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gns3-server/gns3server/compute/iou/utils/iou_export.py

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#!/usr/bin/env python3
# -*- coding: utf-8 -*-
# To use python v2.7 change the first line to:
#!/usr/bin/env python
# Copyright (C) 2015 Bernhard Ehlers
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
# This utility is a stripped down version of dynamips' nvram_export,
# ported from C to Python, see https://github.com/GNS3/dynamips
# nvram_export is (c) 2013 Flávio J. Saraiva
"""
iou_export exports startup/private configuration from IOU NVRAM file.
usage: iou_export [-h] NVRAM startup-config [private-config]
positional arguments:
NVRAM NVRAM file
startup-config startup configuration
private-config private configuration
optional arguments:
-h, --help show this help message and exit
"""
import argparse
import sys
# Uncompress data in .Z file format.
# Ported from dynamips' fs_nvram.c to python
# Adapted from 7zip's ZDecoder.cpp, which is licensed under LGPL 2.1.
def uncompress_LZC(data):
LZC_NUM_BITS_MIN = 9
LZC_NUM_BITS_MAX = 16
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in_data = bytearray(data)
in_len = len(in_data)
out_data = bytearray()
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if in_len == 0:
return out_data
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if in_len < 3:
raise ValueError('invalid length')
if in_data[0] != 0x1F or in_data[1] != 0x9D:
raise ValueError('invalid header')
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maxbits = in_data[2] & 0x1F
numItems = 1 << maxbits
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blockMode = (in_data[2] & 0x80) != 0
if maxbits < LZC_NUM_BITS_MIN or maxbits > LZC_NUM_BITS_MAX:
raise ValueError('not supported')
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parents = [0] * numItems
suffixes = [0] * numItems
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in_pos = 3
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numBits = LZC_NUM_BITS_MIN
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head = 256
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if blockMode:
head += 1
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needPrev = 0
bitPos = 0
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numBufBits = 0
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parents[256] = 0
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suffixes[256] = 0
buf_extend = bytearray([0] * 3)
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while True:
# fill buffer, when empty
if numBufBits == bitPos:
buf_len = min(in_len - in_pos, numBits)
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buf = in_data[in_pos:in_pos + buf_len] + buf_extend
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numBufBits = buf_len << 3
bitPos = 0
in_pos += buf_len
# extract next symbol
bytePos = bitPos >> 3
symbol = buf[bytePos] | buf[bytePos + 1] << 8 | buf[bytePos + 2] << 16
symbol >>= bitPos & 7
symbol &= (1 << numBits) - 1
bitPos += numBits
# check for special conditions: end, bad data, re-initialize dictionary
if bitPos > numBufBits:
break
if symbol >= head:
raise ValueError('invalid data')
if blockMode and symbol == 256:
numBufBits = bitPos = 0
numBits = LZC_NUM_BITS_MIN
head = 257
needPrev = 0
continue
# convert symbol to string
stack = []
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cur = symbol
while cur >= 256:
stack.append(suffixes[cur])
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cur = parents[cur]
stack.append(cur)
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if needPrev:
suffixes[head - 1] = cur
if symbol == head - 1:
stack[0] = cur
stack.reverse()
out_data.extend(stack)
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# update parents, check for numBits change
if head < numItems:
needPrev = 1
parents[head] = symbol
head += 1
if head > (1 << numBits):
if numBits < maxbits:
numBufBits = bitPos = 0
numBits += 1
else:
needPrev = 0
return out_data
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# extract 16 bit unsigned int from data
def get_uint16(data, off):
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return data[off] << 8 | data[off + 1]
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# extract 32 bit unsigned int from data
def get_uint32(data, off):
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return data[off] << 24 | data[off + 1] << 16 | data[off + 2] << 8 | data[off + 3]
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# export IOU NVRAM
def nvram_export(nvram):
nvram = bytearray(nvram)
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# extract startup config
offset = 0
if len(nvram) < offset + 36:
raise ValueError('invalid length')
if get_uint16(nvram, offset + 0) != 0xABCD:
raise ValueError('no startup config')
format = get_uint16(nvram, offset + 2)
length = get_uint32(nvram, offset + 16)
offset += 36
if len(nvram) < offset + length:
raise ValueError('invalid length')
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startup = nvram[offset:offset + length]
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# compressed startup config
if format == 2:
try:
startup = uncompress_LZC(startup)
except ValueError as err:
raise ValueError('uncompress startup: ' + str(err))
offset += length
# alignment to multiple of 4
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offset = (offset + 3) & ~3
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# check for additonal offset of 4
if len(nvram) >= offset + 8 and \
get_uint16(nvram, offset + 4) == 0xFEDC and \
get_uint16(nvram, offset + 6) == 1:
offset += 4
# extract private config
private = None
if len(nvram) >= offset + 16 and get_uint16(nvram, offset + 0) == 0xFEDC:
length = get_uint32(nvram, offset + 12)
offset += 16
if len(nvram) >= offset + length:
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private = nvram[offset:offset + length]
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return (startup, private)
if __name__ == '__main__':
# Main program
parser = argparse.ArgumentParser(description='%(prog)s exports startup/private configuration from IOU NVRAM file.')
parser.add_argument('nvram', metavar='NVRAM',
help='NVRAM file')
parser.add_argument('startup', metavar='startup-config',
help='startup configuration')
parser.add_argument('private', metavar='private-config', nargs='?',
help='private configuration')
args = parser.parse_args()
try:
fd = open(args.nvram, 'rb')
nvram = fd.read()
fd.close()
except (IOError, OSError) as err:
sys.stderr.write("Error reading file: {}\n".format(err))
sys.exit(1)
try:
startup, private = nvram_export(nvram)
except ValueError as err:
sys.stderr.write("nvram_export: {}\n".format(err))
sys.exit(3)
try:
fd = open(args.startup, 'wb')
fd.write(startup)
fd.close()
if args.private is not None:
if private is None:
sys.stderr.write("Warning: No private config\n")
else:
fd = open(args.private, 'wb')
fd.write(private)
fd.close()
except (IOError, OSError) as err:
sys.stderr.write("Error writing file: {}\n".format(err))
sys.exit(1)