=item How do I read data until the other side closes the connection?

If you just want to read your data into a perl scalar, the easiest way
to achieve this is by setting an C<on_read> callback that does nothing,
clearing the C<on_eof> callback and in the C<on_error> callback, the data
will be in C<$_[0]{rbuf}>:

   $handle->on_read (sub { });
   $handle->on_eof (undef);
   $handle->on_error (sub {
      my $data = delete $_[0]{rbuf};
   });

The reason to use C<on_error> is that TCP connections, due to latencies
and packets loss, might get closed quite violently with an error, when in
fact, all data has been received.