# Copyright (C) 2015-2021 all contributors
# License: AGPL-3.0+
#
# Various Message-ID-related functions.
package PublicInbox::MID;
use strict;
use warnings;
use base qw/Exporter/;
our @EXPORT_OK = qw(mid_clean id_compress mid2path mid_escape MID_ESC
mids references mids_for_index mids_in $MID_EXTRACT);
use URI::Escape qw(uri_escape_utf8);
use Digest::SHA qw/sha1_hex/;
require PublicInbox::Address;
use constant {
ID_MAX => 40, # SHA-1 hex length for HTML id anchors
MAX_MID_SIZE => 244, # max term size (Xapian limitation) - length('Q')
};
our $MID_EXTRACT = qr/<([^>]+)>/s;
sub mid_clean {
my ($mid) = @_;
defined($mid) or die "no Message-ID";
# MDA->precheck did more checking for us
if ($mid =~ $MID_EXTRACT) {
$mid = $1;
}
$mid;
}
# this is idempotent, used for HTML anchor/ids and such
sub id_compress {
my ($id, $force) = @_;
if ($force || $id =~ /[^a-zA-Z0-9_\-]/ || length($id) > ID_MAX) {
utf8::encode($id);
return sha1_hex($id);
}
$id;
}
sub mid2path {
my ($mid) = @_;
my ($x2, $x38) = ($mid =~ /\A([a-f0-9]{2})([a-f0-9]{38})\z/);
unless (defined $x38) {
# compatibility with old links (or short Message-IDs :)
$mid = mid_clean($mid);
utf8::encode($mid);
$mid = sha1_hex($mid);
($x2, $x38) = ($mid =~ /\A([a-f0-9]{2})([a-f0-9]{38})\z/);
}
"$x2/$x38";
}
# only intended for Message-ID and X-Alt-Message-ID
sub extract_mids {
my @mids;
for my $v (@_) {
my @cur = ($v =~ /$MID_EXTRACT/g);
if (@cur) {
push(@mids, @cur);
} else {
push(@mids, $v);
}
}
\@mids;
}
sub mids ($) {
my ($hdr) = @_;
my @mids = $hdr->header_raw('Message-ID');
uniq_mids(extract_mids(@mids));
}
# for Resent-Message-ID and maybe others
sub mids_in ($@) {
my ($eml, @headers) = @_;
uniq_mids(extract_mids(map { ($eml->header_raw($_)) } @headers));
}
# we allow searching on X-Alt-Message-ID since PublicInbox::NNTP uses them
# to placate some clients, and we want to ensure NNTP-only clients can
# import and index without relying on HTTP endpoints
sub mids_for_index ($) {
mids_in($_[0], qw(Message-ID X-Alt-Message-ID));
}
# last References should be IRT, but some mail clients do things
# out of order, so trust IRT over References iff IRT exists
sub references ($) {
my ($hdr) = @_;
my @mids;
foreach my $f (qw(References In-Reply-To)) {
my @v = $hdr->header_raw($f);
foreach my $v (@v) {
push(@mids, ($v =~ /$MID_EXTRACT/g));
}
}
# old versions of git-send-email would prompt users for
# In-Reply-To and users' muscle memory would use 'y' or 'n'
# as responses:
my %addr = ( y => 1, n => 1 );
foreach my $f (qw(To From Cc)) {
my @v = $hdr->header_raw($f);
foreach my $v (@v) {
$addr{$_} = 1 for (PublicInbox::Address::emails($v));
}
}
uniq_mids(\@mids, \%addr);
}
sub uniq_mids ($;$) {
my ($mids, $seen) = @_;
my @ret;
$seen ||= {};
foreach my $mid (@$mids) {
$mid =~ tr/\n\t\r//d;
if (length($mid) > MAX_MID_SIZE) {
warn "Message-ID: <$mid> too long, truncating\n";
$mid = substr($mid, 0, MAX_MID_SIZE);
}
$seen->{$mid} //= push(@ret, $mid);
}
\@ret;
}
# RFC3986, section 3.3:
sub MID_ESC () { '^A-Za-z0-9\-\._~!\$\&\'\(\)\*\+,;=:@' }
sub mid_escape ($) { uri_escape_utf8($_[0], MID_ESC) }
1;