use strict;
use warnings;
use WWW::Curl::Easy;
use WWW::Curl::Form;
use Encode;

my $hdr;
my $curl = WWW::Curl::Easy->new();
$curl->setopt(CURLOPT_NOPROGRESS, 1); # shut off the built-in progress meter
$curl->setopt(CURLOPT_HEADER, 0); # don't include hdr in body
$curl->setopt(CURLOPT_ENCODING, 'gzip');
$curl->setopt(CURLOPT_PROXY, ''); # no proxy
open my $fh, ">", \$hdr;
$curl->setopt(CURLOPT_WRITEHEADER, $fh);

$curl->setopt(CURLOPT_URL, 'http://xxx.yyy.zzz:82/vx');

post();
print "FIRST HEADER $hdr\n\n";
$hdr = '';
sleep 2;
post();
print "SECOND HEADER $hdr\n";

sub post {
    my $form = WWW::Curl::Form->new;

    $curl->setopt(CURLOPT_HTTPHEADER, ['Expect:','']);
    $form->formadd('method', 'login');
    $form->formadd('username', 'xxx');
    $form->formadd('password', 'xxx');
    $curl->setopt(CURLOPT_HTTPPOST, $form);

    my $response_body;
    $curl->setopt(CURLOPT_WRITEDATA,\$response_body);

    my $retcode = $curl->perform;
    if ($retcode != 0) {
        die "post_request failed (", $retcode,
            " - ", $curl->errbuf, ")";
    }
    my $decoded_content = decode ('utf-8', $response_body);
}