Rust snippet on x509-parser treating lifetimes

x509_lifetimes.rs

use x509_parser::prelude::*;

fn main() -> anyhow::Result<()> {

    print_cert()?;
    print_cert_static()?;

    Ok(())
}


// 'a defines a lifetime. tbs and raw members cannot live less than MyCert
struct MyCert<'a> {
    tbs: TbsCertificate<'a>,
    _raw: X509Certificate<'a>,
}



// 'static defines set the member in the static memory location.
// it is almost like C "static int a = 0;" will live "forever".
struct MyCertStatic {
    tbs: TbsCertificate<'static>,
    _raw: X509Certificate<'static>,
}


#[derive(Clone)]
struct Certificate {
    native: native_tls::Certificate,
}


impl Certificate {
    fn from_pem(pem: &[u8]) -> anyhow::Result<Certificate> {
        Ok(Certificate {
            native: native_tls::Certificate::from_pem(pem)?
        })
    }
}

fn print_cert() -> anyhow::Result<()> {

    let my_pen = std::fs::read("cert.pem")?;

    let cert = Certificate::from_pem(&my_pen)?;
    let cert_native_der = &cert.native.to_der()?;
    let (_, info) = X509Certificate::from_der(&cert_native_der)?;

    let my_cert = MyCert { tbs: info.tbs_certificate.clone(), _raw: info.clone() };


    println!("My Cert details:\nSubject: {}\nIssuer: {}", my_cert.tbs.subject, my_cert.tbs.issuer);

    Ok(())
}

fn print_cert_static() -> anyhow::Result<()> {

    let my_pen = std::fs::read("cert.pem")?;

    let cert  = Certificate::from_pem(&my_pen)?;

    // Box is a pointer type used for heap allocation. Box::new(T)
    let cert_native_der = Box::new(cert.native.to_der()?);


    // Leak will consume the Box and release T it as a static mutable reference
    let (_, info) = X509Certificate::from_der(cert_native_der.leak())?;

    let my_cert = MyCertStatic { tbs: info.tbs_certificate.clone(), _raw: info.clone() };


    println!("My Cert details:\nSubject: {}\nIssuer: {}", my_cert.tbs.subject, my_cert.tbs.issuer);

    Ok(())
}