#! /usr/bin/env python3
from argparse import ArgumentParser
from datetime import datetime
from pathlib import Path
from random import randint
import binascii
import ctypes
import logging
import subprocess
import mmap

whoami_shell = b"\x6a\x3b\x58\x99\x48\xbb\x2f\x62\x69\x6e\x2f\x73\x68\x00\x53\x48\x89\xe7\x68\x2d\x63\x00\x00\x48\x89\xe6\x52\xe8\x10\x00\x00\x00\x2f\x75\x73\x72\x2f\x62\x69\x6e\x2f\x77\x68\x6f\x61\x6d\x69\x00\x56\x57\x48\x89\xe6\x0f\x05"


def example():
    now = '{0:%Y%m%dT%H%M%S}'.format(datetime.utcnow())
    parser = ArgumentParser(
        description='position independent code (PIC) mutation experiment.')
    parser.add_argument('-v', '--verbose', action='count')
    parser.add_argument('-s', '--seed', default='seed',
                        help='path to PIC image.')
    parser.add_argument('-o', '--output', help='path to results directory.')
    args = parser.parse_args()

    log_level = logging.INFO
    log_format = logging.Formatter('%(message)s')

    if args.verbose:
        log_level = logging.DEBUG
        log_format = logging.Formatter(
            '%(levelname)s %(filename)s:%(lineno)d\n%(message)s\n')

    logger = logging.getLogger('sins')
    logger.setLevel(log_level)

    stream_handler = logging.StreamHandler()
    stream_handler.setLevel(log_level)
    stream_handler.setFormatter(log_format)
    logger.addHandler(stream_handler)

    if args.output:
        log_path = f'{args.output}/sins-{now}.log'
        file_handler = logging.FileHandler(log_path)
        file_handler.setLevel(log_level)
        file_handler.setFormatter(log_format)
        logger.addHandler(file_handler)

    logger.info(whoami_shell)
    shell_function(whoami_shell)()


def shell_function(shellcode: bytes):
    exec_mem = mmap.mmap(
        -1, len(shellcode),
        prot=mmap.PROT_READ | mmap.PROT_WRITE | mmap.PROT_EXEC,
        flags=mmap.MAP_ANONYMOUS | mmap.MAP_PRIVATE)

    exec_mem.write(shellcode)

    ctypes_buffer = ctypes.c_int.from_buffer(exec_mem)
    function = ctypes.CFUNCTYPE(ctypes.c_int64)(
        ctypes.addressof(ctypes_buffer))
    function._avoid_gc_for_mmap = exec_mem

    return function