dhcpserver.py

   1 #!/usr/bin/python
   2 import pydhcplib
   3 from pydhcplib.dhcp_packet import *
   4 from pydhcplib.type_hw_addr import hwmac
   5 from pydhcplib.type_ipv4 import ipv4
   6
   7 from event_logger import Log
   8
   9 import sipb_xen_database
  10
  11 class DhcpBackend:
  12     def __init__(self, database=None):
  13         if database is not None:
  14             sipb_xen_database.connect(database)
  15     def findIP(self, mac):
  16         value = sipb_xen_database.NIC.get_by(mac_addr=mac)
  17         if value is None:
  18             return None
  19         ip = value.ip
  20         if ip is None:  #Deactivated?
  21             return None
  22         return ip
  23
  24     def Discover(self, packet):
  25         Log.Output(Log.debug,"dhcp_backend : Discover ")
  26         chaddr = hwmac(packet.GetHardwareAddress())
  27         ip = self.findIP(str(chaddr))
  28         if ip is not None:
  29             ip = ipv4(ip)
  30             Log.Output(Log.debug,"dhcp_backend : Discover result = "+str(ip))
  31             packet_parameters = {}
  32
  33             # FIXME: Other offer parameters go here
  34             packet_parameters["yiaddr"] = ip.list()
  35
  36             packet.SetMultipleOptions(packet_parameters)
  37             return True
  38         return False
  39
  40     def Request(self, packet):
  41         Log.Output(Log.debug, "dhcp_backend : Request")
  42
  43         discover = self.Discover(packet)
  44
  45         chaddr = hwmac(packet.GetHardwareAddress())
  46         request = packet.GetOption("request_ip_address")
  47         yiaddr = packet.GetOption("yiaddr")
  48
  49         if not discover:
  50             Log.Output(Log.info,"Unknown MAC address: "+str(chaddr))
  51             return False
  52
  53         if yiaddr!="0.0.0.0" and yiaddr == request :
  54             Log.Output(Log.info,"Ack ip "+str(yiaddr)+" for "+str(chaddr))
  55             return True
  56         else:
  57             Log.Output(Log.info,"Requested ip "+str(request)+" not available for "+str(chaddr))
  58         return False
  59
  60     def Decline(self, packet):
  61         pass
  62     def Release(self, packet):
  63         pass
  64
  65
  66 class DhcpServer(pydhcplib.dhcp_network.DhcpServer):
  67     def __init__(self, backend, options = {'client_listenport':68,'server_listenport':67}):
  68         pydhcplib.dhcp_network.DhcpServer.__init__(self,"0.0.0.0",options["client_listen_port"],options["server_listen_port"],)
  69         self.backend = backend
  70         Log.Output(Log.debug, "__init__ DhcpServer")
  71
  72     def SendPacket(self, packet):
  73             """Encode and send the packet."""
  74
  75         giaddr = packet.GetOption('giaddr')
  76
  77         # in all case, if giaddr is set, send packet to relay_agent
  78         # network address defines by giaddr
  79         if giaddr!=[0,0,0,0] :
  80             agent_ip = ".".join(map(str,giaddr))
  81             self.SendDhcpPacketTo(agent_ip,packet)
  82             Log.Output(Log.debug, "SendPacket to agent : "+agent_ip)
  83
  84         # FIXME: This shouldn't broadcast if it has an IP address to send
  85         # it to instead. See RFC2131 part 4.1 for full details
  86         else :
  87             Log.Output(Log.debug, "No agent, broadcast packet.")
  88             self.SendDhcpPacketTo("255.255.255.255",packet)
  89
  90
  91     def HandleDhcpDiscover(self, packet):
  92         """Build and send DHCPOFFER packet in response to DHCPDISCOVER
  93         packet."""
  94
  95         logmsg = "Get DHCPDISCOVER packet from " + hwmac(packet.GetHardwareAddress()).str()
  96
  97         Log.Output(Log.info, logmsg)
  98         offer = DhcpPacket()
  99         offer.CreateDhcpOfferPacketFrom(packet)
 100
 101         if self.backend.Discover(offer) :
 102             self.SendPacket(offer)
 103         # FIXME : what if false ?
 104
 105
 106     def HandleDhcpRequest(self, packet):
 107         """Build and send DHCPACK or DHCPNACK packet in response to
 108         DHCPREQUEST packet. 4 types of DHCPREQUEST exists."""
 109
 110         ip = packet.GetOption("request_ip_address")
 111         sid = packet.GetOption("server_identifier")
 112         ciaddr = packet.GetOption("ciaddr")
 113
 114         if sid != [0,0,0,0] and ciaddr == [0,0,0,0] :
 115             Log.Output(Log.info, "Get DHCPREQUEST_SELECTING_STATE packet")
 116
 117         elif sid == [0,0,0,0] and ciaddr == [0,0,0,0] and ip :
 118             Log.Output(Log.info, "Get DHCPREQUEST_INITREBOOT_STATE packet")
 119
 120         elif sid == [0,0,0,0] and ciaddr != [0,0,0,0] and not ip :
 121             Log.Output(Log.info,"Get DHCPREQUEST_INITREBOOT_STATE packet")
 122
 123         else : Log.Output(Log.info,"Get DHCPREQUEST_UNKNOWN_STATE packet : not implemented")
 124
 125         if self.backend.Request(packet) : packet.TransformToDhcpAckPacket()
 126         else : packet.TransformToDhcpNackPacket()
 127
 128         self.SendPacket(packet)
 129
 130
 131
 132     # FIXME: These are not yet implemented.
 133     def HandleDhcpDecline(self, packet):
 134         Log.Output(Log.info, "Get DHCPDECLINE packet")
 135         self.backend.Decline(packet)
 136
 137     def HandleDhcpRelease(self, packet):
 138         Log.Output(Log.info,"Get DHCPRELEASE packet")
 139         self.backend.Release(packet)
 140
 141     def HandleDhcpInform(self, packet):
 142         Log.Output(Log.info, "Get DHCPINFORM packet")
 143
 144         if self.backend.Request(packet) :
 145             packet.TransformToDhcpAckPacket()
 146             # FIXME : Remove lease_time from options
 147             self.SendPacket(packet)
 148
 149         # FIXME : what if false ?
 150
 151 if '__main__' == __name__:
 152     event_logger.init("stdout", event_logger.INFO, {})
 153     options = { "server_listen_port":67,
 154                 "client_listen_port":68,
 155                 "listen_address":"0.0.0.0"}
 156     backend = DhcpBackend('postgres://sipb-xen@sipb-xen-dev/sipb_xen')
 157     server = DhcpServer(backend, options)
 158
 159     while True : server.GetNextDhcpPacket()