# Copyright (C) 2013-2021 all contributors
# License: AGPL-3.0+
#
# For the -mda script (mail delivery agent)
package PublicInbox::MDA;
use strict;
use warnings;
use PublicInbox::MsgTime;
use PublicInbox::Address;
use constant MAX_SIZE => 1024 * 500; # same as spamc default, should be tunable
use constant MAX_MID_SIZE => 244; # max term size - 1 in Xapian
our @BAD_HEADERS = (
# postfix
qw(delivered-to x-original-to), # prevent training loops
# The rest are taken from Mailman 2.1.15:
# could contain passwords:
qw(approved approve x-approved x-approve urgent),
# could be used phishing:
qw(return-receipt-to disposition-notification-to x-confirm-reading-to),
# Pegasus mail:
qw(x-pmrqc)
);
# drop plus addressing for matching
sub __drop_plus {
my ($str_addr) = @_;
$str_addr =~ s/\+.*\@/\@/;
$str_addr;
}
# do not allow Bcc, only Cc and To if recipient is set
sub precheck {
my ($klass, $simple, $address) = @_;
my @mid = $simple->header('Message-ID');
return 0 if scalar(@mid) != 1;
my $mid = $mid[0];
return 0 if (length($mid) > MAX_MID_SIZE);
return 0 unless usable_str(length(''), $mid) && $mid =~ /\@/;
return 0 unless usable_str(length('u@h'), $simple->header("From"));
return 0 unless usable_str(length(':o'), $simple->header("Subject"));
return 0 unless usable_date($simple->header("Date"));
return 0 if length($simple->as_string) > MAX_SIZE;
alias_specified($simple, $address);
}
sub usable_str {
my ($len, $str) = @_;
defined($str) && length($str) >= $len;
}
sub usable_date {
defined(eval { PublicInbox::MsgTime::str2date_zone($_[0]) });
}
sub alias_specified {
my ($simple, $address) = @_;
my @address = ref($address) eq 'ARRAY' ? @$address : ($address);
my %ok = map {
lc(__drop_plus($_)) => 1;
} @address;
foreach my $line ($simple->header('Cc'), $simple->header('To')) {
my @addrs = PublicInbox::Address::emails($line);
foreach my $addr (@addrs) {
if ($ok{lc(__drop_plus($addr))}) {
return 1;
}
}
}
return 0;
}
sub set_list_headers {
my ($class, $simple, $dst) = @_;
unless (defined $simple->header('List-Id')) {
my $pa = $dst->{-primary_address};
$pa =~ tr/@/./; # RFC2919
$simple->header_set("List-Id", "<$pa>");
}
}
sub inboxes_for_list_id ($$) {
my ($klass, $pi_cfg, $simple) = @_;
# newer Email::Simple allows header_raw, as does Email::MIME:
my @list_ids = $simple->can('header_raw') ?
$simple->header_raw('List-Id') :
$simple->header('List-Id');
my @dests;
for my $list_id (@list_ids) {
$list_id =~ /<[ \t]*(.+)?[ \t]*>/ or next;
if (my $ibx = $pi_cfg->lookup_list_id($1)) {
push @dests, $ibx;
}
}
if (scalar(@list_ids) > 1) {
warn "W: multiple List-IDs in message:\n";
warn "W: List-ID: $_\n" for @list_ids
}
\@dests;
}
1;