querer.py

import os
import socket
import string
import random

# requirements.txt:
# pyzbar (pip) + zbar-gtk (dnf)
# Pillow
# isbnlib

import isbnlib
from PIL import Image
from pyzbar.pyzbar import decode


def get_filename(n):
    return ''.join(random.choices(string.ascii_uppercase + string.digits, k=n))


host = "34.89.220.233"
port = 6010
last_path = ""

try:
    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    s.connect((host, port))

    try:
        print("[+] Connected!")

        if not os.path.exists(".tmp/"):
            os.makedirs(".tmp/")

        while True:
            image_data = s.recv(1024).strip()
            path = ".tmp/" + get_filename(4)
            last_path = path

            with open(path, "w+b") as out:
                out.write(image_data)

            decoded = decode(Image.open(path))
            isbn = str(decoded[0].data, encoding="utf-8")
            book = isbnlib.meta(isbn)['Title']
            print("Found book:", book)

            s.send(bytes(book, encoding="utf-8"))
            res = str(s.recv(6), encoding="utf-8")  # Good!
            os.unlink(path)

    except KeyboardInterrupt:
        print("\n[+] ^C Received, closing connection")
        s.close()

    except EOFError:
        print("\n[+] ^D Received, closing connection")
        s.close()

except socket.error:
    if os.path.isfile(last_path):
        print("[+] Connection dropped, reading flag...")

        with open(last_path, "r+") as flag_file:
            flag = flag_file.readline()
            print(f"[+] Flag: {flag}")
    else:
        print("[-] Connection dropped, but no flag")