Trigger scripts

src/main.rs

@@ -1,6 +1,12 @@
 use clap::Parser;
+use std::collections::HashMap;
+use std::fs;
+use std::fs::File;
+use std::io::{self, BufRead};
+use std::process::Command;
 use std::thread::sleep;
 use std::time::Duration;
+use std::time::{SystemTime, UNIX_EPOCH};
 
 #[derive(Parser, Debug, Clone)]
 #[command(version, about, long_about = None)]
@@ -26,7 +32,7 @@ struct Args {
     dhcp_lease_dir: String,
 
     /// Scan interval
-    #[arg(short = 't', long, default_value_t = 1)] 
+    #[arg(short = 't', long, default_value_t = 1)]
     interval: u8,
 
     /// Interfaces to monitor
@@ -34,24 +40,145 @@ struct Args {
     interfaces: Vec<String>,
 }
 
-struct Monitor{
+struct Monitor {
     args: Args,
+    timestamps: HashMap<String, SystemTime>,
 }
 
 impl Monitor {
     fn new(args: Args) -> Self {
-        Self { args }
+        Self {
+            args,
+            timestamps: HashMap::new(),
+        }
     }
 
-    fn check_iface(&self, iface_name: String) {
-        println!("Checking: {}", iface_name);
+    /// Was the file modified since the last check?
+    fn check_file_modified(&mut self, lease_file_path: &str) -> bool {
+        println!("Checking: file {}", lease_file_path);
+
+        let metadata = fs::metadata(&lease_file_path);
+        let current_timestamp = metadata
+            .expect("Unsupported platform")
+            .modified()
+            .expect("Error getting modification timestamp");
+
+        let last_timestamp = self
+            .timestamps
+            .get(lease_file_path)
+            .copied()
+            .unwrap_or(SystemTime::from(UNIX_EPOCH));
+
+        if current_timestamp > last_timestamp {
+            // Store the new timestamp
+            self.timestamps
+                .insert(lease_file_path.to_string(), current_timestamp);
+
+            return true;
+        }
+
+        false
     }
 
+    /// Generates the lease file path
+    fn get_lease_file_path(&self, iface_name: &str) -> String {
+        let dhcp_lease_dir = &self.args.dhcp_lease_dir;
+        format!("{dhcp_lease_dir}/{iface_name}")
+    }
+
+    fn get_trigger_script_path(&self, iface_name: &str) -> String {
+        let trigger_scripts_path = &self.args.scripts_dir;
+        format!("{trigger_scripts_path}/lease_trigger_{iface_name}")
+    }
+
+    /// Gets the default route for iface from netstat
+    fn get_default_route(&self, iface_name: &str) -> Option<String> {
+        let output = Command::new("netstat")
+            .arg("-rn")
+            .arg("-f")
+            .arg("inet")
+            .output()
+            .expect("Failed to execute netstat");
+
+        if !output.status.success() {
+            println!(
+                "Failed to obtain route (iface: {}): {}",
+                iface_name,
+                output.status.to_string()
+            );
+            return None;
+        }
+
+        let stdout = String::from_utf8_lossy(&output.stdout);
+
+        for line in stdout.lines() {
+            let cols: Vec<&str> = line.split_whitespace().collect();
+            if cols.len() == 8 {
+                let route_iface = cols[7];
+                let route_dest = cols[0];
+                if route_iface == iface_name && route_dest == "default" {
+                    let route_ip = cols[1];
+                    println!("{} {}", route_dest, route_ip);
+                    return Some(route_ip.to_string());
+                }
+            }
+        }
+
+        return None;
+    }
+
+    /// Extracts the IP address from the lease file
+    fn get_lease_ip_addr(&self, lease_file_path: &str) -> Option<String> {
+        if let Ok(f) = File::open(lease_file_path) {
+            let lines = io::BufReader::new(f).lines();
+            for line in lines.flatten() {
+                if let Some((ident, value)) = line.split_once(":") {
+                    if ident.trim() == "ip" {
+                        return Some(value.trim().to_string());
+                    }
+                }
+            }
+        }
+        None
+    }
+
+    /// Execute the trigger script
+    fn trigger_script(&mut self, iface_name: &str, lease_file_path: &str) {
+
+        let default_route = self
+            .get_default_route(iface_name)
+            .unwrap_or(String::from(""));
+        let lease_ip_addr = self
+            .get_lease_ip_addr(lease_file_path)
+            .unwrap_or(String::from(""));
+
+        let trigger_script_path = self.get_trigger_script_path(iface_name);
+        println!(
+            "EXEC: {} {} -> script |{}| IP: {:?} Route: {}",
+            iface_name, lease_file_path, trigger_script_path, lease_ip_addr, default_route
+        );
+
+        let output = Command::new(trigger_script_path)
+            .env("DHCP_IFACE", iface_name)
+            .env("DHCP_IP_ADDR", lease_ip_addr)
+            .env("DHCP_IP_ROUTE", default_route)
+            .output()
+            .expect("Failed to execute trigger script");
+
+        if !output.status.success() {
+            println!("Trigger script execution was unsuccessful: {}", output.status.to_string());
+        }
+    }
+
+    /// The main monitoring loop
     fn run(&mut self) {
-
         loop {
-            for iface in &self.args.interfaces {
-                self.check_iface(iface.to_string());
+            for iface_name in self.args.interfaces.clone() {
+                let lease_file_path = self.get_lease_file_path(&iface_name);
+                if self.check_file_modified(&lease_file_path) {
+                    println!("Was modified!");
+                    self.trigger_script(&iface_name, &lease_file_path);
+                }
             }
             sleep(Duration::new(self.args.interval.into(), 0));
             println!("{:?}", self.args);
@@ -62,11 +189,10 @@ impl Monitor {
 
 fn main() {
     let args = Args::parse();
-    // let mut monitor = Monitor::new(&args);
     let mut monitor = Monitor::new(args.clone());
 
     if args.interfaces.is_empty() {
-        eprintln!("No interfaces to monitor");
+        panic!("No interfaces to monitor");
     }
 
     monitor.run();