Scan IP neighbors on Linux

README.md

@@ -28,6 +28,7 @@ In this case, no other device exists within the LAN, but applications on the sma
 This feature relies on the operating system. Current we support these operating systems:
 
 - Windows (using [PowerShell](https://learn.microsoft.com/powershell/module/nettcpip/get-netneighbor?view=windowsserver2022-ps))
+- Linux (using [iproute2](https://wiki.linuxfoundation.org/networking/iproute2))
 
 ## Project name meaning
 

main/Cargo.toml

@@ -14,6 +14,7 @@ log = "0.4"
 mockall = "0.12"
 prost = "0.12"
 serde = { version = "1.0", features = ["derive"] }
+serde_json = "1"
 tansa-protocol = { path = "../protocol/rust" }
 thiserror = "1"
 tokio = { version = "1", features = ["fs", "process"] }

main/src/network/ip_neighbor/linux.rs

@@ -0,0 +1,151 @@
+use super::IpNeighbor;
+use super::IpNeighborScanError;
+use super::IpNeighborScanner;
+use csv::ReaderBuilder;
+use futures_util::future::BoxFuture;
+use futures_util::FutureExt;
+use serde::Deserialize;
+use std::collections::HashMap;
+use std::net::Ipv6Addr;
+
+pub struct IpRoute2IpNeighborScanner;
+
+impl IpRoute2IpNeighborScanner {
+    async fn scan() -> Result<Vec<IpNeighbor>, IpNeighborScanError> {
+        let ip_links = crate::process::run("ip", &["-json", "link"]).await?;
+        let ip_neighbors = crate::process::run("ip", &["-family", "inet6", "neighbor"]).await?;
+        Self::parse_output(&ip_links, &ip_neighbors).map_err(Into::into)
+    }
+
+    fn parse_output(
+        ip_link_output: &[u8],
+        ip_neighbor_output: &[u8],
+    ) -> Result<Vec<IpNeighbor>, IpNeighborScanError> {
+        let neighbors = ReaderBuilder::new()
+            .has_headers(false)
+            .delimiter(b' ')
+            .from_reader(ip_neighbor_output)
+            .deserialize()
+            .collect::<Result<Vec<Neighbor>, _>>()?;
+        neighbors
+            .iter()
+            .for_each(|n| log::debug!("Scanned IP neighbor: {:?}", n));
+
+        let links: Vec<Link> = serde_json::from_reader(ip_link_output)?;
+        links
+            .iter()
+            .for_each(|l| log::debug!("Scanned IP link: {:?}", l));
+        let links: HashMap<_, _> = links.into_iter().map(|l| (l.ifname.clone(), l)).collect();
+
+        let neighbors: Vec<_> = neighbors
+            .into_iter()
+            .filter(|n| n.state != "FAILED")
+            .filter(|n| n.ip.segments().starts_with(&[0xFE80, 0, 0, 0]))
+            .filter_map(|n| {
+                links.get(&n.ifname).map(|l| IpNeighbor {
+                    address: n.ip,
+                    network_interface_index: l.ifindex,
+                })
+            })
+            .collect();
+        neighbors
+            .iter()
+            .for_each(|n| log::info!("Valid IP neighbor: {:?}", n));
+
+        Ok(neighbors)
+    }
+}
+
+impl IpNeighborScanner for IpRoute2IpNeighborScanner {
+    fn supports_current_operating_system(&self) -> BoxFuture<'static, bool> {
+        crate::process::probe("ip", &["-Version"]).boxed()
+    }
+
+    fn scan(&self) -> BoxFuture<'static, Result<Vec<IpNeighbor>, IpNeighborScanError>> {
+        Self::scan().boxed()
+    }
+}
+
+#[derive(Deserialize, Debug)]
+#[allow(non_snake_case, dead_code)]
+struct Neighbor {
+    ip: Ipv6Addr,
+    dev: String,
+    ifname: String,
+    lladdr: String,
+    mac: String,
+    router: String,
+    state: String,
+}
+
+#[derive(Deserialize, Debug)]
+#[allow(non_snake_case)]
+struct Link {
+    ifindex: u32,
+    ifname: String,
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[tokio::test]
+    async fn scan() {
+        crate::test::init();
+
+        let scanner = IpRoute2IpNeighborScanner;
+
+        if !scanner.supports_current_operating_system().await {
+            println!("`iproute2` does not exist, skipping.");
+            return;
+        }
+
+        scanner.scan().await.unwrap();
+    }
+
+    #[test]
+    fn parse_output() {
+        let ip_neighbor_output = r#"
+fe80::1:abcd dev wlan0 lladdr 00:00:00:00:00:01 router REACHABLE
+fe80::2:abcd dev eth0 lladdr 00:00:00:00:00:02 router STALE
+fe80::3:abcd dev wlan2 lladdr 00:00:00:00:00:03 router STALE
+fe02::4:abcd dev wlan0 lladdr 00:00:00:00:00:04 router REACHABLE
+fe80::5:abcd dev wlan0 lladdr 00:00:00:00:00:05 router FAILED
+        "#
+        .trim();
+        let ip_link_output = r#"
+        [
+          {
+            "ifindex": 1,
+            "ifname": "wlan0",
+            "mtu": 1500
+          },
+          {
+            "ifindex": 2,
+            "ifname": "eth0",
+            "mtu": 1500
+          }
+        ]
+        "#;
+        let expected_neighbors = vec![
+            IpNeighbor {
+                network_interface_index: 1,
+                address: "fe80::1:abcd".parse().unwrap(),
+            },
+            IpNeighbor {
+                network_interface_index: 2,
+                address: "fe80::2:abcd".parse().unwrap(),
+            },
+        ];
+
+        // When
+        let actual_neighbors = IpRoute2IpNeighborScanner::parse_output(
+            ip_link_output.as_bytes(),
+            ip_neighbor_output.as_bytes(),
+        )
+        .unwrap();
+
+        // Then
+        assert_eq!(actual_neighbors, expected_neighbors);
+    }
+}

main/src/network/ip_neighbor/mod.rs

@@ -1,5 +1,7 @@
+mod linux;
 mod windows;
 
+use self::linux::IpRoute2IpNeighborScanner;
 use self::windows::PowerShellIpNeighborScanner;
 use crate::process::ProcessError;
 use futures_util::future::BoxFuture;
@@ -11,8 +13,10 @@ use std::net::SocketAddrV6;
 use thiserror::Error;
 
 pub async fn ip_neighbor_scanner() -> Box<dyn IpNeighborScanner + Send> {
-    let scanners: Vec<Box<dyn IpNeighborScanner + Send>> =
-        vec![Box::new(PowerShellIpNeighborScanner)];
+    let scanners: Vec<Box<dyn IpNeighborScanner + Send>> = vec![
+        Box::new(PowerShellIpNeighborScanner),
+        Box::new(IpRoute2IpNeighborScanner),
+    ];
     if let Some(supported_scanner) = futures_util::stream::iter(scanners)
         .filter(|s| s.supports_current_operating_system())
         .next()
@@ -31,7 +35,10 @@ pub enum IpNeighborScanError {
     ChildProcess(#[from] ProcessError),
 
     #[error("Failed to parse the CSV output of a child process")]
-    ChildProcessCsvOutput(#[from] csv::Error),
+    ParseCsv(#[from] csv::Error),
+
+    #[error("Failed to parse the JSON output of a child process")]
+    ParseJson(#[from] serde_json::Error),
 }
 
 #[automock]

main/src/network/ip_neighbor/windows.rs

@@ -84,8 +84,7 @@ mod test {
             return;
         }
 
-        let neighbors = scanner.scan().await.unwrap();
-        assert!(!neighbors.is_empty());
+        scanner.scan().await.unwrap();
     }
 
     #[test]

main/src/process.rs

@@ -2,6 +2,7 @@ use std::process::Stdio;
 use thiserror::Error;
 use tokio::io::AsyncReadExt;
 use tokio::io::AsyncWriteExt;
+use tokio::process::Child;
 use tokio::process::Command;
 
 pub async fn eval(command: &str, args: &[&str], stdin: &[u8]) -> Result<Vec<u8>, ProcessError> {
@@ -23,14 +24,22 @@ pub async fn eval(command: &str, args: &[&str], stdin: &[u8]) -> Result<Vec<u8>,
         return Err(ProcessError::ExternalCommand);
     }
 
-    let mut stdout = process
-        .stdout
-        .take()
-        .ok_or_else(|| ProcessError::StdioRedirection)?;
+    read_stdout(&mut process).await
+}
 
-    let mut buffer = Default::default();
-    stdout.read_to_end(&mut buffer).await?;
-    Ok(buffer)
+pub async fn run(command: &str, args: &[&str]) -> Result<Vec<u8>, ProcessError> {
+    let mut process = Command::new(command)
+        .args(args)
+        .stdin(Stdio::null())
+        .stdout(Stdio::piped())
+        .stderr(Stdio::inherit())
+        .spawn()?;
+
+    if !process.wait().await?.success() {
+        return Err(ProcessError::ExternalCommand);
+    }
+
+    read_stdout(&mut process).await
 }
 
 pub async fn probe(command: &str, args: &[&str]) -> bool {
@@ -62,6 +71,17 @@ pub async fn probe(command: &str, args: &[&str]) -> bool {
     }
 }
 
+async fn read_stdout(process: &mut Child) -> Result<Vec<u8>, ProcessError> {
+    let mut stdout = process
+        .stdout
+        .take()
+        .ok_or_else(|| ProcessError::StdioRedirection)?;
+
+    let mut buffer = Default::default();
+    stdout.read_to_end(&mut buffer).await?;
+    Ok(buffer)
+}
+
 #[derive(Error, Debug)]
 pub enum ProcessError {
     #[error("Failed in create a child process")]