Uhh, no that is exactly wrong. Clients are expected to
ignore cookies that don't come from matching domains. If
you request a resource from xxx.yyyy.com then the server
that responds can set cookies for *.yyyy.com or xxx.yyyy.com
but nothing else. What you are mixing in is the
protection against you going to "http://www.xxx.com/"
and that page calling a resource from "http://www.eviladplace.com/ad/tracker"
and you picking up a cookie from a site you didn't even
know you visited.
All the domain parameter is for is setting the depth
into your own domain. That way a server at www.cs.xxx.edu
can set one cookie for all *.xxx.edu and another at just
*.cs.xxx.edu and one just for itself at www.cs.xxx.edu!
If I could set cookies in the netscape.com domain for
you from hostile.org you can be sure I would be... =)
LWP is most certainly the right answer tho! Look at
HTTP::Request's perldocs specifically
$you = new YOU;
honk() if $you->love(perl)