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shared.py
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shared.py
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import os
import sys
import random
import time
import bpf
from wrappers import Ethernet, IPv4, UDP, DHCP, DHCPOptions, DHCPOption, ARP
from fields import MACAddres, IPAddress
IFCONFIG_MAC_ADDRESS_LINE = '\tether'
def get_local_mac_addres_of_device(dev):
cmd = 'ifconfig %s' % dev
try:
pipe = os.popen(cmd)
except IOError:
raise Exception('''Can't get MAC addres.''')
for line in pipe:
if line.startswith(IFCONFIG_MAC_ADDRESS_LINE):
return MACAddres(colon_hex_str = line[len(IFCONFIG_MAC_ADDRESS_LINE):])
def request_dhcp_info(fd, local_mac_address, timeout=2.0):
# DISCOVERY
eth = Ethernet(data_dict=dict(
dmac=MACAddres(colon_hex_str='ff:ff:ff:ff:ff:ff'),
smac=local_mac_address,
type=0x0800
))
ipv4 = IPv4(parent=eth, data_dict=dict(
version=4,
header_length=5,
type_of_service=0x00,
total_length=0,
identification=random.getrandbits(16),
flags=0x0,
fragment_offset=0,
time_to_live=255,
protocol=0x11,
header_checksum=0x0000,
saddr=IPAddress(str_val='0.0.0.0'),
daddr=IPAddress(str_val='255.255.255.255'),
))
udp = UDP(parent=ipv4, data_dict=dict(
sport=68,
dport=67,
length=0,
checksum=0x0000,
))
dhcp = DHCP(parent=udp, data_dict=dict(
op=0x01,
htype=0x01,
hlen=0x06,
hops=0x00,
xid=random.getrandbits(32),
secs=0x0000,
flags=0x0000,
ciaddr=IPAddress(str_val='0.0.0.0'),
yiaddr=IPAddress(str_val='0.0.0.0'),
siaddr=IPAddress(str_val='0.0.0.0'),
giaddr=IPAddress(str_val='0.0.0.0'),
chaddr=local_mac_address,
_bootp_legacy='\x00' * 202,
magic_cookie=0x63825363,
dhcp_options=DHCPOptions([
DHCPOption(dhcp_options=chr(53) + chr(1) + '\x01'), # dhcp_message_type
DHCPOption(dhcp_options='\xff'),
DHCPOption(dhcp_options='\x00' * 19),
])
))
udp.payload = dhcp.raw_val(parents=False)
udp.compute_length()
udp.compute_checksum()
ipv4.payload = udp.raw_val(parents=False) + udp.payload
ipv4.compute_length()
ipv4.compute_checksum()
os.write(fd, dhcp.raw_val())
start_time = time.time()
# OFFER
try:
while True:
end_time = time.time()
rest_of_timeout = timeout / 2. - (end_time - start_time)
if rest_of_timeout <= 0.0:
raise bpf.BPFTimeout()
packet = bpf.read_packet(fd, timeout=rest_of_timeout)
in_eth = Ethernet(packet.data)
is_valid_dhcp = False
if in_eth.dmac == local_mac_address \
and in_eth.type == 0x0800:
in_ip = IPv4(parent=in_eth)
if in_ip.version == 4 \
and in_ip.protocol == IPv4.PROTOCOL_UDP:
in_udp = UDP(parent=in_ip)
if in_udp.sport == 67 \
and in_udp.dport == 68:
in_dhcp = DHCP(parent=in_udp)
if in_dhcp.op == 0x02 \
and in_dhcp.htype == 0x01 \
and in_dhcp.xid == dhcp.xid \
and in_dhcp.chaddr == local_mac_address \
and in_dhcp.magic_cookie == 0x63825363 \
and in_dhcp.dhcp_options.get('dhcp_message_type') == '\x02':
offer_dict = { 'yiaddr': in_dhcp.yiaddr }
for name in ('router', 'domain_name_server', 'subnet_mask'):
offer_dict[name] = in_dhcp.dhcp_options.get(name)[0]
is_valid_dhcp = True
if is_valid_dhcp:
break
except bpf.BPFTimeout:
print 'request_dhcp_info(local_mac_address=%s) timed out!' % local_mac_address
sys.exit(1)
# REQUEST
ipv4.identification.val += 1
dhcp.dhcp_options = DHCPOptions([
DHCPOption(dhcp_options=chr(53) + chr(1) + '\x03'), # dhcp_message_type
DHCPOption(dhcp_options=chr(55) + chr(10) + '\x01\x03\x06\x0f\x77\x5f\xfc\x2c\x2e\x2f'), # parameter_request_list
DHCPOption(dhcp_options=chr(57) + chr(2) + '\x05\xdc'), # maximum_dhcp_message_size
DHCPOption(dhcp_options=chr(50) + chr(4) + offer_dict['yiaddr'].raw_val()), # requested_ip_address
DHCPOption(dhcp_options=chr(51) + chr(4) + '\x00\x76\xa7\x00'), # ip_address_lease_time (90 days)
DHCPOption(dhcp_options='\xff'),
DHCPOption(dhcp_options='\x00' * 19),
])
udp.payload = dhcp.raw_val(parents=False)
udp.compute_length()
udp.compute_checksum()
ipv4.payload = udp.raw_val(parents=False) + udp.payload
ipv4.compute_length()
ipv4.compute_checksum()
os.write(fd, dhcp.raw_val())
start_time = time.time()
# ACKNOWLAGE
try:
while True:
end_time = time.time()
rest_of_timeout = timeout - (end_time - start_time)
if rest_of_timeout <= 0.0:
raise bpf.BPFTimeout()
packet = bpf.read_packet(fd, timeout=rest_of_timeout)
in_eth = Ethernet(packet.data)
is_valid_dhcp = False
if in_eth.dmac == local_mac_address \
and in_eth.type == 0x0800:
in_ip = IPv4(parent=in_eth)
if in_ip.version == 4 \
and in_ip.protocol == IPv4.PROTOCOL_UDP:
in_udp = UDP(parent=in_ip)
if in_udp.sport == 67 \
and in_udp.dport == 68:
in_dhcp = DHCP(parent=in_udp)
if in_dhcp.op == 0x02 \
and in_dhcp.htype == 0x01 \
and in_dhcp.xid == dhcp.xid \
and in_dhcp.chaddr == local_mac_address \
and in_dhcp.magic_cookie == 0x63825363 \
and in_dhcp.dhcp_options.get('dhcp_message_type') == '\x05':
return_dict = { 'yiaddr': in_dhcp.yiaddr }
for name in ('router', 'domain_name_server', 'subnet_mask'):
return_dict[name] = in_dhcp.dhcp_options.get(name)[0]
is_valid_dhcp = True
if is_valid_dhcp:
break
except bpf.BPFTimeout:
print 'request_dhcp_info(local_mac_address=%s) timed out!' % local_mac_address
sys.exit(1)
return return_dict
def request_adp_mac_addres(fd, local_mac_address, local_ip_address, remote_ip_address, timeout=1.0):
eth = Ethernet(data_dict=dict(
dmac=MACAddres(colon_hex_str='ff:ff:ff:ff:ff:ff'),
smac=local_mac_address,
type=Ethernet.TYPE_ARP,
))
arp = ARP(parent=eth, data_dict=dict(
htype=0x0001,
ptype=0x0800,
hlen=0x0006,
plen=0x0004,
oper=0x0001,
sha=local_mac_address,
spa=local_ip_address,
tha=MACAddres(colon_hex_str='00:00:00:00:00:00'),
tpa=remote_ip_address,
))
os.write(fd, arp.raw_val())
start_time = time.time()
try:
while True:
end_time = time.time()
rest_of_timeout = timeout - (end_time - start_time)
if rest_of_timeout <= 0.0:
raise bpf.BPFTimeout()
packet = bpf.read_packet(fd, timeout=rest_of_timeout)
in_eth = Ethernet(raw_data=packet.data)
if in_eth.dmac == local_mac_address \
and in_eth.type == Ethernet.TYPE_ARP:
in_arp = ARP(parent=in_eth)
if in_arp.htype == 0x0001 \
and in_arp.ptype == 0x0800 \
and in_arp.hlen == 0x0006 \
and in_arp.plen == 0x0004 \
and in_arp.oper == 0x0002 \
and in_arp.spa == remote_ip_address \
and in_arp.tha == local_mac_address \
and in_arp.tpa == local_ip_address:
return in_arp.sha
except bpf.BPFTimeout:
print 'request_adp_mac_addres(local_mac_address=%s, local_ip_address=%s, remote_ip_address=%s) timed out!' % (
local_mac_address, local_ip_address, remote_ip_address)
sys.exit(1)
if __name__ == '__main__':
LOCAL_DEVICE = 'en1'
REMOTE_IP_ADDRESS = IPAddress(str_val='192.168.1.1')
LOCAL_MAC_ADDRESS = get_local_mac_addres_of_device(LOCAL_DEVICE)
fd = bpf.get_bpf_fg(device=LOCAL_DEVICE)
LOCAL_IP_ADDRESS = request_dhcp_info(fd, LOCAL_MAC_ADDRESS)['yiaddr']
print request_adp_mac_addres(fd, LOCAL_MAC_ADDRESS, LOCAL_IP_ADDRESS, REMOTE_IP_ADDRESS)
bpf.bpf_dispose(fd)