[PATCH] nntp: make ->ALL Xref generation more fuzzy

[Eric Wong <e@80x24.org>]

Eric Wong <e@80x24.org> wrote:
> So every message posted to linux-mtd@lists.infradead.org
> nntp://rskvuqcfnfizkjg6h5jvovwb3wkikzcwskf54lfpymus6mxrzw67b5ad.onion/org.infradead.lists.linux-mtd
> fails to match cross posts to Xref:, which is bad, too...
> 
> I have an idea to make it less bad, maybe it'll work...

Deployed to
nntp://rskvuqcfnfizkjg6h5jvovwb3wkikzcwskf54lfpymus6mxrzw67b5ad.onion/
and it seems to be OK when comparing messages cross-posted
between org.kernel.vger.* and org.infradead.lists.*

-------------8<------------
Subject: [PATCH] nntp: make ->ALL Xref generation more fuzzy

For ->ALL users, this mitigates the regression introduced
by commit 811b8d3cbaa790f59b7b107140b86248da16499b
("nntp: xref: use ->ALL extindex if available"), since
it's common to cross post messages to some mailing
lists with per-list trailers for unsubscribe information.

We won't bother dealing with Bcc-ed messages since those
are nearly all spam when it comes to public mailing lists.

Fixes: 811b8d3cbaa790f5 ("nntp: xref: use ->ALL extindex if available")
Link: https://public-inbox.org/meta/20201130194201.GA6687@dcvr/
---
 lib/PublicInbox/ExtSearch.pm | 31 +++++++++++-----------
 lib/PublicInbox/NNTP.pm      | 50 ++++++++++++++++++++++++++----------
 t/extsearch.t                |  3 ++-
 3 files changed, 53 insertions(+), 31 deletions(-)

diff --git a/lib/PublicInbox/ExtSearch.pm b/lib/PublicInbox/ExtSearch.pm
index 20ec3224..80455d8d 100644
--- a/lib/PublicInbox/ExtSearch.pm
+++ b/lib/PublicInbox/ExtSearch.pm
@@ -50,8 +50,7 @@ sub git {
 	$self->{git} //= PublicInbox::Git->new("$self->{topdir}/ALL.git");
 }
 
-# returns an arrayref of [ $NEWSGROUP_NAME:$ART_NO ] using
-# the `xref3' table
+# returns a hashref of { $NEWSGROUP_NAME => $ART_NO } using the `xref3' table
 sub nntp_xref_for { # NNTP only
 	my ($self, $xibx, $xsmsg) = @_;
 	my $dbh = over($self)->dbh;
@@ -69,7 +68,9 @@ SELECT ibx_id FROM inboxes WHERE eidx_key = ? LIMIT 1
 SELECT docid FROM xref3 WHERE oidbin = ? AND xnum = ? AND ibx_id = ? LIMIT 1
 
 	$sth->bind_param(1, pack('H*', $xsmsg->{blob}), SQL_BLOB);
-	$sth->bind_param(2, $xsmsg->{num});
+
+	# NNTP::cmd_over can set {num} to zero according to RFC 3977 8.3.2
+	$sth->bind_param(2, $xsmsg->{num} || $xsmsg->{-orig_num});
 	$sth->bind_param(3, $xibx_id);
 	$sth->execute;
 	my $docid = $sth->fetchrow_array // do {
@@ -81,9 +82,9 @@ EOF
 
 	# LIMIT is number of newsgroups on server:
 	$sth = $dbh->prepare_cached(<<'', undef, 1);
-SELECT ibx_id,xnum FROM xref3 WHERE docid = ?
+SELECT ibx_id,xnum FROM xref3 WHERE docid = ? AND ibx_id != ?
 
-	$sth->execute($docid);
+	$sth->execute($docid, $xibx_id);
 	my $rows = $sth->fetchall_arrayref;
 
 	my $eidx_key_sth = $dbh->prepare_cached(<<'', undef, 1);
@@ -91,18 +92,16 @@ SELECT eidx_key FROM inboxes WHERE ibx_id = ? LIMIT 1
 
 	my %xref = map {
 		my ($ibx_id, $xnum) = @$_;
-		if ($ibx_id == $xibx_id) {
-			();
-		} else {
-			$eidx_key_sth->execute($ibx_id);
-			my $eidx_key = $eidx_key_sth->fetchrow_array;
-
-			# only include if there's a newsgroup name
-			$eidx_key && index($eidx_key, '/') >= 0 ?
-				() : ($eidx_key => $xnum)
-		}
+
+		$eidx_key_sth->execute($ibx_id);
+		my $eidx_key = $eidx_key_sth->fetchrow_array;
+
+		# only include if there's a newsgroup name
+		$eidx_key && index($eidx_key, '/') >= 0 ?
+			() : ($eidx_key => $xnum)
 	} @$rows;
-	[ map { "$_:$xref{$_}" } sort keys %xref ]; # match NNTP LIST order
+	$xref{$xibx->{newsgroup}} = $xsmsg->{num};
+	\%xref;
 }
 
 sub mm { undef }
diff --git a/lib/PublicInbox/NNTP.pm b/lib/PublicInbox/NNTP.pm
index 3b16a66a..e0916011 100644
--- a/lib/PublicInbox/NNTP.pm
+++ b/lib/PublicInbox/NNTP.pm
@@ -17,6 +17,8 @@ use PublicInbox::DS qw(now);
 use Digest::SHA qw(sha1_hex);
 use Time::Local qw(timegm timelocal);
 use PublicInbox::GitAsyncCat;
+use PublicInbox::Address;
+
 use constant {
 	LINE_MAX => 512, # RFC 977 section 2.3
 	r501 => '501 command syntax error',
@@ -417,27 +419,42 @@ sub header_append ($$$) {
 	$hdr->header_set($k, @v, $v);
 }
 
+sub xref_by_tc ($$$) {
+	my ($xref, $pi_cfg, $smsg) = @_;
+	my $by_addr = $pi_cfg->{-by_addr};
+	my $groups = $pi_cfg->{-by_newsgroup};
+	my $mid = $smsg->{mid};
+	for my $f (qw(to cc)) {
+		my @ibxs = map {
+			$by_addr->{lc($_)} // ()
+		} (PublicInbox::Address::emails($smsg->{$f} // ''));
+		for my $ibx (@ibxs) {
+			$groups->{my $ngname = $ibx->{newsgroup}} or next;
+			next if defined $xref->{$ngname};
+			$xref->{$ngname} = eval { $ibx->mm->num_for($mid) };
+		}
+	}
+}
+
 sub xref ($$$) {
 	my ($self, $cur_ibx, $smsg) = @_;
 	my $nntpd = $self->{nntpd};
-	my $cur_ngname = $cur_ibx->{newsgroup};
-	my $ret = "$nntpd->{servername} $cur_ngname:$smsg->{num}";
+	my $cur_ng = $cur_ibx->{newsgroup};
+	my $xref;
 	if (my $ALL = $nntpd->{pi_config}->ALL) {
-		if (my $ary = $ALL->nntp_xref_for($cur_ibx, $smsg)) {
-			$ret .= join(' ', '', @$ary) if scalar(@$ary);
-		}
-		# better off wrong than slow if there's thousands of groups,
-		# so no fallback to the slow path below:
+		$xref = $ALL->nntp_xref_for($cur_ibx, $smsg);
+		xref_by_tc($xref, $nntpd->{pi_config}, $smsg);
 	} else { # slow path
+		$xref = { $cur_ng => $smsg->{num} };
 		my $mid = $smsg->{mid};
-		my $groups = $nntpd->{pi_config}->{-by_newsgroup};
-		for my $xngname (@{$nntpd->{groupnames}}) {
-			next if $cur_ngname eq $xngname;
-			my $xibx = $groups->{$xngname} or next;
-			my $num = eval { $xibx->mm->num_for($mid) } or next;
-			$ret .= " $xngname:$num";
+		for my $ibx (values %{$nntpd->{pi_config}->{-by_newsgroup}}) {
+			next if defined($xref->{$ibx->{newsgroup}});
+			my $num = eval { $ibx->mm->num_for($mid) } // next;
+			$xref->{$ibx->{newsgroup}} = $num;
 		}
 	}
+	my $ret = "$nntpd->{servername} $cur_ng:".delete($xref->{$cur_ng});
+	$ret .= " $_:$xref->{$_}" for (sort keys %$xref);
 	$ret;
 }
 
@@ -930,8 +947,13 @@ sub cmd_over ($;$) {
 		more($self, '224 Overview information follows (multi-line)');
 
 		# Only set article number column if it's the current group
+		# (RFC 3977 8.3.2)
 		my $self_ng = $self->{ng};
-		$smsg->{num} = 0 if (!$self_ng || $self_ng ne $ng);
+		if (!$self_ng || $self_ng ne $ng) {
+			# set {-orig_num} for nntp_xref_for
+			$smsg->{-orig_num} = $smsg->{num};
+			$smsg->{num} = 0;
+		}
 		more($self, over_line($self, $ng, $smsg));
 		'.';
 	} else {
diff --git a/t/extsearch.t b/t/extsearch.t
index 2a1b05c7..2b8b88ea 100644
--- a/t/extsearch.t
+++ b/t/extsearch.t
@@ -72,7 +72,8 @@ EOF
 	ok($pi_cfg->ALL, '->ALL');
 	my $ibx = $pi_cfg->{-by_newsgroup}->{'v2.example'};
 	my $ret = $pi_cfg->ALL->nntp_xref_for($ibx, $ibx->over->get_art(1));
-	is_deeply($ret, ['v1.example:1'], '->nntp_xref_for');
+	is_deeply($ret, { 'v1.example' => 1, 'v2.example' => 1 },
+		'->nntp_xref_for');
 }
 
 SKIP: {