pub async fn map_domain_ipv6(&self, domain: &Name) -> FakeDnsResult<(Ipv6Addr, Duration)> {
        map_domain_ip!(self, domain, Ipv6Addr, ipv6_addr, ipv6_network)
    }
Get or create an IPv6 mapping for `domain`
crates/shadowsocks-service/src/local/fake_dns/manager.rs