rebuild for precise
[invirt/packages/invirt-dns.git] / 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.common import InvirtConfigError
11 from invirt.config import structs as config
12 import invirt.database
13 import psycopg2
14 import sqlalchemy
15 import time
16 import re
17
18 class DatabaseAuthority(common.ResolverBase):
19     """An Authority that is loaded from a file."""
20
21     soa = None
22
23     def __init__(self, domains=None, database=None):
24         common.ResolverBase.__init__(self)
25         if database is not None:
26             invirt.database.connect(database)
27         else:
28             invirt.database.connect()
29         if domains is not None:
30             self.domains = domains
31         else:
32             self.domains = config.dns.domains
33         ns = config.dns.nameservers[0]
34         self.soa = dns.Record_SOA(mname=ns.hostname,
35                                   rname=config.dns.contact.replace('@','.',1),
36                                   serial=1, refresh=3600, retry=900,
37                                   expire=3600000, minimum=21600, ttl=3600)
38         self.ns = dns.Record_NS(name=ns.hostname, ttl=3600)
39         record = dns.Record_A(address=ns.ip, ttl=3600)
40         self.ns1 = dns.RRHeader(ns.hostname, dns.A, dns.IN,
41                                 3600, record, auth=True)
42
43     
44     def _lookup(self, name, cls, type, timeout = None):
45         for i in range(3):
46             try:
47                 value = self._lookup_unsafe(name, cls, type, timeout = None)
48             except (psycopg2.OperationalError, sqlalchemy.exceptions.SQLError):
49                 if i == 2:
50                     raise
51                 print "Reloading database"
52                 time.sleep(0.5)
53                 continue
54             else:
55                 return value
56
57     def _lookup_unsafe(self, name, cls, type, timeout):
58         invirt.database.clear_cache()
59         
60         ttl = 900
61         name = name.lower()
62
63         if name in self.domains:
64             domain = name
65         else:
66             # Look for the longest-matching domain.
67             best_domain = ''
68             for domain in self.domains:
69                 if name.endswith('.'+domain) and len(domain) > len(best_domain):
70                     best_domain = domain
71             if best_domain == '':
72                 if name.endswith('.in-addr.arpa'):
73                     # Act authoritative for the IP address for reverse resolution requests
74                     best_domain = name
75                 else:
76                     return defer.fail(failure.Failure(dns.DomainError(name)))
77             domain = best_domain
78         results = []
79         authority = []
80         additional = [self.ns1]
81         authority.append(dns.RRHeader(domain, dns.NS, dns.IN,
82                                       3600, self.ns, auth=True))
83
84         # The order of logic:
85         # - What class?
86         # - What domain: in-addr.arpa, domain root, or subdomain?
87         # - What query type: A, PTR, NS, ...?
88
89         if cls != dns.IN:
90             # Hahaha.  No.
91             return defer.fail(failure.Failure(dns.AuthoritativeDomainError(name)))
92
93         if name.endswith(".in-addr.arpa"):
94             if type in (dns.PTR, dns.ALL_RECORDS):
95                 ip = '.'.join(reversed(name.split('.')[:-2]))
96                 value = invirt.database.NIC.query.filter_by(ip=ip).first()
97                 if value and value.hostname:
98                     hostname = value.hostname
99                     if '.' not in hostname:
100                         hostname = hostname + "." + config.dns.domains[0]
101                     record = dns.Record_PTR(hostname, ttl)
102                     results.append(dns.RRHeader(name, dns.PTR, dns.IN,
103                                                 ttl, record, auth=True))
104                 else: # IP address doesn't point to an active host
105                     return defer.fail(failure.Failure(dns.AuthoritativeDomainError(name)))
106             elif type == dns.SOA:
107                 results.append(dns.RRHeader(domain, dns.SOA, dns.IN,
108                                             ttl, self.soa, auth=True))
109             # FIXME: Should only return success with no records if the name actually exists
110
111         elif name == domain or name == '.'+domain:
112             if type in (dns.A, dns.ALL_RECORDS):
113                 record = dns.Record_A(config.dns.nameservers[0].ip, ttl)
114                 results.append(dns.RRHeader(name, dns.A, dns.IN,
115                                             ttl, record, auth=True))
116             elif type == dns.NS:
117                 results.append(dns.RRHeader(domain, dns.NS, dns.IN,
118                                             ttl, self.ns, auth=True))
119                 authority = []
120             elif type == dns.SOA:
121                 results.append(dns.RRHeader(domain, dns.SOA, dns.IN,
122                                             ttl, self.soa, auth=True))
123
124         else:
125             host = name[:-len(domain)-1]
126             value = invirt.database.NIC.query.filter_by(hostname=host).first()
127             if value:
128                 ip = value.ip
129             else:
130                 value = invirt.database.Machine.query().filter_by(name=host).first()
131                 if value:
132                     ip = value.nics[0].ip
133                 else:
134                     return defer.fail(failure.Failure(dns.AuthoritativeDomainError(name)))
135             if ip is None:
136                 return defer.fail(failure.Failure(dns.AuthoritativeDomainError(name)))
137             if type in (dns.A, dns.ALL_RECORDS):
138                 record = dns.Record_A(ip, ttl)
139                 results.append(dns.RRHeader(name, dns.A, dns.IN,
140                                             ttl, record, auth=True))
141             elif type == dns.SOA:
142                 results.append(dns.RRHeader(domain, dns.SOA, dns.IN,
143                                             ttl, self.soa, auth=True))
144
145         if len(results) == 0:
146             authority = []
147             additional = []
148         return defer.succeed((results, authority, additional))
149
150 class DelegatingQuotingBindAuthority(authority.BindAuthority):
151     """
152     A delegating BindAuthority that (almost) deals with quoting correctly
153     
154     This will catch double quotes as marking the start or end of a
155     quoted phrase, unless the double quote is escaped by a backslash
156     """
157     # Match either a quoted or unquoted string literal followed by
158     # whitespace or the end of line.  This yields two groups, one of
159     # which has a match, and the other of which is None, depending on
160     # whether the string literal was quoted or unquoted; this is what
161     # necessitates the subsequent filtering out of groups that are
162     # None.
163     string_pat = \
164             re.compile(r'"((?:[^"\\]|\\.)*)"|((?:[^\\\s]|\\.)+)(?:\s+|\s*$)')
165
166     # For interpreting escapes.
167     escape_pat = re.compile(r'\\(.)')
168
169     def collapseContinuations(self, lines):
170         L = []
171         state = 0
172         for line in lines:
173             if state == 0:
174                 if line.find('(') == -1:
175                     L.append(line)
176                 else:
177                     L.append(line[:line.find('(')])
178                     state = 1
179             else:
180                 if line.find(')') != -1:
181                     L[-1] += ' ' + line[:line.find(')')]
182                     state = 0
183                 else:
184                     L[-1] += ' ' + line
185         lines = L
186         L = []
187
188         for line in lines:
189             in_quote = False
190             split_line = []
191             for m in self.string_pat.finditer(line):
192                 [x] = [x for x in m.groups() if x is not None]
193                 split_line.append(self.escape_pat.sub(r'\1', x))
194             L.append(split_line)
195         return filter(None, L)
196
197     def _lookup(self, name, cls, type, timeout = None):
198         maybeDelegate = False
199         deferredResult = authority.BindAuthority._lookup(self, name, cls,
200                                                          type, timeout)
201         # If we didn't find an exact match for the name we were seeking,
202         # check if it's within a subdomain we're supposed to delegate to
203         # some other DNS server.
204         while (isinstance(deferredResult.result, failure.Failure)
205                and '.' in name):
206             maybeDelegate = True
207             name = name[name.find('.') + 1 :]
208             deferredResult = authority.BindAuthority._lookup(self, name, cls,
209                                                              dns.NS, timeout)
210         # If we found somewhere to delegate the query to, our _lookup()
211         # for the NS record resulted in it being in the 'results' section.
212         # We need to instead return that information in the 'authority'
213         # section to delegate, and return an empty 'results' section
214         # (because we didn't find the name we were asked about).  We
215         # leave the 'additional' section as we received it because it
216         # may contain A records for the DNS server we're delegating to.
217         if maybeDelegate and not isinstance(deferredResult.result,
218                                             failure.Failure):
219             (nsResults, nsAuthority, nsAdditional) = deferredResult.result
220             deferredResult = defer.succeed(([], nsResults, nsAdditional))
221         return deferredResult
222
223 if '__main__' == __name__:
224     resolvers = []
225     try:
226         for zone in config.dns.zone_files:
227             for origin in config.dns.domains:
228                 r = DelegatingQuotingBindAuthority(zone)
229                 # This sucks, but if I want a generic zone file, I have to
230                 # reload the information by hand
231                 r.origin = origin
232                 lines = open(zone).readlines()
233                 lines = r.collapseContinuations(r.stripComments(lines))
234                 r.parseLines(lines)
235                 
236                 resolvers.append(r)
237     except InvirtConfigError:
238         # Don't care if zone_files isn't defined
239         pass
240     resolvers.append(DatabaseAuthority())
241
242     verbosity = 0
243     f = server.DNSServerFactory(authorities=resolvers, verbose=verbosity)
244     p = dns.DNSDatagramProtocol(f)
245     f.noisy = p.noisy = verbosity
246     
247     reactor.listenUDP(53, p)
248     reactor.listenTCP(53, f)
249     reactor.run()