<https_dpm_redirector_cgi> is a CGI script to be run in an APACHE web server
using the mod_gridsite module for certificate and VOMS based authentication.

It implements GET requests to read & write files via HTTPS running on the DPM
head node. 
The script verifies the permissions of a request for the specified file/directory and
a) returns a browsable HTML page for directories
b) returns a redirection URL via HTTP containing a token and a signature
   targeting to the DPM disk server keeping the desired file. The disk server
   veryfies the validity of the presented token and evt. grants access to the
   stored DPM file on that node via HTTP access. The default lifetime of such a
   token is currently 10s.

The key used for signing is taken from "/opt/lcg/etc/dpm/https/keystore/key.pem". 
The redirection target port is port http:777 or https:884 if the initial contact 
was made via https:883.