sntp 0.1.2

/*! Example of using the SNTP client to obtain the current timestamp from an actual time server.

This example only works on Linux for simplicity. Before running the example,
you need to create a TAP interface with Internet access usable by non-privileged users.

To spawn a TAP interface named `tap0`, run the following commands:

```no_rust
sudo ip tuntap add name tap0 mode tap user $USER
sudo ip link set tap0 up
sudo ip addr add 192.168.69.100/24 dev tap0
```

To forward IPv4 traffic to/from the interface, run:

```no_rust
sudo iptables -t nat -A POSTROUTING -s 192.168.69.0/24 -j MASQUERADE
sudo sysctl net.ipv4.ip_forward=1
```

Adjust the interface IP appropriately if you happen to already be on a 192.168.69.0/24 network.

Finally, run the example:

```no_rust
cargo run --example client --features tap
```

You should see something like `SNTP timestamp received: 1589793181` printed to stdout.
*/

#[macro_use]
extern crate log;

use env_logger::Env;
use sntp::{
    net::iface::{EthernetInterfaceBuilder, NeighborCache, Routes},
    net::phy::{wait as phy_wait, TapInterface},
    net::socket::{SocketSet, UdpPacketMetadata, UdpSocketBuffer},
    net::time::Instant,
    net::wire::{EthernetAddress, IpAddress, IpCidr, Ipv4Address},
    Client,
};
use std::collections::BTreeMap;
use std::os::unix::io::AsRawFd;
use std::str::FromStr;

fn main() {
    env_logger::from_env(Env::default().default_filter_or("info")).init();

    let device = TapInterface::new("tap0").unwrap();
    let fd = device.as_raw_fd();

    let server = IpAddress::from_str("62.112.134.4").expect("invalid address format");

    let neighbor_cache = NeighborCache::new(BTreeMap::new());

    let sntp_rx_buffer = UdpSocketBuffer::new([UdpPacketMetadata::EMPTY; 1], vec![0; 900]);
    let sntp_tx_buffer = UdpSocketBuffer::new([UdpPacketMetadata::EMPTY; 1], vec![0; 600]);
    let mut sockets = SocketSet::new(vec![]);

    let ethernet_addr = EthernetAddress([0x02, 0x00, 0x00, 0x00, 0x00, 0x02]);
    let ip_addrs = [IpCidr::new(IpAddress::v4(192, 168, 69, 1), 24)];
    let default_v4_gw = Ipv4Address::new(192, 168, 69, 100);

    let mut routes_storage = [None; 1];
    let mut routes = Routes::new(&mut routes_storage[..]);
    routes.add_default_ipv4_route(default_v4_gw).unwrap();

    let mut iface = EthernetInterfaceBuilder::new(device)
        .ethernet_addr(ethernet_addr)
        .neighbor_cache(neighbor_cache)
        .ip_addrs(ip_addrs)
        .routes(routes)
        .finalize();

    let mut sntp = Client::new(
        &mut sockets,
        sntp_rx_buffer,
        sntp_tx_buffer,
        server,
        Instant::now(),
    );

    loop {
        let timestamp = Instant::now();

        iface.poll(&mut sockets, timestamp).map(|_| ()).ok();

        let network_time = sntp.poll(&mut sockets, timestamp).unwrap_or_else(|e| {
            error!("SNTP error: {}", e);
            None
        });

        if let Some(t) = network_time {
            info!("SNTP timestamp received: {:?}", t);
        }

        let mut timeout = sntp.next_poll(timestamp);

        iface
            .poll_delay(&sockets, timestamp)
            .map(|sockets_timeout| timeout = sockets_timeout);

        phy_wait(fd, Some(timeout)).unwrap_or_else(|e| error!("Wait error: {}", e));
    }
}