5.7.3. Class CombineMatcher

This matcher makes it possible to combine the results of several matchers using logical operations. CombineMatcher uses prefix-notation in its expressions and uses the following format: the operand, a comma, first argument, a comma, second argument. For example, an AND expression should be formatted the following way: (Z_AND, matcher1, matcher2). Expressions using more than one operands should be bracketed, e.g., (Z_OR (Z_AND, matcher1, matcher2), matcher3). The following oprations are available:

  • Z_AND : Logical AND operation.

  • Z_OR : Logical OR operation.

  • Z_XOR : Logical XOR operation.

  • Z_NOT : Logical negation.

  • Z_EQ : Logical equation.

Example 5.21. Whitelisting e-mail recipients

A simple use for CombineMatcher is to filter the recipients of e-mail addresses using the following process:

  1. An SmtpInvalidMatcher (called SmtpCheckrecipient) verifies that the recipient exists.

  2. A RegexpMatcher (called SmtpWhitelist) or RegexpFileMatcher is used to check if the address is on a predefined list (list of permitted addresses).

  3. A CombineMatcher (called SmtpCombineMatcher) sums up the results of the matchers with a logical AND operation.

  4. An SmtpProxy (called SmtpRecipientMatcherProxy) references SmtpCombineMatcher in its recipient_matcher attribute.

Python:
class SmtpRecipientMatcherProxy(SmtpProxy):
recipient_matcher="SmtpCombineMatcher"
def config(self):
super(SmtpRecipientMatcherProxy, self).config()

MatcherPolicy(name="SmtpCombineMatcher", matcher=CombineMatcher (expr=(Z_AND, "SmtpCheckrecipient", "SmtpWhitelist")))
MatcherPolicy(name="SmtpWhitelist", matcher=RegexpMatcher (match_list=("info@example.com",), ignore_list=None))
MatcherPolicy(name="SmtpCheckrecipient", matcher=SmtpInvalidRecipientMatcher (server_port=25, cache_timeout=60, attempt_delivery=FALSE, force_delivery_attempt=FALSE, server_name="recipientcheck.example.com"))
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