def action(ifname):
s = DHCP4Socket(ifname)
poll = select.poll()
poll.register(s, select.POLLIN | select.POLLPRI)
# DISCOVER
discover = dhcp4msg({
'op': BOOTREQUEST,
'chaddr': s.l2addr,
'options': {
'message_type': DHCPDISCOVER,
'parameter_list': [1, 3, 6, 12, 15, 28]
}
})
reply = req(s, poll, discover, expect=DHCPOFFER)
# REQUEST
request = dhcp4msg({
'op': BOOTREQUEST,
'chaddr': s.l2addr,
'options': {
'message_type': DHCPREQUEST,
'requested_ip': reply['yiaddr'],
'server_id': reply['options']['server_id'],
'parameter_list': [1, 3, 6, 12, 15, 28]
}
})
reply = req(s, poll, request, expect=DHCPACK)
pprint(reply)
s.close()
return reply
def put(self, msg=None, dport=67):
'''
Put DHCP message. Parameters:
* msg -- dhcp4msg instance
* dport -- DHCP server port
If `msg` is not provided, it is constructed as default
BOOTREQUEST + DHCPDISCOVER.
Examples::
sock.put(dhcp4msg({'op': BOOTREQUEST,
'chaddr': 'ff:11:22:33:44:55',
'options': {'message_type': DHCPREQUEST,
'parameter_list': [1, 3, 6, 12, 15],
'requested_ip': '172.16.101.2',
'server_id': '172.16.101.1'}}))
The method returns dhcp4msg that was sent, so one can get from
there `xid` (transaction id) and other details.
'''
# DHCP layer
dhcp = msg or dhcp4msg({'chaddr': self.l2addr})
# dhcp transaction id
if dhcp['xid'] is None:
dhcp['xid'] = self.xid_pool.alloc()
data = dhcp.encode().buf
# UDP layer
udp = udpmsg({'sport': self.port,
'dport': dport,
'len': 8 + len(data)})
udph = udp4_pseudo_header({'dst': '255.255.255.255',
'len': 8 + len(data)})
udp['csum'] = self.csum(udph.encode().buf + udp.encode().buf + data)
udp.reset()
# IPv4 layer
ip4 = ip4msg({'len': 20 + 8 + len(data),
'proto': 17,
'dst': '255.255.255.255'})
ip4['csum'] = self.csum(ip4.encode().buf)
ip4.reset()
# MAC layer
eth = ethmsg({'dst': 'ff:ff:ff:ff:ff:ff',
'src': self.l2addr,
'type': 0x800})
data = eth.encode().buf +\
ip4.encode().buf +\
udp.encode().buf +\
data
self.send(data)
dhcp.reset()
return dhcp
def get(self):
'''
Get the next incoming packet from the socket and try
to decode it as IPv4 DHCP. No analysis is done here,
only MAC/IPv4/UDP headers are stripped out, and the
rest is interpreted as DHCP.
'''
(data, addr) = self.recvfrom(4096)
eth = ethmsg(buf=data).decode()
ip4 = ip4msg(buf=data, offset=eth.offset).decode()
udp = udpmsg(buf=data, offset=ip4.offset).decode()
return dhcp4msg(buf=data, offset=udp.offset).decode()
def get(self):
'''
Get the next incoming packet from the socket and try
to decode it as IPv4 DHCP. No analysis is done here,
only MAC/IPv4/UDP headers are stripped out, and the
rest is interpreted as DHCP.
'''
(data, addr) = self.recvfrom(4096)
eth = ethmsg(buf=data).decode()
ip4 = ip4msg(buf=data, offset=eth.offset).decode()
udp = udpmsg(buf=data, offset=ip4.offset).decode()
return dhcp4msg(buf=data, offset=udp.offset).decode()
def action(ifname):
s = DHCP4Socket(ifname)
poll = select.poll()
poll.register(s, select.POLLIN | select.POLLPRI)
# DISCOVER
discover = dhcp4msg({'op': BOOTREQUEST,
'chaddr': s.l2addr,
'options': {'message_type': DHCPDISCOVER,
'parameter_list': [1, 3, 6, 12, 15, 28]}})
reply = req(s, poll, discover, expect=DHCPOFFER)
# REQUEST
request = dhcp4msg({'op': BOOTREQUEST,
'chaddr': s.l2addr,
'options': {'message_type': DHCPREQUEST,
'requested_ip': reply['yiaddr'],
'server_id': reply['options']['server_id'],
'parameter_list': [1, 3, 6, 12, 15, 28]}})
reply = req(s, poll, request, expect=DHCPACK)
pprint(reply)
s.close()
return reply
def put(self, msg=None, dport=67):
'''
Put DHCP message. Parameters:
* msg -- dhcp4msg instance
* dport -- DHCP server port
If `msg` is not provided, it is constructed as default
BOOTREQUEST + DHCPDISCOVER.
Examples::
sock.put(dhcp4msg({'op': BOOTREQUEST,
'chaddr': 'ff:11:22:33:44:55',
'options': {'message_type': DHCPREQUEST,
'parameter_list': [1, 3, 6, 12, 15],
'requested_ip': '172.16.101.2',
'server_id': '172.16.101.1'}}))
The method returns dhcp4msg that was sent, so one can get from
there `xid` (transaction id) and other details.
'''
# DHCP layer
dhcp = msg or dhcp4msg({'chaddr': self.l2addr})
# dhcp transaction id
if dhcp['xid'] is None:
dhcp['xid'] = self.xid_pool.alloc()
data = dhcp.encode().buf
# UDP layer
udp = udpmsg({
'sport': self.port,
'dport': dport,
'len': 8 + len(data)
})
udph = udp4_pseudo_header({
'dst': '255.255.255.255',
'len': 8 + len(data)
})
udp['csum'] = self.csum(udph.encode().buf + udp.encode().buf + data)
udp.reset()
# IPv4 layer
ip4 = ip4msg({
'len': 20 + 8 + len(data),
'proto': 17,
'dst': '255.255.255.255'
})
ip4['csum'] = self.csum(ip4.encode().buf)
ip4.reset()
# MAC layer
eth = ethmsg({
'dst': 'ff:ff:ff:ff:ff:ff',
'src': self.l2addr,
'type': 0x800
})
data = eth.encode().buf +\
ip4.encode().buf +\
udp.encode().buf +\
data
self.send(data)
dhcp.reset()
return dhcp