access to Apache environment vars within Spyce

Hi all,
I'm using Spyce standalone proxied behind Apache and was wondering how 
to get access to Apache environment variables from within Spyce. I came 
across this short thread which was not encouraging:
http://sourceforge.net/mailarchive/message.php?msg_id=15336529

I've found a partial solution and I thought I'd post it here for 
posterity. Some Googling told me that the standard method for passing 
Apache environment variables to a proxy is via mod_headers and the 
RequestHeader directive. However, the use of a RewriteRule resets the 
environment variables so I have to ensure that the variables I'm 
interested in get passed during the rewrite.

So let's say I'm interested in the Apache environment variable 
SERVER_PORT. It's not very interesting information, but it's guaranteed 
to be available so it's good for example code. My Spyce rewrite rule 
looks liks this:

RewriteRule ^(.*\.spy) http://localhost:8000$1 
[p,E=MY_CUSTOM_VARIABLE:%{SERVER_PORT}]

Then I use this RequestHeader rule:
RequestHeader add X-MyCustomHeader %{MY_CUSTOM_VARIABLE}e

Then within Spyce, I can then get the variable like this:

<p>custom header: [[=request.getHeader("X-MyCustomHeader")]]</p>

There's a few problems with this method. You have to be careful that 
what you pass is a valid header. You have to ensure that you don't step 
on any existing headers or allow an opportunity for a hostile user to 
pass fake headers to Spyce. (You should probably consider using 
"RequestHeader unset X-MyCustomHeader" before adding that header.) Last 
but not least, I was unable to get access to all of the environment 
variables I wanted to get to via this process. For some reason, 
REMOTE_USER just won't appear even if I use the LA-U syntax specified 
in the mod_rewrite documentation. As I said, this is only a partial 
solution -- as it turns out I've found another way to solve the problem 
that I was trying to solve with this method, so I don't need to develop 
it any further. I hope it's a useful starting point for someone else.

Cheers
Philip





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