diff options
| -rw-r--r-- | ChangeLog | 8 | ||||
| -rw-r--r-- | dns/resolver.py | 44 |
2 files changed, 43 insertions, 9 deletions
@@ -1,3 +1,11 @@ +2011-03-22 Bob Halley <halley@dnspython.org> + + * dns/resolver.py: a boolean parameter, 'raise_on_no_answer', has + been added to the query() methods. In no-error, no-data + situations, this parameter determines whether NoAnswer should be + raised or not. If True, NoAnswer is raised. If False, then an + Answer() object with a None rrset will be returned. + 2011-01-11 Bob Halley <halley@dnspython.org> * Dnspython was erroneously doing case-insensitive comparisons diff --git a/dns/resolver.py b/dns/resolver.py index 30977f3..ad2223d 100644 --- a/dns/resolver.py +++ b/dns/resolver.py @@ -94,7 +94,8 @@ class Answer(object): @ivar expiration: The time when the answer expires @type expiration: float (seconds since the epoch) """ - def __init__(self, qname, rdtype, rdclass, response): + def __init__(self, qname, rdtype, rdclass, response, + raise_on_no_answer=True): self.qname = qname self.rdtype = rdtype self.rdclass = rdclass @@ -122,11 +123,30 @@ class Answer(object): break continue except KeyError: - raise NoAnswer - raise NoAnswer - if rrset is None: + if raise_on_no_answer: + raise NoAnswer + if raise_on_no_answer: + raise NoAnswer + if rrset is None and raise_on_no_answer: raise NoAnswer self.rrset = rrset + if rrset is None: + while 1: + # Look for a SOA RR whose owner name is a superdomain + # of qname. + try: + srrset = response.find_rrset(response.authority, qname, + rdclass, dns.rdatatype.SOA) + if min_ttl == -1 or srrset.ttl < min_ttl: + min_ttl = srrset.ttl + if srrset[0].minimum < min_ttl: + min_ttl = srrset[0].minimum + break + except KeyError: + try: + qname = qname.parent() + except dns.name.NoParent: + break self.expiration = time.time() + min_ttl def __getattr__(self, attr): @@ -546,7 +566,7 @@ class Resolver(object): return min(self.lifetime - duration, self.timeout) def query(self, qname, rdtype=dns.rdatatype.A, rdclass=dns.rdataclass.IN, - tcp=False, source=None): + tcp=False, source=None, raise_on_no_answer=True): """Query nameservers to find the answer to the question. The I{qname}, I{rdtype}, and I{rdclass} parameters may be objects @@ -564,10 +584,14 @@ class Resolver(object): @type tcp: bool @param source: bind to this IP address (defaults to machine default IP). @type source: IP address in dotted quad notation + @param raise_on_no_answer: raise NoAnswer if there's no answer + (defaults is True). + @type raise_on_no_answer: bool @rtype: dns.resolver.Answer instance @raises Timeout: no answers could be found in the specified lifetime @raises NXDOMAIN: the query name does not exist - @raises NoAnswer: the response did not contain an answer + @raises NoAnswer: the response did not contain an answer and + raise_on_no_answer is True. @raises NoNameservers: no non-broken nameservers are available to answer the question.""" @@ -678,7 +702,8 @@ class Resolver(object): break if all_nxdomain: raise NXDOMAIN - answer = Answer(qname, rdtype, rdclass, response) + answer = Answer(qname, rdtype, rdclass, response, + raise_on_no_answer) if self.cache: self.cache.put((qname, rdtype, rdclass), answer) return answer @@ -731,14 +756,15 @@ def get_default_resolver(): return default_resolver def query(qname, rdtype=dns.rdatatype.A, rdclass=dns.rdataclass.IN, - tcp=False, source=None): + tcp=False, source=None, raise_on_no_answer=True): """Query nameservers to find the answer to the question. This is a convenience function that uses the default resolver object to make the query. @see: L{dns.resolver.Resolver.query} for more information on the parameters.""" - return get_default_resolver().query(qname, rdtype, rdclass, tcp, source) + return get_default_resolver().query(qname, rdtype, rdclass, tcp, source, + raise_on_no_answer) def zone_for_name(name, rdclass=dns.rdataclass.IN, tcp=False, resolver=None): """Find the name of the zone which contains the specified name. |