Mod rewrite/Hide a script

Using mod_rewrite, we'd like to route all requests for a domain sub.example.com/ to be redirected to a single FastCGI script at d/dispatch.fcgi under the document root. This would be trivial, except that a request to sub.example.com/d/dispatch.fcgi has to behave differently depending on whether the request came from the browser or from a rewrite rule.

These are a few minimum criteria for success:

Easy criteria

If the client requests…	then the rewrite must be to…	and PATH_INFO should be…
sub.example.com/	sub.example.com/d/dispatch.fcgi/	/
sub.example.com/foo	sub.example.com/d/dispatch.fcgi/foo	/foo
sub.example.com/foo/	sub.example.com/d/dispatch.fcgi/foo/	/foo/
sub.example.com/foo/bar	sub.example.com/d/dispatch.fcgi/foo/bar	/foo/bar

Difficult criteria

If the client requests…	then the rewrite must be to…	and PATH_INFO should be…
sub.example.com/d	sub.example.com/d/dispatch.fcgi/d	/d
sub.example.com/d/	sub.example.com/d/dispatch.fcgi/d/	/d/
sub.example.com/d/dispatch.fcgi	sub.example.com/d/dispatch.fcgi/d/dispatch.fcgi	/d/dispatch.cgi
sub.example.com/d/dispatch.fcgi/	sub.example.com/d/dispatch.fcgi/d/dispatch.fcgi/	/d/dispatch.fcgi/
sub.example.com/d/dispatch.fcgi/foo	sub.example.com/d/dispatch.fcgi/d/dispatch.fcgi/foo	/d/dispatch.fcgi/foo
sub.example.com/d/dispatch.fcgi/foo/	sub.example.com/d/dispatch.fcgi/d/dispatch.fcgi/foo/	/d/dispatch.fcgi/foo/
sub.example.com/d/dispatch.fcgi/foo/bar	sub.example.com/d/dispatch.fcgi/d/dispatch.fcgi/foo/bar	/d/dispatch.fcgi/foo/bar

Test script

This script is placed at d/dispatch.fcgi under the document root.

#!/usr/bin/perl

use FCGI;

my %original_env = %ENV;
use Data::Dumper;
$Data::Dumper::Sortkeys = 1;

my $counter = 0;
while ( FCGI::accept() >= 0 ) {
	$counter++;

	print "Content-Type: text/plain\n\n";
	print "PATH_INFO: $ENV{PATH_INFO}\n";
	print Dumper { '0-counter' => $counter, '1-initial-env' => \%original_env, '2-script-env' => \%ENV };
}

The trivial (and incorrect) answer

This is the answer we'd give if we didn't care about hiding.

Files

/.htaccess

RewriteEngine on
RewriteRule ^(.*)$ d/dispatch.fcgi/$1 [L]

/d/.htaccess

Without at least RewriteEngine on here, a 500 results.

RewriteEngine on

Failures

If the client requests…	then the rewrite must be to…	and PATH_INFO should be…	but instead, PATH_INFO is…
sub.example.com/d	sub.example.com/d/dispatch.fcgi/d	/d	N/A (The directory listing for /d/ is displayed)
sub.example.com/d/	sub.example.com/d/dispatch.fcgi/d/	/d/	N/A (The directory listing for /d/ is displayed)
sub.example.com/d/dispatch.fcgi	sub.example.com/d/dispatch.fcgi/d/dispatch.fcgi	/d/dispatch.cgi	(empty string)
sub.example.com/d/dispatch.fcgi/	sub.example.com/d/dispatch.fcgi/d/dispatch.fcgi/	/d/dispatch.fcgi/	/
sub.example.com/d/dispatch.fcgi/foo	sub.example.com/d/dispatch.fcgi/d/dispatch.fcgi/foo	/d/dispatch.fcgi/foo	/foo
sub.example.com/d/dispatch.fcgi/foo/	sub.example.com/d/dispatch.fcgi/d/dispatch.fcgi/foo/	/d/dispatch.fcgi/foo/	/foo/
sub.example.com/d/dispatch.fcgi/foo/bar	sub.example.com/d/dispatch.fcgi/d/dispatch.fcgi/foo/bar	/d/dispatch.fcgi/foo/bar	/foo/bar