Added a small explanation and an excerpt from a configuraton file to
the dbfwfilter documentation. It demonstrates the use of both blacklist
and whitelist functionality in the same service.
The `allow` keyword can be used to substitute the `deny` keyword but this
was not documented. Also the fact that neither of them affect the actual
behavior of the filter was not very clearly stated.
The change fixes a crash when no filebase parameter is given for the filter.
The instance creation functions of these filters had spossible memory leaks in
case errors in the configuration occurred. In addition to these, they would be
successfully created even if unexpected parameters were given.
The tee, qlafilter, namedserverfilter and topfilter now support the same filter
options: case, ignorecase and extended. The extended filter option enables
the Extended Regular Expression syntax for the filters which is used when
matching queries.
When configured to log matching queries, the dbfwfilter will log all queries
that match a rule. The rule name, user name and the query itself are logged.
It is also possible to match all queries that do not match a rule. Only the user
name and query is logged in this mode.
