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Request the expected file lengths for the different metadata roles

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This commit is contained in:
Vladimir Diaz 2015-10-15 10:58:10 -04:00
parent d993ccf35e
commit f9f44d7f04
1 changed files with 28 additions and 15 deletions
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43
tuf/client/updater.py
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@ -1124,6 +1124,7 @@ def _get_metadata_file(self, metadata_role, remote_filename,
# If the version number is unspecified, ensure that the version number
# downloaded is greater than the currently trusted version number.
print('metadata_signable: ' + repr(metadata_signable))
version_downloaded = metadata_signable['signed']['version']
if expected_version is None:
if version_downloaded <= expected_version:
@ -1153,7 +1154,7 @@ def _get_metadata_file(self, metadata_role, remote_filename,
else:
logger.exception('Failed to update {0} from all mirrors: {1}'.format(
filepath, file_mirror_errors))
remote_filename, file_mirror_errors))
raise tuf.NoWorkingMirrorError(file_mirror_errors)
@ -1432,12 +1433,12 @@ def _update_metadata(self, metadata_role, upperbound_filelength, version=None,
# "safe" targets.
remote_filename = metadata_filename
filename_version = ''
if self.consistent_snapshot:
filename_version = str(version)
dirname, basename = os.path.split(remote_filename)
remote_filename = os.path.join(dirname, filename_digest + '.' + basename)
dirname, basename = os.path.split(remote_filename)
remote_filename = os.path.join(dirname, filename_version + '.' + basename)
metadata_file_object = \
self._get_metadata_file(metadata_role, remote_filename,
@ -1590,12 +1591,11 @@ def _update_metadata_if_changed(self, metadata_role,
# untrusted data is not decompressed prior to verifying hashes, or
# decompressing a file that may be invalid or partially intact.
compression = None
compressed_fileinfo = None
# Extract the fileinfo of the uncompressed version of 'metadata_role'.
uncompressed_fileinfo = self.metadata['current'][referenced_metadata] \
['meta'] \
[uncompressed_metadata_filename]
# Extract the versioninfo of the uncompressed version of 'metadata_role'.
expected_versioninfo = self.metadata['current'][referenced_metadata] \
['meta'] \
[uncompressed_metadata_filename]
# Check for the availability of compressed versions of 'snapshot.json',
# 'targets.json', and delegated Targets (that also start with 'targets').
@ -1607,8 +1607,6 @@ def _update_metadata_if_changed(self, metadata_role,
if gzip_metadata_filename in self.metadata['current'] \
[referenced_metadata]['meta']:
compression = 'gzip'
compressed_fileinfo = self.metadata['current'][referenced_metadata] \
['meta'][gzip_metadata_filename]
logger.debug('Compressed version of '+\
repr(uncompressed_metadata_filename)+' is available at '+\
@ -1620,7 +1618,7 @@ def _update_metadata_if_changed(self, metadata_role,
# Simply return if the file has not changed, according to the metadata
# about the uncompressed file provided by the referenced metadata.
if not self._versioninfo_has_changed(uncompressed_metadata_filename,
uncompressed_fileinfo):
expected_versioninfo):
logger.info(repr(uncompressed_metadata_filename)+' up-to-date.')
return
@ -1628,9 +1626,24 @@ def _update_metadata_if_changed(self, metadata_role,
logger.debug('Metadata '+repr(uncompressed_metadata_filename)+\
' has changed.')
# The file lengths of metadata are unknown, only their version numbers
# known. Set an upper limit to the length of the download for each
# expected role. Note: The Timestamp role is not updated via this
# function.
if metadata_role == 'snapshot':
upperbound_filelength = tuf.conf.DEFAULT_SNAPSHOT_REQUIRED_LENGTH
elif metadata_role == 'root':
upperbound_filelength = tuf.conf.DEFAULT_ROOT_REQUIRED_LENGTH
# The metadata is considered Targets (or delegated Targets metadata).
else:
upperbound_filelength = tuf.conf.DEFAULT_TARGETS_REQUIRED_LENGTH
try:
self._update_metadata(metadata_role, uncompressed_fileinfo, compression,
compressed_fileinfo)
self._update_metadata(metadata_role, upperbound_filelength,
expected_versioninfo['version'], compression)
except:
# The current metadata we have is not current but we couldn't
# get new metadata. We shouldn't use the old metadata anymore.