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# Copyright (c) 2006, Neville-Neil Consulting
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are
# met:
#
# Redistributions of source code must retain the above copyright notice,
# this list of conditions and the following disclaimer.
#
# Redistributions in binary form must reproduce the above copyright
# notice, this list of conditions and the following disclaimer in the
# documentation and/or other materials provided with the distribution.
#
# Neither the name of Neville-Neil Consulting nor the names of its
# contributors may be used to endorse or promote products derived from
# this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#
# File: $Id: arp.py,v 1.2 2006/08/01 13:35:58 gnn Exp $
#
# Author: George V. Neville-Neil
#
# Description: ARP packet class
import pcs
import struct
from socket import AF_INET, inet_ntop, inet_ntoa
class arp(pcs.Packet):
layout = pcs.Layout()
def __init__(self, bytes = None):
"""initialize an ARP packet"""
hrd = pcs.Field("hrd", 16, default = 1)
pro = pcs.Field("pro", 16, default = 0x800)
hln = pcs.Field("hln", 8, default = 6)
pln = pcs.Field("pln", 8, default = 4)
op = pcs.Field("op", 16)
sha = pcs.StringField("sha", 48)
spa = pcs.Field("spa", 32)
tha = pcs.StringField("tha", 48)
tpa = pcs.Field("tpa", 32)
pcs.Packet.__init__(self, [hrd, pro, hln, pln, op,
sha, spa, tha, tpa], bytes = bytes)
self.description = "ARP"
self.data = None
def __str__(self):
"""return a human readable version of an ARP packet"""
retval = "ARP\n"
retval += "hrd: "
retval += "%d\n" % self.hrd
retval += "pro: "
retval += "%d\n" % self.pro
retval += "hln: "
retval += "%d\n" % self.hln
retval += "pln: "
retval += "%d\n" % self.pln
retval += "op: "
retval += "%d\n" % self.op
retval += "sha: "
for byte in range(0,5):
retval += "%s:" % hex(ord(self.sha[byte]))[2:4]
retval += "%s\n" % hex(ord(self.sha[5]))[2:4]
retval += "spa: "
retval += "%s\n" % inet_ntop(AF_INET, struct.pack('!L', self.spa))
retval += "tha: "
for byte in range(0,5):
retval += "%s:" % hex(ord(self.tha[byte]))[2:4]
retval += "%s\n" % hex(ord(self.tha[5]))[2:4]
retval += "tpa: "
retval += "%s\n" % inet_ntop(AF_INET, struct.pack('!L', self.tpa))
return retval
#
# Functions defined for the module.
#
def ether_atob(pretty):
"""Take a pretty version of an ethernet address and convert it to a
string of bytes.
The input string MUST be of the form xx:yy:zz:aa:bb:cc and leading
zero's must be supplied. Nor error checking is performed.
"""
addr = ""
for i in 0, 3, 6, 9, 12, 15:
addr += "%c" % int(pretty[i:i+2], 16)
return addr
def ether_btoa(bytes):
"""Take a set of bytes and convert them to a pretty version of
and Ethernet address.
The input buffer MUST be at least 6 bytes long and bytes after the
sixth are ignored. No error checking is performed.
"""
pretty = ""
for i in (range(5)):
pretty += hex(bytes[i])[2:4] # Strip the 0x from the string
pretty += ':'
pretty += hex(bytes[5])[2:4] # Strip the 0x from the string
return pretty
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