110 lines
3.2 KiB
Python
110 lines
3.2 KiB
Python
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# This file is part of Scapy
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# Scapy 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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# any later version.
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#
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# Scapy 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 Scapy. If not, see <http://www.gnu.org/licenses/>.
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"""
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Copyright 2012, The MITRE Corporation::
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NOTICE
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This software/technical data was produced for the U.S. Government
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under Prime Contract No. NASA-03001 and JPL Contract No. 1295026
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and is subject to FAR 52.227-14 (6/87) Rights in Data General,
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and Article GP-51, Rights in Data General, respectively.
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This software is publicly released under MITRE case #12-3054
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"""
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# scapy.contrib.description = Self-Delimiting Numeric Values (SDNV)
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# scapy.contrib.status = library
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from scapy.fields import Field, FieldLenField, LenField
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from scapy.compat import raw
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# SDNV definitions
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class SDNVValueError(Exception):
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def __init__(self, maxValue):
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self.maxValue = maxValue
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class SDNV:
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def __init__(self, maxValue=2**32 - 1):
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self.maxValue = maxValue
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return
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def setMax(self, maxValue):
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self.maxValue = maxValue
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def getMax(self):
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return self.maxValue
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def encode(self, number):
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if number > self.maxValue:
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raise SDNVValueError(self.maxValue)
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foo = bytearray()
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foo.append(number & 0x7F)
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number = number >> 7
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while (number > 0):
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thisByte = number & 0x7F
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thisByte |= 0x80
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number = number >> 7
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temp = bytearray()
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temp.append(thisByte)
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foo = temp + foo
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return(foo)
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def decode(self, ba, offset):
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number = 0
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numBytes = 1
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b = ba[offset]
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number = (b & 0x7F)
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while (b & 0x80 == 0x80):
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number = number << 7
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if (number > self.maxValue):
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raise SDNVValueError(self.maxValue)
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b = ba[offset + numBytes]
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number += (b & 0x7F)
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numBytes += 1
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if (number > self.maxValue):
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raise SDNVValueError(self.maxValue)
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return(number, numBytes)
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SDNVUtil = SDNV()
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class SDNV2(Field):
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""" SDNV2 field """
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def addfield(self, pkt, s, val):
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return s + raw(SDNVUtil.encode(val))
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def getfield(self, pkt, s):
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b = bytearray(s)
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val, len = SDNVUtil.decode(b, 0)
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return s[len:], val
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class SDNV2FieldLenField(FieldLenField, SDNV2):
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def addfield(self, pkt, s, val):
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return s + raw(SDNVUtil.encode(FieldLenField.i2m(self, pkt, val)))
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class SDNV2LenField(LenField, SDNV2):
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def addfield(self, pkt, s, val):
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return s + raw(SDNVUtil.encode(LenField.i2m(self, pkt, val)))
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