeacon for visibility_hidden so the event
  survives a navigation. Counts surface in admin presence + CSV export.
- First-claim-wins on join: add_participant raises DuplicateStudentId on
  PK violation; route returns 409 + records a duplicate_join audit event
  with attempted name + IP + UA. Admin dashboard surfaces a per-row red
  badge for hits on real participants and a top-of-page alert for orphan
  attempts.
- DELETE /admin/api/students/{id} as the recovery hatch: clears the
  participant + submissions, kicks active WS sockets so a stale cookie
  cannot continue submitting. quiz.js surfaces the FastAPI detail message
  in the join form so users see the 'already in use' guidance.

Presence panel
- New presence_update WS message; in-process presence map keyed on
  student_id tracks ws_count + last_seen_ms. Admin dashboard renders
  per-student rows: connected/idle/dropped dot, blur+hidden+duplicate
  badges, 'answered current Q' tick, and a clear-student button.

Projector view (public, read-only)
- /projector/?sid=..., GET /api/session/{sid}/projector, WS
  /ws/projector/{sid}. Single self-contained projector_state snapshot
  pushed on every state change. Public leaderboard strips student_id;
  QR rendered server-side as data: URL (CSP-compliant).
- Includes per-Q answer histogram, 8-bucket response-time distribution,
  10-bucket score distribution.
- static/projector.{html,css,js}: editorial-broadside design — masthead,
  registration crosses, conic-gradient countdown ring, SVG stepped-area
  score distribution with median tick, leaderboard row-stagger. Inherits
  light/dark tokens from style.css; honours prefers-reduced-motion. No
  scroll at 1366x768 / 1920x1080 / 3440x1440.

Tests
- tests/test_anti_cheat.py: blur logging + CSV count, unknown-kind 422,
  unauthenticated event 401, duplicate-join 409 + audit, admin
  clear-student happy + 404, server-side submit lockout regression.
- tests/test_projector.py: snapshot shape, leaderboard student_id
  redaction, WS push on state change, 404 for unknown sid, page redirect
  when no sid.
- Existing tests updated for the new presence_update snapshot frame +
  CSV header columns + first-claim-wins refusal of re-key.

57/57 pytest green; smoke-tested locally end-to-end.
2026-05-04 16:08:59 +08:00

189 lines
8.4 KiB
Python

"""Student routes (single-session deployment)."""
from __future__ import annotations
from pathlib import Path
from uuid import uuid4
from fastapi import APIRouter, HTTPException, Request, Response, WebSocket
from fastapi.responses import FileResponse, HTMLResponse, JSONResponse, RedirectResponse
from app import auth
from app.config import Settings
from app.models import JoinRequest, StudentEventRequest
from app.rate_limit import client_ip
from app.room import DuplicateStudentId, RoomManager
def router(settings: Settings, rooms: RoomManager) -> APIRouter:
api = APIRouter()
def resolve_sid(sid: str | None) -> str:
return sid if sid else (rooms.canonical_sid or settings.default_session_id)
@api.get("/")
async def student_entry(sid: str | None = None):
target_sid = resolve_sid(sid)
if not await rooms.session_exists(target_sid):
return HTMLResponse(
"<!doctype html><meta charset='utf-8'>"
"<link rel='stylesheet' href='/static/style.css'>"
"<title>Quiz unavailable</title>"
"<main class='centered-shell'><div class='card narrow'>"
"<h1>Ask your instructor for the link</h1>"
"<p class='muted'>This quiz link is missing or no longer valid.</p>"
"</div></main>",
status_code=404,
)
if not sid:
# Canonicalise the URL so QR codes, share links, and bookmarks
# all converge on the same sid-bearing form.
return RedirectResponse(url=f"/?sid={target_sid}", status_code=302)
return FileResponse(Path("static/student.html"))
@api.get("/api/session/{sid}")
async def session_metadata(sid: str):
if not await rooms.session_exists(sid):
raise HTTPException(status_code=404, detail="Session not found")
session = await rooms.get_session(sid)
return {
"sid": sid,
"title": session["title"],
"state": session["state"],
"current_question_idx": session["current_question_idx"],
"time_limit_default": (await rooms.get_pool_for_session(sid))["time_limit_default"],
}
@api.post("/api/session/{sid}/join")
async def join_session(sid: str, body: JoinRequest, request: Request, response: Response):
if not await rooms.session_exists(sid):
raise HTTPException(status_code=404, detail="Session not found")
student_id = body.student_id.strip()
name = body.name.strip()
cookie_id = str(uuid4())
try:
await rooms.add_participant(sid, student_id, name, cookie_id)
except DuplicateStudentId:
# First-claim-wins anti-hijack: a participant row already
# exists for this student_id. Could be a hijack attempt
# OR a legit student returning after clearing cookies. Log
# the attempt with IP/UA/attempted-name so the instructor
# can surface it on the live presence panel and decide.
await rooms.log_event(
sid,
student_id=student_id,
kind="duplicate_join",
detail={
"attempted_name": name,
"ip": client_ip(request),
"ua": (request.headers.get("user-agent") or "")[:200],
},
)
await rooms.broadcast_presence(sid)
raise HTTPException(
status_code=409,
detail=(
"This student ID is already in use. If this is your ID, "
"ask your instructor to clear it for you."
),
) from None
cookie_value = auth.sign_student(settings, sid, student_id, name, cookie_id)
auth.set_student_cookie(settings, response, cookie_value)
return {"ok": True, "cookie_id": cookie_id}
@api.post("/api/session/{sid}/event")
async def post_event(sid: str, body: StudentEventRequest, request: Request):
# Audit-only endpoint: the student page POSTs here on tab blur
# / visibility-hidden so the instructor can see engagement
# signals during a live question. No state change.
if not await rooms.session_exists(sid):
raise HTTPException(status_code=404, detail="Session not found")
identity = auth.get_student_identity(settings, request, sid)
if not identity:
raise HTTPException(status_code=401, detail="Student cookie required")
await rooms.log_event(
sid,
student_id=identity["student_id"],
kind=body.kind,
question_idx=body.question_idx,
detail={"ip": client_ip(request)},
)
# blur / visibility_hidden are surfaced to the instructor; focus /
# visibility_visible are recorded for completeness but don't need
# an immediate broadcast.
if body.kind in {"blur", "visibility_hidden"}:
await rooms.broadcast_presence(sid)
return {"ok": True}
@api.get("/api/session/{sid}/me")
async def me(sid: str, request: Request):
identity = auth.get_student_identity(settings, request, sid)
if not identity:
raise HTTPException(status_code=401, detail="Student cookie required")
try:
return await rooms.me(sid, identity["student_id"])
except KeyError:
# Cookie's student_id is no longer in the DB (e.g. session reset
# or DB rebuilt while the cookie persisted). Send 401 with the
# cookie cleared so the client renders the join form. We build
# the JSONResponse directly because raising HTTPException would
# bypass the cookie mutation.
resp = JSONResponse({"detail": "Re-join required"}, status_code=401)
resp.delete_cookie(auth.STUDENT_COOKIE, path="/")
return resp
@api.get("/api/session/{sid}/stats")
async def stats(sid: str, request: Request, question_idx: int | None = None):
if not await rooms.session_exists(sid):
raise HTTPException(status_code=404, detail="Session not found")
identity = auth.get_student_identity(settings, request, sid)
return await rooms.stats(sid, question_idx, identity["student_id"] if identity else None)
@api.websocket("/ws/student/{sid}")
async def student_socket(websocket: WebSocket, sid: str):
identity = auth.get_student_identity_ws(settings, websocket, sid)
if not identity or not await rooms.session_exists(sid):
await websocket.close(code=4001)
return
await rooms.student_ws(websocket, sid, identity)
# ---- Projector view (public, read-only) -------------------------------
# The projector page runs at the front of the room on a smart TV / big
# screen. No auth: it shows only aggregate / leaderboard data that
# would already be visible on the student's own screen at reveal
# time. Per-student histograms keep names but redact student_ids
# (the student-id namespace is private).
@api.get("/projector/")
async def projector_page(sid: str | None = None):
target_sid = resolve_sid(sid)
if not await rooms.session_exists(target_sid):
return HTMLResponse(
"<!doctype html><meta charset='utf-8'>"
"<link rel='stylesheet' href='/static/style.css'>"
"<title>Projector — quiz unavailable</title>"
"<main class='centered-shell'><div class='card narrow'>"
"<h1>Projector — no live session</h1>"
"<p class='muted'>Start the quiz from the admin dashboard.</p>"
"</div></main>",
status_code=404,
)
if not sid:
return RedirectResponse(url=f"/projector/?sid={target_sid}", status_code=302)
return FileResponse(Path("static/projector.html"))
@api.get("/api/session/{sid}/projector")
async def projector_state(sid: str):
if not await rooms.session_exists(sid):
raise HTTPException(status_code=404, detail="Session not found")
return await rooms.projector_snapshot(sid)
@api.websocket("/ws/projector/{sid}")
async def projector_socket(websocket: WebSocket, sid: str):
if not await rooms.session_exists(sid):
await websocket.close(code=4001)
return
await rooms.projector_ws(websocket, sid)
return api