Just some small comments below, and the request to fix up the comments.
I did not go too deep on the pyparser part but at a glance, it looks ok.
//Eelco
On 22 Nov 2021, at 12:22, Adrian Moreno wrote:
> Based on pyparsing, create a very simple filtering syntax
>
> It supports basic logic statements (and, &, or, ||, not, !), numerical
> operations (<, >), equality (=) and masking (~=). The latter is only
, and missing…
> supported in certain fields (IntMask, EthMask, IPMask).
>
> Masking operation is semantically equivalent to "includes",
> therefore:
>
> ip_src ~= 192.168.1.1
>
> means that ip_src field is either a host IP address equal to 192.168.1.1
> or an IPMask that includes it (e.g: 192.168.1.1/24)
>
> Signed-off-by: Adrian Moreno <amore...@redhat.com>
> ---
> python/automake.mk | 3 +-
> python/ovs/flows/filter.py | 225 +++++++++++++++++++++++++++++++++++++
> python/setup.py | 2 +-
> 3 files changed, 228 insertions(+), 2 deletions(-)
> create mode 100644 python/ovs/flows/filter.py
>
> diff --git a/python/automake.mk b/python/automake.mk
> index 8b0713cfc..21aa897f2 100644
> --- a/python/automake.mk
> +++ b/python/automake.mk
> @@ -49,7 +49,8 @@ ovs_pyfiles = \
> python/ovs/flows/flow.py \
> python/ovs/flows/ofp.py \
> python/ovs/flows/ofp_act.py \
> - python/ovs/flows/odp.py
> + python/ovs/flows/odp.py \
> + python/ovs/flows/filter.py
Add in alphabetical order
>
> # These python files are used at build time but not runtime,
> # so they are not installed.
> diff --git a/python/ovs/flows/filter.py b/python/ovs/flows/filter.py
> new file mode 100644
> index 000000000..2d3555a60
> --- /dev/null
> +++ b/python/ovs/flows/filter.py
> @@ -0,0 +1,225 @@
> +""" Defines a Flow Filtering syntax
> +"""
> +import pyparsing as pp
> +import netaddr
> +from functools import reduce
> +from operator import and_, or_
> +
> +from ovs.flows.decoders import (
> + decode_default,
> + decode_int,
> + Decoder,
> + IPMask,
> + EthMask,
> +)
> +
> +
> +class EvaluationResult:
> + """An EvaluationResult is the result of an evaluation. It contains the
> + boolean result and the list of key-values that were evaluated
> +
> + Note that since boolean operations (and, not, or) are based only on
> + __bool__ we use bitwise alternatives (&, ||, ~)
> + """
> +
> + def __init__(self, result, *kv):
> + self.result = result
> + self.kv = kv if kv else list()
> +
> + def __and__(self, other):
> + """Logical and operation"""
> + return EvaluationResult(
> + self.result and other.result, *self.kv, *other.kv
> + )
> +
> + def __or__(self, other):
> + """Logical or operation"""
> + return EvaluationResult(
> + self.result or other.result, *self.kv, *other.kv
> + )
> +
> + def __invert__(self):
> + """Logical not operation"""
> + return EvaluationResult(not self.result, *self.kv)
> +
> + def __bool__(self):
> + """Boolean operation"""
> + return self.result
> +
> + def __repr__(self):
> + return "{} [{}]".format(self.result, self.kv)
> +
> +
> +class ClauseExpression:
> + operators = {}
> + type_decoders = {
> + int: decode_int,
> + netaddr.IPAddress: IPMask,
> + netaddr.EUI: EthMask,
> + bool: bool,
> + }
> +
> + def __init__(self, tokens):
> + self.field = tokens[0]
> + self.value = ""
> + self.operator = ""
> +
> + if len(tokens) > 1:
> + self.operator = tokens[1]
> + self.value = tokens[2]
> +
> + def __repr__(self):
> + return "{}(field: {}, operator: {}, value: {})".format(
> + self.__class__.__name__, self.field, self.operator, self.value
> + )
> +
> + def _find_data_in_kv(self, kv_list):
> + """Find a KeyValue for evaluation in a list of KeyValue
> +
> + Args:
> + kv_list (list[KeyValue]): list of KeyValue to look into
> +
> + Returns:
> + If found, tuple (kv, data) where kv is the KeyValue that matched
> + and data is the data to be used for evaluation. None if not
> found.
> + """
> + key_parts = self.field.split(".")
> + field = key_parts[0]
> + kvs = [kv for kv in kv_list if kv.key == field]
> + if not kvs:
> + return None
> +
> + for kv in kvs:
> + if kv.key == self.field:
> + # exact match
> + return (kv, kv.value)
> + if len(key_parts) > 1:
> + data = kv.value
> + for subkey in key_parts[1:]:
> + try:
> + data = data.get(subkey)
> + except Exception:
> + data = None
> + break
> + if not data:
> + break
> + if data:
> + return (kv, data)
> + return None
> +
> + def _find_keyval_to_evaluate(self, flow):
> + """Finds the key-value and data to use for evaluation on a flow
> +
> + Args:
> + flow(Flow): The flow where the lookup is performed
> +
> + Returns:
> + If found, tuple (kv, data) where kv is the KeyValue that matched
> + and data is the data to be used for evaluation. None if not
> found.
> +
> + """
> + for section in flow.sections:
> + data = self._find_data_in_kv(section.data)
> + if data:
> + return data
> + return None
> +
> + def evaluate(self, flow):
> + """
> + Return whether the clause is satisfied by the flow
> +
> + Args:
> + flow (Flow): the flow to evaluate
> + """
> + result = self._find_keyval_to_evaluate(flow)
> +
> + if not result:
> + return EvaluationResult(False)
> +
> + keyval, data = result
> +
> + if not self.value and not self.operator:
> + # just asserting the existance of the key
> + return EvaluationResult(True, keyval)
> +
> + # Decode the value based on the type of data
> + if isinstance(data, Decoder):
> + decoder = data.__class__
> + else:
> + decoder = self.type_decoders.get(data.__class__) or
> decode_default
> +
> + decoded_value = decoder(self.value)
> +
> + if self.operator == "=":
> + return EvaluationResult(decoded_value == data, keyval)
> + elif self.operator == "<":
> + return EvaluationResult(data < decoded_value, keyval)
> + elif self.operator == ">":
> + return EvaluationResult(data > decoded_value, keyval)
> + elif self.operator == "~=":
> + return EvaluationResult(decoded_value in data, keyval)
> +
> +
> +class BoolNot:
> + def __init__(self, t):
> + self.op, self.args = t[0]
> +
> + def __repr__(self):
> + return "NOT({})".format(self.args)
> +
> + def evaluate(self, flow):
> + return ~self.args.evaluate(flow)
> +
> +
> +class BoolAnd:
> + def __init__(self, pattern):
> + self.args = pattern[0][0::2]
> +
> + def __repr__(self):
> + return "AND({})".format(self.args)
> +
> + def evaluate(self, flow):
> + return reduce(and_, [arg.evaluate(flow) for arg in self.args])
> +
> +
> +class BoolOr:
> + def __init__(self, pattern):
> + self.args = pattern[0][0::2]
> +
> + def evaluate(self, flow):
> + return reduce(or_, [arg.evaluate(flow) for arg in self.args])
> +
> + def __repr__(self):
> + return "OR({})".format(self.args)
> +
> +
> +class OFFilter:
There are no test cases for OFFilter, do we need some?
> + w = pp.Word(pp.alphanums + "." + ":" + "_" + "/" + "-")
> + operators = (
> + pp.Literal("=")
> + | pp.Literal("~=")
> + | pp.Literal("<")
> + | pp.Literal(">")
> + | pp.Literal("!=")
> + )
> +
> + clause = (w + operators + w) | w
> + clause.setParseAction(ClauseExpression)
> +
> + statement = pp.infixNotation(
> + clause,
> + [
> + ("!", 1, pp.opAssoc.RIGHT, BoolNot),
> + ("not", 1, pp.opAssoc.RIGHT, BoolNot),
> + ("&&", 2, pp.opAssoc.LEFT, BoolAnd),
> + ("and", 2, pp.opAssoc.LEFT, BoolAnd),
> + ("||", 2, pp.opAssoc.LEFT, BoolOr),
> + ("or", 2, pp.opAssoc.LEFT, BoolOr),
> + ],
> + )
> +
> + def __init__(self, expr):
> + self._filter = self.statement.parseString(expr)
> +
> + def evaluate(self, flow):
> + return self._filter[0].evaluate(flow)
> diff --git a/python/setup.py b/python/setup.py
> index b06370bd9..4e8a9761a 100644
> --- a/python/setup.py
> +++ b/python/setup.py
> @@ -87,7 +87,7 @@ setup_args = dict(
> ext_modules=[setuptools.Extension("ovs._json", sources=["ovs/_json.c"],
> libraries=['openvswitch'])],
> cmdclass={'build_ext': try_build_ext},
> - install_requires=['sortedcontainers', 'netaddr'],
> + install_requires=['sortedcontainers', 'netaddr', 'pyparsing'],
> extras_require={':sys_platform == "win32"': ['pywin32 >= 1.0']},
> )
>
> --
> 2.31.1
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