feat(ics): EtherNet/IP probe + OT service-discovery port scan (#175)

compliance-agent/src/pipeline/ics/ethernetip.rs

@@ -0,0 +1,95 @@
+//! Minimal EtherNet/IP (CIP) reachability probe.
+//!
+//! Sends an EtherNet/IP encapsulation **ListIdentity** command (0x0063) over TCP
+//! 44818 and checks for a valid encapsulation reply — confirming a CIP device
+//! without opening a session or writing anything.
+
+use std::time::Duration;
+
+use tokio::io::{AsyncReadExt, AsyncWriteExt};
+use tokio::net::TcpStream;
+use tokio::time::timeout;
+
+/// Outcome of an EtherNet/IP handshake probe.
+#[derive(Debug, Default, PartialEq, Eq)]
+pub struct EnipProbe {
+    /// A TCP connection to the port was established.
+    pub reachable: bool,
+    /// The endpoint returned a valid EtherNet/IP encapsulation reply.
+    pub is_enip: bool,
+}
+
+/// Probe an EtherNet/IP endpoint with a ListIdentity request. Read-only.
+pub async fn probe(host: &str, port: u16, budget: Duration) -> EnipProbe {
+    let mut out = EnipProbe::default();
+    let Ok(Ok(mut stream)) = timeout(budget, TcpStream::connect((host, port))).await else {
+        return out;
+    };
+    out.reachable = true;
+
+    // Encapsulation header (24 bytes): command(2) length(2) session(4) status(4)
+    // context(8) options(4). ListIdentity = command 0x0063, everything else zero.
+    let mut req = vec![0u8; 24];
+    req[0..2].copy_from_slice(&0x0063u16.to_le_bytes());
+    if timeout(budget, stream.write_all(&req))
+        .await
+        .ok()
+        .and_then(Result::ok)
+        .is_none()
+    {
+        return out;
+    }
+
+    let mut hdr = [0u8; 24];
+    if timeout(budget, stream.read_exact(&mut hdr))
+        .await
+        .ok()
+        .and_then(Result::ok)
+        .is_none()
+    {
+        return out;
+    }
+    let command = u16::from_le_bytes([hdr[0], hdr[1]]);
+    let status = u32::from_le_bytes([hdr[8], hdr[9], hdr[10], hdr[11]]);
+    // Echoed command + success status = a valid EtherNet/IP encapsulation reply.
+    if command == 0x0063 && status == 0 {
+        out.is_enip = true;
+    }
+    out
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use tokio::net::TcpListener;
+
+    async fn mock_server() -> std::net::SocketAddr {
+        let listener = TcpListener::bind("127.0.0.1:0").await.expect("bind");
+        let addr = listener.local_addr().expect("addr");
+        tokio::spawn(async move {
+            let (mut sock, _) = listener.accept().await.expect("accept");
+            let mut req = [0u8; 24];
+            if sock.read_exact(&mut req).await.is_err() {
+                return;
+            }
+            // Reply: echo command 0x0063, status 0, no data.
+            let mut hdr = vec![0u8; 24];
+            hdr[0..2].copy_from_slice(&0x0063u16.to_le_bytes());
+            let _ = sock.write_all(&hdr).await;
+        });
+        addr
+    }
+
+    #[tokio::test]
+    async fn probe_detects_an_ethernetip_device() {
+        let addr = mock_server().await;
+        let p = probe(&addr.ip().to_string(), addr.port(), Duration::from_secs(2)).await;
+        assert!(p.reachable && p.is_enip);
+    }
+
+    #[tokio::test]
+    async fn probe_reports_unreachable_for_a_closed_port() {
+        let p = probe("127.0.0.1", 1, Duration::from_millis(500)).await;
+        assert!(!p.reachable && !p.is_enip);
+    }
+}