Patch WebAuth login via 2FA not returning steamid

steam/webauth.py

@@ -150,7 +150,24 @@ class WebAuth(object):
             raise HTTPError(str(e))
 
     def _finalize_login(self, login_response):
-        self.steam_id = SteamID(login_response['transfer_parameters']['steamid'])
+        if "transfer_parameters" in login_response and ["steamid"] in login_response['transfer_parameters']:
+            self.steam_id = SteamID(login_response['transfer_parameters']['steamid'])
+            return
+        
+        elif "success" in login_response and login_response['success'] and self.session:
+                # If logging in with 2FA, steamid is not returned in transfer_parameters
+                # fetch the steamid from the cookies instead
+
+                # The first 17 chars of steamLoginSecure cookie is the steamid
+                steam_login_secure = self.session.cookies.get('steamLoginSecure', domain='steamcommunity.com')
+                id_from_cookie = steam_login_secure[:17] if steam_login_secure else None
+
+                if id_from_cookie and id_from_cookie.isdigit():
+                    self.steam_id = SteamID(id_from_cookie)
+                    return # Success
+        
+        raise LoginIncorrect("Could not finalize login, no steamid returned")
+
 
     def login(self, password='', captcha='', email_code='', twofactor_code='', language='english'):
         """Attempts web login and returns on a session with cookies set