invirt-dns

   1 #!/usr/bin/python
   2 from twisted.internet import reactor
   3 from twisted.names import server
   4 from twisted.names import dns
   5 from twisted.names import common
   6 from twisted.names import authority
   7 from twisted.internet import defer
   8 from twisted.python import failure
   9
  10 from invirt.config import structs as config
  11 import invirt.database
  12 import psycopg2
  13 import sqlalchemy
  14 import time
  15
  16 class DatabaseAuthority(common.ResolverBase):
  17     """An Authority that is loaded from a file."""
  18
  19     soa = None
  20
  21     def __init__(self, domains=None, database=None):
  22         common.ResolverBase.__init__(self)
  23         if database is not None:
  24             invirt.database.connect(database)
  25         else:
  26             invirt.database.connect()
  27         if domains is not None:
  28             self.domains = domains
  29         else:
  30             self.domains = config.dns.domains
  31         ns = config.dns.nameservers[0]
  32         self.soa = dns.Record_SOA(mname=ns.hostname,
  33                                   rname=config.dns.contact.replace('@','.',1),
  34                                   serial=1, refresh=3600, retry=900,
  35                                   expire=3600000, minimum=21600, ttl=3600)
  36         self.ns = dns.Record_NS(name=ns.hostname, ttl=3600)
  37         record = dns.Record_A(address=ns.ip, ttl=3600)
  38         self.ns1 = dns.RRHeader(ns.hostname, dns.A, dns.IN,
  39                                 3600, record, auth=True)
  40
  41
  42     def _lookup(self, name, cls, type, timeout = None):
  43         for i in range(3):
  44             try:
  45                 value = self._lookup_unsafe(name, cls, type, timeout = None)
  46             except (psycopg2.OperationalError, sqlalchemy.exceptions.SQLError):
  47                 if i == 2:
  48                     raise
  49                 print "Reloading database"
  50                 time.sleep(0.5)
  51                 continue
  52             else:
  53                 return value
  54
  55     def _lookup_unsafe(self, name, cls, type, timeout):
  56         invirt.database.clear_cache()
  57
  58         ttl = 900
  59         name = name.lower()
  60
  61         if name in self.domains:
  62             domain = name
  63         else:
  64             # Look for the longest-matching domain.  (This works because domain
  65             # will remain bound after breaking out of the loop.)
  66             best_domain = ''
  67             for domain in self.domains:
  68                 if name.endswith('.'+domain) and len(domain) > len(best_domain):
  69                     best_domain = domain
  70             if best_domain == '':
  71                 return defer.fail(failure.Failure(dns.DomainError(name)))
  72             domain = best_domain
  73         results = []
  74         authority = []
  75         additional = [self.ns1]
  76         authority.append(dns.RRHeader(domain, dns.NS, dns.IN,
  77                                       3600, self.ns, auth=True))
  78
  79         if cls == dns.IN:
  80             host = name[:-len(domain)-1]
  81             if not host: # Request for the domain itself.
  82                 if type in (dns.A, dns.ALL_RECORDS):
  83                     record = dns.Record_A(config.dns.nameservers[0].ip, ttl)
  84                     results.append(dns.RRHeader(name, dns.A, dns.IN,
  85                                                 ttl, record, auth=True))
  86                 elif type == dns.NS:
  87                     results.append(dns.RRHeader(domain, dns.NS, dns.IN,
  88                                                 ttl, self.ns, auth=True))
  89                     authority = []
  90                 elif type == dns.SOA:
  91                     results.append(dns.RRHeader(domain, dns.SOA, dns.IN,
  92                                                 ttl, self.soa, auth=True))
  93             else: # Request for a subdomain.
  94                 if 'passup' in dir(config.dns) and host in config.dns.passup:
  95                     record = dns.Record_CNAME('%s.%s' % (host, config.dns.parent), ttl)
  96                     return defer.succeed((
  97                         [dns.RRHeader(name, dns.CNAME, dns.IN, ttl, record, auth=True)],
  98                         [], []))
  99
 100                 value = invirt.database.Machine.query().filter_by(name=host).first()
 101                 if value is None or not value.nics:
 102                     return defer.fail(failure.Failure(dns.AuthoritativeDomainError(name)))
 103                 ip = value.nics[0].ip
 104                 if ip is None:  #Deactivated?
 105                     return defer.fail(failure.Failure(dns.AuthoritativeDomainError(name)))
 106
 107                 if type in (dns.A, dns.ALL_RECORDS):
 108                     record = dns.Record_A(ip, ttl)
 109                     results.append(dns.RRHeader(name, dns.A, dns.IN,
 110                                                 ttl, record, auth=True))
 111                 elif type == dns.SOA:
 112                     results.append(dns.RRHeader(domain, dns.SOA, dns.IN,
 113                                                 ttl, self.soa, auth=True))
 114             if len(results) == 0:
 115                 authority = []
 116                 additional = []
 117             return defer.succeed((results, authority, additional))
 118         else:
 119             #Doesn't exist
 120             return defer.fail(failure.Failure(dns.AuthoritativeDomainError(name)))
 121
 122 if '__main__' == __name__:
 123     resolvers = []
 124     for zone in config.dns.zone_files:
 125         for origin in config.dns.domains:
 126             r = authority.BindAuthority(zone)
 127             # This sucks, but if I want a generic zone file, I have to
 128             # reload the information by hand
 129             r.origin = origin
 130             lines = open(zone).readlines()
 131             lines = r.collapseContinuations(r.stripComments(lines))
 132             r.parseLines(lines)
 133
 134             resolvers.append(r)
 135     resolvers.append(DatabaseAuthority())
 136
 137     verbosity = 0
 138     f = server.DNSServerFactory(authorities=resolvers, verbose=verbosity)
 139     p = dns.DNSDatagramProtocol(f)
 140     f.noisy = p.noisy = verbosity
 141
 142     reactor.listenUDP(53, p)
 143     reactor.listenTCP(53, f)
 144     reactor.run()