trust-dns-resolver looking up SOA records in Rust

soa.rs

use trust_dns_resolver::error::ResolveResult;
use trust_dns_resolver::Resolver;
use trust_dns_resolver::{config::*, lookup::SoaLookup};

fn main() {
    // Construct a new Resolver with default configuration options
    let resolver = Resolver::new(ResolverConfig::default(), ResolverOpts::default()).unwrap();

    let soa_response = resolver.soa_lookup("gmail.com.");

    display_soa(&soa_response);
}

fn display_soa(soa_response: &ResolveResult<SoaLookup>) {
    match soa_response {
        Err(_) => println!("No SOA."),
        Ok(soa_response) => {
            let soa_iter = soa_response.iter();
            for record in soa_iter {
                println!("Admin: {}", record.rname());
                let email = convert_rname_to_email_address(&record.rname().to_string());
                println!("Admin Email: {}", email);
                println!("Primary: {}", record.mname());
                println!("Serial: {}", record.serial());
            }
        }
    }
}

fn convert_rname_to_email_address(rname: &String) -> String {
    //Solution found on StackOverFlow :)
    let rname = rname.clone();
    let mut email_address: String = String::new();
    let mut splitter = rname.splitn(2, ".");
    email_address.push_str(splitter.next().unwrap());
    email_address.push_str("@");
    email_address.push_str(splitter.next().unwrap());
    // Remove remaining period (.)
    email_address.pop();
    email_address
}