uhhh what am i doing

src/main.rs

@@ -0,0 +1,50 @@
+use std::{
+    collections::HashSet,
+    fs, iter,
+    net::IpAddr,
+};
+
+use tokio::{io, net::UdpSocket};
+
+#[tokio::main(flavor = "current_thread")]
+async fn main() {
+    wake("lda.lan").await.unwrap();
+}
+
+async fn wake(machine_name: &str) -> io::Result<()> {
+    let sock = UdpSocket::bind("0.0.0.0:0").await?;
+    for (ip, mac) in find_mac(machine_name).await? {
+        let packet: Vec<u8> = iter::once([0xff; 6])
+            .chain(std::iter::repeat_n(mac, 16))
+            .flatten()
+            .collect();
+        sock.send_to(&packet, (ip, 9)).await?;
+    }
+    Ok(())
+}
+
+async fn find_mac(machine_name: &str) -> io::Result<Vec<(IpAddr, [u8; 6])>> {
+    let arp = fs::read_to_string("/proc/net/arp")?;
+    let ips: HashSet<IpAddr> = tokio::net::lookup_host(machine_name)
+        .await?
+        .map(|c| c.ip())
+        .collect();
+
+    Ok(arp
+        .lines()
+        .skip(1)
+        .filter_map(|line| {
+            let mut parts = line.split_ascii_whitespace();
+            let ip: IpAddr = parts.next()?.parse().ok()?;
+            if !ips.contains(&ip) {
+                return None;
+            }
+            let mac_str = parts.nth(2)?;
+            let mut mac = [0u8; 6];
+            for (byte, hex) in mac.iter_mut().zip(mac_str.split(':')) {
+                *byte = u8::from_str_radix(hex, 16).ok()?;
+            }
+            Some((ip, mac))
+        })
+        .collect())
+}