When you request the endpoint /cgi-bin/barf from this domain, Apache uses CGI to call an executable which was compiled using gcc from plain c++ source! When the request comes in a process is spawned to run my program code, which merely spits back (barfback) the remote ip address of the user. Basically, when apache spins up a process to run my program, CGI determines a bunch of environment variables it sets for the child proc, and then also how STDIN and STDOUT are used for POST data and responses.
Originally, I'd been barfing-back the query string from the URL, but I was open to code injection and need to escape html strings! Gotta research that more before I switch that back. Anyway, I also can get mails here now at this domain, under the first name in the title of the site.