mcf-rules.py

from typing import Union
import re


class Reject(object):
    def __init__(self, reason: str):
        self.reason = reason
        
    def run(self):
        print("[REJECT] Mail reject: {}".format(self.reason))

class Drop(object):
    
    def run(self):
        print("[DROP] Mail dropped")

class Filter:
    def __init__(self, pattern: str):
        self.pattern = pattern

    def __call__(self, string: str) -> bool:
        result = False
        if re.match(self.pattern, string):
            result = True
        print("[DEBUG_FILTER] match {} with {} == {}".format(self.pattern, string, result))
        return result


class Or:
    def __init__(self, action: Union[Reject, Drop], *args):
        self.args = args
        self.action = action

    def __call__(self, action: Union[Reject, Drop], *args) -> Union[Reject, Drop, None]:
        if any(arg(action, *args) for arg in self.args):
            return self.action
        else:
            return None


class And:
    def __init__(self, action: Union[Reject, Drop], *args):
        self.args = args
        self.action = action

    def __call__(self, action: Union[Reject, Drop], *args) -> Union[Reject, Drop, None]:
        if all(arg(action, *args) for arg in self.args):
            return self.action
        else:
            return None


if __name__ == "__main__":

    #
    # Liste de filtres
    #
    # And : tous les filtres doivent être validés
    # Or : au moins un filtre doit être validé
    #
    # Or ou And prend en paramètre une fonction et une liste de filtres
    #
    filters = [
        # Marche
        And(Reject("[ACTION] OK car 2x From (AND) !"), Filter(r"^From:.*$"), Filter(r"^From:.*$")),
        # Ne marche pas
        And(Reject("[ACTION] Ne devrait pas passer ici. 1 bad dans un and"), Filter(r"\d+"), Filter(r"\w"), Filter(r".*@.*"), Filter(r".*@.*")),
        # Marche
        Or(lambda: print("[ACTION] Oups une lambda pour montrer qu'une action est n'importe quoi !"), Filter(r"^From:.*$"), Filter(r".*@.*")),
        Or(Drop(), Filter(r"^From:.*$"), Filter(r"^From:.*$")),
        Or(Reject("[ACTION] Ok all bad"), Filter(r"\d+"), Filter(r"\d+")),
    ]

    for filter in filters:
        action = filter("From:[email protected]")
        if action and "run" in dir(action):
            action.run()
        elif action:
            action()

    print("====== AUTRE EXEMPLE ======")
    actionOk = Or(Reject("[ACTION] YES"), Filter("^From:.*$"), Filter(".*@.*"))("From:[email protected]")
    if actionOk:
        print("Action OK")
        actionOk.run()

    actionKo = And(Drop(), Filter("^From:.*$"), Filter("\d"))("From:[email protected]")
    if actionKo:
        print("Action KO")
        actionKo.run()

Ce qui donne:

[DEBUG_FILTER] match ^From:.*$ with From:[email protected] == True
[DEBUG_FILTER] match ^From:.*$ with From:[email protected] == True
[REJECT] Mail reject: [ACTION] OK car 2x From (AND) !
[DEBUG_FILTER] match \d+ with From:[email protected] == False
[DEBUG_FILTER] match ^From:.*$ with From:[email protected] == True
[ACTION] Oups une lambda pour montrer qu'une action est n'importe quoi !
[DEBUG_FILTER] match ^From:.*$ with From:[email protected] == True
[DROP] Mail dropped
[DEBUG_FILTER] match \d+ with From:[email protected] == False
[DEBUG_FILTER] match \d+ with From:[email protected] == False
====== AUTRE EXEMPLE ======
[DEBUG_FILTER] match ^From:.*$ with From:[email protected] == True
Action OK
[REJECT] Mail reject: [ACTION] YES
[DEBUG_FILTER] match ^From:.*$ with From:[email protected] == True
[DEBUG_FILTER] match \d with From:[email protected] == False