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Add purpose and comments to interposition/updater.py

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Pankh 2014-07-10 18:56:47 -04:00
parent a3e63a293c
commit 0cda6d3d22
2 changed files with 52 additions and 40 deletions
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3
tuf/interposition/__init__.py
View file

@ -188,6 +188,9 @@ def __read_configuration(configuration_handler,
parsed_configurations = {}
try:
# open() is function in class Updater. It opens the file with given url
# as a temporary file in the binary mode and remains transparent to the
# software updater.
with open(filename) as tuf_interposition_json:
tuf_interpositions = json.load(tuf_interposition_json)
configurations = tuf_interpositions.get("configurations", {})

89
tuf/interposition/updater.py
View file

@ -12,19 +12,23 @@
See LICENSE for licensing information.
<Purpose>
Interposition is the high-level integration of TUF. 'updater.py' is used to perform high-level integration of TUF to the
software updater. This means that all the processes which are taking place in the low-level integration will be done
automatically. This layer of processes will be transparent to the client.
Interposition is the high-level integration of TUF. 'updater.py' is used to
perform high-level integration of TUF to the software updater. This means
that all the processes which are taking place in the low-level integration
will be done automatically. This layer of processes will be transparent to
the client.
Updater.py have two classes named as Updater and UpdaterController.
TODO: Add more description to purpose.
TODO: Add Pros and Cons of using interposition.
#TODO: Add more description to purpose.
#TODO: Add Pros and Cons of using interposition.
<Example Interpostion>
To implement interpostion client only need to have two files -
1. A python file which client will have to run in order to perform interposition. For example - interposition.py.
1. A python file which client will have to run in order to perform
interposition. For example - interposition.py.
# First import the main module called interposition which contains all the required directories and classes.
# First import the main module called interposition which contains all
# the required directories and classes.
import tuf.interposition
# urllib_tuf and urllib2_tuf are TUF's copy of urllib and urllib2
@ -34,8 +38,9 @@
# From tuf.interposition, configure() method is called.
# configure() is within __init__.py
# Ways to call this method are as follows :
# First, configure() - By default, the configuration object is expected to be situated in the current working directory
# in the file with the name "tuf.interposition.json".
# First, configure() - By default, the configuration object is expected
# to be situated in the current working directory in the file with the
# name "tuf.interposition.json".
# Second, configure(filename="/path/to/json")
# Configure() returns a dictionary of configurations
configurations = tuf.interposition.configure()
@ -46,16 +51,21 @@
urllib.urlretrieve(url)
urllib2.urlopen(url)
# Remove TUF interposition for previously read configurations. That is remove the updater object.
# Remove TUF interposition for previously read configurations. That is
# remove the updater object.
tuf.interposition.deconfigure(configurations)
2. A JSON object which tells tuf.interposition which URLs to intercept, how to transform them (if necessary), and where to forward them
(possibly over SSL) for secure responses via TUF. By default, the name of the file is tuf.interposition.json which is as follows -
2. A JSON object which tells tuf.interposition which URLs to intercept, how
to transform them (if necessary), and where to forward them (possibly over
SSL) for secure responses via TUF. By default, the name of the file is
tuf.interposition.json which is as follows -
# configurations are simply a JSON object which allows you to answer these questions -
# configurations are simply a JSON object which allows you to answer
# these questions -
# - Which network location get intercepted?
# - Given a network location, which TUF mirrors should we forward requests to?
# - Given a network location, which TUF mirrors should we forward
# requests to?
# - Given a network location, which paths should be intercepted?
# - Given a TUF mirror, how do we verify its SSL certificate?
{
@ -81,8 +91,9 @@
}
}
# After making these two files on the client side, run interposition.py. This will start the interposition process. It generates a log
# file in the same directory which can be used for a review.
# After making these two files on the client side, run interposition.py. This
# will start the interposition process. It generates a log file in the same
# directory which can be used for a review.
"""
@ -102,7 +113,7 @@
# We import them directly into our namespace so that there is no name conflict.
from configuration import Configuration, InvalidConfiguration
from utility import Logger, InterpositionException
#TODO: Remove utility because the Logger is it two places.
@ -110,9 +121,7 @@
################################ GLOBAL CLASSES ################################
#TODO: Put this class in the Exception file of TUF.
class URLMatchesNoPattern(InterpositionException):
"""URL matches no user-specified regular expression pattern."""
pass
@ -188,6 +197,23 @@ def download_target(self, target_filepath):
return destination_directory, filename
# TODO: decide prudent course of action in case of failure
def get_target_filepath(self, source_url):
# Locate the fileinfo of 'target_filepath'. updater.target() searches
# Targets metadata in order of trust, according to the currently trusted
# snapshot. To prevent consecutive target file requests from referring to
# different snapshots, top-level metadata is not automatically refreshed.
targets = [self.updater.target(target_filepath)]
# TODO: targets are always updated if destination directory is new, right?
updated_targets = self.updater.updated_targets(targets, destination_directory)
for updated_target in updated_targets:
self.updater.download_target(updated_target, destination_directory)
return destination_directory, filename
# TODO: decide prudent course of action in case of failure
def get_target_filepath(self, source_url):
"""Given source->target map, figure out what TUF *should* download given a
@ -242,8 +268,11 @@ def open(self, url, data=None):
# Windows.
# http://docs.python.org/2/tutorial/inputoutput.html#reading-and-writing-files
# TODO: like tempfile, ensure file is deleted when closed?
# open() in the line below is a predefined function in python.
temporary_file = open(filename, 'rb')
#TODO: addinfourl is not in urllib package anymore. We need to check if
# other option for this is working or not.
# Extend temporary_file with info(), getcode(), geturl()
# http://docs.python.org/2/library/urllib.html#urllib.urlopen
response = urllib.addinfourl(temporary_file, headers, url, code=200)
@ -454,23 +483,3 @@ def remove(self, configuration):
assert isinstance(configuration, Configuration)
repository_mirror_hostnames = configuration.get_repository_mirror_hostnames()
assert configuration.hostname in self.__updaters
assert repository_mirror_hostnames.issubset(self.__repository_mirror_hostnames)
# Get the updater.
updater = self.__updaters.get(configuration.hostname)
# If all is well, remove the stored Updater as well as its associated
# repository mirror hostnames.
updater.cleanup()
del self.__updaters[configuration.hostname]
self.__repository_mirror_hostnames.difference_update(repository_mirror_hostnames)
Logger.info(UPDATER_REMOVED_MESSAGE.format(configuration=configuration))