+sub xref ($$$$) {
+ my ($self, $ng, $n, $mid) = @_;
+ my $ret = $self->{nntpd}->{servername} . " $ng->{newsgroup}:$n";
+
+ # num_for is pretty cheap and sometimes we'll lookup the existence
+ # of an article without getting even the OVER info. In other words,
+ # I'm not sure if its worth optimizing by scanning To:/Cc: and
+ # PublicInbox::ExtMsg on the PSGI end is just as expensive
+ foreach my $other (@{$self->{nntpd}->{grouplist}}) {
+ next if $ng eq $other;
+ my $num = eval { $other->mm->num_for($mid) } or next;
+ $ret .= " $other->{newsgroup}:$num";
+ }
+ $ret;
+}
+
+sub set_nntp_headers ($$$$$) {
+ my ($self, $hdr, $ng, $n, $mid) = @_;
+
+ # why? leafnode requires a Path: header for some inexplicable
+ # reason. We'll fake the shortest one possible.
+ $hdr->header_set('Path', 'y');
+
+ # leafnode (and maybe other NNTP clients) have trouble dealing
+ # with v2 messages which have multiple Message-IDs (either due
+ # to our own content-based dedupe or buggy git-send-email versions).
+ my @mids = $hdr->header('Message-ID');
+ if (scalar(@mids) > 1) {
+ my $mid0 = "<$mid>";
+ $hdr->header_set('Message-ID', $mid0);
+ my @alt = $hdr->header('X-Alt-Message-ID');
+ my %seen = map { $_ => 1 } (@alt, $mid0);
+ foreach my $m (@mids) {
+ next if $seen{$m}++;
+ push @alt, $m;
+ }
+ $hdr->header_set('X-Alt-Message-ID', @alt);
+ }