#!/usr/bin/env python

"""
Gather recovery information for Macs.

Copyright (c) 2019, vit9696
"""

import argparse
import datetime
import json
import os
import random
import sys
import textwrap
import time

try:
  from urllib.request import Request,urlopen
  from urllib.parse import urlencode,urlparse
except ImportError:
  from urllib2 import Request,urlopen
  from urllib import urlencode
  from urlparse import urlparse

SELF_DIR = os.path.dirname(os.path.realpath(__file__))

RECENT_MAC  = 'Mac-7BA5B2D9E42DDD94'
MLB_ZERO    = '00000000000000000'
MLB_VALID   = 'C02749200YGJ803AX'
MLB_PRODUCT = '00000000000J80300'

TYPE_SID = 16
TYPE_K   = 64
TYPE_FG  = 64

INFO_PRODUCT    = 'AP'
INFO_IMAGE_LINK = 'AU'
INFO_IMAGE_HASH = 'AH'
INFO_IMAGE_SESS = 'AT'
INFO_SIGN_LINK  = 'CU'
INFO_SIGN_HASH  = 'CH'
INFO_SIGN_SESS  = 'CT'
INFO_REQURED    = [ INFO_PRODUCT, INFO_IMAGE_LINK, INFO_IMAGE_HASH, INFO_IMAGE_SESS,
                    INFO_SIGN_LINK, INFO_SIGN_HASH, INFO_SIGN_SESS ]

def run_query(url, headers, post=None):
  if post is not None:
    data = '\n'.join([entry + '=' + post[entry] for entry in post])
    if sys.version_info[0] >= 3:
      data = data.encode('utf-8')
  else:
    data = None

  req = Request(url=url, headers=headers, data=data)
  response = urlopen(req)
  return dict(response.info()), response.read()

def generate_id(type, id=None):
  valid_chars = ['0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F']
  if id is None:
    return ''.join(random.choice(valid_chars) for i in range(type))
  return id

def product_mlb(mlb):
  return '00000000000' + mlb[11] + mlb[12] + mlb[13] + mlb[14] + '00'

def mlb_from_eeee(eeee):
  if len(eeee) != 4:
    print('ERROR: Invalid EEEE code length!')
    sys.exit(1)

  return '00000000000' + eeee + '00'

def get_session():
  headers = {
    'Host'      : 'osrecovery.apple.com',
    'Connection': 'close',
    'User-Agent': 'InternetRecovery/1.0',
  }

  headers, output = run_query('http://osrecovery.apple.com/', headers)

  for header in headers:
    if header.lower() == 'set-cookie':
      cookies = headers[header].split('; ')
      for cookie in cookies:
        if cookie.startswith('session='):
          return cookie

  raise RuntimeError('No session in headers ' + str(headers))

def get_image_info(session, bid, mlb=MLB_ZERO, diag = False, os_type = 'default', cid=None):
  headers = {
    'Host'        : 'osrecovery.apple.com',
    'Connection'  : 'close',
    'User-Agent'  : 'InternetRecovery/1.0',
    'Cookie'      : session,
    'Content-Type': 'text/plain',
    'Expect'      : ''
  }

  post = {
    'cid': generate_id(TYPE_SID, cid),
    'sn' : mlb,
    'bid': bid,
    'k'  : generate_id(TYPE_K),
    'fg' : generate_id(TYPE_FG)
  }

  if diag:
    url = 'http://osrecovery.apple.com/InstallationPayload/Diagnostics'
  else:
    url = 'http://osrecovery.apple.com/InstallationPayload/RecoveryImage'
    post['os'] = os_type

  headers, output = run_query(url, headers, post)

  if sys.version_info[0] >= 3:
    output = output.decode('utf-8')

  info = {}
  for line in output.split('\n'):
    try:
      key, value = line.split(': ')
      info[key]  = value
    except:
      continue

  for k in INFO_REQURED:
    if k not in info:
      raise RuntimeError('Missing key ' + k)

  return info

def save_image(url, sess, filename='', dir=''):
  purl = urlparse(url)
  headers = {
    'Host'      : purl.hostname,
    'Connection': 'close',
    'User-Agent': 'InternetRecovery/1.0',
    'Cookie'    : '='.join(['AssetToken', sess])
  }

  if filename == '':
    filename = os.path.basename(purl.path)
  if filename.find('/') >= 0 or filename == '':
    raise RuntimeError('Invalid save path ' + filename)

  print('Saving ' + url + ' to ' + filename + '...')

  with open (os.path.join(dir, filename), 'wb') as fh:
    fh.write(run_query(url, headers)[1])

def action_download(args):
  """
  Reference information for queries:

  Recovery latest:
  cid=3076CE439155BA14
  sn=...
  bid=Mac-E43C1C25D4880AD6
  k=4BE523BB136EB12B1758C70DB43BDD485EBCB6A457854245F9E9FF0587FB790C
  os=latest
  fg=B2E6AA07DB9088BE5BDB38DB2EA824FDDFB6C3AC5272203B32D89F9D8E3528DC

  Recovery default:
  cid=4A35CB95FF396EE7
  sn=...
  bid=Mac-E43C1C25D4880AD6
  k=0A385E6FFC3DDD990A8A1F4EC8B98C92CA5E19C9FF1DD26508C54936D8523121
  os=default
  fg=B2E6AA07DB9088BE5BDB38DB2EA824FDDFB6C3AC5272203B32D89F9D8E3528DC

  Diagnostics:
  cid=050C59B51497CEC8
  sn=...
  bid=Mac-E43C1C25D4880AD6
  k=37D42A8282FE04A12A7D946304F403E56A2155B9622B385F3EB959A2FBAB8C93
  fg=B2E6AA07DB9088BE5BDB38DB2EA824FDDFB6C3AC5272203B32D89F9D8E3528DC
  """

  session = get_session()
  info    = get_image_info(session, bid=args.board_id, mlb=args.mlb,
    diag=args.diagnostics, os_type=args.os_type)
  if args.verbose:
    print(info)
  print('Downloading ' + info[INFO_PRODUCT] + '...')
  dmgname = '' if args.basename == '' else args.basename + '.dmg'
  save_image(info[INFO_IMAGE_LINK], info[INFO_IMAGE_SESS], dmgname, args.outdir)
  cnkname = '' if args.basename == '' else args.basename + '.chunklist'
  save_image(info[INFO_SIGN_LINK], info[INFO_SIGN_SESS], cnkname, args.outdir)
  return 0

def action_selfcheck(args):
  """
  Sanity check server logic for recovery:

  if not valid(bid):
    return error()
  ppp = get_ppp(sn)
  if not valid(ppp):
    return latest_recovery(bid = bid)             # Returns newest for bid.
  if valid(sn):
    if os == 'default':
      return default_recovery(sn = sn, ppp = ppp) # Returns oldest for sn.
    else:
      return latest_recovery(sn = sn, ppp = ppp)  # Returns newest for sn.
  return default_recovery(ppp = ppp)              # Returns oldest.
  """

  session = get_session()
  valid_default    = get_image_info(session, bid=RECENT_MAC, mlb=MLB_VALID,
    diag=False, os_type='default')
  valid_latest     = get_image_info(session, bid=RECENT_MAC, mlb=MLB_VALID,
    diag=False, os_type='latest')
  product_default  = get_image_info(session, bid=RECENT_MAC, mlb=MLB_PRODUCT,
    diag=False, os_type='default')
  product_latest   = get_image_info(session, bid=RECENT_MAC, mlb=MLB_PRODUCT,
    diag=False, os_type='latest')
  generic_default  = get_image_info(session, bid=RECENT_MAC, mlb=MLB_ZERO,
    diag=False, os_type='default')
  generic_latest   = get_image_info(session, bid=RECENT_MAC, mlb=MLB_ZERO,
    diag=False, os_type='latest')

  if args.verbose:
    print(valid_default)
    print(valid_latest)
    print(product_default)
    print(product_latest)
    print(generic_default)
    print(generic_latest)

  if valid_default[INFO_PRODUCT] == valid_latest[INFO_PRODUCT]:
    # Valid MLB must give different default and latest if this is not a too new product.
    print('ERROR: Cannot determine any previous product, got {}'.format(valid_default[INFO_PRODUCT]))
    return 1

  if product_default[INFO_PRODUCT] != product_latest[INFO_PRODUCT]:
    # Product-only MLB must give the same value for default and latest.
    print('ERROR: Latest and default do not match for product MLB, got {} and {}'.format(
      product_default[INFO_PRODUCT], product_latest[INFO_PRODUCT]))
    return 1

  if generic_default[INFO_PRODUCT] != generic_latest[INFO_PRODUCT]:
    # Zero MLB always give the same value for default and latest.
    print('ERROR: Generic MLB gives different product, got {} and {}'.format(
      generic_default[INFO_PRODUCT], generic_latest[INFO_PRODUCT]))
    return 1

  if valid_latest[INFO_PRODUCT] != generic_latest[INFO_PRODUCT]:
    # Valid MLB must always equal generic MLB.
    print('ERROR: Cannot determine unified latest product, got {} and {}'.format(
      valid_latest[INFO_PRODUCT], generic_latest[INFO_PRODUCT]))
    return 1

  if product_default[INFO_PRODUCT] != valid_default[INFO_PRODUCT]:
    # Product-only MLB can give the same value with valid default MLB.
    # This is not an error for all models, but for our chosen code it is.
    print('ERROR: Valid and product MLB give mismatch, got {} and {}'.format(
      product_default[INFO_PRODUCT], valid_default[INFO_PRODUCT]))
    return 1

  print('SUCCESS: Found no discrepancies with MLB validation algorithm!')
  return 0

def action_verify(args):
  """
  Try to verify MLB serial number.
  """
  session = get_session()
  generic_latest   = get_image_info(session, bid=RECENT_MAC, mlb=MLB_ZERO,
    diag=False, os_type='latest')
  uvalid_default   = get_image_info(session, bid=args.board_id, mlb=args.mlb,
    diag=False, os_type='default')
  uvalid_latest    = get_image_info(session, bid=args.board_id, mlb=args.mlb,
    diag=False, os_type='latest')
  uproduct_default = get_image_info(session, bid=args.board_id, mlb=product_mlb(args.mlb),
    diag=False, os_type='default')

  if args.verbose:
    print(generic_latest)
    print(uvalid_default)
    print(uvalid_latest)
    print(uproduct_default)

  # Verify our MLB number.
  if uvalid_default[INFO_PRODUCT] != uvalid_latest[INFO_PRODUCT]:
    if uvalid_latest[INFO_PRODUCT] == generic_latest[INFO_PRODUCT]:
      print('SUCCESS: {} MLB looks valid and supported!'.format(args.mlb))
    else:
      print('SUCCESS: {} MLB looks valid, but probably unsupported!'.format(args.mlb))
    return 0

  print('UNKNOWN: Run selfcheck, check your board-id, or try again later!')

  # Here we have matching default and latest products. This can only be true for very
  # new models. These models get either latest or special builds.
  if uvalid_default[INFO_PRODUCT] == generic_latest[INFO_PRODUCT]:
    print('UNKNOWN: {} MLB can be valid if very new!'.format(args.mlb))
    return 0
  if uproduct_default[INFO_PRODUCT] != uvalid_default[INFO_PRODUCT]:
    print('UNKNOWN: {} MLB looks invalid, other models use product {} instead of {}!'.format(
      args.mlb, uproduct_default[INFO_PRODUCT], uvalid_default[INFO_PRODUCT]))
    return 0
  print('UNKNOWN: {} MLB can be valid if very new and using special builds!'.format(args.mlb))
  return 0

def action_guess(args):
  """
  Attempt to guess which model does this MLB belong.
  """

  mlb  = args.mlb
  anon = mlb.startswith('000')

  with open(args.board_db, 'r') as fh:
    db  = json.load(fh)

  supported = {}

  session = get_session()

  generic_latest  = get_image_info(session, bid=RECENT_MAC, mlb=MLB_ZERO,
    diag=False, os_type='latest')

  for model in db:
    try:
      if anon:
        # For anonymous lookup check when given model does not match latest.
        model_latest  = get_image_info(session, bid=model, mlb=MLB_ZERO,
          diag=False, os_type='latest')

        if model_latest[INFO_PRODUCT] != generic_latest[INFO_PRODUCT]:
          if db[model] == 'current':
            print('WARN: Skipped {} due to using latest product {} instead of {}'.format(
              model, model_latest[INFO_PRODUCT], generic_latest[INFO_PRODUCT]))
          continue

        user_default = get_image_info(session, bid=model, mlb=mlb,
          diag=False, os_type='default')

        if user_default[INFO_PRODUCT] != generic_latest[INFO_PRODUCT]:
          supported[model] = [db[model], user_default[INFO_PRODUCT], generic_latest[INFO_PRODUCT]]
      else:
        # For normal lookup check when given model has mismatching normal and latest.
        user_latest  = get_image_info(session, bid=model, mlb=mlb,
          diag=False, os_type='latest')

        user_default = get_image_info(session, bid=model, mlb=mlb,
          diag=False, os_type='default')

        if user_latest[INFO_PRODUCT] != user_default[INFO_PRODUCT]:
          supported[model] = [db[model], user_default[INFO_PRODUCT], user_latest[INFO_PRODUCT]]

    except Exception as e:
      print('WARN: Failed to check {}, exception: {}'.format(model, str(e)))

  if len(supported) > 0:
    print('SUCCESS: MLB {} looks supported for:'.format(mlb))
    for model in supported:
      print('- {}, up to {}, default: {}, latest: {}'.format(model, supported[model][0],
        supported[model][1], supported[model][2]))
    return 0

  print('UNKNOWN: Failed to determine supported models for MLB {}!'.format(mlb))

def main():
  parser = argparse.ArgumentParser(description='Gather recovery information for Macs')
  parser.add_argument('action', choices = ['download', 'selfcheck', 'verify', 'guess'],
    help='Action to perform: "download" - performs recovery downloading,'
    ' "selfcheck" checks whether MLB serial validation is possible, "verify" performs'
    ' MLB serial verification, "guess" tries to find suitable mac model for MLB.')
  parser.add_argument('-o', '--outdir', type=str, default=os.getcwd(),
    help='customise output directory for downloading, defaults to current directory')
  parser.add_argument('-n', '--basename', type=str, default='',
    help='customise base name for downloading, defaults to remote name')
  parser.add_argument('-b', '--board-id', type=str, default=RECENT_MAC,
    help='use specified board identifier for downloading, defaults to ' + RECENT_MAC)
  parser.add_argument('-m', '--mlb', type=str, default=MLB_ZERO,
    help='use specified logic board serial for downloading, defaults to ' + MLB_ZERO)
  parser.add_argument('-e', '--code', type=str, default='',
    help='generate product logic board serial with specified product EEEE code')
  parser.add_argument('-os', '--os-type', type=str, default='default', choices = ['default', 'latest'],
    help='use specified os type, defaults to default ' + MLB_ZERO)
  parser.add_argument('-diag', '--diagnostics', action='store_true', help='download diagnostics image')
  parser.add_argument('-v', '--verbose', action='store_true', help='print debug information')
  parser.add_argument('-db', '--board-db', type=str, default=os.path.join(SELF_DIR, 'boards.json'),
    help='use custom board list for checking, defaults to boards.json')

  args = parser.parse_args()

  if args.code != '':
    args.mlb = mlb_from_eeee(args.code)

  if len(args.mlb) != 17:
    print('ERROR: Cannot use MLBs in non 17 character format!')
    sys.exit(1)

  if args.action == 'download':
    return action_download(args)
  elif args.action == 'selfcheck':
    return action_selfcheck(args)
  elif args.action == 'verify':
    return action_verify(args)
  elif args.action == 'guess':
    return action_guess(args)
  else:
    assert(False)

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