mirror of
https://github.com/GNS3/gns3-server
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233 lines
7.3 KiB
Python
233 lines
7.3 KiB
Python
#!/usr/bin/env python3
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# To use python v2.7 change the first line to:
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#!/usr/bin/env python
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# Copyright (C) 2015 Bernhard Ehlers
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#
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# This program is free software: you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation, either version 2 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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"""
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iou_import imports startup/private configuration into IOU NVRAM file.
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usage: iou_import [-h] [-c size] NVRAM startup-config [private-config]
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positional arguments:
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NVRAM NVRAM file
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startup-config startup configuration
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private-config private configuration
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optional arguments:
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-h, --help show this help message and exit
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-c size, --create size
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create NVRAM file, size in kByte
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"""
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import struct
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# calculate padding
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def padding(length, start_address):
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pad = -length % 4 # padding to alignment of 4
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# extra padding if pad != 0 and big start_address
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if pad != 0 and (start_address & 0x80000000) != 0:
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pad += 4
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return pad
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# update checksum
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def checksum(data, start, end):
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chk = 0
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# calculate checksum of first two words
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for word in struct.unpack_from(">2H", data, start):
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chk += word
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# add remaining words, ignoring old checksum at offset 4
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struct_format = f">{(end - start - 6) // 2:d}H"
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for word in struct.unpack_from(struct_format, data, start + 6):
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chk += word
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# handle 16 bit overflow
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while chk >> 16:
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chk = (chk & 0xFFFF) + (chk >> 16)
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chk = chk ^ 0xFFFF
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# save checksum
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struct.pack_into(">H", data, start + 4, chk)
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# import IOU NVRAM
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# NVRAM format: https://github.com/ehlers/IOUtools/blob/master/NVRAM.md
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def nvram_import(nvram, startup, private, size):
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DEFAULT_IOS = 0x0F04 # IOS 15.4
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base_address = 0x10000000
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# check size parameter
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if size is not None and (size < 8 or size > 1024):
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raise ValueError("invalid size")
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# create new nvram if nvram is empty or has wrong size
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if nvram is None or (size is not None and len(nvram) != size * 1024):
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nvram = bytearray([0] * (size * 1024))
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else:
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nvram = bytearray(nvram)
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# check nvram size
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nvram_len = len(nvram)
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if nvram_len < 8 * 1024 or nvram_len > 1024 * 1024 or nvram_len % 1024 != 0:
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raise ValueError("invalid NVRAM length")
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nvram_len = nvram_len // 2
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# get size of current config
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config_len = 0
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try:
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(magic, _, _, ios, start_addr, _, length, _, _, _, _, _) = struct.unpack_from(">HHHHIIIIIHHI", nvram, offset=0)
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if magic == 0xABCD:
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base_address = start_addr - 36
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config_len = 36 + length + padding(length, base_address)
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(magic, _, _, _, length) = struct.unpack_from(">HHIII", nvram, offset=config_len)
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if magic == 0xFEDC:
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config_len += 16 + length
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else:
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ios = None
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except struct.error:
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raise ValueError("unknown nvram format")
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if config_len > nvram_len:
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raise ValueError("unknown nvram format")
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# calculate max. config size
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max_config = nvram_len - 2 * 1024 # reserve 2k for files
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idx = max_config
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empty_sector = bytearray([0] * 1024)
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while True:
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idx -= 1024
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if idx < config_len:
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break
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# if valid file header:
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(magic, _, flags, length, _) = struct.unpack_from(">HHHH24s", nvram, offset=idx)
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if magic == 0xDCBA and flags < 8 and length <= 992:
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max_config = idx
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elif nvram[idx : idx + 1024] != empty_sector:
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break
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# import startup config
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new_nvram = bytearray()
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if ios is None:
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# Target IOS version is unknown. As some IOU don't work nicely with
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# the padding of a different version, the startup config is padded
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# with '\n' to the alignment of 4.
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ios = DEFAULT_IOS
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startup += b"\n" * (-len(startup) % 4)
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new_nvram.extend(
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struct.pack(
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">HHHHIIIIIHHI",
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0xABCD, # magic
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1, # raw data
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0, # checksum, not yet calculated
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ios, # IOS version
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base_address + 36, # start address
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base_address + 36 + len(startup), # end address
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len(startup), # length
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0,
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0,
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0,
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0,
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0,
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)
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)
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new_nvram.extend(startup)
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new_nvram.extend([0] * padding(len(new_nvram), base_address))
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# import private config
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if private is None:
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private = b""
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offset = len(new_nvram)
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new_nvram.extend(
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struct.pack(
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">HHIII",
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0xFEDC, # magic
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1, # raw data
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base_address + offset + 16, # start address
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base_address + offset + 16 + len(private), # end address
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len(private),
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)
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) # length
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new_nvram.extend(private)
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# add rest
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if len(new_nvram) > max_config:
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raise ValueError("NVRAM size too small")
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new_nvram.extend([0] * (max_config - len(new_nvram)))
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new_nvram.extend(nvram[max_config:])
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checksum(new_nvram, 0, nvram_len)
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return new_nvram
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if __name__ == "__main__":
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# Main program
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import argparse
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import sys
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def check_size(string):
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try:
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value = int(string)
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except ValueError:
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raise argparse.ArgumentTypeError("invalid int value: " + string)
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if value < 8 or value > 1024:
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raise argparse.ArgumentTypeError("size must be 8..1024")
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return value
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parser = argparse.ArgumentParser(description="%(prog)s imports startup/private configuration into IOU NVRAM file.")
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parser.add_argument("-c", "--create", metavar="size", type=check_size, help="create NVRAM file, size in kByte")
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parser.add_argument("nvram", metavar="NVRAM", help="NVRAM file")
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parser.add_argument("startup", metavar="startup-config", help="startup configuration")
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parser.add_argument("private", metavar="private-config", nargs="?", help="private configuration")
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args = parser.parse_args()
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try:
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if args.create is None:
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fd = open(args.nvram, "rb")
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nvram = fd.read()
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fd.close()
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else:
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nvram = None
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fd = open(args.startup, "rb")
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startup = fd.read()
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fd.close()
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if args.private is None:
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private = None
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else:
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fd = open(args.private, "rb")
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private = fd.read()
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fd.close()
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except OSError as err:
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sys.stderr.write(f"Error reading file: {err}\n")
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sys.exit(1)
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try:
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nvram = nvram_import(nvram, startup, private, args.create)
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except ValueError as err:
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sys.stderr.write(f"nvram_import: {err}\n")
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sys.exit(3)
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try:
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fd = open(args.nvram, "wb")
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fd.write(nvram)
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fd.close()
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except OSError as err:
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sys.stderr.write(f"Error writing file: {err}\n")
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sys.exit(1)
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