contrib/sendmail-8.13.4/contrib/doublebounce.pl

   1 #!/usr/bin/perl
   2 # doublebounce.pl
   3 #
   4 # Return a doubly-bounced e-mail to postmaster.  Specific to sendmail,
   5 # updated to work on sendmail 8.12.6.
   6 #
   7 # Based on the original doublebounce.pl code by jr@terra.net, 12/4/97.
   8 # Updated by bicknell@ufp.org, 12/4/2002 to understand new sendmail DSN
   9 # bounces.  Code cleanup also performed, mainly making things more
  10 # robust.
  11 #
  12 # Original intro included below, lines with ##
  13 ##      attempt to return a doubly-bounced email to a postmaster
  14 ##      jr@terra.net, 12/4/97
  15 ##
  16 ##      invoke by creating an mail alias such as:
  17 ##              doublebounce:   "|/usr/local/sbin/doublebounce"
  18 ##      then adding this line to your sendmail.cf:
  19 ##              O DoubleBounceAddress=doublebounce
  20 ##
  21 ##      optionally, add a "-d" flag in the aliases file, to send a
  22 ##      debug trace to your own postmaster showing what is going on
  23 ##
  24 ##      this allows the "postmaster" address to still go to a human being,
  25 ##      while bounce messages can go to this script, which will bounce them
  26 ##      back to the postmaster at the sending site.
  27 ##
  28 ##      the algorithm is to scan the double-bounce error report generated
  29 ##      by sendmail on stdin, for the original message (it starts after the
  30 ##      second "Orignal message follows" marker), look for From, Sender, and
  31 ##      Received headers from the point closest to the sender back to the point
  32 ##      closest to us, and try to deliver a double-bounce report back to a
  33 ##      postmaster at one of these sites in the hope that they can
  34 ##      return the message to the original sender, or do something about
  35 ##      the fact that that sender's return address is not valid.
  36
  37 use Socket;
  38 use Getopt::Std;
  39 use File::Temp;
  40 use Sys::Syslog qw(:DEFAULT setlogsock);
  41 use strict;
  42 use vars qw( $opt_d $tmpfile);
  43
  44 # parseaddr()
  45 #       parse hostname from From: header
  46 #
  47 sub parseaddr {
  48   my($hdr) = @_;
  49   my($addr);
  50
  51   if ($hdr =~ /<.*>/) {
  52     ($addr) = $hdr =~ m/<(.*)>/;
  53     $addr =~ s/.*\@//;
  54     return $addr;
  55   }
  56   if ($addr =~ /\s*\(/) {
  57     ($addr) = $hdr =~ m/\s*(.*)\s*\(/;
  58     $addr =~ s/.*\@//;
  59     return $addr;
  60   }
  61   ($addr) = $hdr =~ m/\s*(.*)\s*/;
  62   $addr =~ s/.*\@//;
  63   return $addr;
  64 }
  65
  66 # sendbounce()
  67 #       send bounce to postmaster
  68 #
  69 #       this re-invokes sendmail in immediate and quiet mode to try
  70 #       to deliver to a postmaster.  sendmail's exit status tells us
  71 #       whether the delivery attempt really was successful.
  72 #
  73 sub send_bounce {
  74   my($addr, $from) = @_;
  75   my($st);
  76   my($result);
  77
  78   my($dest) = "postmaster\@" . parseaddr($addr);
  79
  80   if ($opt_d) {
  81     syslog ('info', "Attempting to send to user $dest");
  82   }
  83   open(MAIL, "| /usr/sbin/sendmail -oeq $dest");
  84   print MAIL <<EOT;
  85 From: Mail Delivery Subsystem <mail-router>
  86 Subject: Postmaster notify: double bounce
  87 Reply-To: nobody
  88 Errors-To: nobody
  89 Precedence: junk
  90 Auto-Submitted: auto-generated (postmaster notification)
  91
  92 The following message was received for an invalid recipient.  The
  93 sender's address was also invalid.  Since the message originated
  94 at or transited through your mailer, this notification is being
  95 sent to you in the hope that you will determine the real originator
  96 and have them correct their From or Sender address.
  97
  98 The from header on the original e-mail was: $from.
  99
 100    ----- The following is a double bounce -----
 101
 102 EOT
 103
 104   open(MSG, "<$tmpfile");
 105   print MAIL <MSG>;
 106   close(MSG);
 107   $result = close(MAIL);
 108   if ($result) {
 109     syslog('info', 'doublebounce successfully sent to %s', $dest);
 110   }
 111   return $result;
 112 }
 113
 114 sub main {
 115   # Get our command line options
 116   getopts('d');
 117
 118   # Set up syslog
 119   setlogsock('unix');
 120   openlog('doublebounce', 'pid', 'mail');
 121
 122   if ($opt_d) {
 123     syslog('info', 'Processing a doublebounce.');
 124   }
 125
 126   # The bounced e-mail may be large, so we'd better not try to buffer
 127   # it in memory, get a temporary file.
 128   $tmpfile = tmpnam();
 129
 130   if (!open(MSG, ">$tmpfile")) {
 131     syslog('err', "Unable to open temporary file $tmpfile");
 132     exit(75); # 75 is a temporary failure, sendmail should retry
 133   }
 134   print(MSG <STDIN>);
 135   close(MSG);
 136   if (!open(MSG, "<$tmpfile")) {
 137     syslog('err', "Unable to reopen temporary file $tmpfile");
 138     exit(74); # 74 is an IO error
 139   }
 140
 141   # Ok, now we can get down to business, find the original message
 142   my($skip_lines, $in_header, $headers_found, @addresses);
 143   $skip_lines = 0;
 144   $in_header = 0;
 145   $headers_found = 0;
 146   while (<MSG>) {
 147     if ($skip_lines > 0) {
 148       $skip_lines--;
 149       next;
 150     }
 151     chomp;
 152     # Starting message depends on your version of sendmail
 153     if (/^   ----- Original message follows -----$/ ||
 154         /^   ----Unsent message follows----$/ ||
 155         /^Content-Type: message\/rfc822$/) {
 156       # Found the original message
 157       $skip_lines++;
 158       $in_header = 1;
 159       $headers_found++;
 160       next;
 161     }
 162     if (/^$/) {
 163       if ($headers_found >= 2) {
 164          # We only process two deep, even if there are more
 165          last;
 166       }
 167       if ($in_header) {
 168          # We've found the end of a header, scan for the next one
 169          $in_header = 0;
 170       }
 171       next;
 172     }
 173     if ($in_header) {
 174       if (! /^[ \t]/) {
 175         # New Header
 176         if (/^(received): (.*)/i ||
 177             /^(reply-to): (.*)/i ||
 178             /^(sender): (.*)/i ||
 179             /^(from): (.*)/i ) {
 180           $addresses[$headers_found]{$1} = $2;
 181         }
 182         next;
 183       } else {
 184         # continuation header
 185         # we should really process these, but we don't yet
 186         next;
 187       }
 188     } else {
 189       # Nothing to do if we're not in a header
 190       next;
 191     }
 192   }
 193   close(MSG);
 194
 195   # Start with the original (inner) sender
 196   my($addr, $sent);
 197   foreach $addr (keys %{$addresses[2]}) {
 198     if ($opt_d) {
 199       syslog('info', "Trying to send to $addresses[2]{$addr} - $addresses[2]{\"From\"}");
 200     }
 201     $sent = send_bounce($addresses[2]{$addr}, $addresses[2]{"From"});
 202     last if $sent;
 203   }
 204   if (!$sent && $opt_d) {
 205     if ($opt_d) {
 206       syslog('info', 'Unable to find original sender, falling back.');
 207     }
 208     foreach $addr (keys %{$addresses[1]}) {
 209       if ($opt_d) {
 210         syslog('info', "Trying to send to $addresses[2]{$addr} - $addresses[2]{\"From\"}");
 211       }
 212       $sent = send_bounce($addresses[1]{$addr}, $addresses[2]{"From"});
 213       last if $sent;
 214     }
 215     if (!$sent) {
 216       syslog('info', 'Unable to find anyone to send a doublebounce notification');
 217     }
 218   }
 219
 220   unlink($tmpfile);
 221 }
 222
 223 main();
 224 exit(0);
 225