[PATCH] www: redirect /f/$MESSAGE_ID.txt links to /m/$MESSAGE_ID.txt

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

Some people (e.g. myself :p) may try to guess URLs and hit a
404.  Redirect to the /m/ version.

Note: we prefer to redirect to canonical URLs to improve
caching.
---
 lib/PublicInbox/WWW.pm | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/lib/PublicInbox/WWW.pm b/lib/PublicInbox/WWW.pm
index be34e1c..8f06964 100644
--- a/lib/PublicInbox/WWW.pm
+++ b/lib/PublicInbox/WWW.pm
@@ -58,6 +58,10 @@ sub run {
 		my $sp = $2;
 		invalid_list(\%ctx, $1) || get_subject_path(\%ctx, $cgi, $sp);
 
+	} elsif ($path_info =~ m!$LISTNAME_RE/f/\S+\.txt\z!o) {
+		invalid_list_mid(\%ctx, $1, $2) ||
+			redirect_mid_txt(\%ctx, $cgi);
+
 	# convenience redirects, order matters
 	} elsif ($path_info =~ m!$LISTNAME_RE/(m|f|t|s)/(\S+)\z!o) {
 		my $pfx = $2;
@@ -231,6 +235,15 @@ sub redirect_mid {
 	do_redirect($url . ".html$anchor");
 }
 
+# only hit when somebody tries to guess URLs manually:
+sub redirect_mid_txt {
+	my ($ctx, $cgi, $pfx) = @_;
+	my $listname = $ctx->{listname};
+	my $url = self_url($cgi);
+	$url =~ s!/$listname/f/(\S+\.txt)\z!/$listname/m/$1!;
+	do_redirect($url);
+}
+
 sub do_redirect {
 	my ($url) = @_;
 	[ 301,
-- 
EW