searchview: retry queries if uri_unescape-able

It is possible to have double-escaped queries when copy and
pasting into browsers, so try to help users work around this
common error by automatically retrying after unescaping once.

Of course, we must inform the user when doing this results in
success, in case they really meant to search for a
double-escaped term which resulted in nothing.

Reported-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
  https://public-inbox.org/meta/CACBZZX5Gnow08r=0A1J_kt3a=zpGyMfvsqu8nAN7kacNnDm+dg@mail.gmail.com/

1 files changed, 29 insertions, 7 deletions

diff --git a/lib/PublicInbox/SearchView.pm b/lib/PublicInbox/SearchView.pm
index 42bc6482..f92790f4 100644
--- a/lib/PublicInbox/SearchView.pm
+++ b/lib/PublicInbox/SearchView.pm
@@ -5,11 +5,12 @@
 package PublicInbox::SearchView;
 use strict;
 use warnings;
+use URI::Escape qw(uri_unescape uri_escape);
 use PublicInbox::SearchMsg;
 use PublicInbox::Hval qw/ascii_html/;
 use PublicInbox::View;
 use PublicInbox::WwwAtomStream;
-use PublicInbox::MID qw(mid2path mid_mime mid_clean mid_escape);
+use PublicInbox::MID qw(mid2path mid_mime mid_clean mid_escape MID_ESC);
 use PublicInbox::MIME;
 require PublicInbox::Git;
 require PublicInbox::SearchThread;
@@ -29,19 +30,27 @@ sub sres_top_html {
                 mset => 1,
                 relevance => $q->{r},
         };
-        my ($mset, $total);
+        my ($mset, $total, $err, $cb);
+retry:
         eval {
                 $mset = $ctx->{srch}->query($q->{'q'}, $opts);
                 $total = $mset->get_matches_estimated;
         };
-        my $err = $@;
+        $err = $@;
         ctx_prepare($q, $ctx);
-        my $cb;
         if ($err) {
                 $code = 400;
                 $ctx->{-html_tip} = '<pre>'.err_txt($ctx, $err).'</pre><hr>';
                 $cb = *noop;
         } elsif ($total == 0) {
+                if (defined($ctx->{-uxs_retried})) {
+                        # undo retry damage:
+                        $q->{'q'} = $ctx->{-uxs_retried};
+                } elsif (index($q->{'q'}, '%') >= 0) {
+                        $ctx->{-uxs_retried} = $q->{'q'};
+                        $q->{'q'} = uri_unescape($q->{'q'});
+                        goto retry;
+                }
                 $code = 404;
                 $ctx->{-html_tip} = "<pre>\n[No results found]</pre><hr>";
                 $cb = *noop;
@@ -49,7 +58,7 @@ sub sres_top_html {
                 my $x = $q->{x};
                 return adump($_[0], $mset, $q, $ctx) if $x eq 'A';
 
-                $ctx->{-html_tip} = search_nav_top($mset, $q) . "\n\n";
+                $ctx->{-html_tip} = search_nav_top($mset, $q, $ctx) . "\n\n";
                 if ($x eq 't') {
                         $cb = mset_thread($ctx, $mset, $q);
                 } else {
@@ -113,9 +122,22 @@ sub err_txt {
 }
 
 sub search_nav_top {
-        my ($mset, $q) = @_;
+        my ($mset, $q, $ctx) = @_;
+
+        my $rv = '<pre>';
+        my $initial_q = $ctx->{-uxs_retried};
+        if (defined $initial_q) {
+                my $rewritten = $q->{'q'};
+                utf8::decode($initial_q);
+                utf8::decode($rewritten);
+                $initial_q = ascii_html($initial_q);
+                $rewritten = ascii_html($rewritten);
+                $rv .= " Warning: Initial query:\n <b>$initial_q</b>\n";
+                $rv .= " returned no results, used:\n";
+                $rv .= " <b>$rewritten</b>\n instead\n\n";
+        }
 
-        my $rv = "<pre>Search results ordered by [";
+        $rv .= 'Search results ordered by [';
         if ($q->{r}) {
                 my $d = $q->qs_html(r => 0);
                 $rv .= qq{<a\nhref="?$d">date</a>|<b>relevance</b>};