track which namespaces we control

Cargo.lock

@@ -576,6 +576,7 @@ name = "netnsd"
 version = "0.1.0"
 dependencies = [
  "clap",
+ "either",
  "futures",
  "futures-concurrency",
  "humansize",

Cargo.toml

@@ -20,6 +20,7 @@ futures = "0.3.31"
 futures-concurrency = "7.6.3"
 humansize = { version = "2.1.3", features = ["no_alloc"] }
 neli = "0.7.1"
+either = "1.15.0"
 
 [dev-dependencies]
 serde_test = "1.0.177"

src/config/name.rs

@@ -1,11 +1,25 @@
 use serde::de::{Error, Unexpected, Visitor};
 use serde::{Deserialize, Deserializer};
+use std::ffi::OsString;
 use std::fmt::{Display, Formatter};
 use std::path::Path;
 
 #[derive(Debug, Clone, Eq, PartialEq, Hash)]
 pub struct NamespaceName(String);
 
+impl TryFrom<OsString> for NamespaceName {
+    type Error = ();
+
+    fn try_from(value: OsString) -> Result<Self, Self::Error> {
+        let str = value.into_string().map_err(|_| ())?;
+        if validate_name(&str) {
+            Ok(NamespaceName(str))
+        } else {
+            Err(())
+        }
+    }
+}
+
 impl Display for NamespaceName {
     fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
         self.0.fmt(f)
@@ -80,7 +94,7 @@ fn validate_name(name: &str) -> bool {
 
 #[test]
 fn test_de() {
-    use serde_test::{assert_de_tokens, assert_de_tokens_error, Token};
+    use serde_test::{Token, assert_de_tokens, assert_de_tokens_error};
 
     assert_de_tokens(&NamespaceName("foo".into()), &[Token::String("foo")]);
 

src/daemon.rs

@@ -22,7 +22,7 @@ pub fn daemon(config: Config) -> MainResult {
 }
 
 async fn daemon_async(mut config: Config) -> Result<(), DaemonError> {
-    let mut state = State::default();
+    let mut state = State::new()?;
     state.update(&config)?;
 
     // now the namespaces are setup, we can tell systemd to start any service depending on them
@@ -104,12 +104,18 @@ enum Event {
     Info,
 }
 
-#[derive(Default)]
 struct State {
     namespaces: Vec<ActiveNamespace>,
 }
 
 impl State {
+    pub fn new() -> Result<Self, DaemonError> {
+        let namespaces = NetNs::existing()?.map(ActiveNamespace::new).collect::<Result<Vec<_>, _>>()?;
+        Ok(State {
+            namespaces
+        })
+    }
+    
     pub fn update(&mut self, config: &Config) -> Result<(), DaemonError> {
         for removed in self.namespaces.extract_if(.., |namespace| {
             config.get_namespace(namespace.name()).is_none()
@@ -119,7 +125,7 @@ impl State {
 
         for new in &config.namespaces {
             if !self.has_namespace(&new.name) {
-                self.namespaces.push(ActiveNamespace::new(new)?);
+                self.namespaces.push(ActiveNamespace::new(new.name.clone())?);
             }
         }
 
@@ -144,16 +150,13 @@ struct ActiveNamespace {
 }
 
 impl ActiveNamespace {
-    pub fn new(config: &NamespaceConfig) -> Result<Self, DaemonError> {
-        let ns = NetNs::new(config.name.clone())?;
+    pub fn new(name: NamespaceName) -> Result<Self, DaemonError> {
+        let ns = NetNs::new(name)?;
 
-        let mut namespace = ActiveNamespace {
+        Ok(ActiveNamespace {
             ns,
             proxies: Vec::default(),
-        };
-        namespace.update_proxies(config)?;
-
-        Ok(namespace)
+        })
     }
 
     pub fn update_proxies(&mut self, config: &NamespaceConfig) -> Result<(), DaemonError> {

src/namespace/mod.rs

@@ -3,10 +3,12 @@ mod raw;
 use crate::config::NamespaceName;
 use crate::link::{LinkError, link_up_ns};
 use crate::namespace::raw::{NamespaceSetupError, create_network_namespace};
+use either::Either;
 use nix::errno::Errno;
 use nix::mount::{MntFlags, MsFlags, mount, umount2};
-use std::fs::{File, create_dir, remove_file};
+use std::fs::{File, create_dir, read_dir, remove_file};
 use std::io::{Error as IoError, ErrorKind};
+use std::iter::empty;
 use std::os::unix::fs::symlink;
 use std::path::{Path, PathBuf};
 use thiserror::Error;
@@ -15,9 +17,26 @@ use tracing::{debug, error, info};
 pub struct NetNs {
     name: NamespaceName,
     path: PathBuf,
+    nsd_path: PathBuf,
 }
 
 impl NetNs {
+    pub fn existing() -> Result<impl Iterator<Item = NamespaceName>, NamespaceError> {
+        let dir = match read_dir("/var/run/netnsd") {
+            Ok(dir) => Ok(dir),
+            Err(error) if error.kind() == ErrorKind::NotFound => {
+                return Ok(Either::Left(empty()));
+            }
+            Err(error) => Err(NamespaceError::Scan {
+                path: "/var/run/netnsd".into(),
+                error,
+            }),
+        }?;
+        Ok(Either::Right(dir.flatten().flat_map(|entry| {
+            NamespaceName::try_from(entry.file_name()).ok()
+        })))
+    }
+
     /// Create a new named network namespace that will be removed when dropped
     pub fn new(name: NamespaceName) -> Result<Self, NamespaceError> {
         let parent = Path::new("/var/run/netns");
@@ -41,7 +60,8 @@ impl NetNs {
                 }
 
                 return Ok(NetNs {
-                    name: name.clone(),
+                    name,
+                    nsd_path,
                     path,
                 });
             }
@@ -57,7 +77,7 @@ impl NetNs {
                     path: nsd_path.clone(),
                 })?;
             }
-            Result::<_, NamespaceError>::Ok(NetNs { name, path })
+            Result::<_, NamespaceError>::Ok(NetNs { name, path, nsd_path })
         })?;
 
         ns.setup_interfaces()?;
@@ -121,6 +141,10 @@ impl NetNs {
             error,
             path: self.path,
         })?;
+        remove_file(&self.nsd_path).map_err(|error| NamespaceError::Delete {
+            error,
+            path: self.nsd_path,
+        })?;
         Ok(())
     }
 }
@@ -145,6 +169,8 @@ pub enum NamespaceError {
     UnMount(Errno),
     #[error("Failed to setup loopback inside namespace: {0:#}")]
     Link(#[from] LinkError),
+    #[error("Failed to scan {} for namespaces: {error:#}", path.display())]
+    Scan { path: PathBuf, error: IoError },
 }
 
 impl NamespaceError {