Check username for party chat bot

groupchatbot/bot.py

@@ -34,6 +34,12 @@ def check_banned(r, userhash):
             return True
 
 
+def check_name(username: str) -> bool:
+    if len(username) >= 16:
+        return False
+    return all(map(lambda c: c.isalnum(), username))
+
+
 def handle_login(msg, r, from_known_sender):
     def login_usage():
         msg.reply("Usage: `/login [NICK] [PASSWORD]`")
@@ -45,6 +51,9 @@ def handle_login(msg, r, from_known_sender):
     if not check_password(parts[2]):
         ban_sender(r, msg.sender, monotonic() + WRONG_LOGIN_BAN_DURATION)
         return
+    if not check_name(parts[1]):
+        msg.reply("Name can only consist of alphanumeric characters.")
+        return
     r.rpush("hswroconference:users", str(json.dumps({
         "hash": msg.sender,
         "nick": parts[1],