[courier-users] [PATCH] reformime: return exit code of external program

[Flavio Stanchina]

I see that filtering is all the rage here lately, so I'm proposing this 
small patch to reformime that allowed me to create a simple but 
effective virus filter from maildroprc. The patch is against Debian 
version 0.42.2-10. BTW, Racke, I see you read this list too... do you 
have experimental packages for more recent versions?

Background: I'm administering a couple of mail servers and after the 
MyDoom outbreak I took a deeper look into virus filtering. All my users 
on Windows have local virus scanners, but the more viruses I stop on the 
server, the less support requests I get...

I looked at Amavis and other solutions, but I'm uncomfortable with such 
beasts. I was looking for something easier to set up. I discovered the 
existence of reformime a few days ago, and it looked like the -X option 
was what I needed to call ClamAV safely from maildrop, except that 
there's no easy way to signal that a virus has been found. Here's what 
my patch does: if the external program terminates with a nonzero exit 
status, reformime terminates and returns (program exit status + 20).

This is what I put into /etc/courier/maildroprc:
  # log delivered emails for debugging purposes
  logfile ./maildrop.log
  exception {
    `/usr/bin/reformime -X /usr/bin/clamdscan --disable-summary -`
    if ($RETURNCODE == 21)
    {
      log "Virus found!"
      to "./Maildir/.Virus"
    }
  }
This is the log generated by an infected email:
  courierlocal: id=X,from=<Y>,addr=<Z>: stream: OK
  courierlocal: id=X,from=<Y>,addr=<Z>: stream: Worm.Dumaru.Y.enc FOUND
  courierlocal: id=X,from=<Y>,addr=<Z>: reformime: /usr/bin/clamdscan 
exited with status 1.
  courierlocal: id=X,from=<Y>,addr=<Z>,size=21594,success: Message 
delivered.

Please, apply. If you are uncomfortable with changing the current 
behaviour of the -X option, I would suggesti adding a new option for 
this purpose, let's say -Z.

--
Ciao,
    Flavio Stanchina
    Trento - Italy
diff -ur courier-0.42.2-10/debian/changelog courier-0.42.2-10flavio/debian/changelog
--- courier-0.42.2-10/debian/changelog  2004-02-09 16:11:08.000000000 +0100
+++ courier-0.42.2-10flavio/debian/changelog    2004-02-09 16:16:40.000000000 +0100
@@ -1,3 +1,9 @@
+courier (0.42.2-10flavio) experimental; urgency=low
+
+  * reformime: -X returns the exit code of the launched program.
+
+ -- Flavio Stanchina <[EMAIL PROTECTED]>  Mon,  9 Feb 2004 22:15:45 +0100
+
 courier (0.42.2-10) unstable; urgency=low
 
   * updated French translation of debconf templates (Closes: #213816,
diff -ur courier-0.42.2-10/rfc2045/reformime.1 
courier-0.42.2-10flavio/rfc2045/reformime.1
--- courier-0.42.2-10/rfc2045/reformime.1       2003-04-21 22:56:15.000000000 +0200
+++ courier-0.42.2-10flavio/rfc2045/reformime.1 2004-02-09 16:52:39.000000000 +0100
@@ -208,6 +208,10 @@
 \fBreformime\fR's liking. If the \fB-s\fR option is
 not specified, the program runs once
 for every MIME section in the message.
+.B "EXPERIMENTAL:"
+If the external program terminates with a nonzero exit status,
+\fBreformime\fR terminates and returns
+(program exit status + 20).
 .sp
 .RS
 .B "Note:"
diff -ur courier-0.42.2-10/rfc2045/reformime.c 
courier-0.42.2-10flavio/rfc2045/reformime.c
--- courier-0.42.2-10/rfc2045/reformime.c       2003-03-07 01:47:30.000000000 +0100
+++ courier-0.42.2-10flavio/rfc2045/reformime.c 2004-02-09 16:43:34.000000000 +0100
@@ -615,6 +615,16 @@
        while ((p2=wait(&waitstat)) != pid && p2 != -1)
                ;
        free(f);
+
+       if ((p2 == pid) && WIFEXITED(waitstat))
+       {
+               if (WEXITSTATUS(waitstat) != 0)
+               {
+                       fprintf(stderr, "reformime: %s exited with status %d.\n",
+                               argv[0], WEXITSTATUS(waitstat));
+                       exit(WEXITSTATUS(waitstat) + 20);
+               }
+       }
 }
 
 static void extract_section(struct rfc2045 *top_rfcp, const char *mimesection,