feat: starting the TCP client proof of concept

tcp-test/client/src/main.rs

@@ -1,4 +1,44 @@
+use std::net::Ipv4Addr;
+
+use anyhow::anyhow;
+
+use nl_sys::{netlink, route};
+
 #[tokio::main]
-async fn main() {
-    println!("Hello, world!");
+async fn main() -> anyhow::Result<()> {
+    let ip = std::env::args()
+        .skip(1)
+        .next()
+        .ok_or(anyhow!("could not get target IP"))?
+        .parse::<Ipv4Addr>()?;
+
+    let (ifname, src_mac, dst_mac, srcip) = {
+        let socket = netlink::Socket::new()?;
+
+        let routes = socket.get_routes()?;
+        let neighs = socket.get_neigh()?;
+        let links = socket.get_links()?;
+        let addrs = socket.get_addrs()?;
+
+        let (ifname, srcip, srcmac, dstmac) =
+            route::get_macs_and_src_for_ip(&addrs, &routes, &neighs, &links, ip)
+                .ok_or(anyhow!("unable to find a route to the IP"))?;
+
+        (ifname, srcip, srcmac, dstmac)
+    };
+
+    let mut interface = pcap_sys::new_aggregate_interface(false)?;
+
+    interface.set_buffer_size(8192)?;
+    interface.set_non_blocking(true)?;
+    interface.set_promisc(false)?;
+    interface.set_timeout(10)?;
+
+    let mut interface = interface.activate()?;
+
+    interface.set_filter("inbound and tcp port 54249", true, None)?;
+
+    interface.prune(|_, interface| interface.datalink() != pcap_sys::consts::DLT_EN10MB);
+
+    Ok(())
 }