twisted.mail.relaymanager.MXCalculator

class documentation

class MXCalculator: (source)

A utility for looking up mail exchange hosts and tracking whether they are working or not.

Method	`__init__`
Method	`getMX`	Find the name of a host that acts as a mail exchange server for a domain.
Method	`markBad`	Record that a mail exchange host is not currently functioning.
Method	`markGood`	Record that a mail exchange host is functioning.
Instance Variable	`badMXs`	A mapping of non-functioning mail exchange hostname to time at which another attempt at contacting it may be made.
Instance Variable	`clock`	A reactor which will be used to schedule timeouts.
Instance Variable	`fallbackToDomain`	A flag indicating whether to attempt to use the hostname directly when no mail exchange can be found (`True`) or not (`False`).
Instance Variable	`resolver`	A resolver.
Instance Variable	`timeOutBadMX`	Period in seconds between attempts to contact a non-functioning mail exchange host.
Method	`_cbMX`	Try to find the mail exchange host for a domain from the given DNS records.
Method	`_ebMX`	Attempt to use the name of the domain directly when mail exchange lookup fails.
Method	`_filterRecords`	Organize the records of a DNS response by record name.

def __init__(self, resolver=None, clock=None): (source)

Parameters
resolver:`IResolver` provider or `None`	A resolver.
clock:`IReactorTime` provider or `None`	A reactor which will be used to schedule timeouts.

def getMX(self, domain, maximumCanonicalChainLength=3): (source)

Find the name of a host that acts as a mail exchange server for a domain.

Parameters
domain:`bytes`	A domain name.
maximumCanonicalChainLength:`int`	The maximum number of unique canonical name records to follow while looking up the mail exchange host.
Returns
`Deferred` which successfully fires with `Record_MX`	A deferred which succeeds with the MX record for the mail exchange server for the domain or fails if none can be found.

def markBad(self, mx): (source)

Record that a mail exchange host is not currently functioning.

Parameters
mx:`bytes`	The hostname of a mail exchange host.

def markGood(self, mx): (source)

Record that a mail exchange host is functioning.

Parameters
mx:`bytes`	The hostname of a mail exchange host.

badMXs: dict mapping bytes to float = (source)

A mapping of non-functioning mail exchange hostname to time at which another attempt at contacting it may be made.

clock: IReactorTime provider = (source)

A reactor which will be used to schedule timeouts.

fallbackToDomain: bool = (source)

A flag indicating whether to attempt to use the hostname directly when no mail exchange can be found (True) or not (False).

resolver: IResolver = (source)

A resolver.

timeOutBadMX: int = (source)

Period in seconds between attempts to contact a non-functioning mail exchange host.

def _cbMX(self, answers, domain, cnamesLeft): (source)

Try to find the mail exchange host for a domain from the given DNS records.

This will attempt to resolve canonical name record results. It can recognize loops and will give up on non-cyclic chains after a specified number of lookups.

Parameters
answers:`dict` mapping `bytes` to `list` of `IRecord` provider	A mapping of record name to record payload.
domain:`bytes`	A domain name.
cnamesLeft:`int`	The number of unique canonical name records left to follow while looking up the mail exchange host.
Returns
`Record_MX` or `Failure`	An MX record for the mail exchange host or a failure if one cannot be found.

def _ebMX(self, failure, domain): (source)

Attempt to use the name of the domain directly when mail exchange lookup fails.

Parameters
failure:`Failure`	The reason for the lookup failure.
domain:`bytes`	The domain name.
Returns
`Record_MX` or `Failure`	An MX record for the domain or a failure if the fallback to domain option is not in effect and an error, other than not finding an MX record, occurred during lookup.
Raises
`IOError`	When no MX record could be found and the fallback to domain option is not in effect.
`DNSLookupError`	When no MX record could be found and the fallback to domain option is in effect but no address for the domain could be found.

def _filterRecords(self, records): (source)

Organize the records of a DNS response by record name.

Parameters
records:3-`tuple` of (0) `list` of `RRHeader`, (1) `list` of `RRHeader`, (2) `list` of `RRHeader`	Answer resource records, authority resource records and additional resource records.
Returns
`dict` mapping `bytes` to `list` of `IRecord` provider	A mapping of record name to record payload.