Add Network types

Creates & removes the Docker network & reads in the allocated subnet mask.

packages/dns-test/src/container.rs

@@ -1,3 +1,5 @@
+mod network;
+
 use core::str;
 use std::fs;
 use std::net::Ipv4Addr;

packages/dns-test/src/container/network.rs

@@ -0,0 +1,109 @@
+use std::{
+    process::{Command, Stdio},
+    sync::atomic::{self, AtomicUsize},
+};
+
+use crate::Result;
+
+const NETWORK_NAME: &str = "dnssec-network";
+
+/// Represents a network in which to put containers into.
+pub struct Network {
+    name: String,
+}
+
+impl Network {
+    pub fn new() -> Result<Self> {
+        let id = network_count();
+        let network_name = format!("{NETWORK_NAME}-{id}");
+
+        let mut command = Command::new("docker");
+        command
+            .args(["network", "create"])
+            .args(["--internal"])
+            .arg(&network_name);
+
+        // create network
+        let output = command.output().unwrap();
+        let stdout = String::from_utf8_lossy(&output.stdout);
+        let stderr = String::from_utf8_lossy(&output.stderr);
+        assert!(
+            output.status.success(),
+            "--- STDOUT ---\n{stdout}\n--- STDERR ---\n{stderr}"
+        );
+
+        // inspect & parse network details
+
+        Ok(Self { name: network_name })
+    }
+
+    /// Returns the name of the network.
+    pub fn name(&self) -> &str {
+        self.name.as_str()
+    }
+}
+
+/// Collects all important configs.
+pub struct NetworkConfig {
+    /// The CIDR subnet mask, e.g. "172.21.0.0/16"
+    subnet: String,
+}
+
+///
+fn get_network_config(network_name: &str) -> Result<NetworkConfig> {
+    let mut command = Command::new("docker");
+    command
+        .args([
+            "network",
+            "inspect",
+            "-f",
+            "{{range .IPAM.Config}}{{.Subnet}}{{end}}",
+        ])
+        .arg(network_name);
+
+    let output = command.output()?;
+    if !output.status.success() {
+        return Err(format!("{command:?} failed").into());
+    }
+
+    let subnet = std::str::from_utf8(&output.stdout)?.trim().to_string();
+    Ok(NetworkConfig { subnet })
+}
+
+/// This ensure the Docket network is deleted after the test runner process ends.
+impl Drop for Network {
+    fn drop(&mut self) {
+        // Remove the network
+        // TODO check if all containers need to disconnect first
+        let _ = Command::new("docker")
+            .args(["network", "rm", "--force", self.name.as_str()])
+            .stdout(Stdio::null())
+            .stderr(Stdio::null())
+            .status();
+    }
+}
+
+fn network_count() -> usize {
+    static COUNT: AtomicUsize = AtomicUsize::new(1);
+
+    COUNT.fetch_add(1, atomic::Ordering::Relaxed)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn create_works() -> Result<()> {
+        assert!(Network::new().is_ok());
+        Ok(())
+    }
+
+    #[test]
+    fn network_subnet_works() -> Result<()> {
+        let network = Network::new().expect("Failed to create network");
+        let config = get_network_config(network.name());
+        assert!(config.is_ok());
+        Ok(())
+    }
+}