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netarch
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Now handling ARP

This commit is contained in:
Neale Pickett 2008-07-14 17:26:02 -06:00
parent 297598b7de
commit 79daacd3ce
1 changed files with 86 additions and 65 deletions
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57
ip.py
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@ -11,13 +11,7 @@ import heapq
import gapstr
import time
import UserDict
def unpack(fmt, buf):
"""Unpack buf based on fmt, assuming the rest is a string."""
size = struct.calcsize(fmt)
vals = struct.unpack(fmt, buf[:size])
return vals + (buf[size:],)
from __init__ import *
def unpack_nybbles(byte):
return (byte >> 4, byte & 0x0F)
@ -28,7 +22,7 @@ TCP = 6
UDP = 17
class Frame:
"""Turn an ethernet frame into relevant TCP parts"""
"""Turn an ethernet frame into relevant parts"""
def __init__(self, pkt):
((self.time, _, _), frame) = pkt
@ -38,9 +32,23 @@ class Frame:
self.eth_shost,
self.eth_type,
p) = unpack('!6s6sH', frame)
if self.eth_type != 0x0800:
raise ValueError('Not IP %04x' % self.eth_type)
if self.eth_type == 0x0806:
# ARP
self.name = 'ARP'
(self.ar_hrd,
self.ar_pro,
self.ar_hln,
self.ar_pln,
self.ar_op,
self.ar_sha,
self.ar_sip,
self.ar_tha,
self.ar_tip,
p) = unpack('!HHBBH6si6si', p)
self.saddr = self.ar_sip
self.daddr = self.ar_tip
self.__repr__ = self.__arp_repr__
elif self.eth_type == 0x0800:
# IP
(self.ihlvers,
self.tos,
@ -55,7 +63,7 @@ class Frame:
p) = unpack("!BBHHHBBHii", p)
if self.protocol == TCP:
self.name = 'TCP'
self.name = 'TCP/IP'
(self.sport,
self.dport,
self.seq,
@ -71,7 +79,7 @@ class Frame:
self.options, p = p[:opt_length - 20], p[opt_length - 20:]
self.payload = p[:self.tot_len - opt_length - 20]
elif self.protocol == UDP:
self.name = 'UDP'
self.name = 'UDP/IP'
(self.sport,
self.dport,
self.ulen,
@ -79,8 +87,8 @@ class Frame:
p) = unpack("!HHHH", p)
self.payload = p[:self.ulen - 8]
elif self.protocol == ICMP:
self.name = 'ICMP'
self.sport = self.dport = -1
self.name = 'ICMP/IP'
self.sport = self.dport = None
(self.type,
self.code,
self.cheksum,
@ -89,14 +97,20 @@ class Frame:
p) = unpack('!BBHHH', p)
self.payload = p[:self.tot_len - 8]
else:
raise ValueError('Unknown protocol')
self.name = 'IP Protocol %d' % self.protocol
self.sport = self.dport = None
self.payload = p
# Nice formatting
self.src = (self.saddr, self.sport)
self.dst = (self.daddr, self.dport)
# This hash is the same for both sides of the transaction
self.hash = (self.saddr ^ self.sport ^ self.daddr ^ self.dport)
self.hash = (self.saddr ^ (self.sport or 0)
^ self.daddr ^ (self.dport or 0))
else:
self.name = 'Ethernet type %d' % self.eth_type
def get_src_addr(self):
saddr = struct.pack('!i', self.saddr)
@ -111,11 +125,18 @@ class Frame:
dst_addr = property(get_dst_addr)
def __repr__(self):
return '<Frame %s %s:%d -> %s:%d length %d>' % (self.name,
return '<Frame %s %s:%r -> %s:%r length %d>' % (self.name,
self.src_addr, self.sport,
self.dst_addr, self.dport,
len(self.payload))
def __arp_repr__(self):
return '<Frame %s %s(%s) -> %s(%s)>' % (self.name,
self.ar_sha.encode('hex'),
self.src_addr,
self.ar_tha.encode('hex'),
self.dst_addr)
class Chunk:
"""Chunk of frames, possibly with gaps.