ICMP demo code

icmp.rs

fn handle_icmp_echo_request(u: &ipstack::stream::IpStackUnknownTransport) -> Result<()> {
    use etherparse::{IcmpEchoHeader, Icmpv4Header, Icmpv6Header, IpNumber};
    assert!(u.ip_protocol() == IpNumber::ICMP || u.ip_protocol() == IpNumber::IPV6_ICMP);
    if u.src_addr().is_ipv4() {
        let (icmp_header, req_payload) = Icmpv4Header::from_slice(u.payload()).map_err(|e| Error::from(e.to_string()))?;
        if let etherparse::Icmpv4Type::EchoRequest(req) = icmp_header.icmp_type {
            log::info!("#0 ICMPv4 echo");
            let echo = IcmpEchoHeader { id: req.id, seq: req.seq };
            let mut resp = Icmpv4Header::new(etherparse::Icmpv4Type::EchoReply(echo));
            resp.update_checksum(req_payload);
            let mut payload = resp.to_bytes().to_vec();
            payload.extend_from_slice(req_payload);
            u.send(payload)?;
        } else {
            log::info!("#0 unhandled ICMPv4 - {:?}", icmp_header.icmp_type);
        }
    }
    if u.src_addr().is_ipv6() {
        let (icmp_header, req_payload) = Icmpv6Header::from_slice(u.payload()).map_err(|e| Error::from(e.to_string()))?;
        if let etherparse::Icmpv6Type::EchoRequest(req) = icmp_header.icmp_type {
            log::info!("#0 ICMPv6 echo");
            let echo = IcmpEchoHeader { id: req.id, seq: req.seq };
            let mut resp = Icmpv6Header::new(etherparse::Icmpv6Type::EchoReply(echo));
            let (src, dst) = match (u.src_addr(), u.dst_addr()) {
                (std::net::IpAddr::V6(src), std::net::IpAddr::V6(dst)) => (src.octets(), dst.octets()),
                _ => unreachable!(),
            };
            resp.update_checksum(dst, src, req_payload)
                .map_err(|e| Error::from(e.to_string()))?;
            let mut payload = resp.to_bytes().to_vec();
            payload.extend_from_slice(req_payload);
            u.send(payload)?;
        } else {
            log::info!("#0 unhandled ICMPv6 - {:?}", icmp_header.icmp_type);
        }
    }
    Ok(())
}