74 lines
2.0 KiB
Python
74 lines
2.0 KiB
Python
#!/usr/bin/env python3
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# -*- coding: utf-8 -*-
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# Many thanks to kunix!
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"""
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Calculates possible base address.
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"""
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from struct import unpack
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import os.path
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import sys
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FILE = sys.argv[1]
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OFFSET = 0
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if len(sys.argv) > 2:
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OFFSET = int(sys.argv[2])
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BLOCKSIZE = 4096
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END_MARKER = b"\xff\xff\x5a\xa5"
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first_block = True
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end_marker_pos = 0xffffffff
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print("Reading {} ...".format(FILE))
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with open(FILE, "rb") as f:
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f.read(OFFSET)
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while True:
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block = f.read(BLOCKSIZE)
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if first_block:
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dw = unpack("<LLLLL", block[0:20])
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first_block = False
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if END_MARKER in block:
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end_pos = block.find(END_MARKER)
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found_pos = f.tell() - len(block) + end_pos + 2
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if found_pos > end_marker_pos:
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print("Found a second endmarker! Using that one.")
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end_marker_pos = found_pos
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#break
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if len(block) < BLOCKSIZE:
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break
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f.close()
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size = os.path.getsize(FILE)
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print("File is {} (0x{:x}) Bytes.".format(size, size))
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print("First double-words: 0x{:x} / 0x{:x} / 0x{:x} / 0x{:x} / 0x{:x}".format(dw[0], dw[1], dw[2], dw[3], dw[4]))
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print("Assuming this is end marker location in memory: 0x{:x}".format(dw[1]))
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print("Found end marker in file at: 0x{:x}".format(end_marker_pos))
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base_addr = dw[1] - (end_marker_pos - OFFSET)
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if base_addr < 0:
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base_addr += 0xffffffff
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print("This would make Base address probably 0x{:x}".format(base_addr))
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if base_addr % 4 != 0:
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print("However, bad alignment. Calculated base address not aligned to doublewords.")
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if base_addr + size > 0xffffffff:
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print("However, base address can't fit whole file.")
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# Assumes second dword points to hwid
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#if dw[2] % 2 != 0 or dw[2] - base_addr >= end_marker_pos - 3:
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# print("Align & Bounds dw2 wrong.")
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# sys.exit(1)
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# Assumes third dword points to fwid
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#if dw[3] % 2 != 0 or dw[3] - base_addr >= end_marker_pos - 3:
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# print("Align & Bounds dw3 wrong.")
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# sys.exit(1)
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# hwid = dw[2] - base_addr
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# fwid = dw[3] - base_addr
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