missing_RAR2.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-

import zlib
import struct

# !Referenced file not found:
#   \Modern.Family.S02E02.1080p.BluRay.X264-7SinS\
#   7sins-modern.family.s02e02.1080p.x264.r00

path = "C:\\Users\\Me\\Desktop\\rebuild\\"
full = path + "7sins-modern.family.s02e02.1080p.x264.mkv"
part = path + "r27data.bin"
todo = path + "modern.family.s02e11.1080p.bluray-bia.r27"
filenb = 28 # r27

amount = 49999894 # amount of data stored in one volume
sfv_crc = 0xfa6f96b5
start = amount * filenb
end = start + amount
MARKER = "526172211a0700"
archive = "f1fb7301000d00000000000000"
fileh = ("5fbc740301560016f0fa020000605d038dc5d081f192273f14302e00a401"
        "000000000000000000006d6f6465726e2e66616d696c792e733032653131"
        "2e31303830702e626c757261792e783236342d6269612e6d6b76")
arend = "75577b0f40140039e39c7a000000000000000000"

def extract_part(stored_file, output_file):
    with open(stored_file, "rb") as af:
        af.seek(start)
        with open(output_file, "wb") as data:
            data.write(af.read(amount))

def calc_crc(new_data, previous_crc=None):
    """calculate the crc needed in the header from the file/RR
    previous_volume: not used: not a running crc!"""
    # we only look at the stored data in the current file
    if previous_crc:
        crc = zlib.crc32(new_data, previous_crc) & 0xFFFFFFFF
    else:
        crc = zlib.crc32(new_data) & 0xFFFFFFFF
    return crc

def fix_archive_flags(header, first_volume=False):
    """ necessary because we start from .rar or need .rar
    first_volume is true if we need to create the .rar file """
    (flags, ) = struct.unpack("<H", header[3:5])
    if first_volume and not flags & 0x0100:
        flags += 0x0100 # fist volume flag
    elif not first_volume and flags & 0x0100: # the flag is actually set
        flags -= 0x0100
    fixed = header[:3] + struct.pack("<H", flags) + header[5:]
    header_crc = zlib.crc32(fixed[2:]) & 0xFFFF
    return struct.pack("<H", header_crc) + fixed[2:]

def fix_file_flags(header, first_volume=False):
    """ necessary because we start from .rar or need .rar
    first_volume is true if we need to create the .rar file """
    (flags, ) = struct.unpack("<H", header[3:5])
    if first_volume and flags & 0x0001:
        flags -= 0x0001 # file continued from previous volume
    elif not first_volume and not flags & 0x0001:
        flags += 0x0001
    fixed = header[:3] + struct.pack("<H", flags) + header[5:]
    header_crc = zlib.crc32(fixed[2:]) & 0xFFFF
    return struct.pack("<H", header_crc) + fixed[2:]

def fix_file_header(file_header, part_crc, timedate_32bit):
    """ fix the headers before the data """
    lenb = len(file_header)
    # fix crc of the RAR part
    before = file_header[:7+9]
    after = file_header[7+9+4:]
    crc_fixed = before + struct.pack("<I", part_crc) + after
    assert lenb == len(crc_fixed) == 86

    # fix the time if necessary
    before = crc_fixed[:7+9+4]
    after = crc_fixed[7+9+4+4:]
    fixed_crc_header = before + struct.pack("<I", timedate_32bit) + after
    assert lenb == len(fixed_crc_header)

    header_crc = zlib.crc32(fixed_crc_header[2:]) & 0xFFFF
    fixed_crc_header = struct.pack("<H", header_crc) + fixed_crc_header[2:]
    assert lenb == len(fixed_crc_header)
    return fixed_crc_header

def fix_end_header(end_header, crc_all, file_number):
    if end_header == "":
        return ""
    before = end_header[:7]
    after = end_header[7+4+2:]

    # change 12 to the next volume
    fixedh = (before + struct.pack("<I", crc_all) +
              struct.pack("<H", file_number) + after)
    header_crc = zlib.crc32(fixedh[2:]) & 0xFFFF
    return struct.pack("<H", header_crc) + fixedh[2:]

MARKER = MARKER.decode('hex')
archive = archive.decode('hex')
fileh = fileh.decode('hex')
arend = arend.decode('hex')

#print("Grabbing data from extracted file.")
#extract_part(full, part)


print("Calculating CRC file data.")
with open(part, "rb") as data:
    part_crc = calc_crc(data.read())

print("Fixing flags.")
archive = fix_archive_flags(archive)
fileh = fix_file_flags(fileh)

with open(part, "rb") as fh:
    pdata = fh.read()

# f192 to 3793
# 0x92F1 to 0x9337
# to find: fa92273f 0x3F2792FA

# fixing time
for time_index in range(0x3F2792F1, 0x3F279337):
    print("Fixing file header.")
    fileh = fix_file_header(fileh, part_crc, time_index)

    print("Calculating CRC complete RAR volume.")
    # everything except the last 20 bytes
    start = MARKER + archive + fileh

    crc_all = calc_crc(pdata, calc_crc(start))
#   crc_all2 = calc_crc(start + pdata)
#   assert crc_all == crc_all2

#   print("Fixing archive end header.")
#   arend = fix_end_header(arend, crc_all, filenb)
#
#   if zlib.crc32(arend, crc_all) & 0xffffffff == 0xfa6f96b5:
#       print("found it: %d" % i)
#       break
    if crc_all & 0xffffffff == sfv_crc:
        print("found it: %d" % time_index)
        break

print("Creating %s." % todo)
with open(todo, "wb") as fh:
    fh.write(start)
    with open(part, "rb") as fpart:
        fh.write(fpart.read())
#   fh.write(arend)

print("Done!")