nntp: delimit Newsgroup: header with commas

[public-inbox.git] / lib / PublicInbox / NNTP.pm

diff --git a/lib/PublicInbox/NNTP.pm b/lib/PublicInbox/NNTP.pm
index 102ef42cf4455d8e4035b288172f19d693f85901..783c0076e7d0771ba76f6a607be63f26c54ba80a 100644 (file)
--- a/lib/PublicInbox/NNTP.pm
+++ b/lib/PublicInbox/NNTP.pm
@@ -432,12 +432,17 @@ sub set_nntp_headers ($$) {
                $hdr->header_set('X-Alt-Message-ID', @alt);
        }
 
-       # clobber some
+       # clobber some existing headers
        my $ibx = $smsg->{-ibx};
        my $xref = xref($smsg->{nntp}, $ibx, $smsg->{num}, $mid);
        $hdr->header_set('Xref', $xref);
-       $xref =~ s/:[0-9]+//g;
-       $hdr->header_set('Newsgroups', (split(/ /, $xref, 2))[1]);
+
+       # RFC 5536 3.1.4
+       my $newsgroups = (split(/ /, $xref, 2))[1]; # drop server name
+       $newsgroups =~ s/:[0-9]+\b//g; # drop NNTP article numbers
+       $newsgroups =~ tr/ /,/;
+       $hdr->header_set('Newsgroups', $newsgroups);
+
        header_append($hdr, 'List-Post', "<mailto:$ibx->{-primary_address}>");
        if (my $url = $ibx->base_url) {
                $mid = mid_escape($mid);