postfix, integrating memcache as a lookup table using tcp_table

 email, linux, memcached, modules, perl, postfix, smtp  7 Responses »
Jul 202011
 

I have not had time to do the test “postfix memcached patch” because there are no idle servers that can be used for the experiment. instead, I’ve made a tutorial how to integrate memcached as a “postfix lookup table” with the help of tcp_table and a simple perl script.

Indeed, tcp_table “table lookup protocol” is one of the most powerful tools as well as the regexp and pcre, in my opinion. although client-server connection is not protected and and the server is not authenticated.

yes, I did a lot of experiments using tcp_table and perl scripts. it made me realize that I can do almost everything I need and make postfix as my favorite MTA.

Things required:

OK, first we create a simple perl script that allows you to handle the protocols of tcp_table. let’s call it memc.pl

#!/usr/bin/perl
use strict;
use warnings;
use Sys::Syslog qw(:DEFAULT setlogsock);
use Cache::Memcached;

# Configure the memcached server
my $memd = new Cache::Memcached {
            'servers' => [ '127.0.0.1:11211' ],
};

#
# Initalize and open syslog.
#
openlog('postfix/memcached','pid','mail');

sub qrymemc {
        return unless /^get\s+(.+)/i;
        my $kmemc = lc($1);
        chomp($kmemc);
        trim($kmemc);
        my $vmemc = $memd->get($kmemc);
        if (defined $vmemc) {
                return ($kmemc,$vmemc);
        }
        return;
}

sub trim{
        $_[0]=~s/^\s+//;
        $_[0]=~s/\s+$//;
        return;
}

#
# Autoflush standard output.
#
select STDOUT; $|++;

while (<>) {
        chomp;
        if (/^get\s+(.+)/i) {
                my $data = lc($1);
                my @res = qrymemc($data);
                syslog("info","data: %s", $data);
                if (@res) {
                        chomp(@res);
                        print "200 $res[1]\n";
                        syslog("info","Found: key = %s, value = %s", $res[0], $res[1]);
                        next;
                }
        }
        print "200 DUNNO\n";
}

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Postfix, Dynamic OverQuota User Map Script Using Bash And Inotifywait

 bash, database, email, kernel, linux, mysql, postfix, smtp  No Responses »
Jul 142011
 

I recently experimented with a simple bash script, inotifywait and  smtpd_recipient_restrictions (check_recipient_access) to map email users who have exceeded the quota.

Well, during testing, i’ve noticed when using hash/texthash lookup tables, it needed to be reloaded in order smtpd detect changes in table.so i’ve made quick test on mysql_tables it seem updating record on tables will immediately able to be queried

Mapping can be done as follows:
main.cf:

smtpd_recipient_restrictions =
    check_recipient_access mysql:/etc/postfix/mysql_quota_access.cf,
	...
	...

mysql_quota_access.cf

user = user
password = password
hosts = localhost
dbname = postfixdb
query = SELECT qaction FROM quota WHERE username='%s'

create mysql table called quota:

 CREATE TABLE quota (
 id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
 username VARCHAR(100),
 qaction VARCHAR(100)
 ) TYPE=innodb;

Here’s the idea, inotifywait will continuously monitor the maildir directory recursively, and updates “qaction” field on “quota” mysql table whenever new mail arrived or whenever there is email deleted from the maildir.

initial map, can be produced by retrieving user information from database.for example, username information in the database “postfixdb” with the table name “mailbox” and field “username”.

# for i in `mysql -u user -ppassword -D postfixdb -e 'SELECT  username FROM mailbox' | grep -v username`;do mysql -u user -ppassword -D postfixdb -e "INSERT INTO quota (username, qaction) VALUES ('$i', 'DUNNO')";

With this script,value of qaction field on mysql quota table will change continuously as the user’s maildir contents that keeps changing.
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