From: Quentin Smith <quentin@mit.edu>
Date: Fri, 19 Oct 2007 01:49:09 +0000 (-0400)
Subject: Use correct dhcp options, and use SO_BINDTODEVICE to send out the right device
X-Git-Tag: sipb-xen-dhcp/1~8
X-Git-Url: http://xvm.mit.edu/gitweb/invirt/packages/invirt-dhcp.git/commitdiff_plain/f850bd4f861c148b655ea57e66920e4107d5cdca

Use correct dhcp options, and use SO_BINDTODEVICE to send out the right device

svn path=/trunk/dhcp/; revision=202
---

diff --git a/dhcpserver.py b/dhcpserver.py
index 23f45aa..6171843 100644
--- a/dhcpserver.py
+++ b/dhcpserver.py
@@ -7,35 +7,63 @@ from pydhcplib.dhcp_packet import *
 from pydhcplib.type_hw_addr import hwmac
 from pydhcplib.type_ipv4 import ipv4
 from pydhcplib.type_strlist import strlist
+import socket
+import IN
 
 import event_logger
 if '__main__' == __name__:
     event_logger.init("stdout", 'DEBUG', {})
 from event_logger import Log
 
+import psycopg2
+import time
 import sipb_xen_database
+from sqlalchemy import create_engine
 
 dhcp_options = {'subnet_mask': '255.255.0.0',
                 'router': '18.181.0.1',
                 'domain_name_server': '18.70.0.160,18.71.0.151,18.72.0.3',
-                'domain_name': 'mit.edu'}
-    
+                'domain_name': 'mit.edu',
+                'ip_address_lease_time': 60*60*24}
 
 class DhcpBackend:
     def __init__(self, database=None):
         if database is not None:
-            sipb_xen_database.connect(database)
-    def findIP(self, mac):
-        value = sipb_xen_database.NIC.get_by(mac_addr=mac)
-        if value is None:
-            return None
-        ip = value.ip
-        if ip is None:  #Deactivated?
-            return None
-        return ip
-    def getParameters(self):
+            self.database = database
+            sipb_xen_database.connect(create_engine(database))
+    def findNIC(self, mac):
+        for i in range(3):
+            try:
+                value = sipb_xen_database.NIC.get_by(mac_addr=mac)
+            except psycopg2.OperationalError:
+                time.sleep(0.5)
+                if i == 2:  #Try twice to reconnect.
+                    raise
+                #Sigh.  SQLAlchemy should do this itself.
+                sipb_xen_database.connect(create_engine(self.database))
+            else:
+                break
+        return value
+    def find_interface(self, packet):
+        chaddr = hwmac(packet.GetHardwareAddress())
+        nic = self.findNIC(str(chaddr))
+        if nic is None or nic.ip is None:
+            return ("18.181.0.60", None)
+        ipstr = ''.join(reversed(['%02X' % i for i in ipv4(nic.ip).list()]))
+        for line in open('/proc/net/route'):
+            parts = line.split()
+            if parts[1] == ipstr:
+                Log.Output(Log.debug, "find_interface found "+str(nic.ip)+" on "+parts[0])
+                return ("18.181.0.60", parts[0])
+        return ("18.181.0.60", None)
+                            
+    def getParameters(self, **extra):
+        all_options=dict(dhcp_options)
+        all_options.update(extra)
         options = {}
-        for parameter, value in dhcp_options.iteritems():
+        for parameter, value in all_options.iteritems():
+            if value is None:
+                continue
             option_type = DhcpOptionsTypes[DhcpOptions[parameter]]
 
             if option_type == "ipv4" :
@@ -46,7 +74,7 @@ class DhcpBackend:
                 iplist = value.split(",")
                 opt = []
                 for single in iplist :
-                    opt.append(ipv4(single).list())
+                    opt.extend(ipv4(single).list())
                 options[parameter] = opt
             elif option_type == "32-bits" :
                 # This is probably a number...
@@ -75,11 +103,19 @@ class DhcpBackend:
     def Discover(self, packet):
         Log.Output(Log.debug,"dhcp_backend : Discover ")
         chaddr = hwmac(packet.GetHardwareAddress())
-        ip = self.findIP(str(chaddr))
+        nic = self.findNIC(str(chaddr))
+        if nic is None:
+            return False
+        ip = nic.ip
+        if ip is None:  #Deactivated?
+            return False
+        hostname = nic.hostname
+        if hostname is not None:
+            hostname += ".servers.csail.mit.edu"
         if ip is not None:
             ip = ipv4(ip)
             Log.Output(Log.debug,"dhcp_backend : Discover result = "+str(ip))
-            packet_parameters = self.getParameters()
+            packet_parameters = self.getParameters(host_name=hostname)
 
             # FIXME: Other offer parameters go here
             packet_parameters["yiaddr"] = ip.list()
@@ -95,6 +131,8 @@ class DhcpBackend:
         
         chaddr = hwmac(packet.GetHardwareAddress())
         request = packet.GetOption("request_ip_address")
+        if not request:
+            request = packet.GetOption("ciaddr")
         yiaddr = packet.GetOption("yiaddr")
 
         if not discover:
@@ -120,6 +158,19 @@ class DhcpServer(pydhcplib.dhcp_network.DhcpServer):
         self.backend = backend
         Log.Output(Log.debug, "__init__ DhcpServer")
 
+    def SendDhcpPacketTo(self, To, packet):
+        (ip, intf) = self.backend.find_interface(packet)
+        if intf:
+            out_socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+            out_socket.setsockopt(socket.SOL_SOCKET, socket.SO_BROADCAST,1)
+            out_socket.setsockopt(socket.SOL_SOCKET, IN.SO_BINDTODEVICE, intf)
+            #out_socket.bind((ip, self.listen_port))
+            ret = out_socket.sendto(packet.EncodePacket(), (To,self.emit_port))
+            out_socket.close()
+            return ret
+        else:
+            return self.dhcp_socket.sendto(packet.EncodePacket(),(To,self.emit_port))
+
     def SendPacket(self, packet):
         """Encode and send the packet."""
         
@@ -161,6 +212,8 @@ class DhcpServer(pydhcplib.dhcp_network.DhcpServer):
         ip = packet.GetOption("request_ip_address")
         sid = packet.GetOption("server_identifier")
         ciaddr = packet.GetOption("ciaddr")
+        #packet.PrintHeaders()
+        #packet.PrintOptions()
 
         if sid != [0,0,0,0] and ciaddr == [0,0,0,0] :
             Log.Output(Log.info, "Get DHCPREQUEST_SELECTING_STATE packet")