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Avoid interposition cycles with a simple restriction.

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dachshund 2013-03-04 01:04:25 -05:00
parent 7af60c51bb
commit c034d33a2e
1 changed files with 11 additions and 10 deletions
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21
tuf/interposition/updater.py
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@ -42,10 +42,12 @@ def __init__( self, configuration ):
@staticmethod
def build_updater( configuration ):
assert isinstance( configuration, Configuration )
assert configuration.network_location not in Updater.__updaters
Updater.__updaters[ configuration.network_location ] = \
Updater( configuration )
# Restrict each hostname to correspond to a single updater;
# this prevents interposition cycles, amongst other things.
assert configuration.hostname not in Updater.__updaters
Updater.__updaters[ configuration.hostname ] = Updater( configuration )
def download_target( self, target_filepath ):
"""Downloads target with TUF as a side effect."""
@ -132,14 +134,13 @@ def get_updater( url ):
parsed_url = urlparse.urlparse( url )
hostname = parsed_url.hostname
port = parsed_url.port or 80
network_location = \
"{hostname}:{port}".format( hostname = hostname, port = port )
updater = Updater.__updaters.get( hostname )
updater = Updater.__updaters.get( network_location )
# This will raise an exception in case we do not recognize
# how to transform this URL for TUF. In that case, there will be
# no updater for this URL.
if updater is not None:
# Ensure that the updater is meant for this (hostname, port).
if updater is not None and updater.configuration.port == port:
# Raises an exception in case we do not recognize how to
# transform this URL for TUF. In that case, there will be no
# updater for this URL.
target_filepath = updater.get_target_filepath( url )
except:
Logger.warn( WARNING_MESSAGE.format( url = url ) )