diff options
Diffstat (limited to 'dns/resolver.py')
| -rw-r--r-- | dns/resolver.py | 51 |
1 files changed, 46 insertions, 5 deletions
diff --git a/dns/resolver.py b/dns/resolver.py index 10b6ca5..6a9974d 100644 --- a/dns/resolver.py +++ b/dns/resolver.py @@ -170,6 +170,9 @@ class NoAnswer(dns.exception.DNSException): def _fmt_kwargs(self, **kwargs): return super()._fmt_kwargs(query=kwargs['response'].question) + def response(self): + return self.kwargs['response'] + class NoNameservers(dns.exception.DNSException): """All nameservers failed to answer the query. @@ -1368,7 +1371,8 @@ def canonical_name(name): return get_default_resolver().canonical_name(name) -def zone_for_name(name, rdclass=dns.rdataclass.IN, tcp=False, resolver=None): +def zone_for_name(name, rdclass=dns.rdataclass.IN, tcp=False, resolver=None, + lifetime=None): """Find the name of the zone which contains the specified name. *name*, an absolute ``dns.name.Name`` or ``str``, the query name. @@ -1378,12 +1382,19 @@ def zone_for_name(name, rdclass=dns.rdataclass.IN, tcp=False, resolver=None): *tcp*, a ``bool``. If ``True``, use TCP to make the query. *resolver*, a ``dns.resolver.Resolver`` or ``None``, the resolver to use. - If ``None``, the default resolver is used. + If ``None``, the default, then the default resolver is used. + + *lifetime*, a ``float``, the total time to allow for the queries needed + to determine the zone. If ``None``, the default, then only the individual + query limits of the resolver apply. Raises ``dns.resolver.NoRootSOA`` if there is no SOA RR at the DNS root. (This is only likely to happen if you're using non-default root servers in your network and they are misconfigured.) + Raises ``dns.resolver.LifetimeTimeout`` if the answer could not be + found in the alotted lifetime. + Returns a ``dns.name.Name``. """ @@ -1393,14 +1404,44 @@ def zone_for_name(name, rdclass=dns.rdataclass.IN, tcp=False, resolver=None): resolver = get_default_resolver() if not name.is_absolute(): raise NotAbsolute(name) + start = time.time() + if lifetime is not None: + expiration = start + lifetime + else: + expiration = None while 1: try: - answer = resolver.resolve(name, dns.rdatatype.SOA, rdclass, tcp) + if expiration: + rlifetime = expiration - time.time() + if rlifetime <= 0: + rlifetime = 0 + else: + rlifetime = None + answer = resolver.resolve(name, dns.rdatatype.SOA, rdclass, tcp, + lifetime=rlifetime) if answer.rrset.name == name: return name # otherwise we were CNAMEd or DNAMEd and need to look higher - except (dns.resolver.NXDOMAIN, dns.resolver.NoAnswer): - pass + except (dns.resolver.NXDOMAIN, dns.resolver.NoAnswer) as e: + if isinstance(e, dns.resolver.NXDOMAIN): + response = e.responses().get(name) + else: + response = e.response() + if response: + for rrs in response.authority: + if rrs.rdtype == dns.rdatatype.SOA and \ + rrs.rdclass == rdclass: + (nr, _, _) = rrs.name.fullcompare(name) + if nr == dns.name.NAMERELN_SUPERDOMAIN: + # We're doing a proper superdomain check as + # if the name were equal we ought to have gotten + # it in the answer section! We are ignoring the + # possibility that the authority is insane and + # is including multiple SOA RRs for different + # authorities. + return rrs.name + # we couldn't extract anything useful from the response (e.g. it's + # a type 3 NXDOMAIN) try: name = name.parent() except dns.name.NoParent: |