#!/usr/bin/python
# -*- coding: UTF-8 -*-
#
# estr2bc.py
#
# Convert arbitrary string input to Erlang bytecode
#
# Jeremy Brown [jbrown3264/gmail]
# Dec 2020
#
# Example
# > estr2bc.py "ps -aux"
# [112,115,32,45,97,117,120]
#
# > rpc:call('node', file, write_file, ["test", [112,115,32,45,97,117,120]]).
#
# There's probably a native way to do this within Erlang, but this script is
# useful in the exploit chain eg. for generating Riak file:write_file payloads
#

import os
import sys
import argparse
import string

#
# enough for most things
#
string_special_1 = ' !"#$%&\'()*+,-./'
string_special_2 = ':;<=>?@'
string_special_3 = '[\\]^_`'

class Estr2bc(object):
  def __init__(self, args):
    self.input = args.input

  def run(self):
    special_1 = dict()
    for i, c in enumerate(string_special_1):
      special_1[c] = i + 32

    numbers = dict()
    for i, c in enumerate(string.digits):
      numbers[c] = i + 48

    special_2 = dict()
    for i, c in enumerate(string_special_2):
      special_2[c] = i + 58

    alpha_upper = dict()
    for i, c in enumerate(string.ascii_uppercase):
      alpha_upper[c] = i + 65

    special_3 = dict()
    for i, c in enumerate(string_special_3):
      special_3[c] = i + 91

    alpha_lower = dict()
    for i, c in enumerate(string.ascii_lowercase):
      alpha_lower[c] = i + 97

    bytecode = ""

    for c in self.input:
      if(c in string_special_1):
        bc = str(special_1[c])
      elif(c in string.digits):
        bc = str(numbers[c])
      elif(c in string_special_2):
        bc = str(special_2[c])
      elif(c in string.ascii_uppercase):
        bc = str(alpha_upper[c])
      elif(c in string_special_3):
        bc = str(special_3[c])
      elif(c in string.ascii_lowercase):
        bc = str(alpha_lower[c])
      else:
        print("error: can't map character '%s'" % (c))
        return -1

      bytecode += bc + ','

    bytecode = bytecode[:-1]

    print("[%s]" % bytecode)

    return 0

def arg_parse():
  parser = argparse.ArgumentParser()

  parser.add_argument("input",
            type=str,
            help="String you wish to convert to bytecode")

  args = parser.parse_args()

  return args

def main():
  args = arg_parse()

  esb = Estr2bc(args)
  result = esb.run()

  if(result != 0):
    sys.exit(-1)

if(__name__ == '__main__'):
  main()