smoltcp/examples/dhcp_client.rs

#![allow(clippy::option_map_unit_fn)]
mod utils;

use log::*;
use std::os::unix::io::AsRawFd;

use smoltcp::iface::{Config, Interface, SocketSet};
use smoltcp::socket::dhcpv4;
use smoltcp::time::Instant;
use smoltcp::wire::{EthernetAddress, IpCidr, Ipv4Address, Ipv4Cidr};
use smoltcp::{
    phy::{wait as phy_wait, Device, Medium},
    time::Duration,
};

fn main() {
    #[cfg(feature = "log")]
    utils::setup_logging("");

    let (mut opts, mut free) = utils::create_options();
    utils::add_tuntap_options(&mut opts, &mut free);
    utils::add_middleware_options(&mut opts, &mut free);

    let mut matches = utils::parse_options(&opts, free);
    let device = utils::parse_tuntap_options(&mut matches);
    let fd = device.as_raw_fd();
    let mut device =
        utils::parse_middleware_options(&mut matches, device, /*loopback=*/ false);

    // Create interface
    let mut config = match device.capabilities().medium {
        Medium::Ethernet => {
            Config::new(EthernetAddress([0x02, 0x00, 0x00, 0x00, 0x00, 0x01]).into())
        }
        Medium::Ip => Config::new(smoltcp::wire::HardwareAddress::Ip),
        Medium::Ieee802154 => todo!(),
    };
    config.random_seed = rand::random();
    let mut iface = Interface::new(config, &mut device, Instant::now());

    // Initialize with an unspecified address
    set_ipv4_addr(&mut iface, Ipv4Cidr::new(Ipv4Address::UNSPECIFIED, 0));

    // Create sockets
    let mut dhcp_socket = dhcpv4::Socket::new();

    // Set a ridiculously short max lease time to show DHCP renews work properly.
    // This will cause the DHCP client to start renewing after 5 seconds, and give up the
    // lease after 10 seconds if renew hasn't succeeded.
    // IMPORTANT: This should be removed in production.
    dhcp_socket.set_max_lease_duration(Some(Duration::from_secs(10)));

    let mut sockets = SocketSet::new(vec![]);
    let dhcp_handle = sockets.add(dhcp_socket);

    loop {
        let timestamp = Instant::now();
        iface.poll(timestamp, &mut device, &mut sockets);

        let event = sockets.get_mut::<dhcpv4::Socket>(dhcp_handle).poll();
        match event {
            None => {}
            Some(dhcpv4::Event::Configured(config)) => {
                debug!("DHCP config acquired!");

                debug!("IP address:      {}", config.address);
                set_ipv4_addr(&mut iface, config.address);

                if let Some(router) = config.router {
                    debug!("Default gateway: {}", router);
                    iface.routes_mut().add_default_ipv4_route(router).unwrap();
                } else {
                    debug!("Default gateway: None");
                    iface.routes_mut().remove_default_ipv4_route();
                }

                for (i, s) in config.dns_servers.iter().enumerate() {
                    debug!("DNS server {}:    {}", i, s);
                }
            }
            Some(dhcpv4::Event::Deconfigured) => {
                debug!("DHCP lost config!");
                set_ipv4_addr(&mut iface, Ipv4Cidr::new(Ipv4Address::UNSPECIFIED, 0));
                iface.routes_mut().remove_default_ipv4_route();
            }
        }

        phy_wait(fd, iface.poll_delay(timestamp, &sockets)).expect("wait error");
    }
}

/// Clear any existing IP addresses & add the new one
fn set_ipv4_addr(iface: &mut Interface, cidr: Ipv4Cidr) {
    iface.update_ip_addrs(|addrs| {
        addrs.clear();
        addrs.push(IpCidr::Ipv4(cidr)).unwrap();
    });
}