Look at the subroutine 'request' in LWP::Protocol::http for details as to how to handle sockets. Here's a little test program you can debug to watch (from the LWP::UserAgent manpage):

# Create a user agent object
use LWP::UserAgent;
$ua = new LWP::UserAgent;
$ua->agent("AgentName/0.1 " . $ua->agent);
 
# Create a request
my $req = new HTTP::Request GET => 'http://www.espn.com';
 
# Pass request to the user agent and get a response back
my $res = $ua->request($req);
 
# Check the outcome of the response
if ($res->is_success) {
  print $res->content;
} else {
  print "Bad luck this time\n";
}
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Basically, they're using IO::Select to wait for data to become available, with a timeout.:

die "read timeout" if $timeout && !$sel->can_read($timeout);
$n = $socket->sysread($buf, $size, length($buf));
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where $sel is an IO::Select object.