Support for RFC 1893 - Enhanced Mail System Status Codes

Patch by Hanno Hecker <hah@uu-x.de>.

Adds the RFC 1893 status codes to the messages which are returned to the
sending client.

git-svn-id: https://svn.perl.org/qpsmtpd/branches/0.3x@602 958fd67b-6ff1-0310-b445-bb7760255be9

lib/Qpsmtpd/DSN.pm

@@ -0,0 +1,621 @@
+#
+# Enhanced Mail System Status Codes - RFC 1893
+#
+package Qpsmtpd::DSN;
+use strict;
+use Qpsmtpd::Constants;
+
+=head1 NAME
+
+Qpsmtpd::DSN - Enhanced Mail System Status Codes - RFC 1893
+
+=head1 DESCRIPTION
+
+The B<Qpsmtpd::DSN> implements the I<Enhanced Mail System Status Codes> from
+RFC 1893.
+
+=head1 USAGE
+
+Any B<qpsmtpd> plugin can access these status codes. All sub routines are used
+the same way:
+ use Qpsmtpd::DSN;
+ ...;
+ return Qpsmtpd::DSN->relaying_denied();
+
+or
+
+ return Qpsmtpd::DSN->relaying_denied("Relaying from $ip denied");
+
+or 
+
+ return Qpsmtpd::DSN->relaying_denied(DENY,"Relaying from $ip denied");
+
+If no status message was given, it will use the predefined one from the 
+RFC. If the first argument is numeric, it will use this as a return code, 
+else the default return code is used. See below which default return code
+is used in the different functions.
+
+The first example will return 
+I<(DENY, "Relaying denied");>
+the others 
+I<(DENY, "Relaying from $ip denied");>
+which will be returned to qpsmtpd.
+
+In those sub routines which don't start with I<addr_, sys_, net_, proto_, 
+media_, sec_> I've added a default message which describes the status better
+than the RFC message.
+
+=cut
+
+my @rfc1893 = (
+    [ 
+        "Other or Undefined Status",                              # x.0.x
+    ],
+    [
+        "Other address status.",                                  # x.1.0
+        "Bad destination mailbox address.",                       # x.1.1
+        "Bad destination system address.",                        # x.1.2
+        "Bad destination mailbox address syntax.",                # x.1.3
+        "Destination mailbox address ambiguous.",                 # x.1.4
+        "Destination address valid.",                             # x.1.5
+        "Destination mailbox has moved, No forwarding address.",  # x.1.6
+        "Bad sender's mailbox address syntax.",                   # x.1.7
+        "Bad sender's system address.",                           # x.1.8
+    ],
+    [
+        "Other or undefined mailbox status.",                     # x.2.0
+        "Mailbox disabled, not accepting messages.",              # x.2.1
+        "Mailbox full.",                                          # x.2.2
+        "Message length exceeds administrative limit.",           # x.2.3
+        "Mailing list expansion problem.",                        # x.2.4
+    ],
+    [
+        "Other or undefined mail system status.",                 # x.3.0
+        "Mail system full.",                                      # x.3.1
+        "System not accepting network messages.",                 # x.3.2
+        "System not capable of selected features.",               # x.3.3
+        "Message too big for system.",                            # x.3.4
+        "System incorrectly configured.",                         # x.3.5
+    ],
+    [ 
+        "Other or undefined network or routing status.",          # x.4.0
+        "No answer from host.",                                   # x.4.1
+        "Bad connection.",                                        # x.4.2
+        "Directory server failure.",                              # x.4.3
+        "Unable to route.",                                       # x.4.4
+        "Mail system congestion.",                                # x.4.5
+        "Routing loop detected.",                                 # x.4.6
+        "Delivery time expired.",                                 # x.4.7
+    ],
+    [
+        "Other or undefined protocol status.",                    # x.5.0 
+        "Invalid command.",                                       # x.5.1 
+        "Syntax error.",                                          # x.5.2 
+        "Too many recipients.",                                   # x.5.3 
+        "Invalid command arguments.",                             # x.5.4 
+        "Wrong protocol version.",                                # x.5.5 
+    ],
+    [
+        "Other or undefined media error.",                        # x.6.0
+        "Media not supported.",                                   # x.6.1
+        "Conversion required and prohibited.",                    # x.6.2
+        "Conversion required but not supported.",                 # x.6.3
+        "Conversion with loss performed.",                        # x.6.4
+        "Conversion Failed.",                                     # x.6.5
+    ],
+    [
+        "Other or undefined security status.",                    # x.7.0
+        "Delivery not authorized, message refused.",              # x.7.1
+        "Mailing list expansion prohibited.",                     # x.7.2
+        "Security conversion required but not possible.",         # x.7.3
+        "Security features not supported.",                       # x.7.4
+        "Cryptographic failure.",                                 # x.7.5
+        "Cryptographic algorithm not supported.",                 # x.7.6
+        "Message integrity failure.",                             # x.7.7
+    ],
+);
+
+sub _status {
+    my $return = shift;
+    my $const = Qpsmtpd::Constants::return_code($return);
+    if ($const =~ /^DENYSOFT/) {
+        return 4;
+    } 
+    elsif ($const =~ /^DENY/) {
+        return 5;
+    }
+    elsif ($const eq 'OK' or $const eq 'DONE') {
+        return 2;
+    }
+    else { # err .... no :)
+        return 4; # just 2,4,5 are allowed.. temp error by default
+    }
+}
+
+sub _dsn {
+    my ($self,$return,$reason,$default,$subject,$detail) = @_;
+    if (!defined $return) {
+        $return = $default;
+    } 
+    elsif ($return !~ /^\d+$/) {
+        $reason = $return;
+        $return = $default;
+    }
+    my $msg = $rfc1893[$subject][$detail];
+    unless (defined $msg) {
+        $detail = 0;
+        $msg    = $rfc1893[$subject][$detail];
+        unless (defined $msg) {
+            $subject = 0;
+            $msg     = $rfc1893[$subject][$detail];
+        }
+    }
+    my $class = &_status($return);
+    if (defined $reason) {
+        $msg = $reason;
+    }
+    return ($return, "$msg (#$class.$subject.$detail)");
+}
+
+sub unspecified { shift->_dsn(shift,shift,DENYSOFT,0,0); }
+
+=head1 ADDRESS STATUS
+
+=over 9
+
+=item addr_unspecified
+
+X.1.0
+default: DENYSOFT
+
+=cut
+
+sub addr_unspecified { shift->_dsn(shift,shift,DENYSOFT,1,0); }
+
+=item no_such_user, addr_bad_dest_mbox
+
+X.1.1
+default: DENY
+
+=cut
+
+sub no_such_user         { shift->_dsn(shift,(shift||"No such user"),DENY,1,1); }
+sub addr_bad_dest_mbox   { shift->_dsn(shift,shift,DENY,1,1); }
+
+=item addr_bad_dest_system 
+
+X.1.2
+default: DENY
+
+=cut
+
+sub addr_bad_dest_system      { shift->_dsn(shift,shift,DENY,1,2); }
+
+=item addr_bad_dest_syntax
+
+X.1.3
+default: DENY
+
+=cut
+
+sub addr_bad_dest_syntax      { shift->_dsn(shift,shift,DENY,1,3); }
+
+=item addr_dest_ambigous
+
+X.1.4
+default: DENYSOFT
+
+=cut
+
+sub addr_dest_ambigous    { shift->_dsn(shift,shift,DENYSOFT,1,4); }
+
+=item addr_rcpt_ok
+
+X.1.5
+default: OK
+
+=cut
+
+# XXX: do we need this? Maybe in all address verifying plugins?
+sub addr_rcpt_ok  { shift->_dsn(shift,shift,OK,1,5); } 
+
+=item addr_mbox_moved 
+
+X.1.6
+default: DENY
+
+=cut
+
+sub addr_mbox_moved           { shift->_dsn(shift,shift,DENY,1,6); }
+
+=item addr_bad_from_syntax
+
+X.1.7
+default: DENY
+
+=cut 
+
+sub addr_bad_from_syntax      { shift->_dsn(shift,shift,DENY,1,7); }
+
+=item addr_bad_from_system
+
+X.1.8
+default: DENY
+
+=back
+
+=cut
+
+sub addr_bad_from_system      { shift->_dsn(shift,shift,DENY,1,8); }
+   
+=head1 MAILBOX STATUS
+
+=over 5
+
+=item mbox_unspecified
+
+X.2.0
+default: DENYSOFT
+
+=cut
+
+sub mbox_unspecified  { shift->_dsn(shift,shift,DENYSOFT,2,0); }
+
+=item mbox_disabled
+
+X.2.1
+default: DENY ...but RFC says:
+   The mailbox exists, but is not accepting messages.  This may
+   be a permanent error if the mailbox will never be re-enabled
+   or a transient error if the mailbox is only temporarily
+   disabled.
+
+=cut 
+
+sub mbox_disabled           { shift->_dsn(shift,shift,DENY,2,1); }
+
+=item mbox_full
+
+X.2.2
+default: DENYSOFT
+
+=cut
+
+sub mbox_full               { shift->_dsn(shift,shift,DENYSOFT,2,2); }
+
+=item mbox_msg_too_long 
+
+X.2.3
+default: DENY
+
+=cut
+
+sub mbox_msg_too_long            { shift->_dsn(shift,shift,DENY,2,3); }
+
+=item mbox_list_expansion_problem   
+
+X.2.4
+default: DENYSOFT
+
+=back
+
+=cut
+
+sub mbox_list_expansion_problem  { shift->_dsn(shift,shift,DENYSOFT,2,4); }
+
+=head1 MAIL SYSTEM STATUS
+
+=over 4
+
+=item sys_unspecified
+
+X.3.0
+default: DENYSOFT
+
+=cut
+
+sub sys_unspecified        { shift->_dsn(shift,shift,DENYSOFT,3,0); }
+
+=item sys_disk_full
+
+X.3.1
+default: DENYSOFT
+
+=cut
+
+sub sys_disk_full            { shift->_dsn(shift,shift,DENYSOFT,3,1); }
+
+=item sys_not_accepting_mail
+
+X.3.2
+default: DENYSOFT
+
+=cut
+
+sub sys_not_accepting_mail   { shift->_dsn(shift,shift,DENYSOFT,3,2); }
+
+=item sys_not_supported
+
+X.3.3
+default: DENYSOFT
+          Selected features specified for the message are not
+          supported by the destination system.  This can occur in
+          gateways when features from one domain cannot be mapped onto
+          the supported feature in another.
+
+=cut
+
+sub sys_not_supported        { shift->_dsn(shift,shift,DENYSOFT,3,3); }
+
+=item sys_msg_too_big           
+
+X.3.4
+default DENY
+
+=back
+
+=cut
+
+sub sys_msg_too_big          { shift->_dsn(shift,shift,DENY,3,4); }
+
+=head1 NETWORK AND ROUTING STATUS
+
+=cut
+
+=over 4
+
+=item net_unspecified 
+
+X.4.0
+default: DENYSOFT
+
+=cut 
+
+sub net_unspecified                { shift->_dsn(shift,shift,DENYSOFT,4,0); } 
+
+# not useful # sub net_no_answer   { shift->_dsn(shift,shift,4,1); } 
+# not useful # sub net_bad_connection { shift->_dsn(shift,shift,4,2); } 
+
+=item net_directory_server_failed, temp_resolver_failed
+
+X.4.3
+default: DENYSOFT
+
+=cut
+
+sub temp_resolver_failed { 
+      shift->_dsn(shift,
+                 (shift || "Temporary address resolution failure"),
+                 DENYSOFT,4,3); 
+}
+sub net_directory_server_failed  { shift->_dsn(shift,shift,DENYSOFT,4,3); }
+
+# not useful # sub net_unable_to_route { shift->_dsn(shift,shift,4,4); }
+
+=item net_system_congested
+
+X.4.5
+default: DENYSOFT
+
+=cut
+
+sub net_system_congested         { shift->_dsn(shift,shift,DENYSOFT,4,5); }
+
+=item net_routing_loop, too_many_hops
+
+X.4.6
+default: DENY, but RFC says:
+  A routing loop caused the message to be forwarded too many
+  times, either because of incorrect routing tables or a user
+  forwarding loop. This is useful only as a persistent
+  transient error.
+
+Why do we want to DENYSOFT something like this?
+ 
+=back
+
+=cut
+
+sub net_routing_loop   { shift->_dsn(shift,shift,DENY,4,6); }
+sub too_many_hops  { shift->_dsn(shift,(shift || "Too many hops"),DENY,4,6,); }
+# not useful # sub delivery_time_expired    { shift->_dsn(shift,shift,4,7); }
+
+=head1 MAIL DELIVERY PROTOCOL STATUS
+
+=over 6
+
+=item proto_unspecified
+
+X.5.0
+default: DENYSOFT
+
+=cut
+
+sub proto_unspecified     { shift->_dsn(shift,shift,DENYSOFT,5,0); }
+
+=item proto_invalid_command
+
+X.5.1
+default: DENY
+
+=cut
+
+sub proto_invalid_command        { shift->_dsn(shift,shift,DENY,5,1); }
+
+=item proto_syntax_error
+
+X.5.2
+default: DENY
+ 
+=cut
+
+sub proto_syntax_error           { shift->_dsn(shift,shift,DENY,5,2); }
+
+=item proto_rcpt_list_too_long, too_many_rcpts
+
+X.5.3
+default: DENYSOFT
+
+=cut
+
+sub proto_rcpt_list_too_long { shift->_dsn(shift,shift,DENYSOFT,5,3); }
+sub too_many_rcpts           { shift->_dsn(shift,shift,DENYSOFT,5,3); }
+
+=item proto_invalid_cmd_args 
+
+X.5.4
+default: DENY
+
+=cut
+
+sub proto_invalid_cmd_args       { shift->_dsn(shift,shift,DENY,5,4); }
+
+=item proto_wrong_version 
+
+X.5.5
+default: DENYSOFT
+
+=back
+
+=cut
+
+sub proto_wrong_version { shift->_dsn(shift,shift,DENYSOFT,5,5); }
+
+=head1 MESSAGE CONTENT OR MESSAGE MEDIA STATUS
+
+=over 5
+
+=item media_unspecified
+
+X.6.0
+default: DENYSOFT
+
+=cut
+
+sub media_unspecified      { shift->_dsn(shift,shift,DENYSOFT,6,0); }
+
+=item media_unsupported
+
+X.6.1
+default: DENY
+
+=cut
+
+sub media_unsupported      { shift->_dsn(shift,shift,DENY,6,1); }
+
+=item media_conv_prohibited
+
+X.6.2
+default: DENY
+
+=cut
+
+sub media_conv_prohibited        { shift->_dsn(shift,shift,DENY,6,2); }
+
+=item media_conv_unsupported
+
+X.6.3
+default: DENYSOFT
+
+=cut
+
+sub media_conv_unsupported       { shift->_dsn(shift,shift,DENYSOFT,6,3); }
+
+=item media_conv_lossy
+
+X.6.4
+default: DENYSOFT
+
+=back 
+
+=cut
+
+sub media_conv_lossy             { shift->_dsn(shift,shift,DENYSOFT,6,4); }
+
+=head1 SECURITY OR POLICY STATUS
+
+=over 8
+
+=item sec_unspecified
+
+X.7.0
+default: DENYSOFT
+
+=cut
+
+sub sec_unspecified                { shift->_dsn(shift,shift,DENYSOFT,7,0); }
+
+=item sec_sender_unauthorized, bad_sender_ip, relaying_denied 
+
+X.7.1
+default: DENY
+
+=cut
+
+sub sec_sender_unauthorized      { shift->_dsn(shift,shift,DENY,7,1); }
+sub bad_sender_ip { 
+    shift->_dsn(shift,(shift || "Bad sender's IP"),DENY,7,1,); 
+}
+sub relaying_denied { 
+    shift->_dsn(shift,(shift || "Relaying denied"),DENY,7,1); 
+}
+
+=item sec_list_dest_prohibited
+
+X.7.2
+default: DENY
+
+=cut
+
+sub sec_list_dest_prohibited    { shift->_dsn(shift,shift,DENY,7,2); }
+
+=item sec_conv_failed 
+
+X.7.3
+default: DENY
+
+=cut
+
+sub sec_conv_failed              { shift->_dsn(shift,shift,DENY,7,3); }
+
+=item sec_feature_unsupported 
+
+X.7.4
+default: DENY
+
+=cut
+
+sub sec_feature_unsupported      { shift->_dsn(shift,shift,DENY,7,4); }
+
+=item sec_crypto_failure
+
+X.7.5
+default: DENY
+
+=cut
+
+sub sec_crypto_failure               { shift->_dsn(shift,shift,DENY,7,5); }
+
+=item sec_crypto_algorithm_unsupported
+
+X.7.6
+default: DENYSOFT
+
+=cut
+
+sub sec_crypto_algorithm_unsupported { shift->_dsn(shift,shift,DENYSOFT,7,6); }
+
+=item sec_msg_integrity_failure
+
+X.7.7
+default: DENY
+
+=back
+
+=cut
+
+sub sec_msg_integrity_failure         { shift->_dsn(shift,shift,DENY,7,7); }
+
+1;
+
+# vim: st=4 sw=4 expandtab

plugins/check_badrcptto

@@ -1,4 +1,5 @@
 # this plugin checks the badrcptto config (like badmailfrom for rcpt address)
+use Qpsmtpd::DSN;
 
 sub hook_rcpt {
   my ($self, $transaction, $recipient) = @_;
@@ -9,9 +10,9 @@ sub hook_rcpt {
   for my $bad (@badrcptto) {
     $bad = lc $bad;
     $bad =~ s/^\s*(\S+)/$1/;
-    return (DENY, "mail to $bad not accepted here")
+    return Qpsmtpd::DSN->no_such_user("mail to $bad not accepted here")
       if $bad eq $from;
-    return (DENY, "mail to $bad not accepted here")
+    return Qpsmtpd::DSN->no_such_user("mail to $bad not accepted here")
       if substr($bad,0,1) eq '@' && $bad eq "\@$host";
   }
   return (DECLINED);

plugins/check_loop

@@ -25,8 +25,9 @@ Written by Keith C. Ivey
 Released to the public domain, 17 June 2005.
 
 =cut
+use Qpsmtpd::DSN;
 
-sub register {
+sub init {
   my ($self, $qp, @args) = @_;
 
   $self->{_max_hops} = $args[0] || 100;
@@ -45,7 +46,8 @@ sub hook_data_post {
     $transaction->header->get('Delivered-To');
 
   if ( $hops >= $self->{_max_hops} ) {
-    return DENY, "Too many hops. This message is looping.";
+    # default of too_many_hops is DENY, see comment in POD of Qpsmtpd::DSN
+    return Qpsmtpd::DSN->too_many_hops();
   }
 
   return DECLINED;

plugins/rcpt_ok

@@ -2,6 +2,7 @@
 #
 # It should be configured to be run _LAST_!
 #
+use Qpsmtpd::DSN;
 
 sub hook_rcpt {
   my ($self, $transaction, $recipient) = @_;
@@ -30,6 +31,8 @@ sub hook_rcpt {
     return (OK);
   }
   else {
-    return (DENY);
+    # default of relaying_denied is obviously DENY, 
+    # we use the default "Relaying denied" message...
+    return Qpsmtpd::DSN->relaying_denied();
   }
 }

plugins/require_resolvable_fromhost

@@ -1,3 +1,4 @@
+use Qpsmtpd::DSN;
 use Net::DNS qw(mx);
 use Socket;
 
@@ -17,15 +18,21 @@ sub hook_mail {
     }
   }
 
-  $sender->format ne "<>"
-    and $self->qp->config("require_resolvable_fromhost")
-    and !$self->check_dns($sender->host)
-    and return (DENYSOFT, 
-                ($sender->host
-                   ? "Could not resolve ". $sender->host
-                   : "FQDN required in the envelope sender"));
-  
-   return DECLINED;
+  if ($sender ne "<>" 
+      and $self->qp->config("require_resolvable_fromhost")
+      and !$self->check_dns($sender->host)) {
+    if ($sender->host) {
+      # default of temp_resolver_failed is DENYSOFT
+      return Qpsmtpd::DSN->temp_resolver_failed("Could not resolve " . $sender->host);
+    } 
+    else {
+      # default of addr_bad_from_system is DENY, we use DENYSOFT here to
+      # get the same behaviour as without Qpsmtpd::DSN...
+      return Qpsmtpd::DSN->addr_bad_from_system(DENYSOFT, 
+                               "FQDN required in the envelope sender");
+    }
+  }
+  return DECLINED;
 
 }
 

plugins/spamassassin

@@ -71,6 +71,7 @@ Make the "subject munge string" configurable
 =cut
 
 
+use Qpsmtpd::DSN;
 use Socket qw(:DEFAULT :crlf);
 use IO::Handle;
 
@@ -225,7 +226,8 @@ sub check_spam_reject {
   my $score = $self->get_spam_score($transaction) or return DECLINED;  
   $self->log(LOGDEBUG, "check_spam_reject: score=$score");
 
-  return (DENY, "spam score exceeded threshold")
+  # default of media_unsupported is DENY, so just change the message
+  return Qpsmtpd::DSN->media_unsupported("spam score exceeded threshold")
     if $score >= $self->{_args}->{reject_threshold};
 
   $self->log(LOGDEBUG, "check_spam_reject: passed");