dhcpserver.py

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