DNSBL: Check spam IP address in DNS black lists

DNSBL - Spam IP address checker
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DNSBL is a class that performs IP address check in spam blocking lists as described
on http://ru.wikipedia.org/wiki/RBL

URLs of these lists are named 'checkers' in this class.
Available checkers are:
            'spamhaus'  => '.zen.spamhaus.org',
            'spamcop'   => '.bl.spamcop.net',
            'dsbl'      => '.list.dsbl.org',
            'ordb'      => '.relays.ordb.org',
            'sorbs'     => '.dnsbl.sorbs.net',
            'njabl'     => '.dnsbl.njabl.org'
'spamhaus' is the default,
'spamhaus' & spamcop' are available for group checking by default.

You can change the default checker.
You can enable/disable checker for group checking.

DNSBL checks given IP address in default checker by default :-)
It can check in your selected checker or in available fror group checking ones as you wish.

You can take the list of available checkers, the name of default checker.
Also you can set default checker to any of available ones.

Testing method is CheckSpamIP().
It takes up to 2 arguments - ip address and checker (optional).
It returns true when IP exitsts in spam-lists of checker or at least one of all group available checkers,
or false when not or when ip address is local or not correct.

DNSBL correctly processes incorrect some DNS-server answers, as described at
http://www.spamhaus.org/faq/answers.lasso?section=DNSBL%20Usage#243

See example.php for usage.
See DNSBL.php for detailed comments.

Good luck in spam fighting!


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Alexey Znayev, 2011, znaeff@mail.ru, http://xbsoft.org, http://xbsoft.ru