+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 =~ /<([^>]+)>/sg));
+ }
+ }
+
+ # 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);
+ }
+ push(@ret, $mid) unless $seen->{$mid}++;
+ }
+ \@ret;
+}