code/dhcpserver.py

   1 #!/usr/bin/python
   2 import sys
   3 import pydhcplib
   4 import pydhcplib.dhcp_network
   5 from pydhcplib.dhcp_packet import *
   6 from pydhcplib.type_hw_addr import hwmac
   7 from pydhcplib.type_ipv4 import ipv4
   8 from pydhcplib.type_strlist import strlist
   9 import socket
  10 import IN
  11
  12 import event_logger
  13 if '__main__' == __name__:
  14     event_logger.init("stdout", 'DEBUG', {})
  15 from event_logger import Log
  16
  17 import psycopg2
  18 import time
  19 import sipb_xen_database
  20 from sqlalchemy import create_engine
  21
  22 dhcp_options = {'subnet_mask': '255.255.0.0',
  23                 'router': '18.181.0.1',
  24                 'domain_name_server': '18.70.0.160,18.71.0.151,18.72.0.3',
  25                 'ip_address_lease_time': 60*60*24}
  26
  27 class DhcpBackend:
  28     def __init__(self, database=None):
  29         if database is not None:
  30             self.database = database
  31             sipb_xen_database.connect(create_engine(database))
  32     def findNIC(self, mac):
  33         sipb_xen_database.clear_cache()
  34         for i in range(3):
  35             try:
  36                 value = sipb_xen_database.NIC.get_by(mac_addr=mac)
  37             except psycopg2.OperationalError:
  38                 time.sleep(0.5)
  39                 if i == 2:  #Try twice to reconnect.
  40                     raise
  41                 #Sigh.  SQLAlchemy should do this itself.
  42                 sipb_xen_database.connect(create_engine(self.database))
  43             else:
  44                 break
  45         return value
  46     def find_interface(self, packet):
  47         chaddr = hwmac(packet.GetHardwareAddress())
  48         nic = self.findNIC(str(chaddr))
  49         if nic is None or nic.ip is None:
  50             return ("18.181.0.60", None)
  51         ipstr = ''.join(reversed(['%02X' % i for i in ipv4(nic.ip).list()]))
  52         for line in open('/proc/net/route'):
  53             parts = line.split()
  54             if parts[1] == ipstr:
  55                 Log.Output(Log.debug, "find_interface found "+str(nic.ip)+" on "+parts[0])
  56                 return ("18.181.0.60", parts[0])
  57         return ("18.181.0.60", None)
  58
  59     def getParameters(self, **extra):
  60         all_options=dict(dhcp_options)
  61         all_options.update(extra)
  62         options = {}
  63         for parameter, value in all_options.iteritems():
  64             if value is None:
  65                 continue
  66             option_type = DhcpOptionsTypes[DhcpOptions[parameter]]
  67
  68             if option_type == "ipv4" :
  69                 # this is a single ip address
  70                 options[parameter] = map(int,value.split("."))
  71             elif option_type == "ipv4+" :
  72                 # this is multiple ip address
  73                 iplist = value.split(",")
  74                 opt = []
  75                 for single in iplist :
  76                     opt.extend(ipv4(single).list())
  77                 options[parameter] = opt
  78             elif option_type == "32-bits" :
  79                 # This is probably a number...
  80                 digit = int(value)
  81                 options[parameter] = [digit>>24&0xFF,(digit>>16)&0xFF,(digit>>8)&0xFF,digit&0xFF]
  82             elif option_type == "16-bits" :
  83                 digit = int(value)
  84                 options[parameter] = [(digit>>8)&0xFF,digit&0xFF]
  85
  86             elif option_type == "char" :
  87                 digit = int(value)
  88                 options[parameter] = [digit&0xFF]
  89
  90             elif option_type == "bool" :
  91                 if value=="False" or value=="false" or value==0 :
  92                     options[parameter] = [0]
  93                 else : options[parameter] = [1]
  94
  95             elif option_type == "string" :
  96                 options[parameter] = strlist(value).list()
  97
  98             elif option_type == "RFC3397" :
  99                 parsed_value = ""
 100                 for item in value:
 101                     components = item.split('.')
 102                     item_fmt = "".join(chr(len(elt)) + elt for elt in components) + "\x00"
 103                     parsed_value += item_fmt
 104
 105                 options[parameter] = strlist(parsed_value).list()
 106
 107             else :
 108                 options[parameter] = strlist(value).list()
 109         return options
 110
 111     def Discover(self, packet):
 112         Log.Output(Log.debug,"dhcp_backend : Discover ")
 113         chaddr = hwmac(packet.GetHardwareAddress())
 114         nic = self.findNIC(str(chaddr))
 115         if nic is None or nic.machine is None:
 116             return False
 117         ip = nic.ip
 118         if ip is None:  #Deactivated?
 119             return False
 120
 121         options = {}
 122         if nic.hostname and '.' in nic.hostname:
 123             options['host_name'], options['domain_name'] = nic.hostname.split('.', 1)
 124         elif nic.machine.name:
 125             options['host_name'] = nic.machine.name
 126             options['domain_name'] = 'servers.csail.mit.edu'
 127         else:
 128             hostname = None
 129         if DhcpOptions['domain_search'] in packet.GetOption('parameter_request_list'):
 130             options['host_name'] += '.' + options['domain_name']
 131             del options['domain_name']
 132             options['domain_search'] = ['mit.edu']
 133         if ip is not None:
 134             ip = ipv4(ip)
 135             Log.Output(Log.debug,"dhcp_backend : Discover result = "+str(ip))
 136             packet_parameters = self.getParameters(**options)
 137
 138             # FIXME: Other offer parameters go here
 139             packet_parameters["yiaddr"] = ip.list()
 140
 141             packet.SetMultipleOptions(packet_parameters)
 142             return True
 143         return False
 144
 145     def Request(self, packet):
 146         Log.Output(Log.debug, "dhcp_backend : Request")
 147
 148         discover = self.Discover(packet)
 149
 150         chaddr = hwmac(packet.GetHardwareAddress())
 151         request = packet.GetOption("request_ip_address")
 152         if not request:
 153             request = packet.GetOption("ciaddr")
 154         yiaddr = packet.GetOption("yiaddr")
 155
 156         if not discover:
 157             Log.Output(Log.info,"Unknown MAC address: "+str(chaddr))
 158             return False
 159
 160         if yiaddr!="0.0.0.0" and yiaddr == request :
 161             Log.Output(Log.info,"Ack ip "+str(yiaddr)+" for "+str(chaddr))
 162             return True
 163         else:
 164             Log.Output(Log.info,"Requested ip "+str(request)+" not available for "+str(chaddr))
 165         return False
 166
 167     def Decline(self, packet):
 168         pass
 169     def Release(self, packet):
 170         pass
 171
 172
 173 class DhcpServer(pydhcplib.dhcp_network.DhcpServer):
 174     def __init__(self, backend, options = {'client_listenport':68,'server_listenport':67}):
 175         pydhcplib.dhcp_network.DhcpServer.__init__(self,"0.0.0.0",options["client_listen_port"],options["server_listen_port"],)
 176         self.backend = backend
 177         Log.Output(Log.debug, "__init__ DhcpServer")
 178
 179     def SendDhcpPacketTo(self, To, packet):
 180         (ip, intf) = self.backend.find_interface(packet)
 181         if intf:
 182             out_socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
 183             out_socket.setsockopt(socket.SOL_SOCKET, socket.SO_BROADCAST,1)
 184             out_socket.setsockopt(socket.SOL_SOCKET, IN.SO_BINDTODEVICE, intf)
 185             #out_socket.bind((ip, self.listen_port))
 186             ret = out_socket.sendto(packet.EncodePacket(), (To,self.emit_port))
 187             out_socket.close()
 188             return ret
 189         else:
 190             return self.dhcp_socket.sendto(packet.EncodePacket(),(To,self.emit_port))
 191
 192     def SendPacket(self, packet):
 193         """Encode and send the packet."""
 194
 195         giaddr = packet.GetOption('giaddr')
 196
 197         # in all case, if giaddr is set, send packet to relay_agent
 198         # network address defines by giaddr
 199         if giaddr!=[0,0,0,0] :
 200             agent_ip = ".".join(map(str,giaddr))
 201             self.SendDhcpPacketTo(agent_ip,packet)
 202             Log.Output(Log.debug, "SendPacket to agent : "+agent_ip)
 203
 204         # FIXME: This shouldn't broadcast if it has an IP address to send
 205         # it to instead. See RFC2131 part 4.1 for full details
 206         else :
 207             Log.Output(Log.debug, "No agent, broadcast packet.")
 208             self.SendDhcpPacketTo("255.255.255.255",packet)
 209
 210
 211     def HandleDhcpDiscover(self, packet):
 212         """Build and send DHCPOFFER packet in response to DHCPDISCOVER
 213         packet."""
 214
 215         logmsg = "Get DHCPDISCOVER packet from " + hwmac(packet.GetHardwareAddress()).str()
 216
 217         Log.Output(Log.info, logmsg)
 218         offer = DhcpPacket()
 219         offer.CreateDhcpOfferPacketFrom(packet)
 220
 221         if self.backend.Discover(offer):
 222             self.SendPacket(offer)
 223         # FIXME : what if false ?
 224
 225
 226     def HandleDhcpRequest(self, packet):
 227         """Build and send DHCPACK or DHCPNACK packet in response to
 228         DHCPREQUEST packet. 4 types of DHCPREQUEST exists."""
 229
 230         ip = packet.GetOption("request_ip_address")
 231         sid = packet.GetOption("server_identifier")
 232         ciaddr = packet.GetOption("ciaddr")
 233         #packet.PrintHeaders()
 234         #packet.PrintOptions()
 235
 236         if sid != [0,0,0,0] and ciaddr == [0,0,0,0] :
 237             Log.Output(Log.info, "Get DHCPREQUEST_SELECTING_STATE packet")
 238
 239         elif sid == [0,0,0,0] and ciaddr == [0,0,0,0] and ip :
 240             Log.Output(Log.info, "Get DHCPREQUEST_INITREBOOT_STATE packet")
 241
 242         elif sid == [0,0,0,0] and ciaddr != [0,0,0,0] and not ip :
 243             Log.Output(Log.info,"Get DHCPREQUEST_INITREBOOT_STATE packet")
 244
 245         else : Log.Output(Log.info,"Get DHCPREQUEST_UNKNOWN_STATE packet : not implemented")
 246
 247         if self.backend.Request(packet) : packet.TransformToDhcpAckPacket()
 248         else : packet.TransformToDhcpNackPacket()
 249
 250         self.SendPacket(packet)
 251
 252
 253
 254     # FIXME: These are not yet implemented.
 255     def HandleDhcpDecline(self, packet):
 256         Log.Output(Log.info, "Get DHCPDECLINE packet")
 257         self.backend.Decline(packet)
 258
 259     def HandleDhcpRelease(self, packet):
 260         Log.Output(Log.info,"Get DHCPRELEASE packet")
 261         self.backend.Release(packet)
 262
 263     def HandleDhcpInform(self, packet):
 264         Log.Output(Log.info, "Get DHCPINFORM packet")
 265
 266         if self.backend.Request(packet) :
 267             packet.TransformToDhcpAckPacket()
 268             # FIXME : Remove lease_time from options
 269             self.SendPacket(packet)
 270
 271         # FIXME : what if false ?
 272
 273 if '__main__' == __name__:
 274     options = { "server_listen_port":67,
 275                 "client_listen_port":68,
 276                 "listen_address":"0.0.0.0"}
 277     backend = DhcpBackend('postgres://sipb-xen@sipb-xen-dev/sipb_xen')
 278     server = DhcpServer(backend, options)
 279
 280     while True : server.GetNextDhcpPacket()