diff options
Diffstat (limited to 'dns/resolver.py')
| -rw-r--r-- | dns/resolver.py | 103 |
1 files changed, 61 insertions, 42 deletions
diff --git a/dns/resolver.py b/dns/resolver.py index 387bd50..443e1d0 100644 --- a/dns/resolver.py +++ b/dns/resolver.py @@ -48,6 +48,21 @@ if sys.platform == 'win32': class NXDOMAIN(dns.exception.DNSException): """The DNS query name does not exist.""" + supp_kwargs = set(['qname']) + + def __str__(self): + if not 'qname' in self.kwargs: + return super(NXDOMAIN, self).__str__() + + qname = self.kwargs['qname'] + msg = self.__doc__[:-1] + if isinstance(qname, (list, set)): + if len(qname) > 1: + msg = 'None of DNS query names exist' + qname = list(map(str, qname)) + else: + qname = qname[0] + return "%s: %s" % (msg, (str(qname))) class YXDOMAIN(dns.exception.DNSException): """The DNS query name is too long after DNAME substitution.""" @@ -58,40 +73,36 @@ class YXDOMAIN(dns.exception.DNSException): Timeout = dns.exception.Timeout + class NoAnswer(dns.exception.DNSException): """The DNS response does not contain an answer to the question.""" - def __init__(self, question=None): - super(dns.exception.DNSException, self).__init__() - self.question = question - - def __str__(self): - message = self.__doc__ - if self.question: - message = message[0:-1] - for q in self.question: - message += ' %s' % q - return message + fmt = '%s: {query}' % __doc__[:-1] + supp_kwargs = set(['response']) + def _fmt_kwargs(self, **kwargs): + return super(NoAnswer, self)._fmt_kwargs( + query=kwargs['response'].question) class NoNameservers(dns.exception.DNSException): - """No non-broken nameservers are available to answer the query.""" - def __init__(self, errors=[]): - """Optionally construct message with list of servers and errors. + """All nameservers failed to answer the query. - @param errors: list of servers and respective errors - @type errors: [(server ip address, any object convertible to string)] - """ - super(dns.exception.DNSException, self).__init__() - self.errors = errors + @param errors: list of servers and respective errors + @type errors: [(server ip address, any object convertible to string)] + Non-empty errors list will add explanatory message () + """ + + msg = "All nameservers failed to answer the query." + fmt = "%s {query}: {errors}" % msg[:-1] + supp_kwargs = set(['request', 'errors']) + + def _fmt_kwargs(self, **kwargs): + srv_msgs = [] + for err in kwargs['errors']: + srv_msgs.append('Server %s %s port %s anwered %s' % (err[0], + 'TCP' if err[1] else 'UDP', err[2], err[3])) + return super(NoNameservers, self)._fmt_kwargs( + query=kwargs['request'].question, errors='; '.join(srv_msgs)) - def __str__(self): - message = self.__doc__ - if self.errors: - srv_msgs = [] - for err in self.errors: - srv_msgs.append('Server %s %s' % (err[0], err[1])) - message += ' %s' % '; '.join(srv_msgs) - return message class NotAbsolute(dns.exception.DNSException): """An absolute domain name is required but a relative name was provided.""" @@ -164,9 +175,9 @@ class Answer(object): if raise_on_no_answer: raise NoAnswer(question=response.question) if raise_on_no_answer: - raise NoAnswer(question=response.question) + raise NoAnswer(response=response) if rrset is None and raise_on_no_answer: - raise NoAnswer(question=response.question) + raise NoAnswer(response=response) self.canonical_name = qname self.rrset = rrset if rrset is None: @@ -742,18 +753,18 @@ class Resolver(object): def _compute_timeout(self, start): now = time.time() - if now < start: - if start - now > 1: + duration = now - start + if duration < 0: + if duration < -1: # Time going backwards is bad. Just give up. - raise Timeout + raise Timeout(timeout=duration) else: # Time went backwards, but only a little. This can # happen, e.g. under vmware with older linux kernels. # Pretend it didn't happen. now = start - duration = now - start if duration >= self.lifetime: - raise Timeout + raise Timeout(timeout=duration) return min(self.lifetime - duration, self.timeout) def query(self, qname, rdtype=dns.rdatatype.A, rdclass=dns.rdataclass.IN, @@ -839,10 +850,11 @@ class Resolver(object): backoff = 0.10 while response is None: if len(nameservers) == 0: - raise NoNameservers(errors) + raise NoNameservers(request=request, errors=errors) for nameserver in nameservers[:]: timeout = self._compute_timeout(start) try: + tcp_attempt = tcp if tcp: response = dns.query.tcp(request, nameserver, timeout, self.port, @@ -855,6 +867,7 @@ class Resolver(object): source_port=source_port) if response.flags & dns.flags.TC: # Response truncated; retry with TCP. + tcp_attempt = True timeout = self._compute_timeout(start) response = dns.query.tcp(request, nameserver, timeout, self.port, @@ -865,15 +878,17 @@ class Resolver(object): # Communication failure or timeout. Go to the # next server # + errors.append((nameserver, tcp_attempt, self.port, ex, + response)) response = None - errors.append((nameserver, ex)) continue except dns.query.UnexpectedSource as ex: # # Who knows? Keep going. # + errors.append((nameserver, tcp_attempt, self.port, ex, + response)) response = None - errors.append((nameserver, ex)) continue except dns.exception.FormError as ex: # @@ -882,8 +897,9 @@ class Resolver(object): # continue. # nameservers.remove(nameserver) + errors.append((nameserver, tcp_attempt, self.port, ex, + response)) response = None - errors.append((nameserver, ex)) continue except EOFError as ex: # @@ -893,13 +909,15 @@ class Resolver(object): # mix and continue. # nameservers.remove(nameserver) + errors.append((nameserver, tcp_attempt, self.port, ex, + response)) response = None - errors.append((nameserver, ex)) continue rcode = response.rcode() if rcode == dns.rcode.YXDOMAIN: ex = YXDOMAIN() - errors.append((nameserver, ex)) + errors.append((nameserver, tcp_attempt, self.port, ex, + response)) raise ex if rcode == dns.rcode.NOERROR or \ rcode == dns.rcode.NXDOMAIN: @@ -911,7 +929,8 @@ class Resolver(object): # if rcode != dns.rcode.SERVFAIL or not self.retry_servfail: nameservers.remove(nameserver) - errors.append((nameserver, dns.rcode.to_text(rcode))) + errors.append((nameserver, tcp_attempt, self.port, + dns.rcode.to_text(rcode), response)) response = None if not response is None: break @@ -932,7 +951,7 @@ class Resolver(object): all_nxdomain = False break if all_nxdomain: - raise NXDOMAIN + raise NXDOMAIN(qname=qnames_to_try) answer = Answer(qname, rdtype, rdclass, response, raise_on_no_answer) if self.cache: |