NAME

       Mail::Milter::Chain - Perl extension for chaining milter callbacks

SYNOPSIS

           use Mail::Milter::Chain;

           my $chain = new Mail::Milter::Chain({ connect => \&foo, ... }, ...);
           $chain->register({ connect => \&bar, ... });
           $chain->register({ connect => \&baz, ... });

           $chain->accept_break(1);

           use Sendmail::Milter;
           ...
           Sendmail::Milter::register('foo', $chain, SMFI_CURR_ACTS);

DESCRIPTION

       Mail::Milter::Chain allows multiple milter callback sets to be registered in a single milter server
       instance, simulating multiple milters running in separate servers.  This is typically much less resource
       intensive than running each milter in its own server process.

       Any contained milter returning SMFIS_REJECT, SMFIS_TEMPFAIL, or SMFIS_DISCARD will terminate the entire
       chain and return the respective code up to the containing chain or milter server.

       Normally, a milter returning SMFIS_ACCEPT will remove only that milter from the chain, allowing others to
       continue processing the message.  Alternatively, SMFIS_ACCEPT can be made to terminate the entire chain
       as is done for error results; see "accept_break()" below.

       A "Mail::Milter::Chain" is itself a milter callback hash reference, and can thus be passed directly to
       "Sendmail::Milter::register()" or another Mail::Milter::Chain container.  IMPORTANT CAVEAT:  Once this
       object has been registered with a parent container (a milter or another chain), DO NOT call "register()"
       on this object any longer.  This will result in difficult to diagnose problems at callback time.

METHODS

       new([HASHREF, ...])
           Creates  a  Mail::Milter::Chain  object.   For  convenience,  accepts  one  or  more  hash references
           corresponding to individual callback sets that will be registered with this chain.

       accept_break(FLAG)
           If FLAG is 0 (the default), SMFIS_ACCEPT will only  remove  the  current  milter  from  the  list  of
           callbacks, thus simulating a completely independent milter server.

           If  FLAG  is  1,  SMFIS_ACCEPT  will  terminate the entire chain and propagate SMFIS_ACCEPT up to the
           parent chain or milter server.  This allows a milter to provide a sort of "whitelist"  effect,  where
           SMFIS_ACCEPT speaks for the entire chain rather than just one milter callback set.

           This method returns a reference to the object itself, allowing this method call to be chained.

       register(HASHREF)
           Registers  a  callback  set with this chain.  Do not call after this chain has itself been registered
           with a parent container (chain or milter server).

AUTHOR

       Todd Vierling, <tv@duh.org> <tv@pobox.com>

SEE ALSO

       Mail::Milter, Sendmail::Milter

perl v5.36.0                                       2023-01-22                           Mail::Milter::Chain(3pm)