Broken Return-Path: header (better solution!)

[Julian Field]

At 14:41 09/05/2002, you wrote:
>At 12:39 09/05/2002, you wrote:
>>I don't know what it was supposed to do, but when I apply this patch, it
>>just deletes the Return-Path header from the warning message AND from the
>>infected message.
>
>That should only happen if you are using MailScanner on the server that
>does the final message delivery into the user's mailbox.
>
>Is the Return-Path header any use anyway? I don't see why as it is trivial
>to fake.
>
>I'll try to write you a better version of the solution.

Patch required to both sendmail.pl and mta-specific.pl. These patches are a
bit big, so I have attached a new sendmail.pl and mta-specific.pl to this
message.

Note ***THESE ARE FOR THE LATEST VERSION 3.13-2 ONLY***
If you want to add this functionality to earlier releases, you will have to
insert the following patches by hand.

If these work okay, they'll get rolled into the next minor release.

-----------------------------------------------------------
*** /usr/local/mailscanner/mailscanner/bin/sendmail.pl  Tue May  7 05:03:31
2002
--- sendmail.pl Thu May  9 15:12:28 2002
***************
*** 569,578 ****
--- 569,579 ----
       Lock::unlockclose($DfOut);
       #undef $DfOut;

       # Construct all the new headers
       $newheaders = MTA::ConstructHeaders($entities->{$id}->stringify_header);
+     $newheaders = MTA::FixReturnPath($newheaders);
       $newheaders = AddCleanHeader($newheaders) if $Clean eq 'clean';
       $newheaders = AddInfectedHeader($newheaders) if $Clean eq 'dirty';
       $newheaders = AddUnscannedHeader($newheaders) if $Clean eq 'unscanned';
       if (defined($IsSpam->{$id})) {
         $newheaders = MTA::AddHeader($newheaders, $Config::SpamHeader,
-----------------------------------------------------------
and
-----------------------------------------------------------
*** /usr/local/mailscanner/mailscanner/bin/mta-specific.pl      Thu May  9
12:24:34 2002
--- mta-specific.pl     Thu May  9 15:18:35 2002
***************
*** 137,146 ****
--- 137,150 ----
   # Given filehandle open for reading, merge envelope data (excepting
   # headers) from filehandle with headers from string, and return new
   # envelope data in string, ready to be written back to new
   # envelope queue file.
   #
+ # FixReturnPath:
+ # In sendmail the Return-Path: header needs some flags at the start
+ # of the line. Exim requires no change.
+ #
   # KickMessage:
   # Given id, tell MTA to make a delivery attempt.
   #

   my($cat) = "/bin/cat";
***************
*** 467,476 ****
--- 471,485 ----

       $envelope .= $headers;
       return $envelope;
     }

+   sub FixReturnPath {
+     my($headers) = @_;
+     return $headers;
+   }
+
     sub KickMessage {
       my(@ids) = @_;
       my($idlist);

       # Need to check this with Nick to discover how to attempt delivery
of multiple messages
***************
*** 519,529 ****

     sub ReadQf {
       my($RQf) = @_;
       my($InHeader, @results, $msginfo, $from, @to, $subject);
       my($ip);
!     my($Line);

       $InHeader = 0;
       while(<$RQf>) {
         last if /^\./; # Bat book section 23.9.19
         $Line = $_;
--- 528,538 ----

     sub ReadQf {
       my($RQf) = @_;
       my($InHeader, @results, $msginfo, $from, @to, $subject);
       my($ip);
!     my($Line, $Flags);

       $InHeader = 0;
       while(<$RQf>) {
         last if /^\./; # Bat book section 23.9.19
         $Line = $_;
***************
*** 550,562 ****
         }
         $InHeader = 1 if $Line =~ /^H/;
         ($InHeader=0),next unless $Line =~ /^[H\t ]/;
         $Line =~ s/^H//;
         # JKF 18/04/2001 Delete ?flags? for 0 or more flags for sendmail 8.11
!       $Line =~ s/^\?[^?]*\?//;
!       # JKF 06/05/2002 Fix broken Return-Path: header bug
!       next if $Line =~ /^Return-Path:/i;
         push @results, $Line;
         if ($Line =~ /^Subject:\s+(\S.*)$/i) {
           $subject = $1;
           #print "Subject is \"$subject\"\n";
         }
--- 559,572 ----
         }
         $InHeader = 1 if $Line =~ /^H/;
         ($InHeader=0),next unless $Line =~ /^[H\t ]/;
         $Line =~ s/^H//;
         # JKF 18/04/2001 Delete ?flags? for 0 or more flags for sendmail 8.11
!       $Line =~ s/^(\?[^?]*\?)//;
!       $Flags = $1;
!       # JKF 09/05/2002 Fix broken Return-Path: header bug
!       $MTA::ReturnPathFlags = $Flags if $Line =~ /^Return-Path:/i;
         push @results, $Line;
         if ($Line =~ /^Subject:\s+(\S.*)$/i) {
           $subject = $1;
           #print "Subject is \"$subject\"\n";
         }
***************
*** 707,716 ****
--- 717,732 ----
       }

       $envelope .= $headers;
       $envelope .= ".\n";
       return $envelope;
+   }
+
+   sub FixReturnPath {
+     my($headers) = @_;
+     $headers =~ s/^H(Return-Path:)/H$MTA::ReturnPathFlags$1/mi;
+     return $headers;
     }

     sub KickMessage {
       my(@ids) = @_;
       my($idlist);
-----------------------------------------------------------
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--
Julian Field                Teaching Systems Manager
jkf at ecs.soton.ac.uk         Dept. of Electronics & Computer Science
Tel. 023 8059 2817          University of Southampton
                             Southampton SO17 1BJ