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-rw-r--r--lib/PublicInbox/View.pm552
1 files changed, 297 insertions, 255 deletions
diff --git a/lib/PublicInbox/View.pm b/lib/PublicInbox/View.pm
index 26094082..44e1f2a8 100644
--- a/lib/PublicInbox/View.pm
+++ b/lib/PublicInbox/View.pm
@@ -7,6 +7,7 @@ package PublicInbox::View;
 use strict;
 use v5.10.1;
 use List::Util qw(max);
+use Text::Wrap qw(wrap); # stdlib, we need Perl 5.6+ for $huge
 use PublicInbox::MsgTime qw(msg_datestamp);
 use PublicInbox::Hval qw(ascii_html obfuscate_addrs prurl mid_href
                         ts2str fmt_ts);
@@ -19,6 +20,7 @@ use PublicInbox::WwwStream qw(html_oneshot);
 use PublicInbox::Reply;
 use PublicInbox::ViewDiff qw(flush_diff);
 use PublicInbox::Eml;
+use POSIX qw(strftime);
 use Time::Local qw(timegm);
 use PublicInbox::Smsg qw(subject_normalized);
 use PublicInbox::ContentHash qw(content_hash);
@@ -36,14 +38,12 @@ sub msg_page_i {
                                 : $ctx->gone('over');
                 $ctx->{mhref} = ($ctx->{nr} || $ctx->{smsg}) ?
                                 "../${\mid_href($smsg->{mid})}/" : '';
-                my $obuf = $ctx->{obuf} = _msg_page_prepare_obuf($eml, $ctx);
-                if (length($$obuf)) {
-                        multipart_text_as_html($eml, $ctx);
-                        $$obuf .= '</pre><hr>';
+                if (_msg_page_prepare($eml, $ctx, $smsg->{ts})) {
+                        $eml->each_part(\&add_text_body, $ctx, 1);
+                        print { $ctx->{zfh} } '</pre><hr>';
                 }
-                delete $ctx->{obuf};
-                $$obuf .= html_footer($ctx, $ctx->{first_hdr}) if !$ctx->{smsg};
-                $$obuf;
+                html_footer($ctx, $ctx->{first_hdr}) if !$ctx->{smsg};
+                ''; # XXX TODO cleanup
         } else { # called by WwwStream::async_next or getline
                 $ctx->{smsg}; # may be undef
         }
@@ -56,14 +56,12 @@ sub no_over_html ($) {
         my $eml = PublicInbox::Eml->new($bref);
         $ctx->{mhref} = '';
         PublicInbox::WwwStream::init($ctx);
-        my $obuf = $ctx->{obuf} = _msg_page_prepare_obuf($eml, $ctx);
-        if (length($$obuf)) {
-                multipart_text_as_html($eml, $ctx);
-                $$obuf .= '</pre><hr>';
+        if (_msg_page_prepare($eml, $ctx)) { # sets {-title_html}
+                $eml->each_part(\&add_text_body, $ctx, 1);
+                print { $ctx->{zfh} } '</pre><hr>';
         }
-        delete $ctx->{obuf};
-        eval { $$obuf .= html_footer($ctx, $eml) };
-        html_oneshot($ctx, 200, $obuf);
+        html_footer($ctx, $eml);
+        $ctx->html_done;
 }
 
 # public functions: (unstable)
@@ -82,7 +80,8 @@ sub msg_page {
         # allow user to easily browse the range around this message if
         # they have ->over
         $ctx->{-t_max} = $smsg->{ts};
-        PublicInbox::WwwStream::aresponse($ctx, 200, \&msg_page_i);
+        $ctx->{-spfx} = '../' if $ibx->{-repo_objs};
+        PublicInbox::WwwStream::aresponse($ctx, \&msg_page_i);
 }
 
 # /$INBOX/$MESSAGE_ID/#R
@@ -184,6 +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 {
@@ -208,7 +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;
@@ -217,9 +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;
@@ -242,20 +294,22 @@ sub eml_entry {
                 my $html = ascii_html($irt);
                 $rv .= qq(In-Reply-To: &lt;<a\nhref="$href">$html</a>&gt;\n)
         }
-        $rv .= "\n";
+        say { $ctx->zfh } $rv;
 
         # scan through all parts, looking for displayable text
         $ctx->{mhref} = $mhref;
-        $ctx->{obuf} = \$rv;
-        $eml->each_part(\&add_text_body, $ctx, 1);
-        delete $ctx->{obuf};
+        $ctx->{changed_href} = "#e$id"; # for diffstat "files? changed,"
+        $eml->each_part(\&add_text_body, $ctx, 1); # expensive
 
         # add the footer
-        $rv .= "\n<a\nhref=#$id_m\nid=e$id>^</a> ".
+        $rv = "\n<a\nhref=#$id_m\nid=e$id>^</a> ".
                 "<a\nhref=\"$mhref\">permalink</a>" .
                 " <a\nhref=\"${mhref}raw\">raw</a>" .
                 " <a\nhref=\"${mhref}#R\">reply</a>";
 
+        delete($ctx->{-qry}) and
+                $rv .= qq[ <a\nhref="${mhref}#related">related</a>];
+
         my $hr;
         if (defined(my $pct = $smsg->{pct})) { # used by SearchView.pm
                 $rv .= "\t[relevance $pct%]";
@@ -300,8 +354,7 @@ sub _th_index_lite {
         my $rv = '';
         my $mapping = $ctx->{mapping} or return $rv;
         my $pad = '  ';
-        my $mid_map = $mapping->{$mid_raw};
-        defined $mid_map or
+        my $mid_map = $mapping->{$mid_raw} //
                 return 'public-inbox BUG: '.ascii_html($mid_raw).' not mapped';
         my ($attr, $node, $idx, $level) = @$mid_map;
         my $children = $node->{children};
@@ -333,10 +386,10 @@ sub _th_index_lite {
         }
         my $s_s = nr_to_s($nr_s, 'sibling', 'siblings');
         my $s_c = nr_to_s($nr_c, 'reply', 'replies');
-        $attr =~ s!\n\z!</b>\n!s;
+        chop $attr; # remove "\n"
         $attr =~ s!<a\nhref.*</a> (?:&#34; )?!!s; # no point in dup subject
         $attr =~ s!<a\nhref=[^>]+>([^<]+)</a>!$1!s; # no point linking to self
-        $rv .= "<b>@ $attr";
+        $rv .= "<b>@ $attr</b>\n";
         if ($nr_c) {
                 my $cmid = $children->[0] ? $children->[0]->{mid} : undef;
                 $rv .= $pad . _skel_hdr($mapping, $cmid);
@@ -386,7 +439,9 @@ sub pre_thread  { # walk_thread callback
 sub thread_eml_entry {
         my ($ctx, $eml) = @_;
         my ($beg, $end) = thread_adj_level($ctx, $ctx->{level});
-        $beg . '<pre>' . eml_entry($ctx, $eml) . '</pre>' . $end;
+        print { $ctx->zfh } $beg, '<pre>';
+        print { $ctx->{zfh} } eml_entry($ctx, $eml), '</pre>';
+        $end;
 }
 
 sub next_in_queue ($$) {
@@ -413,15 +468,15 @@ sub stream_thread_i { # PublicInbox::WwwStream::getline callback
                                 if (!$ghost_ok) { # first non-ghost
                                         $ctx->{-title_html} =
                                                 ascii_html($smsg->{subject});
-                                        $ctx->zmore($ctx->html_top);
+                                        print { $ctx->zfh } $ctx->html_top;
                                 }
                                 return $smsg;
                         }
                         # buffer the ghost entry and loop
-                        $ctx->zmore(ghost_index_entry($ctx, $lvl, $smsg));
+                        print { $ctx->zfh } ghost_index_entry($ctx, $lvl, $smsg)
                 } else { # all done
-                        $ctx->zmore(join('', thread_adj_level($ctx, 0)));
-                        $ctx->zmore(${delete($ctx->{skel})});
+                        print { $ctx->zfh } thread_adj_level($ctx, 0),
+                                                ${delete($ctx->{skel})};
                         return;
                 }
         }
@@ -430,7 +485,7 @@ sub stream_thread_i { # PublicInbox::WwwStream::getline callback
 sub stream_thread ($$) {
         my ($rootset, $ctx) = @_;
         @{$ctx->{-queue}} = map { (0, $_) } @$rootset;
-        PublicInbox::WwwStream::aresponse($ctx, 200, \&stream_thread_i);
+        PublicInbox::WwwStream::aresponse($ctx, \&stream_thread_i);
 }
 
 # /$INBOX/$MSGID/t/ and /$INBOX/$MSGID/T/
@@ -441,10 +496,11 @@ sub thread_html {
         my $ibx = $ctx->{ibx};
         my ($nr, $msgs) = $ibx->over->get_thread($mid);
         return missing_thread($ctx) if $nr == 0;
+        $ctx->{-spfx} = '../../' if $ibx->{-repo_objs};
 
         # 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>';
@@ -481,7 +537,7 @@ EOF
         # flat display: lazy load the full message from smsg
         $ctx->{msgs} = $msgs;
         $ctx->{-html_tip} = '<pre>';
-        PublicInbox::WwwStream::aresponse($ctx, 200, \&thread_html_i);
+        PublicInbox::WwwStream::aresponse($ctx, \&thread_html_i);
 }
 
 sub thread_html_i { # PublicInbox::WwwStream::getline callback
@@ -490,7 +546,7 @@ sub thread_html_i { # PublicInbox::WwwStream::getline callback
                 my $smsg = $ctx->{smsg};
                 if (exists $ctx->{-html_tip}) {
                         $ctx->{-title_html} = ascii_html($smsg->{subject});
-                        $ctx->zmore($ctx->html_top);
+                        print { $ctx->zfh } $ctx->html_top;
                 }
                 return eml_entry($ctx, $eml);
         } else {
@@ -498,31 +554,19 @@ sub thread_html_i { # PublicInbox::WwwStream::getline callback
                         return $smsg if exists($smsg->{blob});
                 }
                 my $skel = delete($ctx->{skel}) or return; # all done
-                $ctx->zmore($$skel);
+                print { $ctx->zfh } $$skel;
                 undef;
         }
 }
 
-sub multipart_text_as_html {
-        # ($mime, $ctx) = @_; # each_part may do "$_[0] = undef"
-
-        # scan through all parts, looking for displayable text
-        $_[0]->each_part(\&add_text_body, $_[1], 1);
-}
-
 sub submsg_hdr ($$) {
         my ($ctx, $eml) = @_;
-        my $obfs_ibx = $ctx->{-obfs_ibx};
-        my $rv = $ctx->{obuf};
-        $$rv .= "\n";
+        my $s = "\n";
         for my $h (qw(From To Cc Subject Date Message-ID X-Alt-Message-ID)) {
-                my @v = $eml->header($h);
-                for my $v (@v) {
-                        obfuscate_addrs($obfs_ibx, $v) if $obfs_ibx;
-                        $v = ascii_html($v);
-                        $$rv .= "$h: $v\n";
-                }
+                $s .= "$h: $_\n" for $eml->header($h);
         }
+        obfuscate_addrs($ctx->{-obfs_ibx}, $s) if $ctx->{-obfs_ibx};
+        ascii_html($s);
 }
 
 sub attach_link ($$$$;$) {
@@ -533,7 +577,6 @@ sub attach_link ($$$$;$) {
         # downloads for 0-byte multipart attachments
         return unless $part->{bdy};
 
-        my $nl = $idx eq '1' ? '' : "\n"; # like join("\n", ...)
         my $size = length($part->body);
         delete $part->{bdy}; # save memory
 
@@ -549,23 +592,17 @@ sub attach_link ($$$$;$) {
         } else {
                 $sfn = 'a.bin';
         }
-        my $rv = $ctx->{obuf};
-        $$rv .= qq($nl<a\nhref="$ctx->{mhref}$idx-$sfn">);
-        if ($err) {
-                $$rv .= <<EOF;
+        my $rv = $idx eq '1' ? '' : "\n"; # like join("\n", ...)
+        $rv .= qq(<a\nhref="$ctx->{mhref}$idx-$sfn">);
+        $rv .= <<EOF if $err;
 [-- Warning: decoded text below may be mangled, UTF-8 assumed --]
 EOF
-        }
-        $$rv .= "[-- Attachment #$idx: ";
-        my $ts = "Type: $ct, Size: $size bytes";
+        $rv .= "[-- Attachment #$idx: ";
         my $desc = $part->header('Content-Description') // $fn // '';
-        $desc = ascii_html($desc);
-        $$rv .= ($desc eq '') ? "$ts --]" : "$desc --]\n[-- $ts --]";
-        $$rv .= "</a>\n";
-
-        submsg_hdr($ctx, $part) if $part->{is_submsg};
-
-        undef;
+        $rv .= ascii_html($desc)." --]\n[-- " if $desc ne '';
+        $rv .= "Type: $ct, Size: $size bytes --]</a>\n";
+        $rv .= submsg_hdr($ctx, $part) if $part->{is_submsg};
+        $rv;
 }
 
 sub add_text_body { # callback for each_part
@@ -578,13 +615,9 @@ sub add_text_body { # callback for each_part
         my $ct = $part->content_type || 'text/plain';
         my $fn = $part->filename;
         my ($s, $err) = msg_part_text($part, $ct);
-        return attach_link($ctx, $ct, $p, $fn) unless defined $s;
-
-        my $rv = $ctx->{obuf};
-        if ($part->{is_submsg}) {
-                submsg_hdr($ctx, $part);
-                $$rv .= "\n";
-        }
+        my $zfh = $ctx->zfh;
+        $s // return print $zfh (attach_link($ctx, $ct, $p, $fn) // '');
+        say $zfh submsg_hdr($ctx, $part) if $part->{is_submsg};
 
         # makes no difference to browsers, and don't screw up filename
         # link generation in diffs with the extra '%0D'
@@ -607,24 +640,6 @@ sub add_text_body { # callback for each_part
                 $ctx->{-anchors} = {} if $s =~ /^diff --git /sm;
                 $diff = 1;
                 delete $ctx->{-long_path};
-                my $spfx;
-                # absolute URL (Atom feeds)
-                if ($ibx->{coderepo}) {
-                        if (index($upfx, '//') >= 0) {
-                                $spfx = $upfx;
-                                $spfx =~ s!/([^/]*)/\z!/!;
-                        } else {
-                                my $n_slash = $upfx =~ tr!/!/!;
-                                if ($n_slash == 0) {
-                                        $spfx = '../';
-                                } elsif ($n_slash == 1) {
-                                        $spfx = '';
-                                } else { # nslash == 2
-                                        $spfx = '../../';
-                                }
-                        }
-                }
-                $ctx->{-spfx} = $spfx;
         };
 
         # split off quoted and unquoted blocks:
@@ -632,110 +647,122 @@ sub add_text_body { # callback for each_part
         undef $s; # free memory
         if (defined($fn) || ($depth > 0 && !$part->{is_submsg}) || $err) {
                 # badly-encoded message with $err? tell the world about it!
-                attach_link($ctx, $ct, $p, $fn, $err);
-                $$rv .= "\n";
+                say $zfh attach_link($ctx, $ct, $p, $fn, $err);
         }
         delete $part->{bdy}; # save memory
-        foreach my $cur (@sections) {
+        for my $cur (@sections) { # $cur may be huge
                 if ($cur =~ /\A>/) {
                         # we use a <span> here to allow users to specify
                         # their own color for quoted text
-                        $$rv .= qq(<span\nclass="q">);
-                        $$rv .= $l->to_html($cur);
-                        $$rv .= '</span>';
+                        print $zfh qq(<span\nclass="q">),
+                                        $l->to_html($cur), '</span>';
                 } elsif ($diff) {
                         flush_diff($ctx, \$cur);
-                } else {
-                        # regular lines, OK
-                        $$rv .= $l->to_html($cur);
+                } else { # regular lines, OK
+                        print $zfh $l->to_html($cur);
                 }
                 undef $cur; # free memory
         }
 }
 
-sub _msg_page_prepare_obuf {
-        my ($eml, $ctx) = @_;
-        my $over = $ctx->{ibx}->over;
-        my $obfs_ibx = $ctx->{-obfs_ibx};
-        my $rv = '';
+sub _msg_page_prepare {
+        my ($eml, $ctx, $ts) = @_;
+        my $have_over = !!$ctx->{ibx}->over;
         my $mids = mids_for_index($eml);
         my $nr = $ctx->{nr}++;
         if ($nr) { # unlikely
                 if ($ctx->{chash} eq content_hash($eml)) {
                         warn "W: BUG? @$mids not deduplicated properly\n";
-                        return \$rv;
+                        return;
                 }
-                $rv .=
-"<pre>WARNING: multiple messages have this Message-ID\n</pre>";
-                $rv .= '<pre>';
+                $ctx->{-html_tip} =
+qq[<pre>WARNING: multiple messages have this Message-ID (<a
+href="d/">diff</a>)</pre><pre>];
         } else {
                 $ctx->{first_hdr} = $eml->header_obj;
                 $ctx->{chash} = content_hash($eml) if $ctx->{smsg}; # reused MID
-                $rv .= "<pre\nid=b>"; # anchor for body start
+                $ctx->{-html_tip} = "<pre\nid=b>"; # anchor for body start
         }
-        $ctx->{-upfx} = '../' if $over;
+        $ctx->{-upfx} = '../';
         my @title; # (Subject[0], From[0])
+        my $hbuf = '';
         for my $v ($eml->header('From')) {
                 my @n = PublicInbox::Address::names($v);
-                $v = ascii_html($v);
-                $title[1] //= ascii_html(join(', ', @n));
-                if ($obfs_ibx) {
-                        obfuscate_addrs($obfs_ibx, $v);
-                        obfuscate_addrs($obfs_ibx, $title[1]);
-                }
-                $rv .= "From: $v\n" if $v ne '';
+                $title[1] //= join(', ', @n);
+                $hbuf .= "From: $v\n" if $v ne '';
         }
-        foreach my $h (qw(To Cc)) {
+        for my $h (qw(To Cc)) {
                 for my $v ($eml->header($h)) {
                         fold_addresses($v);
-                        $v = ascii_html($v);
-                        obfuscate_addrs($obfs_ibx, $v) if $obfs_ibx;
-                        $rv .= "$h: $v\n" if $v ne '';
+                        $hbuf .= "$h: $v\n" if $v ne '';
                 }
         }
         my @subj = $eml->header('Subject');
-        if (@subj) {
-                my $v = ascii_html(shift @subj);
-                obfuscate_addrs($obfs_ibx, $v) if $obfs_ibx;
-                $rv .= 'Subject: ';
-                $rv .= $over ? qq(<a\nhref="#r"\nid=t>$v</a>\n) : "$v\n";
-                $title[0] = $v;
-                for $v (@subj) { # multi-Subject message :<
-                        $v = ascii_html($v);
-                        obfuscate_addrs($obfs_ibx, $v) if $obfs_ibx;
-                        $rv .= "Subject: $v\n";
-                }
-        } else { # dummy anchor for thread skeleton at bottom of page
-                $rv .= qq(<a\nhref="#r"\nid=t></a>) if $over;
-                $title[0] = '(no subject)';
+        $hbuf .= "Subject: $_\n" for @subj;
+        $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, $hbuf);
+                obfuscate_addrs($obfs_ibx, $ctx->{-title_html});
         }
-        for my $v ($eml->header('Date')) {
-                $v = ascii_html($v);
-                obfuscate_addrs($obfs_ibx, $v) if $obfs_ibx; # possible :P
-                $rv .= qq{Date: $v\t<a\nhref="#r">[thread overview]</a>\n};
-        }
-        if (!$nr) { # first (and only) message, common case
-                $ctx->{-title_html} = join(' - ', @title);
-                $rv = $ctx->html_top . $rv;
+
+        # [thread overview] link is typically added after Date,
+        # but added after Subject, or even nothing.
+        if ($have_over) {
+                chop $hbuf; # drop "\n", or noop if $rv eq ''
+                $hbuf .= qq{\t<a\nhref="#r">[thread overview]</a>\n};
+                $hbuf =~ s!^Subject:\x20(.*?)(\n[A-Z]|\z)
+                                !Subject: <a\nhref="#r"\nid=t>$1</a>$2!msx or
+                        $hbuf .= qq(<a\nhref="#r\nid=t></a>);
         }
         if (scalar(@$mids) == 1) { # common case
-                my $mhtml = ascii_html($mids->[0]);
-                $rv .= "Message-ID: &lt;$mhtml&gt; ";
-                $rv .= "(<a\nhref=\"raw\">raw</a>)\n";
+                my $x = ascii_html($mids->[0]);
+                $hbuf .= qq[Message-ID: &lt;$x&gt; (<a href="raw">raw</a>)\n];
+        }
+        if (!$nr) { # first (and only) message, common case
+                print { $ctx->zfh } $ctx->html_top, $hbuf;
         } else {
+                delete $ctx->{-title_html};
+                print { $ctx->zfh } $ctx->{-html_tip}, $hbuf;
+        }
+        $ctx->{-linkify} //= PublicInbox::Linkify->new;
+        $hbuf = '';
+        if (scalar(@$mids) != 1) { # unlikely, but it happens :<
                 # X-Alt-Message-ID can happen if a message is injected from
                 # public-inbox-nntpd because of multiple Message-ID headers.
-                my $lnk = PublicInbox::Linkify->new;
-                my $s = '';
                 for my $h (qw(Message-ID X-Alt-Message-ID)) {
-                        $s .= "$h: $_\n" for ($eml->header_raw($h));
+                        $hbuf .= "$h: $_\n" for ($eml->header_raw($h));
                 }
-                $lnk->linkify_mids('..', \$s, 1);
-                $rv .= $s;
+                $ctx->{-linkify}->linkify_mids('..', \$hbuf, 1); # escapes HTML
+                print { $ctx->{zfh} } $hbuf;
+                $hbuf = '';
         }
-        $rv .= _parent_headers($eml, $over);
-        $rv .= "\n";
-        \$rv;
+        my @irt = $eml->header_raw('In-Reply-To');
+        my $refs;
+        if (@irt) { # ("so-and-so's message of $DATE") added by some MUAs
+                for (grep(/=\?/, @irt)) {
+                        s/(=\?.*)\z/PublicInbox::Eml::mhdr_decode $1/se;
+                }
+        } else {
+                $refs = references($eml);
+                $irt[0] = pop(@$refs) if scalar @$refs;
+        }
+        $hbuf .= "In-Reply-To: $_\n" for @irt;
+
+        # do not display References: if search is present,
+        # we show the thread skeleton at the bottom, instead.
+        if (!$have_over) {
+                $refs //= references($eml);
+                $hbuf .= 'References: <'.join(">\n\t<", @$refs).">\n" if @$refs;
+        }
+        $ctx->{-linkify}->linkify_mids('..', \$hbuf); # escapes HTML
+        say { $ctx->{zfh} } $hbuf;
+        1;
 }
 
 sub SKEL_EXPAND () {
@@ -772,7 +799,6 @@ sub thread_skel ($$$) {
         # when multiple Subject: headers are present, so we follow suit:
         my $subj = $hdr->header('Subject') // '';
         $subj = '(no subject)' if $subj eq '';
-        $ctx->{prev_subj} = [ split(/ /, subject_normalized($subj)) ];
         $ctx->{cur} = $mid;
         $ctx->{prev_attr} = '';
         $ctx->{prev_level} = 0;
@@ -785,54 +811,47 @@ sub thread_skel ($$$) {
         $ctx->{parent_msg} = $parent;
 }
 
-sub _parent_headers {
-        my ($hdr, $over) = @_;
-        my $rv = '';
-        my @irt = $hdr->header_raw('In-Reply-To');
-        my $refs;
-        if (@irt) {
-                my $lnk = PublicInbox::Linkify->new;
-                $rv .= "In-Reply-To: $_\n" for @irt;
-                $lnk->linkify_mids('..', \$rv);
-        } else {
-                $refs = references($hdr);
-                my $irt = pop @$refs;
-                if (defined $irt) {
-                        my $html = ascii_html($irt);
-                        my $href = mid_href($irt);
-                        $rv .= "In-Reply-To: &lt;";
-                        $rv .= "<a\nhref=\"../$href/\">$html</a>&gt;\n";
-                }
-        }
-
-        # do not display References: if search is present,
-        # we show the thread skeleton at the bottom, instead.
-        return $rv if $over;
-
-        $refs //= references($hdr);
-        if (@$refs) {
-                @$refs = map { linkify_ref_no_over($_) } @$refs;
-                $rv .= 'References: '. join("\n\t", @$refs) . "\n";
-        }
-        $rv;
-}
-
-# returns a string buffer
+# writes to zbuf
 sub html_footer {
         my ($ctx, $hdr) = @_;
-        my $ibx = $ctx->{ibx};
         my $upfx = '../';
-        my $skel;
-        my $rv = '<pre>';
-        if ($ibx->over) {
+        my (@related, $skel);
+        my $foot = '<pre>';
+        my $qry = delete $ctx->{-qry};
+        if ($qry && $ctx->{ibx}->isrch) {
+                my $q = ''; # search for either ancestor or descendent patches
+                for (@{$qry->{dfpre}}, @{$qry->{dfpost}}) {
+                        chop if length > 7; # include 1 abbrev "older" patches
+                        $q .= "dfblob:$_ ";
+                }
+                chop $q; # omit trailing SP
+                local $Text::Wrap::columns = COLS;
+                local $Text::Wrap::huge = 'overflow';
+                $q = wrap('', '', $q);
+                my $rows = ($q =~ tr/\n/\n/) + 1;
+                $q = ascii_html($q);
+                $related[0] = <<EOM;
+<form id=related
+action=$upfx
+><pre>find likely ancestor, descendant, or conflicting patches for <a
+href=#t>this message</a>:
+<textarea name=q cols=${\COLS} rows=$rows>$q</textarea>
+<input type=submit value=search
+/>\t(<a href=${upfx}_/text/help/#search>help</a>)</pre></form>
+EOM
+                # TODO: related codesearch
+                # my $csrchv = $ctx->{ibx}->{-csrch} // [];
+                # push @related, '<pre>'.ascii_html(Dumper($csrchv)).'</pre>';
+        }
+        if ($ctx->{ibx}->over) {
                 my $t = ts2str($ctx->{-t_max});
                 my $t_fmt = fmt_ts($ctx->{-t_max});
-                $skel .= <<EOF;
-        other threads:[<a
+                my $fallback = @related ? "\t" : "<a id=related>\t</a>";
+                $skel = <<EOF;
+${fallback}other threads:[<a
 href="$upfx?t=$t">~$t_fmt UTC</a>|<a
 href="$upfx">newest</a>]
 EOF
-
                 thread_skel(\$skel, $ctx, $hdr);
                 my ($next, $prev);
                 my $parent = '       ';
@@ -840,43 +859,32 @@ EOF
 
                 if (my $n = $ctx->{next_msg}) {
                         $n = mid_href($n);
-                        $next = "<a\nhref=\"$upfx$n/\"\nrel=next>next</a>";
+                        $next = qq(<a\nhref="$upfx$n/"\nrel=next>next</a>);
                 }
-                my $u;
                 my $par = $ctx->{parent_msg};
-                if ($par) {
-                        $u = mid_href($par);
-                        $u = "$upfx$u/";
-                }
+                my $u = $par ? $upfx.mid_href($par).'/' : undef;
                 if (my $p = $ctx->{prev_msg}) {
                         $prev = mid_href($p);
                         if ($p && $par && $p eq $par) {
-                                $prev = "<a\nhref=\"$upfx$prev/\"\n" .
+                                $prev = qq(<a\nhref="$upfx$prev/"\n) .
                                         'rel=prev>prev parent</a>';
                                 $parent = '';
                         } else {
-                                $prev = "<a\nhref=\"$upfx$prev/\"\n" .
+                                $prev = qq(<a\nhref="$upfx$prev/"\n) .
                                         'rel=prev>prev</a>';
-                                $parent = " <a\nhref=\"$u\">parent</a>" if $u;
+                                $parent = qq( <a\nhref="$u">parent</a>) if $u;
                         }
                 } elsif ($u) { # unlikely
-                        $parent = " <a\nhref=\"$u\"\nrel=prev>parent</a>";
+                        $parent = qq( <a\nhref="$u"\nrel=prev>parent</a>);
                 }
-                $rv .= "$next $prev$parent ";
+                $foot .= "$next $prev$parent ";
         } else { # unindexed inboxes w/o over
                 $skel = qq( <a\nhref="$upfx">latest</a>);
         }
-        $rv .= qq(<a\nhref="#R">reply</a>);
-        $rv .= $skel;
-        $rv .= '</pre>';
-        $rv .= msg_reply($ctx, $hdr);
-}
-
-sub linkify_ref_no_over {
-        my ($mid) = @_;
-        my $href = mid_href($mid);
-        my $html = ascii_html($mid);
-        "&lt;<a\nhref=\"../$href/\">$html</a>&gt;";
+        # $skel may be big for big threads, don't append it to $foot
+        print { $ctx->zfh } $foot, qq(<a\nhref="#R">reply</a>),
+                                $skel, '</pre>', @related,
+                                msg_reply($ctx, $hdr);
 }
 
 sub ghost_parent {
@@ -937,8 +945,8 @@ sub thread_results {
                         my $tip = splice(@$rootset, $idx, 1);
                         @$rootset = reverse @$rootset;
                         unshift @$rootset, $tip;
-                        $ctx->{sl_note} = strict_loose_note($nr);
                 }
+                $ctx->{sl_note} = strict_loose_note($nr);
         }
         $rootset
 }
@@ -1074,6 +1082,8 @@ sub _skel_ghost {
         1;
 }
 
+# note: we favor Date: here because git-send-email increments it
+# to preserve [PATCH $N/$M] ordering in series (it can't control Received:)
 sub sort_ds {
         @{$_[0]} = sort {
                 (eval { $a->topmost->{ds} } || 0) <=>
@@ -1095,9 +1105,10 @@ sub acc_topic { # walk_thread callback
         if ($has_blob) {
                 my $subj = subject_normalized($smsg->{subject});
                 $subj = '(no subject)' if $subj eq '';
+                my $ts = $smsg->{ts};
                 my $ds = $smsg->{ds};
                 if ($level == 0) { # new, top-level topic
-                        my $topic = [ $ds, 1, { $subj => $mid }, $subj ];
+                        my $topic = [ $ts, $ds, 1, { $subj => $mid }, $subj ];
                         $ctx->{-cur_topic} = $topic;
                         push @{$ctx->{order}}, $topic;
                         return 1;
@@ -1105,10 +1116,11 @@ sub acc_topic { # walk_thread callback
 
                 # continue existing topic
                 my $topic = $ctx->{-cur_topic}; # should never be undef
-                $topic->[0] = $ds if $ds > $topic->[0];
-                $topic->[1]++; # bump N+ message counter
-                my $seen = $topic->[2];
-                if (scalar(@$topic) == 3) { # parent was a ghost
+                $topic->[0] = $ts if $ts > $topic->[0];
+                $topic->[1] = $ds if $ds > $topic->[1];
+                $topic->[2]++; # bump N+ message counter
+                my $seen = $topic->[3];
+                if (scalar(@$topic) == 4) { # parent was a ghost
                         push @$topic, $subj;
                 } elsif (!defined($seen->{$subj})) {
                         push @$topic, $level, $subj; # @extra messages
@@ -1116,7 +1128,7 @@ sub acc_topic { # walk_thread callback
                 $seen->{$subj} = $mid; # latest for subject
         } else { # ghost message
                 return 1 if $level != 0; # ignore child ghosts
-                my $topic = $ctx->{-cur_topic} = [ -666, 0, {} ];
+                my $topic = $ctx->{-cur_topic} = [ -666, -666, 0, {} ];
                 push @{$ctx->{order}}, $topic;
         }
         1;
@@ -1131,12 +1143,13 @@ sub dump_topics {
         }
 
         my @out;
-        my $ibx = $ctx->{ibx};
-        my $obfs_ibx = $ibx->{obfuscate} ? $ibx : undef;
-
+        my $obfs_ibx = $ctx->{ibx}->{obfuscate} ? $ctx->{ibx} : undef;
+        if (my $note = delete $ctx->{t_note}) {
+                push @out, $note; # "messages from ... to ..."
+        }
         # sort by recency, this allows new posts to "bump" old topics...
         foreach my $topic (sort { $b->[0] <=> $a->[0] } @$order) {
-                my ($ds, $n, $seen, $top_subj, @extra) = @$topic;
+                my ($ts, $ds, $n, $seen, $top_subj, @extra) = @$topic;
                 @$topic = ();
                 next unless defined $top_subj;  # ghost topic
                 my $mid = delete $seen->{$top_subj};
@@ -1158,9 +1171,9 @@ sub dump_topics {
 
                 my $s = "<a\nhref=\"$href/T/$anchor\">$top_subj</a>\n" .
                         " $ds UTC $n\n";
-                for (my $i = 0; $i < scalar(@extra); $i += 2) {
-                        my $level = $extra[$i];
-                        my $subj = $extra[$i + 1]; # already normalized
+                while (@extra) {
+                        my $level = shift @extra;
+                        my $subj = shift @extra; # already normalized
                         $mid = delete $seen->{$subj};
                         my @subj = split(/ /, $subj);
                         my @next_prev = @subj; # full copy
@@ -1192,7 +1205,11 @@ sub pagination_footer ($$) {
                 $next = $next ? "$next | " : '             | ';
                 $prev .= qq[ | <a\nhref="$latest">latest</a>];
         }
-        "<hr><pre>page: $next$prev</pre>";
+        my $rv = '<hr><pre id=nav>';
+        $rv .= "page: $next$prev\n" if $next || $prev;
+        $rv .= q{- recent:[<b>subjects (threaded)</b>|<a
+href="./topics_new.html">topics (new)</a>|<a
+href="./topics_active.html">topics (active)</a>]</pre>};
 }
 
 sub paginate_recent ($$) {
@@ -1207,23 +1224,30 @@ sub paginate_recent ($$) {
         $t =~ s/\A([0-9]{8,14})-// and $after = str2ts($1);
         $t =~ /\A([0-9]{8,14})\z/ and $before = str2ts($1);
 
-        my $ibx = $ctx->{ibx};
-        my $msgs = $ibx->recent($opts, $after, $before);
-        my $nr = scalar @$msgs;
-        if ($nr < $lim && defined($after)) {
+        my $msgs = $ctx->{ibx}->over->recent($opts, $after, $before);
+        if (defined($after) && scalar(@$msgs) < $lim) {
                 $after = $before = undef;
-                $msgs = $ibx->recent($opts);
-                $nr = scalar @$msgs;
+                $msgs = $ctx->{ibx}->over->recent($opts);
         }
-        my $more = $nr == $lim;
+        my $more = scalar(@$msgs) == $lim;
         my ($newest, $oldest);
-        if ($nr) {
+        if (@$msgs) {
                 $newest = $msgs->[0]->{ts};
                 $oldest = $msgs->[-1]->{ts};
                 # if we only had $after, our SQL query in ->recent ordered
                 if ($newest < $oldest) {
                         ($oldest, $newest) = ($newest, $oldest);
-                        $more = 0 if defined($after) && $after < $oldest;
+                        $more = undef if defined($after) && $after < $oldest;
+                }
+                if (defined($after // $before)) {
+                        my $n = strftime('%Y-%m-%d %H:%M:%S', gmtime($newest));
+                        my $o = strftime('%Y-%m-%d %H:%M:%S', gmtime($oldest));
+                        $ctx->{t_note} = <<EOM;
+ messages from $o to $n UTC [<a href="#nav">more...</a>]
+EOM
+                        my $s = ts2str($newest);
+                        $ctx->{prev_page} = qq[<a\nhref="?t=$s-"\nrel=prev>] .
+                                                'prev (newer)</a>';
                 }
         }
         if (defined($oldest) && $more) {
@@ -1231,11 +1255,6 @@ sub paginate_recent ($$) {
                 $ctx->{next_page} = qq[<a\nhref="?t=$s"\nrel=next>] .
                                         'next (older)</a>';
         }
-        if (defined($newest) && (defined($before) || defined($after))) {
-                my $s = ts2str($newest);
-                $ctx->{prev_page} = qq[<a\nhref="?t=$s-"\nrel=prev>] .
-                                        'prev (newer)</a>';
-        }
         $msgs;
 }
 
@@ -1243,11 +1262,8 @@ sub paginate_recent ($$) {
 sub index_topics {
         my ($ctx) = @_;
         my $msgs = paginate_recent($ctx, 200); # 200 is our window
-        if (@$msgs) {
-                walk_thread(thread_results($ctx, $msgs), $ctx, \&acc_topic);
-        }
-        html_oneshot($ctx, dump_topics($ctx), \pagination_footer($ctx, '.'));
-
+        walk_thread(thread_results($ctx, $msgs), $ctx, \&acc_topic) if @$msgs;
+        html_oneshot($ctx, dump_topics($ctx), pagination_footer($ctx, '.'));
 }
 
 sub thread_adj_level {
@@ -1281,4 +1297,30 @@ sub ghost_index_entry {
                 . '</pre>' . $end;
 }
 
+# /$INBOX/$MSGID/d/ endpoint
+sub diff_msg {
+        my ($ctx) = @_;
+        require PublicInbox::MailDiff;
+        my $ibx = $ctx->{ibx};
+        my $over = $ibx->over or return no_over_html($ctx);
+        my ($id, $prev);
+        my $md = bless { ctx => $ctx }, 'PublicInbox::MailDiff';
+        my $next_arg = $md->{next_arg} = [ $ctx->{mid}, \$id, \$prev ];
+        my $smsg = $md->{smsg} = $over->next_by_mid(@$next_arg) or
+                return; # undef == 404
+        $ctx->{-t_max} = $smsg->{ts};
+        $ctx->{-upfx} = '../../';
+        $ctx->{-apfx} = '//'; # fail on to_attr()
+        $ctx->{-linkify} = PublicInbox::Linkify->new;
+        my $mid = ascii_html($smsg->{mid});
+        $ctx->{-title_html} = "diff for duplicates of &lt;$mid&gt;";
+        PublicInbox::WwwStream::html_init($ctx);
+        print { $ctx->{zfh} } '<pre>diff for duplicates of &lt;<a href="../">',
+                                $mid, "</a>&gt;\n\n";
+        sub {
+                $ctx->attach($_[0]->([200, delete $ctx->{-res_hdr}]));
+                $md->begin_mail_diff;
+        };
+}
+
 1;