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# $Id: dhcp.py 23 2006-11-08 15:45:33Z dugsong $
# -*- coding: utf-8 -*-
"""Dynamic Host Configuration Protocol."""
from __future__ import print_function
from __future__ import absolute_import
import struct
from . import arp
from . import dpkt
from .compat import compat_ord
DHCP_OP_REQUEST = 1
DHCP_OP_REPLY = 2
DHCP_MAGIC = 0x63825363
# DHCP option codes
DHCP_OPT_NETMASK = 1 # I: subnet mask
DHCP_OPT_TIMEOFFSET = 2
DHCP_OPT_ROUTER = 3 # s: list of router ips
DHCP_OPT_TIMESERVER = 4
DHCP_OPT_NAMESERVER = 5
DHCP_OPT_DNS_SVRS = 6 # s: list of DNS servers
DHCP_OPT_LOGSERV = 7
DHCP_OPT_COOKIESERV = 8
DHCP_OPT_LPRSERV = 9
DHCP_OPT_IMPSERV = 10
DHCP_OPT_RESSERV = 11
DHCP_OPT_HOSTNAME = 12 # s: client hostname
DHCP_OPT_BOOTFILESIZE = 13
DHCP_OPT_DUMPFILE = 14
DHCP_OPT_DOMAIN = 15 # s: domain name
DHCP_OPT_SWAPSERV = 16
DHCP_OPT_ROOTPATH = 17
DHCP_OPT_EXTENPATH = 18
DHCP_OPT_IPFORWARD = 19
DHCP_OPT_SRCROUTE = 20
DHCP_OPT_POLICYFILTER = 21
DHCP_OPT_MAXASMSIZE = 22
DHCP_OPT_IPTTL = 23
DHCP_OPT_MTUTIMEOUT = 24
DHCP_OPT_MTUTABLE = 25
DHCP_OPT_MTUSIZE = 26
DHCP_OPT_LOCALSUBNETS = 27
DHCP_OPT_BROADCASTADDR = 28
DHCP_OPT_DOMASKDISCOV = 29
DHCP_OPT_MASKSUPPLY = 30
DHCP_OPT_DOROUTEDISC = 31
DHCP_OPT_ROUTERSOLICIT = 32
DHCP_OPT_STATICROUTE = 33
DHCP_OPT_TRAILERENCAP = 34
DHCP_OPT_ARPTIMEOUT = 35
DHCP_OPT_ETHERENCAP = 36
DHCP_OPT_TCPTTL = 37
DHCP_OPT_TCPKEEPALIVE = 38
DHCP_OPT_TCPALIVEGARBAGE = 39
DHCP_OPT_NISDOMAIN = 40
DHCP_OPT_NISSERVERS = 41
DHCP_OPT_NISTIMESERV = 42
DHCP_OPT_VENDSPECIFIC = 43
DHCP_OPT_NBNS = 44
DHCP_OPT_NBDD = 45
DHCP_OPT_NBTCPIP = 46
DHCP_OPT_NBTCPSCOPE = 47
DHCP_OPT_XFONT = 48
DHCP_OPT_XDISPLAYMGR = 49
DHCP_OPT_REQ_IP = 50 # I: IP address
DHCP_OPT_LEASE_SEC = 51 # I: lease seconds
DHCP_OPT_OPTIONOVERLOAD = 52
DHCP_OPT_MSGTYPE = 53 # B: message type
DHCP_OPT_SERVER_ID = 54 # I: server IP address
DHCP_OPT_PARAM_REQ = 55 # s: list of option codes
DHCP_OPT_MESSAGE = 56
DHCP_OPT_MAXMSGSIZE = 57
DHCP_OPT_RENEWTIME = 58
DHCP_OPT_REBINDTIME = 59
DHCP_OPT_VENDOR_ID = 60 # s: vendor class id
DHCP_OPT_CLIENT_ID = 61 # Bs: idtype, id (idtype 0: FQDN, idtype 1: MAC)
DHCP_OPT_NISPLUSDOMAIN = 64
DHCP_OPT_NISPLUSSERVERS = 65
DHCP_OPT_MOBILEIPAGENT = 68
DHCP_OPT_SMTPSERVER = 69
DHCP_OPT_POP3SERVER = 70
DHCP_OPT_NNTPSERVER = 71
DHCP_OPT_WWWSERVER = 72
DHCP_OPT_FINGERSERVER = 73
DHCP_OPT_IRCSERVER = 74
DHCP_OPT_STSERVER = 75
DHCP_OPT_STDASERVER = 76
# DHCP message type values
DHCPDISCOVER = 1
DHCPOFFER = 2
DHCPREQUEST = 3
DHCPDECLINE = 4
DHCPACK = 5
DHCPNAK = 6
DHCPRELEASE = 7
DHCPINFORM = 8
class DHCP(dpkt.Packet):
"""Dynamic Host Configuration Protocol.
TODO: Longer class information....
Attributes:
__hdr__: Header fields of DHCP.
TODO.
"""
__hdr__ = (
('op', 'B', DHCP_OP_REQUEST),
('hrd', 'B', arp.ARP_HRD_ETH), # just like ARP.hrd
('hln', 'B', 6), # and ARP.hln
('hops', 'B', 0),
('xid', 'I', 0xdeadbeef),
('secs', 'H', 0),
('flags', 'H', 0),
('ciaddr', 'I', 0),
('yiaddr', 'I', 0),
('siaddr', 'I', 0),
('giaddr', 'I', 0),
('chaddr', '16s', 16 * b'\x00'),
('sname', '64s', 64 * b'\x00'),
('file', '128s', 128 * b'\x00'),
('magic', 'I', DHCP_MAGIC),
)
opts = (
(DHCP_OPT_MSGTYPE, chr(DHCPDISCOVER)),
(DHCP_OPT_PARAM_REQ, ''.join(map(chr, (DHCP_OPT_REQ_IP,
DHCP_OPT_ROUTER,
DHCP_OPT_NETMASK,
DHCP_OPT_DNS_SVRS))))
) # list of (type, data) tuples
def __len__(self):
return self.__hdr_len__ + \
sum([2 + len(o[1]) for o in self.opts]) + 1 + len(self.data)
def __bytes__(self):
return self.pack_hdr() + self.pack_opts() + bytes(self.data)
def pack_opts(self):
"""Return packed options string."""
if not self.opts:
return b''
l_ = []
for t, data in self.opts:
l_.append(struct.pack("BB%is" % len(data), t, len(data), data))
l_.append(b'\xff')
return b''.join(l_)
def unpack(self, buf):
dpkt.Packet.unpack(self, buf)
self.chaddr = self.chaddr[:self.hln]
buf = self.data
l_ = []
while buf:
t = compat_ord(buf[0])
if t == 0xff:
buf = buf[1:]
break
elif t == 0:
buf = buf[1:]
else:
n = compat_ord(buf[1])
l_.append((t, buf[2:2 + n]))
buf = buf[2 + n:]
self.opts = l_
self.data = buf
def test_dhcp():
s = (
b'\x01\x01\x06\x00\xad\x53\xc8\x63\xb8\x87\x80\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
b'\x00\x00\x00\x00\x02\x55\x82\xf3\xa6\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x63\x82\x53\x63\x35\x01\x01\xfb\x01\x01\x3d\x07\x01\x00'
b'\x02\x55\x82\xf3\xa6\x32\x04\x0a\x00\x01\x65\x0c\x09\x47\x75\x69\x6e\x65\x76\x65\x72\x65\x3c\x08\x4d'
b'\x53\x46\x54\x20\x35\x2e\x30\x37\x0a\x01\x0f\x03\x06\x2c\x2e\x2f\x1f\x21\x2b\xff\x00\x00\x00\x00\x00'
)
dhcp = DHCP(s)
assert (s == bytes(dhcp))
assert len(dhcp) == 300
assert isinstance(dhcp.chaddr, bytes)
assert isinstance(dhcp.sname, bytes)
assert isinstance(dhcp.file, bytes)
# Test default construction
dhcp = DHCP()
assert isinstance(dhcp.chaddr, bytes)
assert isinstance(dhcp.sname, bytes)
assert isinstance(dhcp.file, bytes)
def test_no_opts():
from binascii import unhexlify
buf_small_hdr = unhexlify(
'00' # op
'00' # hrd
'06' # hln
'12' # hops
'deadbeef' # xid
'1234' # secs
'9866' # flags
'00000000' # ciaddr
'00000000' # yiaddr
'00000000' # siaddr
'00000000' # giaddr
)
buf = b''.join([
buf_small_hdr,
b'\x00' * 16, # chaddr
b'\x11' * 64, # sname
b'\x22' * 128, # file
b'\x44' * 4, # magic
b'\x00' # data
])
dhcp = DHCP(buf)
assert dhcp.opts == []
assert dhcp.data == b''
assert dhcp.pack_opts() == b''