new

server/DnsHandler.py

@@ -0,0 +1,80 @@
+import dns
+
+class DnsHandler(threading.Thread):
+    def __init__(self, msgQueue, tsigKey, nsAddress, ttl, nullIp):
+        threading.Thread.__init__(self)
+        self.msgQueue = msgQueue
+        self.nullIp = nullIp
+        self.nsAddress = nsAddress
+        self.ttl = ttl
+        self.keyring = dns.tsigkeyring.from_text(tsigKey)
+
+    def run(self):
+        while(True):
+            msg = self.msgQueue.get()
+            
+            if msg.successFlag:
+                # success
+                Logger.dbg("DnsManipulator: retrieved positive message")
+                if not self.statusMap.has_key(msg.ip) or not self.statusMap[msg.ip]:
+                    self.statusMap[msg.ip] = True
+                    self.insertARR(msg.ip)
+                    
+                    self.notifyQueue.put(NotificationMessage("Server returned", "Server %s is back" % msg.ip))
+            else:
+                # failure
+                Logger.dbg("DnsManipulator: retrieved negative message")
+                if not self.statusMap.has_key(msg.ip) or self.statusMap[msg.ip]:
+                    self.statusMap[msg.ip] = False
+                    self.deleteARR(msg.ip)
+
+                    self.notifyQueue.put(NotificationMessage("Server unavailable", "Server %s has gone" % msg.ip))
+
+            failureCnt = 0
+            for v in self.statusMap.values():
+                if not v:
+                    failureCnt += 1
+            
+            if failureCnt > 0 and not self.exitServerFlag:
+                self.insertARR(self.exitServerIp)
+                self.exitServerFlag = True
+                
+            if failureCnt == 0 and self.exitServerFlag:
+                self.deleteARR(self.exitServerIp)
+                self.exitServerFlag = False
+
+                self.notifyQueue.put(NotificationMessage("All clear", "All clear, exit-server removed from DNS"))
+                    
+    def insertARR(self, ip):
+        # send A-RR insertion for ip to DNS server
+        Logger.log("insert ARR %s" % ip)
+
+        rr = dns.rdtypes.IN.A.A(dns.rdataclass.IN, dns.rdatatype.A, ip)
+        u = dns.update.Update(self.zone, keyring=self.keyring)
+        u.add(self.name, self.ttl, rr)
+        r = dns.query.tcp(u, self.nsAddress)
+
+        if r.rcode() != 0:
+            # failure
+            Logger.log("failure when inserting A-RR for %s" % ip)
+        else:
+            # success
+            pass
+
+    def deleteARR(self, ip):
+        # send A-RR deletion for ip to DNS server
+        Logger.log("delete ARR %s" % ip)
+                
+        rr = dns.rdtypes.IN.A.A(dns.rdataclass.IN, dns.rdatatype.A, ip)
+        u = dns.update.Update(self.zone, keyring=self.keyring)
+        u.delete(self.name, rr)
+        r = dns.query.tcp(u, self.nsAddress)
+
+        if r.rcode() != 0:
+            # failure
+            Logger.log("failure when deleting A-RR for %s" % ip)
+        else:
+            # success
+            pass
+
+