speedup iptables by prefetching the variables

Author: kollyma

systemvm/patches/debian/config/opt/cloud/bin/configure.py

@@ -775,66 +775,71 @@ def processForwardRule(self, rule):
             self.forward_vr(rule)
 
     def forward_vr(self, rule):
+        #prefetch iptables variables
+        public_fwinterface = self.getDeviceByIp(rule['public_ip'])
+        internal_fwinterface = self.getDeviceByIp(rule['internal_ip'])
+        public_fwports = self.portsToString(rule['public_ports'], ':')
+        internal_fwports = self.portsToString(rule['internal_ports'], '-')
         fw1 = "-A PREROUTING -d %s/32 -i %s -p %s -m %s --dport %s -j DNAT --to-destination %s:%s" % \
               (
                 rule['public_ip'],
-                self.getDeviceByIp(rule['public_ip']),
+                public_fwinterface,
                 rule['protocol'],
                 rule['protocol'],
-                self.portsToString(rule['public_ports'], ':'),
+                public_fwports,
                 rule['internal_ip'],
-                self.portsToString(rule['internal_ports'], '-')
+                internal_fwports
               )
         fw2 = "-A PREROUTING -d %s/32 -i %s -p %s -m %s --dport %s -j DNAT --to-destination %s:%s" % \
               (
                 rule['public_ip'],
-                self.getDeviceByIp(rule['internal_ip']),
+                internal_fwinterface,
                 rule['protocol'],
                 rule['protocol'],
-                self.portsToString(rule['public_ports'], ':'),
+                public_fwports,
                 rule['internal_ip'],
-                self.portsToString(rule['internal_ports'], '-')
+                internal_fwports
               )
         fw3 = "-A OUTPUT -d %s/32 -p %s -m %s --dport %s -j DNAT --to-destination %s:%s" % \
               (
                 rule['public_ip'],
                 rule['protocol'],
                 rule['protocol'],
-                self.portsToString(rule['public_ports'], ':'),
+                public_fwports,
                 rule['internal_ip'],
-                self.portsToString(rule['internal_ports'], '-')
+                internal_fwports
               )
         fw4 = "-j SNAT --to-source %s -A POSTROUTING -s %s -d %s/32 -o %s -p %s -m %s --dport %s" % \
               (
                 self.getGuestIp(),
                 self.getNetworkByIp(rule['internal_ip']),
                 rule['internal_ip'],
-                self.getDeviceByIp(rule['internal_ip']),
+                internal_fwinterface,
                 rule['protocol'],
                 rule['protocol'],
                 self.portsToString(rule['internal_ports'], ':')
               )
         fw5 = "-A PREROUTING -d %s/32 -i %s -p %s -m %s --dport %s -j MARK --set-xmark %s/0xffffffff" % \
               (
                 rule['public_ip'],
-                self.getDeviceByIp(rule['public_ip']),
+                public_fwinterface,
                 rule['protocol'],
                 rule['protocol'],
-                self.portsToString(rule['public_ports'], ':'),
-                hex(int(self.getDeviceByIp(rule['public_ip'])[3:]))
+                public_fwports,
+                hex(int(public_fwinterface[3:]))
               )
         fw6 = "-A PREROUTING -d %s/32 -i %s -p %s -m %s --dport %s -m state --state NEW -j CONNMARK --save-mark --nfmask 0xffffffff --ctmask 0xffffffff" % \
               (
                 rule['public_ip'],
-                self.getDeviceByIp(rule['public_ip']),
+                public_fwinterface,
                 rule['protocol'],
                 rule['protocol'],
-                self.portsToString(rule['public_ports'], ':'),
+                public_fwports,
               )
         fw7 = "-A FORWARD -i %s -o %s -p %s -m %s --dport %s -m state --state NEW,ESTABLISHED -j ACCEPT" % \
               (
-                self.getDeviceByIp(rule['public_ip']),
-                self.getDeviceByIp(rule['internal_ip']),
+                public_fwinterface,
+                internal_fwinterface,
                 rule['protocol'],
                 rule['protocol'],
                 self.portsToString(rule['internal_ports'], ':')