[PATCH 5/6] www: linkify inbox addresses in To/Cc headers

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

This makes it easier to discover contemporary messages
crossposted to other groups within the same WWW instance.
The internal cache is necessary for giant threads, and the
expiry mechanism is necessary to prevent attackers from
trivially OOM-ing.
---
 lib/PublicInbox/SearchView.pm |  2 +-
 lib/PublicInbox/View.pm       | 70 +++++++++++++++++++++++++++++++----
 2 files changed, 64 insertions(+), 8 deletions(-)

diff --git a/lib/PublicInbox/SearchView.pm b/lib/PublicInbox/SearchView.pm
index 8f851738..2d3e942c 100644
--- a/lib/PublicInbox/SearchView.pm
+++ b/lib/PublicInbox/SearchView.pm
@@ -322,7 +322,7 @@ EOM
 
 	# link $INBOX_DIR/description text to "recent" view around
 	# the newest message in this result set:
-	$ctx->{-t_max} = max(map { delete $_->{ts} } @$msgs);
+	$ctx->{-t_max} = max(map { $_->{ts} } @$msgs);
 
 	@$msgs = reverse @$msgs if $r;
 	$ctx->{msgs} = $msgs;
diff --git a/lib/PublicInbox/View.pm b/lib/PublicInbox/View.pm
index 02b93d7b..39ec35c3 100644
--- a/lib/PublicInbox/View.pm
+++ b/lib/PublicInbox/View.pm
@@ -38,7 +38,7 @@ sub msg_page_i {
 				: $ctx->gone('over');
 		$ctx->{mhref} = ($ctx->{nr} || $ctx->{smsg}) ?
 				"../${\mid_href($smsg->{mid})}/" : '';
-		if (_msg_page_prepare($eml, $ctx)) {
+		if (_msg_page_prepare($eml, $ctx, $smsg->{ts})) {
 			$eml->each_part(\&add_text_body, $ctx, 1);
 			print { $ctx->{zfh} } '</pre><hr>';
 		}
@@ -183,6 +183,59 @@ sub nr_to_s ($$$) {
 	$nr == 1 ? "$nr $singular" : "$nr $plural";
 }
 
+sub addr2urlmap ($) {
+	my ($ctx) = @_;
+	# cache makes a huge difference with /[tT] and large threads
+	my $key = PublicInbox::Git::host_prefix_url($ctx->{env}, '');
+	my $ent = $ctx->{www}->{pi_cfg}->{-addr2urlmap}->{$key} // do {
+		my $by_addr = $ctx->{www}->{pi_cfg}->{-by_addr};
+		my (%addr2url, $url);
+		while (my ($addr, $ibx) = each %$by_addr) {
+			$url = $ibx->base_url // $ibx->base_url($ctx->{env});
+			$addr2url{$addr} = ascii_html($url) if defined $url;
+		}
+		# don't allow attackers to randomly change Host: headers
+		# and OOM us if the server handles all hostnames:
+		my $tmp = $ctx->{www}->{pi_cfg}->{-addr2urlmap};
+		my @k = keys %$tmp; # random order
+		delete @$tmp{@k[0..3]} if scalar(@k) > 7;
+		my $re = join('|', map { quotemeta } keys %addr2url);
+		$tmp->{$key} = [ qr/\b($re)\b/i, \%addr2url ];
+	};
+	@$ent;
+}
+
+sub to_cc_html ($$$$) {
+	my ($ctx, $eml, $field, $t) = @_;
+	my @vals = $eml->header($field) or return ('', 0);
+	my (undef, $addr2url) = addr2urlmap($ctx);
+	my $pairs = PublicInbox::Address::pairs(join(', ', @vals));
+	my ($len, $line_len, $html) = (0, 0, '');
+	my ($pair, $url);
+	my ($cur_ibx, $env) = @$ctx{qw(ibx env)};
+	# avoid excessive ascii_html calls (already hot in profiles):
+	my @html = split /\n/, ascii_html(join("\n", map {
+		$_->[0] // (split(/\@/, $_->[1]))[0]; # addr user if no name
+	} @$pairs));
+	for my $n (@html) {
+		$pair = shift @$pairs;
+		if ($line_len) { # 9 = display width of ",\t":
+			if ($line_len + length($n) > COLS - 9) {
+				$html .= ",\n\t";
+				$len += $line_len;
+				$line_len = 0;
+			} else {
+				$html .= ', ';
+				$line_len += 2;
+			}
+		}
+		$line_len += length($n);
+		$url = $addr2url->{lc $pair->[1]};
+		$html .= $url ? qq(<a\nhref="$url$t">$n</a>) : $n;
+	}
+	($html, $len + $line_len);
+}
+
 # Displays the text of of the message for /$INBOX/$MSGID/[Tt]/ endpoint
 # this is already inside a <pre>
 sub eml_entry {
@@ -207,7 +260,8 @@ sub eml_entry {
 	my $ds = delete $smsg->{ds}; # for v1 non-Xapian/SQLite users
 
 	# Deleting these fields saves about 400K as we iterate across 1K msgs
-	delete @$smsg{qw(ts blob)};
+	my ($t, undef) = delete @$smsg{qw(ts blob)};
+	$t = $t ? '?t='.ts2str($t) : '';
 
 	my $from = _hdr_names_html($eml, 'From');
 	obfuscate_addrs($obfs_ibx, $from) if $obfs_ibx;
@@ -216,9 +270,8 @@ sub eml_entry {
 	my $mhref = $upfx . mid_href($mid_raw) . '/';
 	$rv .= qq{ (<a\nhref="$mhref">permalink</a> / };
 	$rv .= qq{<a\nhref="${mhref}raw">raw</a>)\n};
-	my $to = fold_addresses(_hdr_names_html($eml, 'To'));
-	my $cc = fold_addresses(_hdr_names_html($eml, 'Cc'));
-	my ($tlen, $clen) = (length($to), length($cc));
+	my ($to, $tlen) = to_cc_html($ctx, $eml, 'To', $t);
+	my ($cc, $clen) = to_cc_html($ctx, $eml, 'Cc', $t);
 	my $to_cc = '';
 	if (($tlen + $clen) > COLS) {
 		$to_cc .= '  To: '.$to."\n" if $tlen;
@@ -447,7 +500,7 @@ sub thread_html {
 
 	# link $INBOX_DIR/description text to "index_topics" view around
 	# the newest message in this thread
-	my $t = ts2str($ctx->{-t_max} = max(map { delete $_->{ts} } @$msgs));
+	my $t = ts2str($ctx->{-t_max} = max(map { $_->{ts} } @$msgs));
 	my $t_fmt = fmt_ts($ctx->{-t_max});
 
 	my $skel = '<hr><pre>';
@@ -613,7 +666,7 @@ sub add_text_body { # callback for each_part
 }
 
 sub _msg_page_prepare {
-	my ($eml, $ctx) = @_;
+	my ($eml, $ctx, $ts) = @_;
 	my $have_over = !!$ctx->{ibx}->over;
 	my $mids = mids_for_index($eml);
 	my $nr = $ctx->{nr}++;
@@ -649,6 +702,9 @@ href="d/">diff</a>)</pre><pre>];
 	$title[0] = $subj[0] // '(no subject)';
 	$hbuf .= "Date: $_\n" for $eml->header('Date');
 	$hbuf = ascii_html($hbuf);
+	my $t = $ts ? '?t='.ts2str($ts) : '';
+	my ($re, $addr2url) = addr2urlmap($ctx);
+	$hbuf =~ s!$re!qq(<a\nhref=").$addr2url->{lc $1}.qq($t">$1</a>)!sge;
 	$ctx->{-title_html} = ascii_html(join(' - ', @title));
 	if (my $obfs_ibx = $ctx->{-obfs_ibx}) {
 		obfuscate_addrs($obfs_ibx, $hbuf);