KAV4LMS EXIM-DLFUNC-FILTER 
================================================================================

1. Description
--------------------------------------------------------------------------------
Exim-dlfunc is a new method for integrating our product
with Exim. It is similar to local_scan() API method,
but it does not require to have a special build of Exim.
It is inspired by Victor Ustugov's work [1], and
it is the first such implementation that is able to
modify e-mails, not just to scan them.
It is based on dlfunc string expansion method [2] and
a series of ACL's [3]. As a result of calling the dlfunc
string expansion, our own library is loaded, and it has
access to local_scan() API and Exim's queue. The library
uses a GPL'd implementation of the communication protocol
to communicate with KAV4LMS server for scanning emails.
All kav4lms actions are supported: warn, drop, reject,
cure, delete, rename and skip.


2. Building
--------------------------------------------------------------------------------
In order to build it, you need to do the following, in
exim-dlfunc directory:

./configure
make

The binaries will be created in:
exim-dlfunc/command-gpl/.libs
exim-dlfunc/exim-lib/.libs

3. Integration/installation with Exim
--------------------------------------------------------------------------------
In order for the library to be called, you need to add the
following lines into the Exim configuration file, ACLs section
(begin acls), in the acl_check_data ACL:

-----
  warn set acl_m0 = ${dlfunc{/path/to/libkavexim.so}{kav}\
       {local:/var/run/kav4lms/kavmd.sock}{/tmp/exim-dlfunc}}
  accept condition = ${if match{$acl_m0}{\N^kav: continue\N}{yes}{no}}
       logwrite = kav returned continue
  deny condition = ${if match{$acl_m0}{\N^kav: reject.*\N}{yes}{no}}
       logwrite = kav returned reject
       message = Kaspersky Anti-Virus rejected the mail
  discard condition = ${if match{$acl_m0}{\N^kav: drop.*\N}{yes}{no}}
       logwrite = kav returned drop
       message = Kaspersky Anti-Virus dropped the mail
  defer condition = ${if match{$acl_m0}{\N^kav: temporary failure.*\N}{yes}{no}}
       logwrite = kav returned temporary failure
       message = Temporary failure
-----

The last two parameters are the socket to be used for
communicating with kavmd and the temporary directory.
The socket can be either a local socket as in the above
example, which is also the default setting, or it can
be of the form:

inet:<port>@<ip/host>

In this case, a TCP/IP socket is used.

Notes:
- depending on the OS and distribution, there may be a
single configuration file containing all the sections,
or there may be several files containing one or more
sections each
- acl_check_data may have another name, and is defined
by using acl_smtp_data directive in the main configuration
area/file.


4. References
--------------------------------------------------------------------------------
[1] - http://mta.org.ua/exim-4.67-conf/dlfunc/aveserver/
[2] - http://exim.org/exim-html-current/doc/html/spec_html/ch11.html#SECTexpansionitems
[3] - http://exim.org/exim-html-current/doc/html/spec_html/ch40.html