add basic session & credential dealing

.gitignore

@@ -0,0 +1 @@
+*.pyc

public/buzzer.js

@@ -1,5 +1,10 @@
 "use strict"
 
+/* global document, window */
+const crypto = window.crypto
+const location = document.location
+const storage = window.sessionStorage
+
 // TODOs
 // - measure/report latency
 // - use server reported time to find winner
@@ -44,7 +49,8 @@ let socket,
   servertime,
   toffset_ms,
   clients = [],
-  me
+  me,
+  session_key
 
 function hide(e) {
   q(`#${e}`).style.display = "none"
@@ -60,7 +66,7 @@ function session_id() {
 }
 
 function new_session_id() {
-  if (!window.crypto) {
+  if (!crypto) {
     return Math.random().toString(36).substr(2)
   }
   const data = new Uint8Array(10)
@@ -96,7 +102,7 @@ function redraw_clients(me, clients) {
       text: c.name,
       data: { cid: c.id },
       appendTo: ul,
-      cls: c.id === me ? "me" : "",
+      cls: c.id === me.id ? "me" : "",
     })
   }
 }
@@ -193,8 +199,14 @@ function setup_ws() {
       servertime = msg.value
       toffset_ms = performance.now()
     } else if (msg.type === "id") {
-      me = msg.value
+      me = { id: msg.id, key: msg.key }
+      storage["my_id"] = me.id
+      storage["my_key"] = me.key
       redraw_clients(me, clients)
+    } else if (msg.type === "session_key") {
+      session_key = { path: msg.path, key: msg.key }
+      storage["session_path"] = session_key.path
+      storage["session_key"] = session_key.key
     } else if (msg.type === "buzz") {
       const buzztime_ns = msg.time
       const client_id = msg.client

quiz/__main__.py

@@ -1,6 +1,7 @@
 import asyncio
 import logging
 
+from . import config
 from .quiz import server
 
 
@@ -12,7 +13,7 @@ def main():
         level=logging.INFO,
     )
 
-    asyncio.get_event_loop().run_until_complete(server())
+    asyncio.get_event_loop().run_until_complete(server(config.ws_host, config.ws_port))
     asyncio.get_event_loop().run_forever()
 
 

quiz/config.py

@@ -0,0 +1,3 @@
+path_prefix = "/quiz/"
+ws_host = "0.0.0.0"
+ws_port = 8765

quiz/quiz.py

@@ -1,7 +1,6 @@
 import asyncio
 import logging
 import unicodedata
-from collections import defaultdict
 from dataclasses import dataclass, field
 from json import dumps, loads
 from secrets import token_hex
@@ -10,39 +9,70 @@ from typing import *
 
 import websockets
 
+from . import config
+
+log = logging.getLogger(__name__)
+
+Path = str
+Token = NewType("Token", str)
 Websocket = websockets.WebSocketServerProtocol
 
 
+def token() -> Token:
+    return Token(token_hex(8))
+
+
 @dataclass
 class Client:
     ws: Websocket
-    path: str
-    id: str = field(default_factory=lambda: token_hex(8))
+    path: Path
+    id: Token = field(default_factory=token)
     name: str = ""
+    points: int = 0
+    secret: Token = field(default_factory=token)
+    session: Optional["Session"] = None
 
     def __str__(self):
         return f"{ascii(self.id)[1:-1]}:{ascii(self.name)[1:-1]}"
 
+    @property
+    def is_admin(self):
+        return self.session is not None and self.session.admin == self.id
 
-sessions: dict[str, dict[str, Client]] = defaultdict(dict)
-
-log = logging.getLogger("buzzer")
+    def others(self, include_self=True) -> Iterable["Client"]:
+        if self.session is None:
+            return []
+        clients = self.session.clients.values()
+        if include_self:
+            return clients
+        return [c for c in clients if c.id != self.id]
 
 
-async def send_time(client):
-    await client.ws.send(dumps({"type": "time", "value": perf_counter_ns()}))
+@dataclass
+class Session:
+    path: Path
+    admin: Token
+    secret: Token = field(default_factory=token)
+    clients: dict[Token, Client] = field(default_factory=dict)
 
 
-async def send_buzz(target, client, time):
-    await target.ws.send(dumps({"type": "buzz", "client": client.id, "time": time}))
+def msg(type_: str, **args):
+    return dumps({"type": type_, **args})
 
 
-async def send_clients(client):
-    clients = [
-        {"name": c.name or "<noname>", "id": c.id}
-        for c in sessions[client.path].values()
-    ]
-    await client.ws.send(dumps({"type": "clients", "value": clients}))
+async def send_time(client: Client):
+    await client.ws.send(msg("time", value=perf_counter_ns()))
+
+
+async def send_buzz(target, client: Client, time):
+    await target.ws.send(msg("buzz", client=client.id, time=time))
+
+
+async def send_clients(client: Client):
+    if not client.session:
+        return
+    clients = [{"name": c.name or "<noname>", "id": c.id} for c in client.others()]
+    await client.ws.send(msg("clients", value=clients))
 
 
 async def wait(coros, **kwds):
@@ -53,33 +83,45 @@ async def wait(coros, **kwds):
     return await asyncio.wait(tasks, **kwds)
 
 
-async def broadcast_client(client):
-    msg = dumps(
-        {
-            "type": "client",
-            "value": {"name": client.name or "<noname>", "id": client.id},
-        }
+async def broadcast_client(client: Client):
+    if not client.session:
+        return
+    m = msg("client", value={"name": client.name or "<noname>", "id": client.id})
+    await wait(c.ws.send(m) for c in client.others())
+
+
+async def broadcast_clients(client: Client):
+    if not client.session:
+        return
+    await wait(send_clients(c) for c in client.others())
+
+
+async def broadcast_buzz(client: Client, time):
+    if not client.session:
+        return
+    await wait(send_buzz(c, client, time) for c in client.others())
+
+
+async def send_credentials(client: Client):
+    await client.ws.send(msg("id", id=client.id, key=client.secret))
+
+
+async def send_keys_to_the_city(client: Client):
+    if not client.session:
+        return
+    await client.ws.send(
+        msg("session_key", path=client.path, key=client.session.secret)
     )
-    await wait(c.ws.send(msg) for c in sessions[client.path].values())
 
 
-async def broadcast_clients(client):
-    await wait(send_clients(c) for c in sessions[client.path].values())
+async def send_hello(client: Client):
+    msgs = [send_time(client), send_credentials(client), send_clients(client)]
+    if client.is_admin:
+        msgs.append(send_keys_to_the_city(client))
+    await wait(msgs)
 
 
-async def broadcast_buzz(client, time):
-    await wait(send_buzz(c, client, time) for c in sessions[client.path].values())
-
-
-async def send_id(client):
-    await client.ws.send(dumps({"type": "id", "value": client.id}))
-
-
-async def send_hello(client):
-    await wait([send_time(client), send_id(client), send_clients(client)])
-
-
-async def send_heartbeat(client):
+async def send_heartbeat(client: Client):
     await asyncio.sleep(5.0)
     await send_time(client)
 
@@ -89,7 +131,7 @@ def printable(s: str) -> str:
     return "".join(c for c in s if not unicodedata.category(c).startswith("C"))
 
 
-async def handle_messages(client):
+async def handle_messages(client: Client):
     async for message in client.ws:
         log.debug("[%s] got a message: %a", client, message)
         mdata = loads(message)
@@ -107,7 +149,7 @@ async def handle_messages(client):
             log.error("[%s] received borked message", client)
 
 
-async def juggle(client):
+async def juggle(client: Client):
     while client.ws.open:
         done, pending = await wait(
             [send_heartbeat(client), handle_messages(client)],
@@ -117,24 +159,41 @@ async def juggle(client):
             task.cancel()
 
 
+sessions: dict[Path, Session] = {}
+
+
 async def connected(ws: Websocket, path: str):
-    if not path.startswith("/quiz/"):
+    # We'll throw out anything not starting with a certain path prefix just to
+    # get rid of internet spam - mass scans for security problems, etc.
+    # No need to waste resources on this kinda crap.
+    # Ideally the same rule should already be enforced by an upstream proxy.
+    if not path.startswith(config.path_prefix):
         await ws.close()
         return
+
     client = Client(ws, path)
     log.info("[%s] new client on %a", client, path)
-    sessions[path][client.id] = client
+
+    if path not in sessions:
+        sessions[path] = Session(path, admin=client.id)
+        log.info("[%s] new session on %a", client, path)
+    sessions[path].clients[client.id] = client
+    client.session = sessions[path]  # Note: This creates a ref cycle.
+
     try:
         await send_hello(client)
         await juggle(client)
     finally:
         log.info("[%s] client disconnected", client)
-        del sessions[path][client.id]
+        client.session = (
+            None  # Not sure if this is necessary, but it breaks the ref cycle.
+        )
+        del sessions[path].clients[client.id]
         await broadcast_clients(client)
         # Clean up sessions map
-        if not sessions[path]:
+        if not sessions[path].clients:
             del sessions[path]
 
 
-def server(host="0.0.0.0", port=8765):
+def server(host: str, port: int):
     return websockets.serve(connected, host, port)

requirements.txt

@@ -1 +1 @@
-websockets>=8.1
+websockets>=8.1

scripts/dev-ws

@@ -11,4 +11,4 @@ exec docker run --init --name dumpr-quiz-ws \
     --label org.dumpr.quiz.service=ws \
     -p 8765:8765 \
     -v "$RUN_DIR":/var/quiz:ro \
-    "$image":"$tag" "$@"
+    "$image":"$tag"