in sign/src/sign.rs [211:220]
fn calc_md5(body: Option<&[u8]>) -> (String, usize) {
if let Some(content) = body {
let len = content.len();
if len > 0 {
let content_md5 = format!("{:X}", md5::compute(content));
return (content_md5, len);
}
}
(String::default(), 0)
}