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Viewing changes to vendor/Twisted-10.0.0/twisted/names/resolve.py

  • Committer: Jesse Andrews
  • Date: 2010-05-28 06:05:26 UTC
  • Revision ID: git-v1:bf6e6e718cdc7488e2da87b21e258ccc065fe499
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vendor/Twisted-10.0.0/twisted/names/resolve.py
 
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# Copyright (c) 2001-2004 Twisted Matrix Laboratories.
 
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# See LICENSE for details.
 
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"""
 
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Lookup a name using multiple resolvers.
 
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Future Plans: This needs someway to specify which resolver answered
 
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the query, or someway to specify (authority|ttl|cache behavior|more?)
 
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@author: Jp Calderone
 
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"""
 
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from twisted.internet import defer, interfaces
 
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from twisted.names import dns
 
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from zope.interface import implements
 
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import common
 
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class FailureHandler:
 
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    def __init__(self, resolver, query, timeout):
 
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        self.resolver = resolver
 
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        self.query = query
 
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        self.timeout = timeout
 
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    def __call__(self, failure):
 
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        # AuthoritativeDomainErrors should halt resolution attempts
 
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        failure.trap(dns.DomainError, defer.TimeoutError, NotImplementedError)
 
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        return self.resolver(self.query, self.timeout)
 
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class ResolverChain(common.ResolverBase):
 
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    """Lookup an address using multiple C{IResolver}s"""
 
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    implements(interfaces.IResolver)
 
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    def __init__(self, resolvers):
 
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        common.ResolverBase.__init__(self)
 
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        self.resolvers = resolvers
 
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    def _lookup(self, name, cls, type, timeout):
 
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        q = dns.Query(name, type, cls)
 
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        d = self.resolvers[0].query(q, timeout)
 
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        for r in self.resolvers[1:]:
 
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            d = d.addErrback(
 
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                FailureHandler(r.query, q, timeout)
 
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            )
 
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        return d
 
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    def lookupAllRecords(self, name, timeout = None):
 
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        d = self.resolvers[0].lookupAllRecords(name, timeout)
 
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        for r in self.resolvers[1:]:
 
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            d = d.addErrback(
 
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                FailureHandler(r.lookupAllRecords, name, timeout)
 
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            )
 
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        return d