Public Member Functions |
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def | __init__ |
| def | dns |
| | Cached DNS lookup.
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def | dns_txt |
Static Public Attributes |
| tuple | SAFE2CACHE |
| | Additional DNS RRs we can safely cache.
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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 |
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self, |
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name, |
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qtype, |
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cnames = None |
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) |
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Cached DNS lookup.
- Parameters
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| 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)
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Member Data Documentation
| tuple Milter.dns.Session.SAFE2CACHE |
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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.
The documentation for this class was generated from the following file:
