import dns
import dns.query
import dns.update
import dns.rdataclass
import dns.rdatatype
import dns.rdtypes.IN.A
import dns.tsigkeyring 
import threading
from logger import Logger


class DnsHandler(threading.Thread):
    def __init__(self, msgQueue, tsigKey, nsAddress, ttl, statusMap):
        threading.Thread.__init__(self)
        self.msgQueue = msgQueue
        self.nsAddress = nsAddress
        self.ttl = ttl
        self.keyring = dns.tsigkeyring.from_text(tsigKey)
        self.statusMap = statusMap
        self.setDaemon(True)


    def run(self):
        while(True):
            msg = self.msgQueue.get()

	    dynid = msg.dynid
	    name = msg.name
            zone = msg.zone
            address = msg.address
            
            fullName = name + '.' + zone

            if self.statusMap.has_key(fullName):
                if self.statusMap[fullName] != address:
                    self.deleteARR(dynid, name, zone, self.statusMap[fullName])
                    self.insertARR(dynid, name, zone, address)
                    self.statusMap[fullName] = address
            else:
                self.insertARR(dynid, name, zone, address)
                self.statusMap[fullName] = address
                
                    
    def insertARR(self, dynid, name, zone, address):
        # send A-RR insertion for ip to DNS server
        rr = dns.rdtypes.IN.A.A(dns.rdataclass.IN, dns.rdatatype.A, address)
        u = dns.update.Update(zone, keyring=self.keyring)
        u.add(name, self.ttl, rr)
        r = dns.query.tcp(u, self.nsAddress)

        if r.rcode() != 0:
            # failure
            Logger.log("failure for %s when inserting A-RR %s -> %s into %s" % 
		       (dynid, name, address, zone))
        else:
            # success
            Logger.log("insert for %s ARR %s -> %s into %s" % 
		       (dynid, name, address, zone))


    def deleteARR(self, dynid, name, zone, address):
        # send A-RR deletion for ip to DNS server
        rr = dns.rdtypes.IN.A.A(dns.rdataclass.IN, dns.rdatatype.A, address)
        u = dns.update.Update(zone, keyring=self.keyring)
        u.delete(name, rr)
        r = dns.query.tcp(u, self.nsAddress)

        if r.rcode() != 0:
            # failure
            Logger.log("failure for %s when deleting A-RR %s -> %s from %s" % 
		       (dynid, name, address, zone))
        else:
            # success
            Logger.log("delete for %s ARR %s -> %s from %s" % 
		       (dynid, name, address, zone))