[pmg-devel] [PATCH pmg-api v3 2/2] fix #2795: add support for DSN
Stoiko Ivanov
s.ivanov at proxmox.com
Thu Nov 25 20:20:01 CET 2021
store the esmtp parameters for the MAIL and RCPT command needed to
support Delivery status notifications (DSN - RFC 3464 [0]) and pass
them to the outbound postfix instance (port 10025) used for sending
the mail further (see also [1]).
Postfix does syntax-checking before passing the mail to the proxy
also in before-queue filtering mode.
Since the handling is done by postfix we don't need to generate any
DSN in the regular case.
For mail put into quarantine I decided to skip sending a delivery
notification (on the expectation, that few people are using quarantine
outbound, and that I would not consider a mail put in quarantine as
delivered successfully)
We only store a whitelist of parameters, instead of passing all,
because some parameters might not be valid anymore after processing
(e.g. SIZE)
The DSN EHLO keyword was added for the after-queue filtering case -
else the inbound postfix is the system that sends out the
notification.
tested with various combinations of the -V, -N and -R parameters to
sendmail (e.g.):
```
/usr/sbin/sendmail -N success,delay,failure \
-V '<xxxxxxxx at test.proxmox.com>'\
-R hdrs test at test.domain.example
```
tested the following scenarios in before and after-queue filter mode:
* successful delivery
* successful delivery with set DSN
* failed delivery (recipient rejects with 544)
* failed delivery with DSN
* delivering a mail with empty envelope sender (bounce)
some tests with invalid combinations were also done with netcat.
[0] https://tools.ietf.org/html/rfc3464
[1] http://www.postfix.org/DSN_README.html
Signed-off-by: Stoiko Ivanov <s.ivanov at proxmox.com>
---
src/PMG/RuleDB/Accept.pm | 2 +-
src/PMG/RuleDB/BCC.pm | 6 +++++-
src/PMG/SMTP.pm | 23 ++++++++++++++++++++---
src/PMG/Utils.pm | 19 ++++++++++++++++---
src/bin/pmg-smtp-filter | 1 +
5 files changed, 43 insertions(+), 8 deletions(-)
diff --git a/src/PMG/RuleDB/Accept.pm b/src/PMG/RuleDB/Accept.pm
index 0bcf250..cd67ea2 100644
--- a/src/PMG/RuleDB/Accept.pm
+++ b/src/PMG/RuleDB/Accept.pm
@@ -122,7 +122,7 @@ sub execute {
} else {
my ($qid, $code, $mess) = PMG::Utils::reinject_mail(
$entity, $msginfo->{sender}, $tg,
- $msginfo->{xforward}, $msginfo->{fqdn});
+ $msginfo->{xforward}, $msginfo->{fqdn}, $msginfo->{param});
if ($qid) {
foreach (@$tg) {
syslog('info', "%s: accept mail to <%s> (%s) (rule: %s)", $queue->{logid}, encode('UTF-8', $_), $qid, $rulename);
diff --git a/src/PMG/RuleDB/BCC.pm b/src/PMG/RuleDB/BCC.pm
index a8db3f5..d364690 100644
--- a/src/PMG/RuleDB/BCC.pm
+++ b/src/PMG/RuleDB/BCC.pm
@@ -156,9 +156,13 @@ sub execute {
$entity->print ($fh);
print $fh "bcc end\n";
} else {
+ my $param = {};
+ for my $bcc (@bcc_targets) {
+ $param->{rcpt}->{$bcc}->{notify} = "never";
+ }
my $qid = PMG::Utils::reinject_mail(
$entity, $msginfo->{sender}, \@bcc_targets,
- $msginfo->{xforward}, $msginfo->{fqdn}, 1);
+ $msginfo->{xforward}, $msginfo->{fqdn}, $param);
foreach (@bcc_targets) {
if ($qid) {
syslog('info', "%s: bcc to <%s> (rule: %s, %s)", $queue->{logid}, $_, $rulename, $qid);
diff --git a/src/PMG/SMTP.pm b/src/PMG/SMTP.pm
index b3550d4..fbf5c95 100644
--- a/src/PMG/SMTP.pm
+++ b/src/PMG/SMTP.pm
@@ -38,6 +38,7 @@ sub reset {
delete $self->{smtputf8};
delete $self->{xforward};
delete $self->{status};
+ delete $self->{param};
}
sub abort {
@@ -77,6 +78,7 @@ sub loop {
$self->reply ("250-ENHANCEDSTATUSCODES");
$self->reply ("250-8BITMIME");
$self->reply ("250-SMTPUTF8");
+ $self->reply ("250-DSN");
$self->reply ("250-XFORWARD NAME ADDR PROTO HELO");
$self->reply ("250 OK.");
$self->{lmtp} = 1 if ($cmd eq 'lhlo');
@@ -103,9 +105,16 @@ sub loop {
if ($args =~ m/^from:\s*<([^\s\>]*?)>( .*)?$/i) {
delete $self->{to};
my ($from, $opts) = ($1, $2 // '');
- if ($opts =~ m/\sSMTPUTF8/) {
- $self->{smtputf8} = 1;
- $from = decode('UTF-8', $from);
+
+ for my $opt (split(' ', $opts)) {
+ if ($opt =~ /(ret|envid)=([^ =]+)/i ) {
+ $self->{param}->{mail}->{$1} = $2;
+ } elsif ($opt =~ m/smtputf8/i) {
+ $self->{smtputf8} = 1;
+ $from = decode('UTF-8', $from);
+ } else {
+ #ignore everything else
+ }
}
$self->{from} = $from;
$self->reply ('250 2.5.0 OK');
@@ -117,7 +126,15 @@ sub loop {
} elsif ($cmd eq 'rcpt') {
if ($args =~ m/^to:\s*<([^\s\>]+?)>( .*)?$/i) {
my $to = $self->{smtputf8} ? decode('UTF-8', $1) : $1;
+ my $opts = $2 // '';
push @{$self->{to}} , $to;
+ for my $opt (split(' ', $opts)) {
+ if ($opt =~ /(notify|orcpt)=([^ =]+)/i ) {
+ $self->{param}->{rcpt}->{$to}->{$1} = $2;
+ } else {
+ #ignore everything else
+ }
+ }
$self->reply ('250 2.5.0 OK');
next;
} else {
diff --git a/src/PMG/Utils.pm b/src/PMG/Utils.pm
index 92c3a7a..4eebfa5 100644
--- a/src/PMG/Utils.pm
+++ b/src/PMG/Utils.pm
@@ -203,7 +203,7 @@ sub subst_values {
}
sub reinject_mail {
- my ($entity, $sender, $targets, $xforward, $me, $nodsn) = @_;
+ my ($entity, $sender, $targets, $xforward, $me, $params) = @_;
my $smtp;
my $resid;
@@ -244,15 +244,28 @@ sub reinject_mail {
$mail_opts .= " SMTPUTF8" if $has_utf8_targets;
}
+ if (defined($params->{mail})) {
+ my $mailparams = $params->{mail};
+ for my $p (keys %$mailparams) {
+ $mail_opts .= " $p=$mailparams->{$p}";
+ }
+ }
+
if (!$smtp->_MAIL("FROM:" . $sender_addr . $mail_opts)) {
syslog('err', "smtp error - got: %s %s", $smtp->code, scalar ($smtp->message));
die "smtp from: ERROR";
}
- my $rcpt_opts = $nodsn ? " NOTIFY=NEVER" : "";
-
foreach my $target (@$targets) {
my $rcpt_addr;
+ my $rcpt_opts = '';
+ if (defined($params->{rcpt}->{$target})) {
+ my $rcptparams = $params->{rcpt}->{$target};
+ for my $p (keys %$rcptparams) {
+ $rcpt_opts .= " $p=$rcptparams->{$p}";
+ }
+ }
+
if (utf8::is_utf8($target)) {
$rcpt_addr = encode('UTF-8', $smtp->_addr($target));
} else {
diff --git a/src/bin/pmg-smtp-filter b/src/bin/pmg-smtp-filter
index b070c8e..45eb125 100755
--- a/src/bin/pmg-smtp-filter
+++ b/src/bin/pmg-smtp-filter
@@ -640,6 +640,7 @@ sub handle_smtp {
$msginfo->{sender} = $smtp->{from};
$msginfo->{xforward} = $smtp->{xforward};
$msginfo->{targets} = $smtp->{to};
+ $msginfo->{param} = $smtp->{param};
my $dkim_sign = $msginfo->{trusted} && $pmg_cfg->get('admin', 'dkim_sign');
if ($dkim_sign) {
--
2.30.2
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