95 lines
2.7 KiB
Python
95 lines
2.7 KiB
Python
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#!/usr/bin/python3
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# SPDX-License-Identifier: GPL-2.0-or-later
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#
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# Copyright (C) 2024 OpenWrt.org
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#
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# ./belkin-header.py <ImageFileIn> <ImageFileOut> <BelkinHeader> <BelkinModel>
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#
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# This script adds an image header for Belkin devices. As of now only Realtek
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# based switches of the Linksys LGS3xxC/LGS3xxMPC series are known to use this
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# format. It resembles a U-Boot legacy format image header, all data in network
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# byte order (aka natural aka big endian).
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#
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# Known values for BelkinHeader are
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#
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# 0x07800001 : RTL838x based switch
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# 0x07600001 : RTL93xx based switch
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#
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# Known values for BelkinModel are
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#
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# BKS-RTL83xx : RTL838x based switch
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# BKS-RTL93xx : RTL93xx based switch
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import argparse
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import os
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import zlib
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import array
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import sys
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import time
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VERSION1 = 1
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VERSION2 = 1
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VERSION3 = 2
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VERSION4 = 2
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COMPANY = "belkin"
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MODULE = "IMG"
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def xcrc32(buf):
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return (0xffffffff - zlib.crc32(buf, 0xffffffff)).to_bytes(4, 'big')
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def encode_model(model):
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map = " 0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz-"
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code = bytearray()
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code.append(map.index(model[:1]))
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model = model[1:]
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model = model + " " * (3 - len(model) % 4)
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while model != "":
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b1 = map.index(model[0:1])
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b2 = map.index(model[1:2])
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b3 = map.index(model[2:3])
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b4 = map.index(model[3:4])
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model = model[4:]
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code.append(b1 << 2 | b2 >> 4)
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code.append((b2 & 0xf) << 4 | b3 >> 2)
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code.append((b3 & 0x3) << 6 | b4)
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return code
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def create_header(buf, belkin_header, belkin_model):
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head = bytearray(32)
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head[0:4] = int(belkin_header, 0).to_bytes(4, 'big')
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head[8:12] = int(time.time()).to_bytes(4, 'big')
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head[12:16] = len(buf).to_bytes(4, 'big')
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head[24:28] = xcrc32(buf)
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head[28:29] = VERSION1.to_bytes(1)
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head[29:30] = VERSION2.to_bytes(1)
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head[30:31] = VERSION3.to_bytes(1)
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head[31:32] = VERSION4.to_bytes(1)
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head[16:16 + len(COMPANY)] = bytes(COMPANY,'ascii')
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mod = MODULE + "-{:1d}.{:02d}.{:02d}.{:02d}".format(VERSION1, VERSION2, VERSION3, VERSION4)
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head.extend(bytes(mod,'ascii'))
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head.append(0x00)
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head.extend(encode_model(belkin_model))
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head.extend(bytes([0x00] * (64 - len(head))))
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head[4:8] = xcrc32(head)
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return head
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parser = argparse.ArgumentParser(description='Generate Belkin header.')
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parser.add_argument('source', type=argparse.FileType('r+b'))
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parser.add_argument('dest', type=argparse.FileType('wb'))
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parser.add_argument('belkin_header')
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parser.add_argument('belkin_model')
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args = parser.parse_args()
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buf = bytearray(args.source.read())
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head = create_header(buf, args.belkin_header, args.belkin_model)
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args.dest.write(head)
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args.dest.write(buf)
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