dccifd do not compute Body checksum when the message body is under 30 bytes

Martin Pála Martin.Pala@oskar.cz
Mon Aug 22 15:17:47 UTC 2005


Hello,

during tests of dccifd conected to postfix as before-queue filter i tried to send short message:

--8<--
Subject: test
Body: test
--8<--

Message was posted via postfix/SMTP:

--8<--
[root@e2sgw01 ~]# telnet e2sgw01 25
Trying 217.77.161.168...
Connected to e2sgw01.
Escape character is '^]'.
220 e2sgw01.oskarmobil.cz ESMTP Postfix
EHLO test
250-e2sgw01.oskarmobil.cz
250-PIPELINING
250-SIZE 786432
250-ETRN
250 8BITMIME
MAIL FROM:<test@test.cz>
250 Ok
RCPT TO:<foo@bar.cz>
250 Ok
DATA
354 End data with <CR><LF>.<CR><LF>
Subject: test

test
.
250 Ok: queued as 06C4218049
QUIT
221 Bye
Connection closed by foreign host.
--8<--


Postfix then adds several headers (such as Received, etc.) and pass it to dccifd proxy running on 127.0.0.1:10025.

Dccifd received the mail, but has not computed the Body checksum - is it correct?

I tried then to increase the message size, the Body checksum started to be computed as soon as the message body size was 30 bytes or more.


I think it could be better when dccifd will report the Body checksum even in the case that the message has one byte. This way can dccifd defend the mailboxes against flood of short messages (i think it is no problem to write some spam under 30 bytes or just use it as mailbox DOS).



The dccifd message log follows:
--8<--
[root@e2sgw01 ~]# cat /var/dcc/log/msg.2ndJeP
VERSION: 3
DATE: 08/22/05 16:33:18 CEST
IP: e2sgw01.oskarmobil.cz  ::ffff:217.77.161.168
HELO: test
env_From: <test@test.cz>  mail_host=test.cz
env_To: <foo@bar.cz>  addr=  dir=

Received: from test (e2sgw01.oskarmobil.cz [217.77.161.168])
        by e2sgw01.oskarmobil.cz (Postfix) with ESMTP
        for <foo@bar.cz>; Mon, 22 Aug 2005 16:33:16 +0200 (CEST)
Subject: test

test

### end of message body ########################
2ndJeP pass SMTP response: 220 e2sgw01.oskarmobil.cz ESMTP Postfix
2ndJeP SMTP command: EHLO e2sgw01.oskarmobil.cz
2ndJeP pass SMTP response: 250-e2sgw01.oskarmobil.cz
2ndJeP pass SMTP response: 250-PIPELINING
2ndJeP pass SMTP response: 250-SIZE 786432
2ndJeP pass SMTP response: 250-ETRN
2ndJeP pass SMTP response: 250-XFORWARD NAME ADDR PROTO HELO SOURCE
2ndJeP pass SMTP response: 250 8BITMIME
2ndJeP SMTP command: XFORWARD NAME=e2sgw01.oskarmobil.cz ADDR=217.77.161.168 HELO=test PROTO=ESMTP ...

X-DCC-OSKAR-Metrics: e2sgw01.oskarmobil.cz 100; Body=0
                            reported: 1               checksum
                       IP: df769584 d584a974 0f1c5464 4d2b5373
                 env_From: 69d68da1 f0f9158d 5cfe1513 26b65b13
               Message-ID: d41d8cd9 8f00b204 e9800998 ecf8427e
                 Received: 8ebeb9d0 88937c32 655d5051 884c84a9

2ndJeP pass SMTP response: 250 Ok: queued as 06C4218049
result: accept
--8<--





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