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Submitter Guideline

The submitter module is a vital part of Fast, responsible for the actual submission of flags to the competition's flag-checking service. Fast is adaptable to any A/D competition because it lets you write this module yourself. To work properly with Fast, your submitter script must follow the simple guideline specified below.

Structure of the Submitter Module

The submitter script must define a function named submit that takes a list of flags (as string values) ready for submission. This function is responsible for submitting the flags to the flag-checking service and collecting the responses.

The submit function returns a tuple of two dictionaries:

  1. Accepted Flags: A dictionary containing the flags that were accepted by the service, with the flag as the key and the corresponding response as the value.
  2. Rejected Flags: A dictionary containing the flags that were rejected by the service, with the flag as the key and the corresponding response as the value.

You can adapt the submit function to work with various flag submission mechanisms, such as submitting through a REST API, or over a raw TCP connection. See below for examples.

import requests

def submit(flags):
    flag_responses = requests.post('http://example.ctf/flags', json=flags).json()
    accepted_flags = { item['flag']: item['response'] for item in flag_responses if item['response'].endswith('OK') }
    rejected_flags = { item['flag']: item['response'] for item in flag_responses if not item['response'].endswith('OK') }
    return accepted_flags, rejected_flags

from pwn import *

def submit(flags):
    accepted_flags, rejected_flags = {}
    r = remote('flags.example.ctf', 1337)
    for flag in flags:
        r.sendline(flag.encode())
        response = r.recvline().decode().strip()
        if response.endswith('OK')
            accepted_flags[flag] = response
        else:
            rejected_flags[flag] = response
    return accepted_flags, rejected_flags

Template

If you like type hints, you can use the following template.

from typing import List, Tuple, Dict

def submit(flags: List[str]) -> Tuple[Dict[str, str], Dict[str, str]]:
    accepted_flags = {}
    rejected_flags = {}

    # Submit and categorize flags

    return accepted_flags, rejected_flags

Integration

The script must be placed in the same directory as your server.yaml configuration file. By default, it must be named submitter.py.

If you need to name it differently, see the example in the User Manual.