commit f23c5312b671dd2bd41baa5a0c24568592ac3241 Author: Damian Johnson <atagar@torproject.org> Date: Sat Sep 8 11:23:08 2012 -0700 Validating the order of fields in documents As mentioned in the prior commit, to be valid network status fields need to appear in a particular order. Checking for this as part of document validation. --- stem/descriptor/networkstatus.py | 33 ++++++++++++++++++++++++++++++++- 1 files changed, 32 insertions(+), 1 deletions(-) diff --git a/stem/descriptor/networkstatus.py b/stem/descriptor/networkstatus.py index e55c06f..5676c16 100644 --- a/stem/descriptor/networkstatus.py +++ b/stem/descriptor/networkstatus.py @@ -255,8 +255,8 @@ class NetworkStatusDocument(stem.descriptor.Descriptor): document_file = StringIO(raw_content) header, footer, routers_end = _get_document_content(document_file, validate) - self._parse(header, footer, validate) self._parse_old(header + footer, validate) + self._parse(header, footer, validate) if document_file.tell() < routers_end: self.routers = tuple(_get_routers(document_file, validate, self, routers_end, self._get_router_type())) @@ -298,6 +298,7 @@ class NetworkStatusDocument(stem.descriptor.Descriptor): is_consensus = header_entries['vote-status'][0][0] == "consensus" self._check_for_missing_and_disallowed_fields(is_consensus, header_entries, footer_entries) + self._check_for_misordered_fields(is_consensus, header_entries, footer_entries) def _parse_old(self, raw_content, validate): # preamble @@ -430,6 +431,36 @@ class NetworkStatusDocument(stem.descriptor.Descriptor): if disallowed_fields: raise ValueError("Network status document has fields that shouldn't appear in this document type: %s" % ', '.join(disallowed_fields)) + + def _check_for_misordered_fields(self, is_consensus, header_entries, footer_entries): + """ + To be valid a network status document's fiends need to appear in a specific + order. Checks that known fields appear in that order (unrecognized fields + are ignored). + """ + + # Earlier validation has ensured that our fields either belong to our + # document type or are unknown. Remove the unknown fields since they + # reflect a spec change and can appear anywhere in the document. + + expected_header = [attr[0] for attr in HEADER_STATUS_DOCUMENT_FIELDS] + expected_footer = [attr[0] for attr in FOOTER_STATUS_DOCUMENT_FIELDS] + + actual_header = filter(lambda field: field in expected_header, header_entries.keys()) + actual_footer = filter(lambda field: field in expected_footer, footer_entries.keys()) + + # Narrow the expected_header and expected_footer to just what we have. If + # the lists then match then the order's valid. + + expected_header = filter(lambda field: field in actual_header, expected_header) + expected_footer = filter(lambda field: field in actual_footer, expected_footer) + + for label, actual, expected in (('header', actual_header, expected_header), + ('footer', actual_footer, expected_footer)): + if actual != expected: + actual_label = ', '.join(actual) + expected_label = ', '.join(expected) + raise ValueError("The fields in the document's %s are misordered. It should be '%s' but was '%s'" % (lable, actual_label, expected_label)) class DirectoryAuthority(stem.descriptor.Descriptor): """