Milter.dns.Session Class Reference

Inheritance diagram for Milter.dns.Session:

Public Member Functions
def	__init__
def	dns
	Cached DNS lookup. More...
def	dns_txt

Public Attributes
	cache

Static Public Attributes
tuple	SAFE2CACHE
	Additional DNS RRs we can safely cache. More...

Detailed Description

A Session object has a simple cache with no TTL that is valid
 for a single "session", for example an SMTP conversation.

Member Function Documentation

def Milter.dns.Session.dns	(		self,
			name,
			qtype,
			cnames = None
	)

Cached DNS lookup.

Parameters

name	the DNS label to query
qtype	the query type, e.g. 'A'
cnames	tracks CNAMES already followed in recursive calls DNS query. If the result is in cache, return that. Otherwise pull the result from DNS, and cache ALL answers, so additional info is available for further queries later. CNAMEs are followed. If there is no data, [] is returned. pre: qtype in ['A', 'AAAA', 'MX', 'PTR', 'TXT', 'SPF'] post: isinstance(__return__, types.ListType)

References Milter.dns.Session.cache, Milter.cache.AddrCache.cache, Milter.dns.Session.dns(), and Milter.dns.DNSLookup().

Referenced by Milter.dns.Session.dns().

Member Data Documentation

tuple Milter.dns.Session.SAFE2CACHE

static

Initial value:

= frozenset((
    ('MX','MX'), ('MX','A'),
    ('CNAME','CNAME'), ('CNAME','A'),
    ('A','A'),
    ('AAAA','AAAA'),
    ('PTR','PTR'),
    ('NS','NS'), ('NS','A'),
    ('TXT','TXT'),
    ('SPF','SPF')
  ))

Additional DNS RRs we can safely cache.

We have to be careful which additional DNS RRs we cache. For instance, PTR records are controlled by the connecting IP, and they could poison our local cache with bogus A and MX records. Each entry is a tuple of (query_type,rr_type). So for instance, the entry ('MX','A') says it is safe (for milter purposes) to cache any 'A' RRs found in an 'MX' query.

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The documentation for this class was generated from the following file:

• Milter/dns.py