twisted.names.client.Resolver : API documentation

_waiting =

A dict mapping tuple keys of query name/type/class to Deferreds which will be called back with the result of those queries. This is used to avoid issuing the same query more than once in parallel. This is more efficient on the network and helps avoid a "birthday paradox" attack by keeping the number of outstanding requests for a particular query fixed at one instead of allowing the attacker to raise it to an arbitrary number.

_reactor =

A provider of IReactorTCP, IReactorUDP, and IReactorTime which will be used to set up network resources and track timeouts.

def __init__(self, resolv=None, servers=None, timeout=(1, 3, 11, 45), reactor=None): (source)

overrides twisted.names.common.ResolverBase.__init__

Construct a resolver which will query domain name servers listed in the resolv.conf(5)-format file given by resolv as well as those in the given servers list. Servers are queried in a round-robin fashion. If given, resolv is periodically checked for modification and re-parsed if it is noticed to have changed.

Parameters	servers	If not None, interpreted as a list of (host, port) pairs specifying addresses of domain name servers to attempt to use for this lookup. Host addresses should be in IPv4 dotted-quad form. If specified, overrides `resolv`. (type: `list` of `(str, int)` or `None`)
	resolv	Filename to read and parse as a resolver(5) configuration file. (type: `str`)
	timeout	Default number of seconds after which to reissue the query. When the last timeout expires, the query is considered failed. (type: Sequence of `int`)
	reactor	A provider of `IReactorTime`, `IReactorUDP`, and `IReactorTCP` which will be used to establish connections, listen for DNS datagrams, and enforce timeouts. If not provided, the global reactor will be used.
Raises	ValueError	Raised if no nameserver addresses can be found.

def __getstate__(self): (source)

Undocumented

def __setstate__(self, state): (source)

Undocumented

def _openFile(self, path): (source)

Wrapper used for opening files in the class, exists primarily for unit testing purposes.

def maybeParseConfig(self): (source)

Undocumented

def parseConfig(self, resolvConf): (source)

Undocumented

def pickServer(self): (source)

Return the address of a nameserver.

TODO: Weight servers for response time so faster ones can be preferred.

def _connectedProtocol(self): (source)

Return a new DNSDatagramProtocol bound to a randomly selected port number.

def connectionMade(self, protocol): (source)

Called by associated dns.DNSProtocol instances when they connect.

def connectionLost(self, protocol): (source)

Called by associated dns.DNSProtocol instances when they disconnect.

def messageReceived(self, message, protocol, address=None): (source)

Undocumented

def _query(self, *args): (source)

Get a new DNSDatagramProtocol instance from _connectedProtocol, issue a query to it using *args, and arrange for it to be disconnected from its transport after the query completes.

Parameters	*args	Positional arguments to be passed to `DNSDatagramProtocol.query`.
Returns	A `Deferred` which will be called back with the result of the query.

def queryUDP(self, queries, timeout=None): (source)

Make a number of DNS queries via UDP.

Parameters	queries	The queries to make. (type: A `list` of `dns.Query` instances)
	timeout	Number of seconds after which to reissue the query. When the last timeout expires, the query is considered failed. (type: Sequence of `int`)
Returns	(type: `Deferred` @raise `twisted.internet.defer.TimeoutError`: When the query times out.)

def _reissue(self, reason, addressesLeft, addressesUsed, query, timeout): (source)

Undocumented

def queryTCP(self, queries, timeout=10): (source)

Make a number of DNS queries via TCP.

Parameters	queries	The queries to make. (type: Any non-zero number of `dns.Query` instances)
	timeout	The number of seconds after which to fail. (type: `int`)
Returns	(type: `Deferred`)

def filterAnswers(self, message): (source)

Extract results from the given message.

If the message was truncated, re-attempt the query over TCP and return a Deferred which will fire with the results of that query.

If the message's result code is not dns.OK, return a Failure indicating the type of error which occurred.

Otherwise, return a three-tuple of lists containing the results from the answers section, the authority section, and the additional section.

def _lookup(self, name, cls, type, timeout): (source)

overrides twisted.names.common.ResolverBase._lookup

Build a dns.Query for the given parameters and dispatch it via UDP.

If this query is already outstanding, it will not be re-issued. Instead, when the outstanding query receives a response, that response will be re-used for this query as well.

Returns A Deferred which fires with a three-tuple giving the answer, authority, and additional sections of the response or with a Failure if the response code is anything other than dns.OK.

def lookupZone(self, name, timeout=10): (source)

overrides twisted.names.common.ResolverBase.lookupZone

Undocumented

def _timeoutZone(self, d, controller, connector, seconds): (source)

Undocumented

def _cbLookupZone(self, result, connector): (source)

Undocumented

Method	exceptionForCode	Convert a response code (one of the possible values of `dns.Message.rCode` to an exception instance representing it.
Method	query	Undocumented
Method	lookupAddress	Undocumented
Method	lookupIPV6Address	Undocumented
Method	lookupAddress6	Undocumented
Method	lookupMailExchange	Undocumented
Method	lookupNameservers	Undocumented
Method	lookupCanonicalName	Undocumented
Method	lookupMailBox	Undocumented
Method	lookupMailGroup	Undocumented
Method	lookupMailRename	Undocumented
Method	lookupPointer	Undocumented
Method	lookupAuthority	Undocumented
Method	lookupNull	Undocumented
Method	lookupWellKnownServices	Undocumented
Method	lookupService	Undocumented
Method	lookupHostInfo	Undocumented
Method	lookupMailboxInfo	Undocumented
Method	lookupText	Undocumented
Method	lookupSenderPolicy	Undocumented
Method	lookupResponsibility	Undocumented
Method	lookupAFSDatabase	Undocumented
Method	lookupNamingAuthorityPointer	Undocumented
Method	lookupAllRecords	Undocumented
Method	getHostByName	Undocumented
Class Variable	_errormap	A `dict` mapping DNS protocol failure response codes to exception classes which will be used to represent those failures.
Method	_cbRecords	Undocumented

Method	__init__	No summary
Method	__getstate__	Undocumented
Method	__setstate__	Undocumented
Method	maybeParseConfig	Undocumented
Method	parseConfig	Undocumented
Method	pickServer	Return the address of a nameserver.
Method	connectionMade	Called by associated `dns.DNSProtocol` instances when they connect.
Method	connectionLost	Called by associated `dns.DNSProtocol` instances when they disconnect.
Method	messageReceived	Undocumented
Method	queryUDP	Make a number of DNS queries via UDP.
Method	queryTCP	Make a number of DNS queries via TCP.
Method	filterAnswers	Extract results from the given message.
Method	lookupZone	Undocumented
Instance Variable	_waiting	A `dict` mapping tuple keys of query name/type/class to Deferreds which will be called back with the result of those queries. This is used to avoid issuing the same query more than once in parallel. This is more efficient on the network and helps avoid a "birthday paradox" attack by keeping the number of outstanding requests for a particular query fixed at one instead of allowing the attacker to raise it to an arbitrary number.
Instance Variable	_reactor	A provider of `IReactorTCP`, `IReactorUDP`, and `IReactorTime` which will be used to set up network resources and track timeouts.
Method	_openFile	Wrapper used for opening files in the class, exists primarily for unit testing purposes.
Method	_connectedProtocol	Return a new `DNSDatagramProtocol` bound to a randomly selected port number.
Method	_query	Get a new `DNSDatagramProtocol` instance from `_connectedProtocol`, issue a query to it using `*args`, and arrange for it to be disconnected from its transport after the query completes.
Method	_reissue	Undocumented
Method	_lookup	Build a `dns.Query` for the given parameters and dispatch it via UDP.
Method	_timeoutZone	Undocumented
Method	_cbLookupZone	Undocumented

t.n.c.Resolver(common.ResolverBase) : class documentation