use LWP::UserAgent;

{
   package MyUA;
   use vars qw(@ISA);
   @ISA = qw(LWP::UserAgent);

   my @try = (['foo', 'bar'], ['', ''], ['guest', ''], ['guest', 'guest']);

   sub get_basic_credentials {
	my($self,$realm, $uri, $proxy) = @_;
	print "$realm:$uri:$proxy => ";
	my $p = shift @try;
	print join("/", @$p), "\n";
	return @$p;
   }

}

my $ua = MyUA->new(keep_alive => 1);

my $req = HTTP::Request->new(GET => "http://jigsaw.w3.org/HTTP/Digest/");
my $res = $ua->request($req);