From: Eric Wong <e@80x24.org>
To: meta@public-inbox.org
Subject: [PATCH] examples/unsubscribe.milter: limit scope of munging
Date: Sat, 25 Nov 2023 01:52:25 +0000 [thread overview]
Message-ID: <20231125015225.4052893-1-e@80x24.org> (raw)
We don't want the milter to munge List-Unsubscribe headers from
external (incoming) mlmmj lists, only lists hosted on the server
running unsubscribe.milter.
Adding support for an allow_domains file should've been enough,
but this further restricts the milter to only operating on Postfix
connections from localhost.
---
examples/unsubscribe.milter | 38 ++++++++++++++++++++++++++++++++++++-
1 file changed, 37 insertions(+), 1 deletion(-)
diff --git a/examples/unsubscribe.milter b/examples/unsubscribe.milter
index 216b0ddd..8c682012 100644
--- a/examples/unsubscribe.milter
+++ b/examples/unsubscribe.milter
@@ -27,6 +27,28 @@ my $crypt = Crypt::CBC->new(-key => $key,
-cipher => 'Blowfish');
$fh = $iv = $key = undef;
+my $allow_domains = '/etc/unsubscribe-milter.allow_domains';
+my $ALLOW_DOMAINS;
+if (open my $fh, '<', $allow_domains) {
+ local $/ = "\n";
+ chomp(my @l = <$fh>);
+ die "close: $!" unless eof($fh) && close($fh);
+ my %l = map { lc($_) => 1 } @l;
+ $ALLOW_DOMAINS = \%l;
+} else {
+ warn <<EOM;
+W: open $allow_domains: $! (all domains allowed)
+W: all mlmmj-looking messages will have List-Unsubscribe added,
+W: this is probably not what you want.
+EOM
+}
+
+# only allow users hitting SMTP server locally:
+# Is a config file necessary? Regexps are ugly for IP addresses
+# but Net::Patricia (or similar) seems like overkill. Ugly it is:
+my @ALLOW_ADDR = (qr/\A::1\z/, qr/\A127\./);
+my $ALLOW_ADDR = join('|', @ALLOW_ADDR);
+
my %cbs;
$cbs{connect} = sub {
my ($ctx) = @_;
@@ -88,10 +110,24 @@ $cbs{eom} = sub {
eval {
my $priv = $ctx->getpriv;
$ctx->setpriv({ header => {}, envrcpt => {} });
- my @rcpt = keys %{$priv->{envrcpt}};
+
+ # XXX my postfix (3.5.18-0+deb11u1) + Sendmail::PMilter
+ # instance doesn't seem to get {client_addr}, but
+ # {daemon_addr} seems to make sense since I only want it
+ # to apply to users connecting to postfix locally:
+ if ($ALLOW_ADDR) {
+ my $x = $ctx->getsymval('{daemon_addr}');
+ return SMFIS_CONTINUE if $x && $x !~ /$ALLOW_ADDR/;
+ }
# one recipient, one unique HTTP(S) URL
+ my @rcpt = keys %{$priv->{envrcpt}};
return SMFIS_CONTINUE if @rcpt != 1;
+ if ($ALLOW_DOMAINS) {
+ my $addr = $ctx->getsymval('{mail_addr}');
+ my (undef, $d) = split /\@/, $addr;
+ return SMFIS_CONTINUE if !$ALLOW_DOMAINS->{$d};
+ }
return SMFIS_CONTINUE if archive_addr(lc($rcpt[0]));
my $unsub = $priv->{header}->{'list-unsubscribe'} || [];
reply other threads:[~2023-11-25 1:52 UTC|newest]
Thread overview: [no followups] expand[flat|nested] mbox.gz Atom feed
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