/usr/lib/python2.7/dist-packages/ip.py is in python-pyip 0.7-2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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# pyip is a Python package offering assembling/disassembling of raw ip packet
# including ip, udp, and icmp. Also it includes 2 utilities based on raw ip,
# traceroute and ping.
#
# pyip is released under PYTHON SOFTWARE FOUNDATION LICENSE VERSION 2, and is
# a project inspired by 'ping' written by Jeremy Hylton.
#
# Author: Kenneth Jiang, kenneth.jiang@gmail.com
#
import inetutils
import socket
import struct
import string
import os
IPVERSION = 4
IP_DF = 0x4000
IP_MF = 0x2000
IP_MAXPACKET = 65535
IPTOS_LOWDELAY = 0x10
IPTOS_THROUGHPUT = 0x08
IPTOS_RELIABILITY = 0x04
IPTOS_PREC_NETCONTROL = 0xe0
IPTOS_PREC_INTERNETCONTROL = 0xc0
IPTOS_PREC_CRITIC_ECP = 0xa0
IPTOS_PREC_FLASHOVERRIDE = 0x80
IPTOS_PREC_FLASH = 0x60
IPTOS_PREC_IMMEDIATE = 0x40
IPTOS_PREC_PRIORITY = 0x20
IPTOS_PREC_ROUTINE = 0x00
IPOPT_CONTROL = 0x00
IPOPT_RESERVED1 = 0x20
IPOPT_DEBMEAS = 0x40
IPOPT_RESERVED2 = 0x60
IPOPT_EOL = 0
IPOPT_NOP = 1
IPOPT_RR = 7
IPOPT_TS = 68
IPOPT_SECURITY = 130
IPOPT_LSRR = 131
IPOPT_SATID = 136
IPOPT_SSRR = 137
IPOPT_OPTVAL = 0
IPOPT_OLEN = 1
IPOPT_OFFSET = 2
IPOPT_MINOFF = 4
IPOPT_TS_TSONLY = 0
IPOPT_TS_TSANDADDR = 1
IPOPT_TS_PRESPEC = 2
IPOPT_SECUR_UNCLASS = 0x0000
IPOPT_SECUR_CONFID = 0xf135
IPOPT_SECUR_EFTO = 0x789a
IPOPT_SECUR_MMMM = 0xbc4d
IPOPT_SECUR_RESTR = 0xaf13
IPOPT_SECUR_SECRET = 0xd788
IPOPT_SECUR_TOPSECRET = 0x6bc5
MAXTTL = 255
IPFRAGTTL = 60
IPTTLDEC = 1
IP_MSS = 576
MIN_HDR_SIZE_IN_BYTES = 20
class Packet:
"""An IP packet.
Doesn't handle IP options yet (but you have the option of adding
support).
"""
def __init__(self,
v = IPVERSION,
hl = 5,
tos = IPTOS_PREC_ROUTINE,
len = 20,
id = 0,
df = 0,
off = 0,
ttl = 0,
p = 0,
sum = 0,
src = None,
dst = None,
data = ''):
self.v = v
self.hl = hl # this implement punts on options
self.tos = tos
self.len = len # begin with header length
self.id = id
self.df = df
self.off = off
self.ttl = ttl
self.p = p
self.sum = sum
self.src = src
self.dst = dst
self.data = data
self.raw_packet = ''
def __repr__(self):
begin = "<IPv%d id=%d proto=%d src=%s dst=%s datalen=%d " % \
(self.v, self.id, self.p, self.src, self.dst,
self.len - self.hl * 4)
if len(self.data) == 0:
rep = begin + "\'\'>"
elif len(self.data) < 10:
rep = begin + "%s>" % repr(self.data)
else:
rep = begin + "%s>" % repr(self.data[:10] + '...')
return rep
def __eq__(self, other):
if not isinstance(other, Packet):
return 0
return self.v == other.v and \
self.hl == other.hl and \
self.tos == other.tos and \
self.len == other.len and \
self.id == other.id and \
self.df == other.df and \
self.off == other.off and \
self.ttl == other.ttl and \
self.p == other.p and \
self.sum == other.sum and \
self.src == other.src and \
self.dst == other.dst and \
self.data == other.data
def _assemble(self, cksum):
"Get a packet suitable for sending over an IP socket."
# make sure all the data is ready
assert self.src, "src needed before assembling."
assert self.dst, "dst needed before assembling."
self.len = self.hl * 4 + len(self.data)
self.__parse_addrs()
# create the packet
header = struct.pack('ccHHHcc',
chr((self.v & 0x0f) << 4
| (self.hl & 0x0f)), # 4bits each
chr(self.tos & 0xff),
self.len,
self.id,
(self.df & 0x01) << 14
| self.off, # what about flags?
chr(self.ttl & 0xff),
chr(self.p & 0xff))
if cksum:
self.sum = inetutils.cksum(header + '\000\000' + self.__src +
self.__dst)
packet = header + struct.pack('H', self.sum) \
+ self.__src + self.__dst
else:
packet = header + '\000\000' + self.__src + self.__dst
packet = packet + self.data
self.__packet = inetutils.iph2net(packet)
return self.__packet
def __parse_addrs(self):
try:
self.__src = socket.inet_aton(self.src)
except ValueError:
try:
self.__src = socket.inet_aton(socket.gethostbyname(self.src))
except ValueError:
raise ValueError, "invalid source address"
try:
self.__dst = socket.inet_aton(self.dst)
except ValueError:
try:
self.__dst = socket.inet_aton(socket.gethostbyname(self.dst))
except ValueError:
raise ValueError, "invalid source address"
def __unparse_addrs(self):
src = struct.unpack('cccc', self.src)
self.src = string.joinfields(map(lambda x:str(ord(x)), src), '.')
dst = struct.unpack('cccc', self.dst)
self.dst = string.joinfields(map(lambda x:str(ord(x)), dst), '.')
def _disassemble(self, raw_packet, cksum):
# The kernel computes the checksum, even on a raw packet.
packet = inetutils.net2iph(raw_packet)
b1 = ord(packet[0])
self.v = (b1 >> 4) & 0x0f
self.hl = b1 & 0x0f
if self.v != IPVERSION:
raise ValueError, "cannot handle IPv%d packets" % self.v
hl = self.hl * 4
# verify the checksum
self.sum = struct.unpack('H', packet[10:12])[0] & 0xffff
if cksum:
our_cksum = inetutils.cksum(packet[:20])
if our_cksum != 0:
raise ValueError, packet
# unpack the fields
elts = struct.unpack('ccHHHcc', packet[:hl-10])
# struct didn't do !<> when this was written
self.tos = ord(elts[1])
self.len = elts[2] & 0xffff
self.id = elts[3] & 0xffff
self.off = elts[4] & 0xffff
self.ttl = ord(elts[5])
self.p = ord(elts[6])
self.data = packet[hl:]
self.src = packet[hl-8:hl-4]
self.dst = packet[hl-4:hl]
self.__unparse_addrs()
def assemble(packet, cksum = 0):
return packet._assemble(cksum)
def disassemble(buffer, cksum = 0):
packet = Packet()
packet._disassemble(buffer, cksum)
return packet
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