1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
|
import pcs
from pcs.packets.ipv4 import ipv4
from pcs.packets.ipv6 import ipv6
from pcs.packets.arp import arp
ETHERTYPE_IP = 0x0800 # IP protocol
ETHERTYPE_ARP = 0x0806 # Addr. resolution protocol
ETHERTYPE_REVARP = 0x8035 # reverse Addr. resolution protocol
ETHERTYPE_VLAN = 0x8100 # IEEE 802.1Q VLAN tagging
ETHERTYPE_IPV6 = 0x86dd # IPv6
class ethernet(pcs.Packet):
layout = pcs.Layout()
def __init__(self, bytes = None):
"""initialize an ethernet packet"""
src = pcs.StringField("src", 48)
dst = pcs.StringField("dst", 48)
type = pcs.Field("type", 16)
etherlen = 14
pcs.Packet.__init__(self, [dst, src, type], bytes = bytes)
self.description = "Ethernet"
if (bytes != None):
self.data = self.next(bytes[etherlen:len(bytes)])
else:
self.data = None
def __str__(self):
"""return a human readable version of an Ethernet packet"""
retval = "Ethernet\n"
retval += "dst: "
for byte in range(0,5):
retval += "%s:" % hex(ord(self.dst[byte]))[2:4]
retval += "%s" % hex(ord(self.dst[5]))[2:4]
retval += "\nsrc: "
for byte in range(0,5):
retval += "%s:" % hex(ord(self.src[byte]))[2:4]
retval += "%s" % hex(ord(self.src[5]))[2:4]
retval += "\ntype: %s" % hex(self.type)
return retval
def next(self, bytes):
"""Decode the type of a packet and return the correct higher
level protocol object"""
## the ethertype of the packet
if self.type == ETHERTYPE_ARP:
return arp(bytes)
if self.type == ETHERTYPE_IP:
return ipv4(bytes)
if self.type == ETHERTYPE_IPV6:
return ipv6(bytes)
return None
#
# 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(ord(bytes[i]))[2:4] # Strip the 0x from the string
pretty += ':'
pretty += hex(ord(bytes[5]))[2:4] # Strip the 0x from the string
return pretty
|
