CURL php总是返回TRUE？

Question

curl php总是curl_exec()返回TRUE？ 我做CURL Php并且总是TRUE，虽然没有互联网？以下编码有什么问题？

$POST = array(
        'salesdata' => json_encode($sales_data)
);

$ch = curl_init();

curl_setopt($ch, CURLOPT_URL,"http://accordpos.skyware.systems/api");
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS,http_build_query($POST));

// receive server response ...
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);

$server_output = curl_exec ($ch);
$conn = $this->is_connected();
$this->db->trans_begin();

$this->sync_model->sales_sync($sales);

if(($server_output === false) ||($conn == 0))
{
    echo "Error Number:".curl_errno($ch)."<br>";
    echo "Error String:".curl_error($ch);
    $this->db->trans_rollback();
}
else {
    $this->db->trans_commit();
}
curl_close($ch);