Shibboleth SP attributes character encoding

[Robert Führicht]

Hi,

I'm looking for some pointers on this issue I'm having with character encoding in
headers and environment variables provided by Shibboleth SP.

I got this third party app (deployed as a .war file in Tomcat 7.x and sadly not changeable) 
which uses certain HTTP headers from trusted sources to manage authentication and authorization. 
I set up a SP and let Apache proxy to it via AJP. Sadly, said headers *must* contain
non-ASCII characters (umlauts) for it to work.

According to the SP's docs, the passed attributes are supposed to be treated as
Unicode. Tomcat does treat them as ISO-8859-1, and, apart from recompiling it,
there seems no way to change that. As far as I can tell, it doesn't even try to use the
request's advertised encoding. It doesn't matter if I proxy via AJP or HTTP, or
if I pass them as headers or attributes.

If I understood correctly, the Tomcat devs claim (see http://svn.apache.org/repos/asf/tomcat/tc7.0.x/trunk/java/org/apache/tomcat/util/buf/ByteChunk.java)
that the Servlet API requires the ISO encoding.

I'm not sure how to proceed with this. Did I miss some config setting somewhere
to make this work?
It does seem to me that either Shibboleth SP or Tomcat have to be changed to support
this, but I don't know which should "budge".

What's your take on this?

-Robert