pydhcplib/dhcp_packet.py

   1 # Anemon Dhcp
   2 # Copyright (C) 2005 Mathieu Ignacio -- mignacio@april.org
   3 #
   4 # This program is free software; you can redistribute it and/or modify
   5 # it under the terms of the GNU General Public License as published by
   6 # the Free Software Foundation; either version 2 of the License, or
   7 # (at your option) any later version.
   8 #
   9 # This program is distributed in the hope that it will be useful,
  10 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 # GNU General Public License for more details.
  13 #
  14 # You should have received a copy of the GNU General Public License
  15 # along with this program; if not, write to the Free Software
  16 # Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301, USA
  17
  18 import operator
  19 from struct import unpack
  20 from struct import pack
  21 from dhcp_basic_packet import *
  22 from dhcp_constants import *
  23 from type_ipv4 import ipv4
  24 from type_strlist import strlist
  25 class DhcpPacket(DhcpBasicPacket):
  26
  27
  28     # Useful function for debugging
  29     def PrintHeaders(self):
  30         print "# Header fields\n"
  31         print "readable_dhcp_headers = {"
  32         for opt in  ['op','htype','hlen','hops','xid','secs','flags',
  33                      'ciaddr','yiaddr','siaddr','giaddr','chaddr','sname','file'] :
  34             begin = DhcpFields[opt][0]
  35             end = DhcpFields[opt][0]+DhcpFields[opt][1]
  36             data = self.packet_data[begin:end]
  37             if DhcpFieldsTypes[opt] == "int" : result = str(data[0])
  38             if DhcpFieldsTypes[opt] == "int2" : result = str(data[0]*256+data[0])
  39             if DhcpFieldsTypes[opt] == "int4" : result = str(ipv4(data).int())
  40             if DhcpFieldsTypes[opt] == "str" : result = strlist(data).str()
  41             if DhcpFieldsTypes[opt] == "ipv4" : result = ipv4(data).str()
  42             if DhcpFieldsTypes[opt] == "hwmac" : result = "".join(map(chr,data))
  43
  44             line = "\t'"+opt+"':"+str(data)+",\t# "+result
  45             print line
  46         print "\t'end':'true'}"
  47
  48     # Useful function for debugging
  49     def PrintOptions(self):
  50         print "# Options fields"
  51         print "readable_dhcp_options = {"
  52         for opt in self.options_data.keys():
  53             data = self.options_data[opt]
  54             result = ""
  55             optnum  = DhcpOptions[opt]
  56             if DhcpOptionsTypes[optnum] == "char" : result = str(data[0])
  57             if DhcpOptionsTypes[optnum] == "16-bits" : result = str(data[0]*256+data[0])
  58             if DhcpOptionsTypes[optnum] == "32bits" : result = str(ipv4(data).int())
  59             if DhcpOptionsTypes[optnum] == "string" : result = strlist(data).str()
  60             if DhcpOptionsTypes[optnum] == "ipv4" : result = ipv4(data).str()
  61             if DhcpOptionsTypes[optnum] == "ipv4+" :
  62                 for i in range(0,len(data),4) :
  63                     if len(data[i:i+4]) == 4 :
  64                         result += ipv4(data[i:i+4]).str() + " - "
  65             line = "\t'"+opt+"':"+str(data)+",\t# "+result
  66             print line
  67         print "\t'end':'true'}"
  68
  69
  70
  71     # FIXME: This is called from IsDhcpSomethingPacket, but is this really
  72     # needed?  Or maybe this testing should be done in
  73     # DhcpBasicPacket.DecodePacket().
  74
  75     # Test Packet Type
  76     def IsDhcpSomethingPacket(self,type):
  77         if self.IsDhcpPacket() == False : return False
  78         if self.IsOption("dhcp_message_type") == False : return False
  79         if self.GetOption("dhcp_message_type") != type : return False
  80         return True
  81
  82     def IsDhcpDiscoverPacket(self):
  83         return self.IsDhcpSomethingPacket([1])
  84
  85     def IsDhcpOfferPacket(self):
  86         return self.IsDhcpSomethingPacket([2])
  87
  88     def IsDhcpRequestPacket(self):
  89         return self.IsDhcpSomethingPacket([3])
  90
  91     def IsDhcpDeclinePacket(self):
  92         return self.IsDhcpSomethingPacket([4])
  93
  94     def IsDhcpAckPacket(self):
  95         return self.IsDhcpSomethingPacket([5])
  96
  97     def IsDhcpNackPacket(self):
  98         return self.IsDhcpSomethingPacket([6])
  99
 100     def IsDhcpReleasePacket(self):
 101         return self.IsDhcpSomethingPacket([7])
 102
 103     def IsDhcpInformPacket(self):
 104         return self.IsDhcpSomethingPacket([8])
 105
 106
 107     def GetMultipleOptions(self,options=()):
 108         result = {}
 109         for each in options:
 110             result[each] = self.GetOption(each)
 111         return result
 112
 113     def SetMultipleOptions(self,options={}):
 114         for each in options.keys():
 115             self.SetOption(each,options[each])
 116
 117
 118
 119
 120
 121
 122     # Creating Response Packet
 123
 124     # Server-side functions
 125     # From RFC 2132 page 28/29
 126     def CreateDhcpOfferPacketFrom(self,src): # src = discover packet
 127         self.SetOption("htype",src.GetOption("htype"))
 128         self.SetOption("xid",src.GetOption("xid"))
 129         self.SetOption("flags",src.GetOption("flags"))
 130         self.SetOption("giaddr",src.GetOption("giaddr"))
 131         self.SetOption("chaddr",src.GetOption("chaddr"))
 132         self.SetOption("ip_address_lease_time",src.GetOption("ip_address_lease_time"))
 133         self.TransformToDhcpOfferPacket()
 134
 135     def TransformToDhcpOfferPacket(self):
 136         self.SetOption("dhcp_message_type",[2])
 137         self.SetOption("op",[2])
 138         self.SetOption("hlen",[6])
 139
 140         self.DeleteOption("secs")
 141         self.DeleteOption("ciaddr")
 142         self.DeleteOption("request_ip_address")
 143         self.DeleteOption("parameter_request_list")
 144         self.DeleteOption("client_identifier")
 145         self.DeleteOption("maximum_message_size")
 146
 147
 148
 149
 150
 151     """ Dhcp ACK packet creation """
 152     def CreateDhcpAckPacketFrom(self,src): # src = request or inform packet
 153         self.SetOption("htype",src.GetOption("htype"))
 154         self.SetOption("xid",src.GetOption("xid"))
 155         self.SetOption("ciaddr",src.GetOption("ciaddr"))
 156         self.SetOption("flags",src.GetOption("flags"))
 157         self.SetOption("giaddr",src.GetOption("giaddr"))
 158         self.SetOption("chaddr",src.GetOption("chaddr"))
 159         self.SetOption("ip_address_lease_time_option",src.GetOption("ip_address_lease_time_option"))
 160         self.TransformToDhcpAckPacket()
 161
 162     def TransformToDhcpAckPacket(self): # src = request or inform packet
 163         self.SetOption("op",[2])
 164         self.SetOption("hlen",[6])
 165         self.SetOption("dhcp_message_type",[5])
 166
 167         self.DeleteOption("secs")
 168         self.DeleteOption("request_ip_address")
 169         self.DeleteOption("parameter_request_list")
 170         self.DeleteOption("client_identifier")
 171         self.DeleteOption("maximum_message_size")
 172
 173
 174     """ Dhcp NACK packet creation """
 175     def CreateDhcpNackPacketFrom(self,src): # src = request or inform packet
 176
 177         self.SetOption("htype",src.GetOption("htype"))
 178         self.SetOption("xid",src.GetOption("xid"))
 179         self.SetOption("flags",src.GetOption("flags"))
 180         self.SetOption("giaddr",src.GetOption("giaddr"))
 181         self.SetOption("chaddr",src.GetOption("chaddr"))
 182         self.TransformToDhcpNackPacket()
 183
 184     def TransformToDhcpNackPacket(self):
 185         self.SetOption("op",[2])
 186         self.SetOption("hlen",[6])
 187         self.DeleteOption("secs")
 188         self.DeleteOption("ciaddr")
 189         self.DeleteOption("yiaddr")
 190         self.DeleteOption("siaddr")
 191         self.DeleteOption("sname")
 192         self.DeleteOption("file")
 193         self.DeleteOption("request_ip_address")
 194         self.DeleteOption("ip_address_lease_time_option")
 195         self.DeleteOption("parameter_request_list")
 196         self.DeleteOption("client_identifier")
 197         self.DeleteOption("maximum_message_size")
 198         self.SetOption("dhcp_message_type",[6])
 199
 200
 201
 202
 203
 204
 205
 206     """ GetClientIdentifier """
 207
 208     def GetClientIdentifier(self) :
 209         if self.IsOption("client_identifier") :
 210             return self.GetOption("client_identifier")
 211         return []
 212
 213     def GetGiaddr(self) :
 214         return self.GetOption("giaddr")
 215
 216     def GetHardwareAddress(self) :
 217         length = self.GetOption("hlen")[0]
 218         full_hw = self.GetOption("chaddr")
 219         if length!=[] and length<len(full_hw) : return full_hw[0:length]
 220         return full_hw
 221