While troubleshooting or developing new features in OVS, a considerable amount of time is spent analyzing flows (whether that's Openflow flows or datapath flows). Currently, OVS has tools to dump flows with different levels of verbosity as well as to filter flows prior to dumping them, e.g: 'ovs-ofctl dump-flows', 'ovs-appctl dpctl/dump-flows', etc.
The output of these commands is considered stable so it should be possible to write more layered tools that enable advanced flow analysis. However, the way flows are formatted into strings is not trivial to parse. This series introduces the a flow parsing library capable of parsing both Openflow and DPIF flows. The library is based on generic key-value and list parsers and a number of common decoders. Based on that, an Openflow flow parser and a DPIF flow parser are introduced by defining a way to decode each possible field and action they might contain. The library has the following features: - Parsed key-value pairs keep some metadata that refer to the original strings they were extracted from. That way the flows can be printed and formatted in flexible ways. - It includes a basic flow filtering mechanism. A filter can be defined combining logical (||, &&, !), arithmetical (<, >, =) or mask (~=) operations - It supports IPAddress and Ethernet masking (based on netaddr) - The decoder to use for each key (match or action) is set explicitly to avoid expensive runtime type-guessing. - The decoders to use for Openflow fields is automatically generated based on meta-flow.h - Additional dependencies: - netaddr: For IP and Ethernet Address management. - pyparsing: For filtering syntax. - pytest: For unit tests. One key goal challenge of including this library is avoiding diversion between the C code that prints/parses the flows and the python parsing code. To that effect, the series introduces the following mechanisms: - Decoding information of openflow fields is automatically generated based on meta-flow.h - The calls to ovs-ofctl made from tests/ofp-actions.at are wrapped by a python script that also runs the python parsers. If an exception is raised by the python code (meaning it was not capable of parsing the flow string), the test will fail - The calls to the test-odp made from tests/odp.at are wrapped by a python script that also runs the python parsers. If an exception is raised by the python code (meaning it was not capable of parsing the flow string), the test will fail. - A python unit test testsuite ensures python code works and it's easy to add more flow examples to it - A dependency check is introduced. The python parsing code mainly depends on lib/ofp-actions.c and lib/odp-util.c. This series stores the md5sum of such files and adds a build target that ensures the files have not been changed. That way, anyone who modifies those files will get a warning the fist time they build the project. Dependency digests are easily updated using a string so hopefully this warning would not be too inconvenient. Library usage ------------- >>> from ovs.flows.ofp import OFPFlow >>> flow = OFPFlow("cookie=0x2b32ab4d, table=41, n_packets=11, n_bytes=462, >>> priority=33,ip,reg15=0x2/0x2,nw_src=10.128.0.2/24 >>> actions=move:NXM_OF_TCP_DST[]->NXM_NX_XXREG0[32..47],ct(table=16,zone=NXM_NX_REG13[0..15],nat)") >>> flow.info {'cookie': 724740941, 'table': 41, 'n_packets': 11, 'n_bytes': 462} >>> flow.match {'priority': 33, 'ip': True, 'reg15': Mask32('0x2/0x2'), 'nw_src': IPMask('10.128.0.2/24')} >>> flow.actions [{'move': {'src': {'field': 'NXM_OF_TCP_DST'}, 'dst': {'field': 'NXM_NX_XXREG0', 'start': 32, 'end': 47}}}, {'ct': {'table': 16, 'zone': {'field': 'NXM_NX_REG13', 'start': 0, 'end': 15}, 'nat': True}}] >>> from ovs.flows.filter import OFFilter >>> filt = OFFilter("nw_src ~= 10.128.0.10 and (table = 42 or n_packets > 0)") >>> filt.evaluate(flow) True Another way to try the library would be with a utility called ovs-ofparse that I'll send to the list as RFC soon. V1 -> V2: - list/kv parsers: changed the API to accept the string to parse in the constructor. - list/kv parsers: allow re.split() to return less than 3 elements (enables support for python 3.6). - decoders: add a more accurate IPv6 regexp and remove confusing max() in IPMask and EthMask. - odp/ofp flows: remove the *Factory class and implement caching of decoders using class variables. - odp/ofp flows: homogenize names of functions and made them static. - moved pytest unit tests from a build target to a testsuite and added their requirements to python/test_requirements.txt. - Formatting fixes and missing dots (lots of them!). RFC -> V1: - filters: created a class to represent the filtering result. That way we can store more information such as what key actually triggered the match. This enables functionality such as highlighting of keys based on an expression - Formatted python code according to flake8 requirements - Split ofp actions in ofp_act.py - drop ofparse utility (will send a RFC to the mail list soon) - Moved the initialization of the decoders objects to a factory so they are cached. This significantly decreases parsing time of large dumps. Adrian Moreno (18): python: add generic Key-Value parser python: add mask, ip and eth decoders python: add list parser build-aux: split extract-ofp-fields build-aux: generate ofp field decoders python: add flow base class python: introduce OpenFlow Flow parsing python: add ovs datapath flow parsing python: add flow filtering syntax python: add a json encoder to flow fields tests: wrap ovs-ofctl calls to test python parser tests: Wrap test-odp to also run python parsers python: detect changes in flow formatting code python: introduce unit tests python: add unit tests for ListParser python: add unit tests for openflow parsing python: add unit tests to datapath parsing python: add unit tests for filtering engine .github/workflows/build-and-test.yml | 3 + .gitignore | 1 + Documentation/intro/install/general.rst | 4 + Makefile.am | 3 +- build-aux/automake.mk | 3 +- build-aux/extract-ofp-fields | 706 ++++++--------------- build-aux/gen_ofp_field_decoders | 69 +++ python/.gitignore | 1 + python/automake.mk | 42 +- python/build/extract_ofp_fields.py | 386 ++++++++++++ python/build/flow-parse-deps.py | 106 ++++ python/ovs/flows/__init__.py | 0 python/ovs/flows/decoders.py | 538 ++++++++++++++++ python/ovs/flows/deps.py | 5 + python/ovs/flows/filter.py | 261 ++++++++ python/ovs/flows/flow.py | 125 ++++ python/ovs/flows/kv.py | 320 ++++++++++ python/ovs/flows/list.py | 124 ++++ python/ovs/flows/odp.py | 783 ++++++++++++++++++++++++ python/ovs/flows/ofp.py | 453 ++++++++++++++ python/ovs/flows/ofp_act.py | 243 ++++++++ python/ovs/tests/test_filter.py | 221 +++++++ python/ovs/tests/test_kv.py | 76 +++ python/ovs/tests/test_list.py | 66 ++ python/ovs/tests/test_odp.py | 527 ++++++++++++++++ python/ovs/tests/test_ofp.py | 524 ++++++++++++++++ python/setup.py | 4 +- python/test_requirements.txt | 3 + tests/atlocal.in | 19 + tests/automake.mk | 6 + tests/odp.at | 36 +- tests/ofp-actions.at | 46 +- tests/ovs-test-dpparse.py | 70 +++ tests/ovs-test-ofparse.py | 94 +++ tests/pytest.at | 7 + tests/testsuite.at | 1 + 36 files changed, 5314 insertions(+), 562 deletions(-) create mode 100755 build-aux/gen_ofp_field_decoders create mode 100644 python/build/extract_ofp_fields.py create mode 100755 python/build/flow-parse-deps.py create mode 100644 python/ovs/flows/__init__.py create mode 100644 python/ovs/flows/decoders.py create mode 100644 python/ovs/flows/deps.py create mode 100644 python/ovs/flows/filter.py create mode 100644 python/ovs/flows/flow.py create mode 100644 python/ovs/flows/kv.py create mode 100644 python/ovs/flows/list.py create mode 100644 python/ovs/flows/odp.py create mode 100644 python/ovs/flows/ofp.py create mode 100644 python/ovs/flows/ofp_act.py create mode 100644 python/ovs/tests/test_filter.py create mode 100644 python/ovs/tests/test_kv.py create mode 100644 python/ovs/tests/test_list.py create mode 100644 python/ovs/tests/test_odp.py create mode 100644 python/ovs/tests/test_ofp.py create mode 100644 python/test_requirements.txt create mode 100755 tests/ovs-test-dpparse.py create mode 100755 tests/ovs-test-ofparse.py create mode 100644 tests/pytest.at -- 2.34.1 _______________________________________________ dev mailing list d...@openvswitch.org https://mail.openvswitch.org/mailman/listinfo/ovs-dev