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|
#!/usr/bin/perl -w
# Copyright (C) all contributors <meta@public-inbox.org>
# License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt>
use strict;
use Sendmail::PMilter qw(:all);
use IO::Socket;
use Crypt::CBC;
use MIME::Base64 qw(encode_base64url);
my $key_file = shift @ARGV or die "Usage: $0 KEY_FILE\n";
open my $fh, '<', $key_file or die "failed to open $key_file\n";
my ($key, $iv);
if (read($fh, $key, 8) != 8 || read($fh, $iv, 8) != 8 ||
read($fh, my $end, 8) != 0) {
die "KEY_FILE must be 16 bytes\n";
}
# optionally support unique mailto: subject in List-Unsubscribe,
# requires a custom rule in front of mlmmj, see __END__
my $unique_mailto = $ENV{UNIQUE_MAILTO};
# these parameters were chosen to generate shorter parameters
# to reduce the possibility of copy+paste errors
my $crypt = Crypt::CBC->new(-key => $key,
-iv => $iv,
-header => 'none',
-cipher => 'Blowfish');
$fh = $iv = $key = undef;
my %cbs;
$cbs{connect} = sub {
my ($ctx) = @_;
eval { $ctx->setpriv({ header => {}, envrcpt => {} }) };
warn $@ if $@;
SMFIS_CONTINUE;
};
$cbs{envrcpt} = sub {
my ($ctx, $addr) = @_;
eval {
$addr =~ tr!<>!!d;
$ctx->getpriv->{envrcpt}->{$addr} = 1;
};
warn $@ if $@;
SMFIS_CONTINUE;
};
$cbs{header} = sub {
my ($ctx, $k, $v) = @_;
eval {
my $k_ = lc $k;
if ($k_ eq 'list-unsubscribe') {
my $header = $ctx->getpriv->{header} ||= {};
my $ary = $header->{$k_} ||= [];
# we create placeholders in case there are
# multiple headers of the same name
my $cur = [];
push @$ary, $cur;
# This relies on mlmmj convention:
# $LIST+unsubscribe@$DOMAIN
if ($v =~ /\A<mailto:([^@]+)\+unsubscribe@([^>]+)>\z/) {
@$cur = ($k, $v, $1, $2);
# Mailman convention:
# $LIST-request@$DOMAIN?subject=unsubscribe
} elsif ($v =~ /\A<mailto:([^@]+)-request@
([^\?]+)\?subject=unsubscribe>\z/x) {
# @$cur = ($k, $v, $1, $2);
}
}
};
warn $@ if $@;
SMFIS_CONTINUE;
};
# We don't want people unsubscribing archivers:
sub archive_addr {
my ($addr) = @_;
return 1 if ($addr =~ /\@m\.gmane(?:-mx)?\.org\z/);
return 1 if ($addr eq 'archive@mail-archive.com');
0
}
$cbs{eom} = sub {
my ($ctx) = @_;
eval {
my $priv = $ctx->getpriv;
$ctx->setpriv({ header => {}, envrcpt => {} });
my @rcpt = keys %{$priv->{envrcpt}};
# one recipient, one unique HTTP(S) URL
return SMFIS_CONTINUE if @rcpt != 1;
return SMFIS_CONTINUE if archive_addr(lc($rcpt[0]));
my $unsub = $priv->{header}->{'list-unsubscribe'} || [];
my $n = 0;
my $added;
foreach my $u (@$unsub) {
# Milter indices are 1-based,
# not 0-based like Perl arrays
my $index = ++$n;
my ($k, $v, $list, $domain) = @$u;
next unless $k && $v && $list && $domain;
my $u = $crypt->encrypt($rcpt[0]);
$u = encode_base64url($u);
if ($unique_mailto) {
# $u needs to be in the Subject: header since
# +$EXTENSION is case-insensitive
my $s = "subject=$u";
$v = "<mailto:$list+unique-unsub\@$domain?$s>";
}
$v .= ",\n <https://$domain/u/$u/$list>";
$ctx->chgheader($k, $index, $v);
$added = 1;
}
# RFC 8058
$added and $ctx->addheader('List-Unsubscribe-Post',
'List-Unsubscribe=One-Click');
};
warn $@ if $@;
SMFIS_CONTINUE;
};
my $milter = Sendmail::PMilter->new;
# Try to inherit a socket from systemd or similar:
my $fds = $ENV{LISTEN_FDS};
if ($fds && (($ENV{LISTEN_PID} || 0) == $$)) {
die "$0 can only listen on one FD\n" if $fds != 1;
my $start_fd = 3;
my $s = IO::Socket->new_from_fd($start_fd, 'r') or
die "inherited bad FD from LISTEN_FDS: $!\n";
$milter->set_socket($s);
} else {
# fall back to binding a socket:
my $sock = 'unix:/var/spool/postfix/unsubscribe/unsubscribe.sock';
$milter->set_listen(1024);
my $umask = umask 0000;
$milter->setconn($sock);
umask $umask;
}
$milter->register('unsubscribe', \%cbs, SMFI_CURR_ACTS);
$milter->main();
__END__
# TMPMSG comes from dc-dlvr, it's populated before the above runs:
# TMPMSG=$(mktemp -t dc-dlvr.orig.$USER.XXXXXX || exit 1)
# cat >$TMPMSG
# I use something like this in front of mlmmj for UNIQUE_MAILTO
# $EXTENSION and $ORIGINAL_RECIPIENT are set by postfix, $list
# is a local mapping of addresses to mailing list names.
case $ORIGINAL_RECIPIENT in
foo+*) list=foo ;;
# ...
esac
case $EXTENSION in
unique-unsub)
u="$(formail -z -c -x Subject <$TMPMSG)"
d=$(expr "$ORIGINAL_RECIPIENT" : '^.*@\(.*\)')
# forward this to the unsubscribe.psgi service
curl -sSf https://$d/u/$u/$list >/dev/null
exit
;;
esac
/usr/bin/mlmmj-receive -L /path/to/mlmmj-spool/$list <"$TMPMSG"
exit
|
