boringtun wip

Tracing has support for intervals and a great os_log integration.

.github/workflows/build-rust.yml

@@ -17,21 +17,24 @@ jobs:
           platform: Linux
           packages:
           - gcc-aarch64-linux-gnu
-          targets:
+          test-targets:
           - x86_64-unknown-linux-gnu
+          targets:
           - aarch64-unknown-linux-gnu
         - os: macos-12
           platform: macOS
-          targets:
+          test-targets:
           - x86_64-apple-darwin
+          targets:
           - aarch64-apple-darwin
           - aarch64-apple-ios
           - aarch64-apple-ios-sim
           - x86_64-apple-ios
         - os: windows-2022
           platform: Windows
-          targets:
+          test-targets:
           - x86_64-pc-windows-msvc
+          targets:
           - aarch64-pc-windows-msvc
     runs-on: ${{ matrix.os }}
     env:
@@ -57,6 +60,11 @@ jobs:
         toolchain: stable
         components: rustfmt
         targets: ${{ join(matrix.targets, ', ') }}
+    - name: Setup Rust Cache
+      uses: Swatinem/rust-cache@v2
     - name: Build
       shell: bash
-      run: cargo build --verbose --workspace --all-features --target ${{ join(matrix.targets, ' --target ') }}
+      run: cargo build --verbose --workspace --all-features --target ${{ join(matrix.targets, ' --target ') }} --target ${{ join(matrix.test-targets, ' --target ') }}
+    - name: Test
+      shell: bash
+      run: cargo test --verbose --workspace --all-features --target ${{ join(matrix.test-targets, ' --target ') }}

.vscode/settings.json

@@ -8,15 +8,6 @@
     "editor.acceptSuggestionOnEnter": "on",
     "rust-analyzer.restartServerOnConfigChange": true,
     "rust-analyzer.cargo.features": "all",
-    "rust-analyzer.check.overrideCommand": [
-        "cargo",
-        "clippy",
-        "--fix",
-        "--workspace",
-        "--message-format=json",
-        "--all-targets",
-        "--allow-dirty"
-    ],
     "[rust]": {
         "editor.defaultFormatter": "rust-lang.rust-analyzer",
     }

Apple/NetworkExtension/PacketTunnelProvider.swift

@@ -1,7 +1,22 @@
+import libburrow
 import NetworkExtension
+import OSLog
 
 class PacketTunnelProvider: NEPacketTunnelProvider {
+    let logger = Logger(subsystem: "com.hackclub.burrow", category: "General")
     override func startTunnel(options: [String: NSObject]?, completionHandler: @escaping (Error?) -> Void) {
+        let fild = libburrow.retrieve()
+        if fild == -1 {
+            // Not sure if this is the right way to return an error
+            logger.error("Failed to retrieve file descriptor for burrow.")
+            let err = NSError(
+                domain: "com.hackclub.burrow",
+                code: 1_010,
+                userInfo: [NSLocalizedDescriptionKey: "Failed to find TunInterface"]
+            )
+            completionHandler(err)
+        }
+        logger.info("fd: \(fild)")
         completionHandler(nil)
     }
 

Apple/NetworkExtension/libburrow/libburrow.h

@@ -1 +1 @@
-
+int retrieve();

README.md

@@ -17,9 +17,9 @@ Apple/ # Xcode project for burrow on macOS and iOS
 burrow/ # Higher-level API library for tun and tun-async
 tun/ # Low-level interface to OS networking
     src/
+        tokio/ # Async/Tokio code
         unix/ # macOS and Linux code
         windows/ # Windows networking code
-tun-async/ # Async interface to tun
 ```
 
 ## Installation 

burrow/Cargo.toml

@@ -7,14 +7,23 @@ edition = "2021"
 crate-type = ["lib", "staticlib"]
 
 [dependencies]
-tokio = { version = "1.21", features = ["rt", "macros"] }
-tun = { version = "0.1", path = "../tun" }
+anyhow = "1.0"
+tokio = { version = "1.21", features = ["rt", "macros", "sync", "io-util"] }
+tun = { version = "0.1", path = "../tun", features = ["serde"] }
 clap = { version = "4.3.2", features = ["derive"] }
+tracing = "0.1"
+tracing-log = "0.1"
+tracing-journald = "0.3"
+tracing-oslog = {git = "https://github.com/Stormshield-robinc/tracing-oslog"}
+tracing-subscriber = "0.3"
 env_logger = "0.10"
 log = "0.4"
+serde = { version = "1", features = ["derive"] }
+serde_json = "1"
 
 [target.'cfg(target_os = "linux")'.dependencies]
 caps = "0.5.5"
+libsystemd = "0.6"
 
 [target.'cfg(target_vendor = "apple")'.dependencies]
 nix = { version = "0.26.2" }

burrow/src/boringtun/Cargo.toml

@@ -0,0 +1,66 @@
+[package]
+name = "boringtun"
+description = "an implementation of the WireGuard® protocol designed for portability and speed"
+version = "0.6.0"
+authors = [
+    "Noah Kennedy <nkennedy@cloudflare.com>",
+    "Andy Grover <agrover@cloudflare.com>",
+    "Jeff Hiner <jhiner@cloudflare.com>",
+]
+license = "BSD-3-Clause"
+repository = "https://github.com/cloudflare/boringtun"
+documentation = "https://docs.rs/boringtun/0.5.2/boringtun/"
+edition = "2018"
+
+[features]
+default = []
+device = ["socket2", "thiserror"]
+jni-bindings = ["ffi-bindings", "jni"]
+ffi-bindings = ["tracing-subscriber"]
+# mocks std::time::Instant with mock_instant
+mock-instant = ["mock_instant"]
+
+[workspace]
+
+[dependencies]
+base64 = "0.13"
+hex = "0.4"
+untrusted = "0.9.0"
+libc = "0.2"
+parking_lot = "0.12"
+tracing = "0.1.29"
+tracing-subscriber = { version = "0.3", features = ["fmt"], optional = true }
+ip_network = "0.4.1"
+ip_network_table = "0.2.0"
+ring = "0.16"
+x25519-dalek = { version = "2.0.0", features = [
+    "reusable_secrets",
+    "static_secrets",
+] }
+rand_core = { version = "0.6.3", features = ["getrandom"] }
+chacha20poly1305 = "0.10.0-pre.1"
+aead = "0.5.0-pre.2"
+blake2 = "0.10"
+hmac = "0.12"
+jni = { version = "0.19.0", optional = true }
+mock_instant = { version = "0.2", optional = true }
+socket2 = { version = "0.4.7", features = ["all"], optional = true }
+thiserror = { version = "1", optional = true }
+
+[target.'cfg(unix)'.dependencies]
+nix = { version = "0.25", default-features = false, features = [
+    "time",
+    "user",
+] }
+
+[dev-dependencies]
+etherparse = "0.12"
+tracing-subscriber = "0.3"
+criterion = { version = "0.3.5", features = ["html_reports"] }
+
+[lib]
+crate-type = ["staticlib", "cdylib", "rlib"]
+
+[[bench]]
+name = "crypto_benches"
+harness = false

burrow/src/boringtun/src/device/mod.rs

@@ -0,0 +1,902 @@
+// Copyright (c) 2019 Cloudflare, Inc. All rights reserved.
+// SPDX-License-Identifier: BSD-3-Clause
+
+pub mod allowed_ips;
+pub mod api;
+mod dev_lock;
+pub mod drop_privileges;
+#[cfg(test)]
+mod integration_tests;
+pub mod peer;
+
+#[cfg(any(target_os = "macos", target_os = "ios"))]
+#[path = "kqueue.rs"]
+pub mod poll;
+
+#[cfg(target_os = "linux")]
+#[path = "epoll.rs"]
+pub mod poll;
+
+#[cfg(any(target_os = "macos", target_os = "ios"))]
+#[path = "tun_darwin.rs"]
+pub mod tun;
+
+#[cfg(target_os = "linux")]
+#[path = "tun_linux.rs"]
+pub mod tun;
+
+use std::collections::HashMap;
+use std::io::{self, Write as _};
+use std::mem::MaybeUninit;
+use std::net::{IpAddr, Ipv4Addr, Ipv6Addr, SocketAddr, SocketAddrV4, SocketAddrV6};
+use std::os::unix::io::AsRawFd;
+use std::sync::atomic::{AtomicUsize, Ordering};
+use std::sync::Arc;
+use std::thread;
+use std::thread::JoinHandle;
+
+use crate::noise::errors::WireGuardError;
+use crate::noise::handshake::parse_handshake_anon;
+use crate::noise::rate_limiter::RateLimiter;
+use crate::noise::{Packet, Tunn, TunnResult};
+use crate::x25519;
+use allowed_ips::AllowedIps;
+use parking_lot::Mutex;
+use peer::{AllowedIP, Peer};
+use poll::{EventPoll, EventRef, WaitResult};
+use rand_core::{OsRng, RngCore};
+use socket2::{Domain, Protocol, Type};
+use tun::TunSocket;
+
+use dev_lock::{Lock, LockReadGuard};
+
+const HANDSHAKE_RATE_LIMIT: u64 = 100; // The number of handshakes per second we can tolerate before using cookies
+
+const MAX_UDP_SIZE: usize = (1 << 16) - 1;
+const MAX_ITR: usize = 100; // Number of packets to handle per handler call
+
+#[derive(Debug, thiserror::Error)]
+pub enum Error {
+    #[error("i/o error: {0}")]
+    IoError(#[from] io::Error),
+    #[error("{0}")]
+    Socket(io::Error),
+    #[error("{0}")]
+    Bind(String),
+    #[error("{0}")]
+    FCntl(io::Error),
+    #[error("{0}")]
+    EventQueue(io::Error),
+    #[error("{0}")]
+    IOCtl(io::Error),
+    #[error("{0}")]
+    Connect(String),
+    #[error("{0}")]
+    SetSockOpt(String),
+    #[error("Invalid tunnel name")]
+    InvalidTunnelName,
+    #[cfg(any(target_os = "macos", target_os = "ios"))]
+    #[error("{0}")]
+    GetSockOpt(io::Error),
+    #[error("{0}")]
+    GetSockName(String),
+    #[cfg(target_os = "linux")]
+    #[error("{0}")]
+    Timer(io::Error),
+    #[error("iface read: {0}")]
+    IfaceRead(io::Error),
+    #[error("{0}")]
+    DropPrivileges(String),
+    #[error("API socket error: {0}")]
+    ApiSocket(io::Error),
+}
+
+// What the event loop should do after a handler returns
+enum Action {
+    Continue, // Continue the loop
+    Yield,    // Yield the read lock and acquire it again
+    Exit,     // Stop the loop
+}
+
+// Event handler function
+type Handler = Box<dyn Fn(&mut LockReadGuard<Device>, &mut ThreadData) -> Action + Send + Sync>;
+
+pub struct DeviceHandle {
+    device: Arc<Lock<Device>>, // The interface this handle owns
+    threads: Vec<JoinHandle<()>>,
+}
+
+#[derive(Debug, Clone, Copy)]
+pub struct DeviceConfig {
+    pub n_threads: usize,
+    pub use_connected_socket: bool,
+    #[cfg(target_os = "linux")]
+    pub use_multi_queue: bool,
+    #[cfg(target_os = "linux")]
+    pub uapi_fd: i32,
+}
+
+impl Default for DeviceConfig {
+    fn default() -> Self {
+        DeviceConfig {
+            n_threads: 4,
+            use_connected_socket: true,
+            #[cfg(target_os = "linux")]
+            use_multi_queue: true,
+            #[cfg(target_os = "linux")]
+            uapi_fd: -1,
+        }
+    }
+}
+
+pub struct Device {
+    key_pair: Option<(x25519::StaticSecret, x25519::PublicKey)>,
+    queue: Arc<EventPoll<Handler>>,
+
+    listen_port: u16,
+    fwmark: Option<u32>,
+
+    iface: Arc<TunSocket>,
+    udp4: Option<socket2::Socket>,
+    udp6: Option<socket2::Socket>,
+
+    yield_notice: Option<EventRef>,
+    exit_notice: Option<EventRef>,
+
+    peers: HashMap<x25519::PublicKey, Arc<Mutex<Peer>>>,
+    peers_by_ip: AllowedIps<Arc<Mutex<Peer>>>,
+    peers_by_idx: HashMap<u32, Arc<Mutex<Peer>>>,
+    next_index: IndexLfsr,
+
+    config: DeviceConfig,
+
+    cleanup_paths: Vec<String>,
+
+    mtu: AtomicUsize,
+
+    rate_limiter: Option<Arc<RateLimiter>>,
+
+    #[cfg(target_os = "linux")]
+    uapi_fd: i32,
+}
+
+struct ThreadData {
+    iface: Arc<TunSocket>,
+    src_buf: [u8; MAX_UDP_SIZE],
+    dst_buf: [u8; MAX_UDP_SIZE],
+}
+
+impl DeviceHandle {
+    pub fn new(name: &str, config: DeviceConfig) -> Result<DeviceHandle, Error> {
+        let n_threads = config.n_threads;
+        let mut wg_interface = Device::new(name, config)?;
+        wg_interface.open_listen_socket(0)?; // Start listening on a random port
+
+        let interface_lock = Arc::new(Lock::new(wg_interface));
+
+        let mut threads = vec![];
+
+        for i in 0..n_threads {
+            threads.push({
+                let dev = Arc::clone(&interface_lock);
+                thread::spawn(move || DeviceHandle::event_loop(i, &dev))
+            });
+        }
+
+        Ok(DeviceHandle {
+            device: interface_lock,
+            threads,
+        })
+    }
+
+    pub fn wait(&mut self) {
+        while let Some(thread) = self.threads.pop() {
+            thread.join().unwrap();
+        }
+    }
+
+    pub fn clean(&mut self) {
+        for path in &self.device.read().cleanup_paths {
+            // attempt to remove any file we created in the work dir
+            let _ = std::fs::remove_file(path);
+        }
+    }
+
+    fn event_loop(_i: usize, device: &Lock<Device>) {
+        #[cfg(target_os = "linux")]
+        let mut thread_local = ThreadData {
+            src_buf: [0u8; MAX_UDP_SIZE],
+            dst_buf: [0u8; MAX_UDP_SIZE],
+            iface: if _i == 0 || !device.read().config.use_multi_queue {
+                // For the first thread use the original iface
+                Arc::clone(&device.read().iface)
+            } else {
+                // For for the rest create a new iface queue
+                let iface_local = Arc::new(
+                    TunSocket::new(&device.read().iface.name().unwrap())
+                        .unwrap()
+                        .set_non_blocking()
+                        .unwrap(),
+                );
+
+                device
+                    .read()
+                    .register_iface_handler(Arc::clone(&iface_local))
+                    .ok();
+
+                iface_local
+            },
+        };
+
+        #[cfg(not(target_os = "linux"))]
+        let mut thread_local = ThreadData {
+            src_buf: [0u8; MAX_UDP_SIZE],
+            dst_buf: [0u8; MAX_UDP_SIZE],
+            iface: Arc::clone(&device.read().iface),
+        };
+
+        #[cfg(not(target_os = "linux"))]
+        let uapi_fd = -1;
+        #[cfg(target_os = "linux")]
+        let uapi_fd = device.read().uapi_fd;
+
+        loop {
+            // The event loop keeps a read lock on the device, because we assume write access is rarely needed
+            let mut device_lock = device.read();
+            let queue = Arc::clone(&device_lock.queue);
+
+            loop {
+                match queue.wait() {
+                    WaitResult::Ok(handler) => {
+                        let action = (*handler)(&mut device_lock, &mut thread_local);
+                        match action {
+                            Action::Continue => {}
+                            Action::Yield => break,
+                            Action::Exit => {
+                                device_lock.trigger_exit();
+                                return;
+                            }
+                        }
+                    }
+                    WaitResult::EoF(handler) => {
+                        if uapi_fd >= 0 && uapi_fd == handler.fd() {
+                            device_lock.trigger_exit();
+                            return;
+                        }
+                        handler.cancel();
+                    }
+                    WaitResult::Error(e) => tracing::error!(message = "Poll error", error = ?e),
+                }
+            }
+        }
+    }
+}
+
+impl Drop for DeviceHandle {
+    fn drop(&mut self) {
+        self.device.read().trigger_exit();
+        self.clean();
+    }
+}
+
+impl Device {
+    fn next_index(&mut self) -> u32 {
+        self.next_index.next()
+    }
+
+    fn remove_peer(&mut self, pub_key: &x25519::PublicKey) {
+        if let Some(peer) = self.peers.remove(pub_key) {
+            // Found a peer to remove, now purge all references to it:
+            {
+                let p = peer.lock();
+                p.shutdown_endpoint(); // close open udp socket and free the closure
+                self.peers_by_idx.remove(&p.index());
+            }
+            self.peers_by_ip
+                .remove(&|p: &Arc<Mutex<Peer>>| Arc::ptr_eq(&peer, p));
+
+            tracing::info!("Peer removed");
+        }
+    }
+
+    #[allow(clippy::too_many_arguments)]
+    fn update_peer(
+        &mut self,
+        pub_key: x25519::PublicKey,
+        remove: bool,
+        _replace_ips: bool,
+        endpoint: Option<SocketAddr>,
+        allowed_ips: &[AllowedIP],
+        keepalive: Option<u16>,
+        preshared_key: Option<[u8; 32]>,
+    ) {
+        if remove {
+            // Completely remove a peer
+            return self.remove_peer(&pub_key);
+        }
+
+        // Update an existing peer
+        if self.peers.get(&pub_key).is_some() {
+            // We already have a peer, we need to merge the existing config into the newly created one
+            panic!("Modifying existing peers is not yet supported. Remove and add again instead.");
+        }
+
+        let next_index = self.next_index();
+        let device_key_pair = self
+            .key_pair
+            .as_ref()
+            .expect("Private key must be set first");
+
+        let tunn = Tunn::new(
+            device_key_pair.0.clone(),
+            pub_key,
+            preshared_key,
+            keepalive,
+            next_index,
+            None,
+        )
+        .unwrap();
+
+        let peer = Peer::new(tunn, next_index, endpoint, allowed_ips, preshared_key);
+
+        let peer = Arc::new(Mutex::new(peer));
+        self.peers.insert(pub_key, Arc::clone(&peer));
+        self.peers_by_idx.insert(next_index, Arc::clone(&peer));
+
+        for AllowedIP { addr, cidr } in allowed_ips {
+            self.peers_by_ip
+                .insert(*addr, *cidr as _, Arc::clone(&peer));
+        }
+
+        tracing::info!("Peer added");
+    }
+
+    pub fn new(name: &str, config: DeviceConfig) -> Result<Device, Error> {
+        let poll = EventPoll::<Handler>::new()?;
+
+        // Create a tunnel device
+        let iface = Arc::new(TunSocket::new(name)?.set_non_blocking()?);
+        let mtu = iface.mtu()?;
+
+        #[cfg(not(target_os = "linux"))]
+        let uapi_fd = -1;
+        #[cfg(target_os = "linux")]
+        let uapi_fd = config.uapi_fd;
+
+        let mut device = Device {
+            queue: Arc::new(poll),
+            iface,
+            config,
+            exit_notice: Default::default(),
+            yield_notice: Default::default(),
+            fwmark: Default::default(),
+            key_pair: Default::default(),
+            listen_port: Default::default(),
+            next_index: Default::default(),
+            peers: Default::default(),
+            peers_by_idx: Default::default(),
+            peers_by_ip: AllowedIps::new(),
+            udp4: Default::default(),
+            udp6: Default::default(),
+            cleanup_paths: Default::default(),
+            mtu: AtomicUsize::new(mtu),
+            rate_limiter: None,
+            #[cfg(target_os = "linux")]
+            uapi_fd,
+        };
+
+        if uapi_fd >= 0 {
+            device.register_api_fd(uapi_fd)?;
+        } else {
+            device.register_api_handler()?;
+        }
+        device.register_iface_handler(Arc::clone(&device.iface))?;
+        device.register_notifiers()?;
+        device.register_timers()?;
+
+        #[cfg(target_os = "macos")]
+        {
+            // Only for macOS write the actual socket name into WG_TUN_NAME_FILE
+            if let Ok(name_file) = std::env::var("WG_TUN_NAME_FILE") {
+                if name == "utun" {
+                    std::fs::write(&name_file, device.iface.name().unwrap().as_bytes()).unwrap();
+                    device.cleanup_paths.push(name_file);
+                }
+            }
+        }
+
+        Ok(device)
+    }
+
+    fn open_listen_socket(&mut self, mut port: u16) -> Result<(), Error> {
+        // Binds the network facing interfaces
+        // First close any existing open socket, and remove them from the event loop
+        if let Some(s) = self.udp4.take() {
+            unsafe {
+                // This is safe because the event loop is not running yet
+                self.queue.clear_event_by_fd(s.as_raw_fd())
+            }
+        };
+
+        if let Some(s) = self.udp6.take() {
+            unsafe { self.queue.clear_event_by_fd(s.as_raw_fd()) };
+        }
+
+        for peer in self.peers.values() {
+            peer.lock().shutdown_endpoint();
+        }
+
+        // Then open new sockets and bind to the port
+        let udp_sock4 = socket2::Socket::new(Domain::IPV4, Type::DGRAM, Some(Protocol::UDP))?;
+        udp_sock4.set_reuse_address(true)?;
+        udp_sock4.bind(&SocketAddrV4::new(Ipv4Addr::UNSPECIFIED, port).into())?;
+        udp_sock4.set_nonblocking(true)?;
+
+        if port == 0 {
+            // Random port was assigned
+            port = udp_sock4.local_addr()?.as_socket().unwrap().port();
+        }
+
+        let udp_sock6 = socket2::Socket::new(Domain::IPV6, Type::DGRAM, Some(Protocol::UDP))?;
+        udp_sock6.set_reuse_address(true)?;
+        udp_sock6.bind(&SocketAddrV6::new(Ipv6Addr::UNSPECIFIED, port, 0, 0).into())?;
+        udp_sock6.set_nonblocking(true)?;
+
+        self.register_udp_handler(udp_sock4.try_clone().unwrap())?;
+        self.register_udp_handler(udp_sock6.try_clone().unwrap())?;
+        self.udp4 = Some(udp_sock4);
+        self.udp6 = Some(udp_sock6);
+
+        self.listen_port = port;
+
+        Ok(())
+    }
+
+    fn set_key(&mut self, private_key: x25519::StaticSecret) {
+        let mut bad_peers = vec![];
+
+        let public_key = x25519::PublicKey::from(&private_key);
+        let key_pair = Some((private_key.clone(), public_key));
+
+        // x25519 (rightly) doesn't let us expose secret keys for comparison.
+        // If the public keys are the same, then the private keys are the same.
+        if Some(&public_key) == self.key_pair.as_ref().map(|p| &p.1) {
+            return;
+        }
+
+        let rate_limiter = Arc::new(RateLimiter::new(&public_key, HANDSHAKE_RATE_LIMIT));
+
+        for peer in self.peers.values_mut() {
+            let mut peer_mut = peer.lock();
+
+            if peer_mut
+                .tunnel
+                .set_static_private(
+                    private_key.clone(),
+                    public_key,
+                    Some(Arc::clone(&rate_limiter)),
+                )
+                .is_err()
+            {
+                // In case we encounter an error, we will remove that peer
+                // An error will be a result of bad public key/secret key combination
+                bad_peers.push(Arc::clone(peer));
+            }
+        }
+
+        self.key_pair = key_pair;
+        self.rate_limiter = Some(rate_limiter);
+
+        // Remove all the bad peers
+        for _ in bad_peers {
+            unimplemented!();
+        }
+    }
+
+    #[cfg(any(target_os = "android", target_os = "fuchsia", target_os = "linux"))]
+    fn set_fwmark(&mut self, mark: u32) -> Result<(), Error> {
+        self.fwmark = Some(mark);
+
+        // First set fwmark on listeners
+        if let Some(ref sock) = self.udp4 {
+            sock.set_mark(mark)?;
+        }
+
+        if let Some(ref sock) = self.udp6 {
+            sock.set_mark(mark)?;
+        }
+
+        // Then on all currently connected sockets
+        for peer in self.peers.values() {
+            if let Some(ref sock) = peer.lock().endpoint().conn {
+                sock.set_mark(mark)?
+            }
+        }
+
+        Ok(())
+    }
+
+    fn clear_peers(&mut self) {
+        self.peers.clear();
+        self.peers_by_idx.clear();
+        self.peers_by_ip.clear();
+    }
+
+    fn register_notifiers(&mut self) -> Result<(), Error> {
+        let yield_ev = self
+            .queue
+            // The notification event handler simply returns Action::Yield
+            .new_notifier(Box::new(|_, _| Action::Yield))?;
+        self.yield_notice = Some(yield_ev);
+
+        let exit_ev = self
+            .queue
+            // The exit event handler simply returns Action::Exit
+            .new_notifier(Box::new(|_, _| Action::Exit))?;
+        self.exit_notice = Some(exit_ev);
+        Ok(())
+    }
+
+    fn register_timers(&self) -> Result<(), Error> {
+        self.queue.new_periodic_event(
+            // Reset the rate limiter every second give or take
+            Box::new(|d, _| {
+                if let Some(r) = d.rate_limiter.as_ref() {
+                    r.reset_count()
+                }
+                Action::Continue
+            }),
+            std::time::Duration::from_secs(1),
+        )?;
+
+        self.queue.new_periodic_event(
+            // Execute the timed function of every peer in the list
+            Box::new(|d, t| {
+                let peer_map = &d.peers;
+
+                let (udp4, udp6) = match (d.udp4.as_ref(), d.udp6.as_ref()) {
+                    (Some(udp4), Some(udp6)) => (udp4, udp6),
+                    _ => return Action::Continue,
+                };
+
+                // Go over each peer and invoke the timer function
+                for peer in peer_map.values() {
+                    let mut p = peer.lock();
+                    let endpoint_addr = match p.endpoint().addr {
+                        Some(addr) => addr,
+                        None => continue,
+                    };
+
+                    match p.update_timers(&mut t.dst_buf[..]) {
+                        TunnResult::Done => {}
+                        TunnResult::Err(WireGuardError::ConnectionExpired) => {
+                            p.shutdown_endpoint(); // close open udp socket
+                        }
+                        TunnResult::Err(e) => tracing::error!(message = "Timer error", error = ?e),
+                        TunnResult::WriteToNetwork(packet) => {
+                            match endpoint_addr {
+                                SocketAddr::V4(_) => {
+                                    udp4.send_to(packet, &endpoint_addr.into()).ok()
+                                }
+                                SocketAddr::V6(_) => {
+                                    udp6.send_to(packet, &endpoint_addr.into()).ok()
+                                }
+                            };
+                        }
+                        _ => panic!("Unexpected result from update_timers"),
+                    };
+                }
+                Action::Continue
+            }),
+            std::time::Duration::from_millis(250),
+        )?;
+        Ok(())
+    }
+
+    pub(crate) fn trigger_yield(&self) {
+        self.queue
+            .trigger_notification(self.yield_notice.as_ref().unwrap())
+    }
+
+    pub(crate) fn trigger_exit(&self) {
+        self.queue
+            .trigger_notification(self.exit_notice.as_ref().unwrap())
+    }
+
+    pub(crate) fn cancel_yield(&self) {
+        self.queue
+            .stop_notification(self.yield_notice.as_ref().unwrap())
+    }
+
+    fn register_udp_handler(&self, udp: socket2::Socket) -> Result<(), Error> {
+        self.queue.new_event(
+            udp.as_raw_fd(),
+            Box::new(move |d, t| {
+                // Handler that handles anonymous packets over UDP
+                let mut iter = MAX_ITR;
+                let (private_key, public_key) = d.key_pair.as_ref().expect("Key not set");
+
+                let rate_limiter = d.rate_limiter.as_ref().unwrap();
+
+                // Loop while we have packets on the anonymous connection
+
+                // Safety: the `recv_from` implementation promises not to write uninitialised
+                // bytes to the buffer, so this casting is safe.
+                let src_buf =
+                    unsafe { &mut *(&mut t.src_buf[..] as *mut [u8] as *mut [MaybeUninit<u8>]) };
+                while let Ok((packet_len, addr)) = udp.recv_from(src_buf) {
+                    let packet = &t.src_buf[..packet_len];
+                    // The rate limiter initially checks mac1 and mac2, and optionally asks to send a cookie
+                    let parsed_packet = match rate_limiter.verify_packet(
+                        Some(addr.as_socket().unwrap().ip()),
+                        packet,
+                        &mut t.dst_buf,
+                    ) {
+                        Ok(packet) => packet,
+                        Err(TunnResult::WriteToNetwork(cookie)) => {
+                            let _: Result<_, _> = udp.send_to(cookie, &addr);
+                            continue;
+                        }
+                        Err(_) => continue,
+                    };
+
+                    let peer = match &parsed_packet {
+                        Packet::HandshakeInit(p) => {
+                            parse_handshake_anon(private_key, public_key, p)
+                                .ok()
+                                .and_then(|hh| {
+                                    d.peers.get(&x25519::PublicKey::from(hh.peer_static_public))
+                                })
+                        }
+                        Packet::HandshakeResponse(p) => d.peers_by_idx.get(&(p.receiver_idx >> 8)),
+                        Packet::PacketCookieReply(p) => d.peers_by_idx.get(&(p.receiver_idx >> 8)),
+                        Packet::PacketData(p) => d.peers_by_idx.get(&(p.receiver_idx >> 8)),
+                    };
+
+                    let peer = match peer {
+                        None => continue,
+                        Some(peer) => peer,
+                    };
+
+                    let mut p = peer.lock();
+
+                    // We found a peer, use it to decapsulate the message+
+                    let mut flush = false; // Are there packets to send from the queue?
+                    match p
+                        .tunnel
+                        .handle_verified_packet(parsed_packet, &mut t.dst_buf[..])
+                    {
+                        TunnResult::Done => {}
+                        TunnResult::Err(_) => continue,
+                        TunnResult::WriteToNetwork(packet) => {
+                            flush = true;
+                            let _: Result<_, _> = udp.send_to(packet, &addr);
+                        }
+                        TunnResult::WriteToTunnelV4(packet, addr) => {
+                            if p.is_allowed_ip(addr) {
+                                t.iface.write4(packet);
+                            }
+                        }
+                        TunnResult::WriteToTunnelV6(packet, addr) => {
+                            if p.is_allowed_ip(addr) {
+                                t.iface.write6(packet);
+                            }
+                        }
+                    };
+
+                    if flush {
+                        // Flush pending queue
+                        while let TunnResult::WriteToNetwork(packet) =
+                            p.tunnel.decapsulate(None, &[], &mut t.dst_buf[..])
+                        {
+                            let _: Result<_, _> = udp.send_to(packet, &addr);
+                        }
+                    }
+
+                    // This packet was OK, that means we want to create a connected socket for this peer
+                    let addr = addr.as_socket().unwrap();
+                    let ip_addr = addr.ip();
+                    p.set_endpoint(addr);
+                    if d.config.use_connected_socket {
+                        if let Ok(sock) = p.connect_endpoint(d.listen_port, d.fwmark) {
+                            d.register_conn_handler(Arc::clone(peer), sock, ip_addr)
+                                .unwrap();
+                        }
+                    }
+
+                    iter -= 1;
+                    if iter == 0 {
+                        break;
+                    }
+                }
+                Action::Continue
+            }),
+        )?;
+        Ok(())
+    }
+
+    fn register_conn_handler(
+        &self,
+        peer: Arc<Mutex<Peer>>,
+        udp: socket2::Socket,
+        peer_addr: IpAddr,
+    ) -> Result<(), Error> {
+        self.queue.new_event(
+            udp.as_raw_fd(),
+            Box::new(move |_, t| {
+                // The conn_handler handles packet received from a connected UDP socket, associated
+                // with a known peer, this saves us the hustle of finding the right peer. If another
+                // peer gets the same ip, it will be ignored until the socket does not expire.
+                let iface = &t.iface;
+                let mut iter = MAX_ITR;
+
+                // Safety: the `recv_from` implementation promises not to write uninitialised
+                // bytes to the buffer, so this casting is safe.
+                let src_buf =
+                    unsafe { &mut *(&mut t.src_buf[..] as *mut [u8] as *mut [MaybeUninit<u8>]) };
+
+                while let Ok(read_bytes) = udp.recv(src_buf) {
+                    let mut flush = false;
+                    let mut p = peer.lock();
+                    match p.tunnel.decapsulate(
+                        Some(peer_addr),
+                        &t.src_buf[..read_bytes],
+                        &mut t.dst_buf[..],
+                    ) {
+                        TunnResult::Done => {}
+                        TunnResult::Err(e) => eprintln!("Decapsulate error {:?}", e),
+                        TunnResult::WriteToNetwork(packet) => {
+                            flush = true;
+                            let _: Result<_, _> = udp.send(packet);
+                        }
+                        TunnResult::WriteToTunnelV4(packet, addr) => {
+                            if p.is_allowed_ip(addr) {
+                                iface.write4(packet);
+                            }
+                        }
+                        TunnResult::WriteToTunnelV6(packet, addr) => {
+                            if p.is_allowed_ip(addr) {
+                                iface.write6(packet);
+                            }
+                        }
+                    };
+
+                    if flush {
+                        // Flush pending queue
+                        while let TunnResult::WriteToNetwork(packet) =
+                            p.tunnel.decapsulate(None, &[], &mut t.dst_buf[..])
+                        {
+                            let _: Result<_, _> = udp.send(packet);
+                        }
+                    }
+
+                    iter -= 1;
+                    if iter == 0 {
+                        break;
+                    }
+                }
+                Action::Continue
+            }),
+        )?;
+        Ok(())
+    }
+
+    fn register_iface_handler(&self, iface: Arc<TunSocket>) -> Result<(), Error> {
+        self.queue.new_event(
+            iface.as_raw_fd(),
+            Box::new(move |d, t| {
+                // The iface_handler handles packets received from the WireGuard virtual network
+                // interface. The flow is as follows:
+                // * Read a packet
+                // * Determine peer based on packet destination ip
+                // * Encapsulate the packet for the given peer
+                // * Send encapsulated packet to the peer's endpoint
+                let mtu = d.mtu.load(Ordering::Relaxed);
+
+                let udp4 = d.udp4.as_ref().expect("Not connected");
+                let udp6 = d.udp6.as_ref().expect("Not connected");
+
+                let peers = &d.peers_by_ip;
+                for _ in 0..MAX_ITR {
+                    let src = match iface.read(&mut t.src_buf[..mtu]) {
+                        Ok(src) => src,
+                        Err(Error::IfaceRead(e)) => {
+                            let ek = e.kind();
+                            if ek == io::ErrorKind::Interrupted || ek == io::ErrorKind::WouldBlock {
+                                break;
+                            }
+                            eprintln!("Fatal read error on tun interface: {:?}", e);
+                            return Action::Exit;
+                        }
+                        Err(e) => {
+                            eprintln!("Unexpected error on tun interface: {:?}", e);
+                            return Action::Exit;
+                        }
+                    };
+
+                    let dst_addr = match Tunn::dst_address(src) {
+                        Some(addr) => addr,
+                        None => continue,
+                    };
+
+                    let mut peer = match peers.find(dst_addr) {
+                        Some(peer) => peer.lock(),
+                        None => continue,
+                    };
+
+                    match peer.tunnel.encapsulate(src, &mut t.dst_buf[..]) {
+                        TunnResult::Done => {}
+                        TunnResult::Err(e) => {
+                            tracing::error!(message = "Encapsulate error", error = ?e)
+                        }
+                        TunnResult::WriteToNetwork(packet) => {
+                            let mut endpoint = peer.endpoint_mut();
+                            if let Some(conn) = endpoint.conn.as_mut() {
+                                // Prefer to send using the connected socket
+                                let _: Result<_, _> = conn.write(packet);
+                            } else if let Some(addr @ SocketAddr::V4(_)) = endpoint.addr {
+                                let _: Result<_, _> = udp4.send_to(packet, &addr.into());
+                            } else if let Some(addr @ SocketAddr::V6(_)) = endpoint.addr {
+                                let _: Result<_, _> = udp6.send_to(packet, &addr.into());
+                            } else {
+                                tracing::error!("No endpoint");
+                            }
+                        }
+                        _ => panic!("Unexpected result from encapsulate"),
+                    };
+                }
+                Action::Continue
+            }),
+        )?;
+        Ok(())
+    }
+}
+
+/// A basic linear-feedback shift register implemented as xorshift, used to
+/// distribute peer indexes across the 24-bit address space reserved for peer
+/// identification.
+/// The purpose is to obscure the total number of peers using the system and to
+/// ensure it requires a non-trivial amount of processing power and/or samples
+/// to guess other peers' indices. Anything more ambitious than this is wasted
+/// with only 24 bits of space.
+struct IndexLfsr {
+    initial: u32,
+    lfsr: u32,
+    mask: u32,
+}
+
+impl IndexLfsr {
+    /// Generate a random 24-bit nonzero integer
+    fn random_index() -> u32 {
+        const LFSR_MAX: u32 = 0xffffff; // 24-bit seed
+        loop {
+            let i = OsRng.next_u32() & LFSR_MAX;
+            if i > 0 {
+                // LFSR seed must be non-zero
+                return i;
+            }
+        }
+    }
+
+    /// Generate the next value in the pseudorandom sequence
+    fn next(&mut self) -> u32 {
+        // 24-bit polynomial for randomness. This is arbitrarily chosen to
+        // inject bitflips into the value.
+        const LFSR_POLY: u32 = 0xd80000; // 24-bit polynomial
+        let value = self.lfsr - 1; // lfsr will never have value of 0
+        self.lfsr = (self.lfsr >> 1) ^ ((0u32.wrapping_sub(self.lfsr & 1u32)) & LFSR_POLY);
+        assert!(self.lfsr != self.initial, "Too many peers created");
+        value ^ self.mask
+    }
+}
+
+impl Default for IndexLfsr {
+    fn default() -> Self {
+        let seed = Self::random_index();
+        IndexLfsr {
+            initial: seed,
+            lfsr: seed,
+            mask: Self::random_index(),
+        }
+    }
+}

burrow/src/boringtun/src/device/peer.rs

@@ -0,0 +1,170 @@
+// Copyright (c) 2019 Cloudflare, Inc. All rights reserved.
+// SPDX-License-Identifier: BSD-3-Clause
+
+use parking_lot::RwLock;
+use socket2::{Domain, Protocol, Type};
+
+use std::net::{IpAddr, Ipv4Addr, Ipv6Addr, Shutdown, SocketAddr, SocketAddrV4, SocketAddrV6};
+use std::str::FromStr;
+
+use crate::device::{AllowedIps, Error};
+use crate::noise::{Tunn, TunnResult};
+
+#[derive(Default, Debug)]
+pub struct Endpoint {
+    pub addr: Option<SocketAddr>,
+    pub conn: Option<socket2::Socket>,
+}
+
+pub struct Peer {
+    /// The associated tunnel struct
+    pub(crate) tunnel: Tunn,
+    /// The index the tunnel uses
+    index: u32,
+    endpoint: RwLock<Endpoint>,
+    allowed_ips: AllowedIps<()>,
+    preshared_key: Option<[u8; 32]>,
+}
+
+#[derive(Copy, Clone, Ord, PartialOrd, Eq, PartialEq, Hash, Debug)]
+pub struct AllowedIP {
+    pub addr: IpAddr,
+    pub cidr: u8,
+}
+
+impl FromStr for AllowedIP {
+    type Err = String;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        let ip: Vec<&str> = s.split('/').collect();
+        if ip.len() != 2 {
+            return Err("Invalid IP format".to_owned());
+        }
+
+        let (addr, cidr) = (ip[0].parse::<IpAddr>(), ip[1].parse::<u8>());
+        match (addr, cidr) {
+            (Ok(addr @ IpAddr::V4(_)), Ok(cidr)) if cidr <= 32 => Ok(AllowedIP { addr, cidr }),
+            (Ok(addr @ IpAddr::V6(_)), Ok(cidr)) if cidr <= 128 => Ok(AllowedIP { addr, cidr }),
+            _ => Err("Invalid IP format".to_owned()),
+        }
+    }
+}
+
+impl Peer {
+    pub fn new(
+        tunnel: Tunn,
+        index: u32,
+        endpoint: Option<SocketAddr>,
+        allowed_ips: &[AllowedIP],
+        preshared_key: Option<[u8; 32]>,
+    ) -> Peer {
+        Peer {
+            tunnel,
+            index,
+            endpoint: RwLock::new(Endpoint {
+                addr: endpoint,
+                conn: None,
+            }),
+            allowed_ips: allowed_ips.iter().map(|ip| (ip, ())).collect(),
+            preshared_key,
+        }
+    }
+
+    pub fn update_timers<'a>(&mut self, dst: &'a mut [u8]) -> TunnResult<'a> {
+        self.tunnel.update_timers(dst)
+    }
+
+    pub fn endpoint(&self) -> parking_lot::RwLockReadGuard<'_, Endpoint> {
+        self.endpoint.read()
+    }
+
+    pub(crate) fn endpoint_mut(&self) -> parking_lot::RwLockWriteGuard<'_, Endpoint> {
+        self.endpoint.write()
+    }
+
+    pub fn shutdown_endpoint(&self) {
+        if let Some(conn) = self.endpoint.write().conn.take() {
+            tracing::info!("Disconnecting from endpoint");
+            conn.shutdown(Shutdown::Both).unwrap();
+        }
+    }
+
+    pub fn set_endpoint(&self, addr: SocketAddr) {
+        let mut endpoint = self.endpoint.write();
+        if endpoint.addr != Some(addr) {
+            // We only need to update the endpoint if it differs from the current one
+            if let Some(conn) = endpoint.conn.take() {
+                conn.shutdown(Shutdown::Both).unwrap();
+            }
+
+            endpoint.addr = Some(addr);
+        }
+    }
+
+    pub fn connect_endpoint(
+        &self,
+        port: u16,
+        fwmark: Option<u32>,
+    ) -> Result<socket2::Socket, Error> {
+        let mut endpoint = self.endpoint.write();
+
+        if endpoint.conn.is_some() {
+            return Err(Error::Connect("Connected".to_owned()));
+        }
+
+        let addr = endpoint
+            .addr
+            .expect("Attempt to connect to undefined endpoint");
+
+        let udp_conn =
+            socket2::Socket::new(Domain::for_address(addr), Type::STREAM, Some(Protocol::UDP))?;
+        udp_conn.set_reuse_address(true)?;
+        let bind_addr = if addr.is_ipv4() {
+            SocketAddrV4::new(Ipv4Addr::UNSPECIFIED, port).into()
+        } else {
+            SocketAddrV6::new(Ipv6Addr::UNSPECIFIED, port, 0, 0).into()
+        };
+        udp_conn.bind(&bind_addr)?;
+        udp_conn.connect(&addr.into())?;
+        udp_conn.set_nonblocking(true)?;
+
+        #[cfg(any(target_os = "android", target_os = "fuchsia", target_os = "linux"))]
+        if let Some(fwmark) = fwmark {
+            udp_conn.set_mark(fwmark)?;
+        }
+
+        tracing::info!(
+            message="Connected endpoint",
+            port=port,
+            endpoint=?endpoint.addr.unwrap()
+        );
+
+        endpoint.conn = Some(udp_conn.try_clone().unwrap());
+
+        Ok(udp_conn)
+    }
+
+    pub fn is_allowed_ip<I: Into<IpAddr>>(&self, addr: I) -> bool {
+        self.allowed_ips.find(addr.into()).is_some()
+    }
+
+    pub fn allowed_ips(&self) -> impl Iterator<Item = (IpAddr, u8)> + '_ {
+        self.allowed_ips.iter().map(|(_, ip, cidr)| (ip, cidr))
+    }
+
+    pub fn time_since_last_handshake(&self) -> Option<std::time::Duration> {
+        self.tunnel.time_since_last_handshake()
+    }
+
+    pub fn persistent_keepalive(&self) -> Option<u16> {
+        self.tunnel.persistent_keepalive()
+    }
+
+    pub fn preshared_key(&self) -> Option<&[u8; 32]> {
+        self.preshared_key.as_ref()
+    }
+
+    pub fn index(&self) -> u32 {
+        self.index
+    }
+}

burrow/src/boringtun/src/lib.rs

@@ -0,0 +1,27 @@
+// Copyright (c) 2019 Cloudflare, Inc. All rights reserved.
+// SPDX-License-Identifier: BSD-3-Clause
+
+//! Simple implementation of the client-side of the WireGuard protocol.
+//!
+//! <code>git clone https://github.com/cloudflare/boringtun.git</code>
+
+#[cfg(feature = "device")]
+pub mod device;
+
+#[cfg(feature = "ffi-bindings")]
+pub mod ffi;
+#[cfg(feature = "jni-bindings")]
+pub mod jni;
+pub mod noise;
+
+#[cfg(not(feature = "mock-instant"))]
+pub(crate) mod sleepyinstant;
+
+pub(crate) mod serialization;
+
+/// Re-export of the x25519 types
+pub mod x25519 {
+    pub use x25519_dalek::{
+        EphemeralSecret, PublicKey, ReusableSecret, SharedSecret, StaticSecret,
+    };
+}

burrow/src/boringtun/src/noise/errors.rs

@@ -0,0 +1,23 @@
+// Copyright (c) 2019 Cloudflare, Inc. All rights reserved.
+// SPDX-License-Identifier: BSD-3-Clause
+
+#[derive(Debug)]
+pub enum WireGuardError {
+    DestinationBufferTooSmall,
+    IncorrectPacketLength,
+    UnexpectedPacket,
+    WrongPacketType,
+    WrongIndex,
+    WrongKey,
+    InvalidTai64nTimestamp,
+    WrongTai64nTimestamp,
+    InvalidMac,
+    InvalidAeadTag,
+    InvalidCounter,
+    DuplicateCounter,
+    InvalidPacket,
+    NoCurrentSession,
+    LockFailed,
+    ConnectionExpired,
+    UnderLoad,
+}

burrow/src/boringtun/src/noise/handshake.rs

@@ -0,0 +1,941 @@
+// Copyright (c) 2019 Cloudflare, Inc. All rights reserved.
+// SPDX-License-Identifier: BSD-3-Clause
+
+use super::{HandshakeInit, HandshakeResponse, PacketCookieReply};
+use crate::noise::errors::WireGuardError;
+use crate::noise::session::Session;
+#[cfg(not(feature = "mock-instant"))]
+use crate::sleepyinstant::Instant;
+use crate::x25519;
+use aead::{Aead, Payload};
+use blake2::digest::{FixedOutput, KeyInit};
+use blake2::{Blake2s256, Blake2sMac, Digest};
+use chacha20poly1305::XChaCha20Poly1305;
+use rand_core::OsRng;
+use ring::aead::{Aad, LessSafeKey, Nonce, UnboundKey, CHACHA20_POLY1305};
+use std::convert::TryInto;
+use std::time::{Duration, SystemTime};
+
+#[cfg(feature = "mock-instant")]
+use mock_instant::Instant;
+
+pub(crate) const LABEL_MAC1: &[u8; 8] = b"mac1----";
+pub(crate) const LABEL_COOKIE: &[u8; 8] = b"cookie--";
+const KEY_LEN: usize = 32;
+const TIMESTAMP_LEN: usize = 12;
+
+// initiator.chaining_key = HASH(CONSTRUCTION)
+const INITIAL_CHAIN_KEY: [u8; KEY_LEN] = [
+    96, 226, 109, 174, 243, 39, 239, 192, 46, 195, 53, 226, 160, 37, 210, 208, 22, 235, 66, 6, 248,
+    114, 119, 245, 45, 56, 209, 152, 139, 120, 205, 54,
+];
+
+// initiator.chaining_hash = HASH(initiator.chaining_key || IDENTIFIER)
+const INITIAL_CHAIN_HASH: [u8; KEY_LEN] = [
+    34, 17, 179, 97, 8, 26, 197, 102, 105, 18, 67, 219, 69, 138, 213, 50, 45, 156, 108, 102, 34,
+    147, 232, 183, 14, 225, 156, 101, 186, 7, 158, 243,
+];
+
+#[inline]
+pub(crate) fn b2s_hash(data1: &[u8], data2: &[u8]) -> [u8; 32] {
+    let mut hash = Blake2s256::new();
+    hash.update(data1);
+    hash.update(data2);
+    hash.finalize().into()
+}
+
+#[inline]
+/// RFC 2401 HMAC+Blake2s, not to be confused with *keyed* Blake2s
+pub(crate) fn b2s_hmac(key: &[u8], data1: &[u8]) -> [u8; 32] {
+    use blake2::digest::Update;
+    type HmacBlake2s = hmac::SimpleHmac<Blake2s256>;
+    let mut hmac = HmacBlake2s::new_from_slice(key).unwrap();
+    hmac.update(data1);
+    hmac.finalize_fixed().into()
+}
+
+#[inline]
+/// Like b2s_hmac, but chain data1 and data2 together
+pub(crate) fn b2s_hmac2(key: &[u8], data1: &[u8], data2: &[u8]) -> [u8; 32] {
+    use blake2::digest::Update;
+    type HmacBlake2s = hmac::SimpleHmac<Blake2s256>;
+    let mut hmac = HmacBlake2s::new_from_slice(key).unwrap();
+    hmac.update(data1);
+    hmac.update(data2);
+    hmac.finalize_fixed().into()
+}
+
+#[inline]
+pub(crate) fn b2s_keyed_mac_16(key: &[u8], data1: &[u8]) -> [u8; 16] {
+    let mut hmac = Blake2sMac::new_from_slice(key).unwrap();
+    blake2::digest::Update::update(&mut hmac, data1);
+    hmac.finalize_fixed().into()
+}
+
+#[inline]
+pub(crate) fn b2s_keyed_mac_16_2(key: &[u8], data1: &[u8], data2: &[u8]) -> [u8; 16] {
+    let mut hmac = Blake2sMac::new_from_slice(key).unwrap();
+    blake2::digest::Update::update(&mut hmac, data1);
+    blake2::digest::Update::update(&mut hmac, data2);
+    hmac.finalize_fixed().into()
+}
+
+pub(crate) fn b2s_mac_24(key: &[u8], data1: &[u8]) -> [u8; 24] {
+    let mut hmac = Blake2sMac::new_from_slice(key).unwrap();
+    blake2::digest::Update::update(&mut hmac, data1);
+    hmac.finalize_fixed().into()
+}
+
+#[inline]
+/// This wrapper involves an extra copy and MAY BE SLOWER
+fn aead_chacha20_seal(ciphertext: &mut [u8], key: &[u8], counter: u64, data: &[u8], aad: &[u8]) {
+    let mut nonce: [u8; 12] = [0; 12];
+    nonce[4..12].copy_from_slice(&counter.to_le_bytes());
+
+    aead_chacha20_seal_inner(ciphertext, key, nonce, data, aad)
+}
+
+#[inline]
+fn aead_chacha20_seal_inner(
+    ciphertext: &mut [u8],
+    key: &[u8],
+    nonce: [u8; 12],
+    data: &[u8],
+    aad: &[u8],
+) {
+    let key = LessSafeKey::new(UnboundKey::new(&CHACHA20_POLY1305, key).unwrap());
+
+    ciphertext[..data.len()].copy_from_slice(data);
+
+    let tag = key
+        .seal_in_place_separate_tag(
+            Nonce::assume_unique_for_key(nonce),
+            Aad::from(aad),
+            &mut ciphertext[..data.len()],
+        )
+        .unwrap();
+
+    ciphertext[data.len()..].copy_from_slice(tag.as_ref());
+}
+
+#[inline]
+/// This wrapper involves an extra copy and MAY BE SLOWER
+fn aead_chacha20_open(
+    buffer: &mut [u8],
+    key: &[u8],
+    counter: u64,
+    data: &[u8],
+    aad: &[u8],
+) -> Result<(), WireGuardError> {
+    let mut nonce: [u8; 12] = [0; 12];
+    nonce[4..].copy_from_slice(&counter.to_le_bytes());
+
+    aead_chacha20_open_inner(buffer, key, nonce, data, aad)
+        .map_err(|_| WireGuardError::InvalidAeadTag)?;
+    Ok(())
+}
+
+#[inline]
+fn aead_chacha20_open_inner(
+    buffer: &mut [u8],
+    key: &[u8],
+    nonce: [u8; 12],
+    data: &[u8],
+    aad: &[u8],
+) -> Result<(), ring::error::Unspecified> {
+    let key = LessSafeKey::new(UnboundKey::new(&CHACHA20_POLY1305, key).unwrap());
+
+    let mut inner_buffer = data.to_owned();
+
+    let plaintext = key.open_in_place(
+        Nonce::assume_unique_for_key(nonce),
+        Aad::from(aad),
+        &mut inner_buffer,
+    )?;
+
+    buffer.copy_from_slice(plaintext);
+
+    Ok(())
+}
+
+#[derive(Debug)]
+/// This struct represents a 12 byte [Tai64N](https://cr.yp.to/libtai/tai64.html) timestamp
+struct Tai64N {
+    secs: u64,
+    nano: u32,
+}
+
+#[derive(Debug)]
+/// This struct computes a [Tai64N](https://cr.yp.to/libtai/tai64.html) timestamp from current system time
+struct TimeStamper {
+    duration_at_start: Duration,
+    instant_at_start: Instant,
+}
+
+impl TimeStamper {
+    /// Create a new TimeStamper
+    pub fn new() -> TimeStamper {
+        TimeStamper {
+            duration_at_start: SystemTime::now()
+                .duration_since(SystemTime::UNIX_EPOCH)
+                .unwrap(),
+            instant_at_start: Instant::now(),
+        }
+    }
+
+    /// Take time reading and generate a 12 byte timestamp
+    pub fn stamp(&self) -> [u8; 12] {
+        const TAI64_BASE: u64 = (1u64 << 62) + 37;
+        let mut ext_stamp = [0u8; 12];
+        let stamp = Instant::now().duration_since(self.instant_at_start) + self.duration_at_start;
+        ext_stamp[0..8].copy_from_slice(&(stamp.as_secs() + TAI64_BASE).to_be_bytes());
+        ext_stamp[8..12].copy_from_slice(&stamp.subsec_nanos().to_be_bytes());
+        ext_stamp
+    }
+}
+
+impl Tai64N {
+    /// A zeroed out timestamp
+    fn zero() -> Tai64N {
+        Tai64N { secs: 0, nano: 0 }
+    }
+
+    /// Parse a timestamp from a 12 byte u8 slice
+    fn parse(buf: &[u8; 12]) -> Result<Tai64N, WireGuardError> {
+        if buf.len() < 12 {
+            return Err(WireGuardError::InvalidTai64nTimestamp);
+        }
+
+        let (sec_bytes, nano_bytes) = buf.split_at(std::mem::size_of::<u64>());
+        let secs = u64::from_be_bytes(sec_bytes.try_into().unwrap());
+        let nano = u32::from_be_bytes(nano_bytes.try_into().unwrap());
+
+        // WireGuard does not actually expect tai64n timestamp, just monotonically increasing one
+        //if secs < (1u64 << 62) || secs >= (1u64 << 63) {
+        //    return Err(WireGuardError::InvalidTai64nTimestamp);
+        //};
+        //if nano >= 1_000_000_000 {
+        //   return Err(WireGuardError::InvalidTai64nTimestamp);
+        //}
+
+        Ok(Tai64N { secs, nano })
+    }
+
+    /// Check if this timestamp represents a time that is chronologically after the time represented
+    /// by the other timestamp
+    pub fn after(&self, other: &Tai64N) -> bool {
+        (self.secs > other.secs) || ((self.secs == other.secs) && (self.nano > other.nano))
+    }
+}
+
+/// Parameters used by the noise protocol
+struct NoiseParams {
+    /// Our static public key
+    static_public: x25519::PublicKey,
+    /// Our static private key
+    static_private: x25519::StaticSecret,
+    /// Static public key of the other party
+    peer_static_public: x25519::PublicKey,
+    /// A shared key = DH(static_private, peer_static_public)
+    static_shared: x25519::SharedSecret,
+    /// A pre-computation of HASH("mac1----", peer_static_public) for this peer
+    sending_mac1_key: [u8; KEY_LEN],
+    /// An optional preshared key
+    preshared_key: Option<[u8; KEY_LEN]>,
+}
+
+impl std::fmt::Debug for NoiseParams {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("NoiseParams")
+            .field("static_public", &self.static_public)
+            .field("static_private", &"<redacted>")
+            .field("peer_static_public", &self.peer_static_public)
+            .field("static_shared", &"<redacted>")
+            .field("sending_mac1_key", &self.sending_mac1_key)
+            .field("preshared_key", &self.preshared_key)
+            .finish()
+    }
+}
+
+struct HandshakeInitSentState {
+    local_index: u32,
+    hash: [u8; KEY_LEN],
+    chaining_key: [u8; KEY_LEN],
+    ephemeral_private: x25519::ReusableSecret,
+    time_sent: Instant,
+}
+
+impl std::fmt::Debug for HandshakeInitSentState {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("HandshakeInitSentState")
+            .field("local_index", &self.local_index)
+            .field("hash", &self.hash)
+            .field("chaining_key", &self.chaining_key)
+            .field("ephemeral_private", &"<redacted>")
+            .field("time_sent", &self.time_sent)
+            .finish()
+    }
+}
+
+#[derive(Debug)]
+enum HandshakeState {
+    /// No handshake in process
+    None,
+    /// We initiated the handshake
+    InitSent(HandshakeInitSentState),
+    /// Handshake initiated by peer
+    InitReceived {
+        hash: [u8; KEY_LEN],
+        chaining_key: [u8; KEY_LEN],
+        peer_ephemeral_public: x25519::PublicKey,
+        peer_index: u32,
+    },
+    /// Handshake was established too long ago (implies no handshake is in progress)
+    Expired,
+}
+
+pub struct Handshake {
+    params: NoiseParams,
+    /// Index of the next session
+    next_index: u32,
+    /// Allow to have two outgoing handshakes in flight, because sometimes we may receive a delayed response to a handshake with bad networks
+    previous: HandshakeState,
+    /// Current handshake state
+    state: HandshakeState,
+    cookies: Cookies,
+    /// The timestamp of the last handshake we received
+    last_handshake_timestamp: Tai64N,
+    // TODO: make TimeStamper a singleton
+    stamper: TimeStamper,
+    pub(super) last_rtt: Option<u32>,
+}
+
+#[derive(Default)]
+struct Cookies {
+    last_mac1: Option<[u8; 16]>,
+    index: u32,
+    write_cookie: Option<[u8; 16]>,
+}
+
+#[derive(Debug)]
+pub struct HalfHandshake {
+    pub peer_index: u32,
+    pub peer_static_public: [u8; 32],
+}
+
+pub fn parse_handshake_anon(
+    static_private: &x25519::StaticSecret,
+    static_public: &x25519::PublicKey,
+    packet: &HandshakeInit,
+) -> Result<HalfHandshake, WireGuardError> {
+    let peer_index = packet.sender_idx;
+    // initiator.chaining_key = HASH(CONSTRUCTION)
+    let mut chaining_key = INITIAL_CHAIN_KEY;
+    // initiator.hash = HASH(HASH(initiator.chaining_key || IDENTIFIER) || responder.static_public)
+    let mut hash = INITIAL_CHAIN_HASH;
+    hash = b2s_hash(&hash, static_public.as_bytes());
+    // msg.unencrypted_ephemeral = DH_PUBKEY(initiator.ephemeral_private)
+    let peer_ephemeral_public = x25519::PublicKey::from(*packet.unencrypted_ephemeral);
+    // initiator.hash = HASH(initiator.hash || msg.unencrypted_ephemeral)
+    hash = b2s_hash(&hash, peer_ephemeral_public.as_bytes());
+    // temp = HMAC(initiator.chaining_key, msg.unencrypted_ephemeral)
+    // initiator.chaining_key = HMAC(temp, 0x1)
+    chaining_key = b2s_hmac(
+        &b2s_hmac(&chaining_key, peer_ephemeral_public.as_bytes()),
+        &[0x01],
+    );
+    // temp = HMAC(initiator.chaining_key, DH(initiator.ephemeral_private, responder.static_public))
+    let ephemeral_shared = static_private.diffie_hellman(&peer_ephemeral_public);
+    let temp = b2s_hmac(&chaining_key, &ephemeral_shared.to_bytes());
+    // initiator.chaining_key = HMAC(temp, 0x1)
+    chaining_key = b2s_hmac(&temp, &[0x01]);
+    // key = HMAC(temp, initiator.chaining_key || 0x2)
+    let key = b2s_hmac2(&temp, &chaining_key, &[0x02]);
+
+    let mut peer_static_public = [0u8; KEY_LEN];
+    // msg.encrypted_static = AEAD(key, 0, initiator.static_public, initiator.hash)
+    aead_chacha20_open(
+        &mut peer_static_public,
+        &key,
+        0,
+        packet.encrypted_static,
+        &hash,
+    )?;
+
+    Ok(HalfHandshake {
+        peer_index,
+        peer_static_public,
+    })
+}
+
+impl NoiseParams {
+    /// New noise params struct from our secret key, peers public key, and optional preshared key
+    fn new(
+        static_private: x25519::StaticSecret,
+        static_public: x25519::PublicKey,
+        peer_static_public: x25519::PublicKey,
+        preshared_key: Option<[u8; 32]>,
+    ) -> Result<NoiseParams, WireGuardError> {
+        let static_shared = static_private.diffie_hellman(&peer_static_public);
+
+        let initial_sending_mac_key = b2s_hash(LABEL_MAC1, peer_static_public.as_bytes());
+
+        Ok(NoiseParams {
+            static_public,
+            static_private,
+            peer_static_public,
+            static_shared,
+            sending_mac1_key: initial_sending_mac_key,
+            preshared_key,
+        })
+    }
+
+    /// Set a new private key
+    fn set_static_private(
+        &mut self,
+        static_private: x25519::StaticSecret,
+        static_public: x25519::PublicKey,
+    ) -> Result<(), WireGuardError> {
+        // Check that the public key indeed matches the private key
+        let check_key = x25519::PublicKey::from(&static_private);
+        assert_eq!(check_key.as_bytes(), static_public.as_bytes());
+
+        self.static_private = static_private;
+        self.static_public = static_public;
+
+        self.static_shared = self.static_private.diffie_hellman(&self.peer_static_public);
+        Ok(())
+    }
+}
+
+impl Handshake {
+    pub(crate) fn new(
+        static_private: x25519::StaticSecret,
+        static_public: x25519::PublicKey,
+        peer_static_public: x25519::PublicKey,
+        global_idx: u32,
+        preshared_key: Option<[u8; 32]>,
+    ) -> Result<Handshake, WireGuardError> {
+        let params = NoiseParams::new(
+            static_private,
+            static_public,
+            peer_static_public,
+            preshared_key,
+        )?;
+
+        Ok(Handshake {
+            params,
+            next_index: global_idx,
+            previous: HandshakeState::None,
+            state: HandshakeState::None,
+            last_handshake_timestamp: Tai64N::zero(),
+            stamper: TimeStamper::new(),
+            cookies: Default::default(),
+            last_rtt: None,
+        })
+    }
+
+    pub(crate) fn is_in_progress(&self) -> bool {
+        !matches!(self.state, HandshakeState::None | HandshakeState::Expired)
+    }
+
+    pub(crate) fn timer(&self) -> Option<Instant> {
+        match self.state {
+            HandshakeState::InitSent(HandshakeInitSentState { time_sent, .. }) => Some(time_sent),
+            _ => None,
+        }
+    }
+
+    pub(crate) fn set_expired(&mut self) {
+        self.previous = HandshakeState::Expired;
+        self.state = HandshakeState::Expired;
+    }
+
+    pub(crate) fn is_expired(&self) -> bool {
+        matches!(self.state, HandshakeState::Expired)
+    }
+
+    pub(crate) fn has_cookie(&self) -> bool {
+        self.cookies.write_cookie.is_some()
+    }
+
+    pub(crate) fn clear_cookie(&mut self) {
+        self.cookies.write_cookie = None;
+    }
+
+    // The index used is 24 bits for peer index, allowing for 16M active peers per server and 8 bits for cyclic session index
+    fn inc_index(&mut self) -> u32 {
+        let index = self.next_index;
+        let idx8 = index as u8;
+        self.next_index = (index & !0xff) | u32::from(idx8.wrapping_add(1));
+        self.next_index
+    }
+
+    pub(crate) fn set_static_private(
+        &mut self,
+        private_key: x25519::StaticSecret,
+        public_key: x25519::PublicKey,
+    ) -> Result<(), WireGuardError> {
+        self.params.set_static_private(private_key, public_key)
+    }
+
+    pub(super) fn receive_handshake_initialization<'a>(
+        &mut self,
+        packet: HandshakeInit,
+        dst: &'a mut [u8],
+    ) -> Result<(&'a mut [u8], Session), WireGuardError> {
+        // initiator.chaining_key = HASH(CONSTRUCTION)
+        let mut chaining_key = INITIAL_CHAIN_KEY;
+        // initiator.hash = HASH(HASH(initiator.chaining_key || IDENTIFIER) || responder.static_public)
+        let mut hash = INITIAL_CHAIN_HASH;
+        hash = b2s_hash(&hash, self.params.static_public.as_bytes());
+        // msg.sender_index = little_endian(initiator.sender_index)
+        let peer_index = packet.sender_idx;
+        // msg.unencrypted_ephemeral = DH_PUBKEY(initiator.ephemeral_private)
+        let peer_ephemeral_public = x25519::PublicKey::from(*packet.unencrypted_ephemeral);
+        // initiator.hash = HASH(initiator.hash || msg.unencrypted_ephemeral)
+        hash = b2s_hash(&hash, peer_ephemeral_public.as_bytes());
+        // temp = HMAC(initiator.chaining_key, msg.unencrypted_ephemeral)
+        // initiator.chaining_key = HMAC(temp, 0x1)
+        chaining_key = b2s_hmac(
+            &b2s_hmac(&chaining_key, peer_ephemeral_public.as_bytes()),
+            &[0x01],
+        );
+        // temp = HMAC(initiator.chaining_key, DH(initiator.ephemeral_private, responder.static_public))
+        let ephemeral_shared = self
+            .params
+            .static_private
+            .diffie_hellman(&peer_ephemeral_public);
+        let temp = b2s_hmac(&chaining_key, &ephemeral_shared.to_bytes());
+        // initiator.chaining_key = HMAC(temp, 0x1)
+        chaining_key = b2s_hmac(&temp, &[0x01]);
+        // key = HMAC(temp, initiator.chaining_key || 0x2)
+        let key = b2s_hmac2(&temp, &chaining_key, &[0x02]);
+
+        let mut peer_static_public_decrypted = [0u8; KEY_LEN];
+        // msg.encrypted_static = AEAD(key, 0, initiator.static_public, initiator.hash)
+        aead_chacha20_open(
+            &mut peer_static_public_decrypted,
+            &key,
+            0,
+            packet.encrypted_static,
+            &hash,
+        )?;
+
+        ring::constant_time::verify_slices_are_equal(
+            self.params.peer_static_public.as_bytes(),
+            &peer_static_public_decrypted,
+        )
+        .map_err(|_| WireGuardError::WrongKey)?;
+
+        // initiator.hash = HASH(initiator.hash || msg.encrypted_static)
+        hash = b2s_hash(&hash, packet.encrypted_static);
+        // temp = HMAC(initiator.chaining_key, DH(initiator.static_private, responder.static_public))
+        let temp = b2s_hmac(&chaining_key, self.params.static_shared.as_bytes());
+        // initiator.chaining_key = HMAC(temp, 0x1)
+        chaining_key = b2s_hmac(&temp, &[0x01]);
+        // key = HMAC(temp, initiator.chaining_key || 0x2)
+        let key = b2s_hmac2(&temp, &chaining_key, &[0x02]);
+        // msg.encrypted_timestamp = AEAD(key, 0, TAI64N(), initiator.hash)
+        let mut timestamp = [0u8; TIMESTAMP_LEN];
+        aead_chacha20_open(&mut timestamp, &key, 0, packet.encrypted_timestamp, &hash)?;
+
+        let timestamp = Tai64N::parse(&timestamp)?;
+        if !timestamp.after(&self.last_handshake_timestamp) {
+            // Possibly a replay
+            return Err(WireGuardError::WrongTai64nTimestamp);
+        }
+        self.last_handshake_timestamp = timestamp;
+
+        // initiator.hash = HASH(initiator.hash || msg.encrypted_timestamp)
+        hash = b2s_hash(&hash, packet.encrypted_timestamp);
+
+        self.previous = std::mem::replace(
+            &mut self.state,
+            HandshakeState::InitReceived {
+                chaining_key,
+                hash,
+                peer_ephemeral_public,
+                peer_index,
+            },
+        );
+
+        self.format_handshake_response(dst)
+    }
+
+    pub(super) fn receive_handshake_response(
+        &mut self,
+        packet: HandshakeResponse,
+    ) -> Result<Session, WireGuardError> {
+        // Check if there is a handshake awaiting a response and return the correct one
+        let (state, is_previous) = match (&self.state, &self.previous) {
+            (HandshakeState::InitSent(s), _) if s.local_index == packet.receiver_idx => (s, false),
+            (_, HandshakeState::InitSent(s)) if s.local_index == packet.receiver_idx => (s, true),
+            _ => return Err(WireGuardError::UnexpectedPacket),
+        };
+
+        let peer_index = packet.sender_idx;
+        let local_index = state.local_index;
+
+        let unencrypted_ephemeral = x25519::PublicKey::from(*packet.unencrypted_ephemeral);
+        // msg.unencrypted_ephemeral = DH_PUBKEY(responder.ephemeral_private)
+        // responder.hash = HASH(responder.hash || msg.unencrypted_ephemeral)
+        let mut hash = b2s_hash(&state.hash, unencrypted_ephemeral.as_bytes());
+        // temp = HMAC(responder.chaining_key, msg.unencrypted_ephemeral)
+        let temp = b2s_hmac(&state.chaining_key, unencrypted_ephemeral.as_bytes());
+        // responder.chaining_key = HMAC(temp, 0x1)
+        let mut chaining_key = b2s_hmac(&temp, &[0x01]);
+        // temp = HMAC(responder.chaining_key, DH(responder.ephemeral_private, initiator.ephemeral_public))
+        let ephemeral_shared = state
+            .ephemeral_private
+            .diffie_hellman(&unencrypted_ephemeral);
+        let temp = b2s_hmac(&chaining_key, &ephemeral_shared.to_bytes());
+        // responder.chaining_key = HMAC(temp, 0x1)
+        chaining_key = b2s_hmac(&temp, &[0x01]);
+        // temp = HMAC(responder.chaining_key, DH(responder.ephemeral_private, initiator.static_public))
+        let temp = b2s_hmac(
+            &chaining_key,
+            &self
+                .params
+                .static_private
+                .diffie_hellman(&unencrypted_ephemeral)
+                .to_bytes(),
+        );
+        // responder.chaining_key = HMAC(temp, 0x1)
+        chaining_key = b2s_hmac(&temp, &[0x01]);
+        // temp = HMAC(responder.chaining_key, preshared_key)
+        let temp = b2s_hmac(
+            &chaining_key,
+            &self.params.preshared_key.unwrap_or([0u8; 32])[..],
+        );
+        // responder.chaining_key = HMAC(temp, 0x1)
+        chaining_key = b2s_hmac(&temp, &[0x01]);
+        // temp2 = HMAC(temp, responder.chaining_key || 0x2)
+        let temp2 = b2s_hmac2(&temp, &chaining_key, &[0x02]);
+        // key = HMAC(temp, temp2 || 0x3)
+        let key = b2s_hmac2(&temp, &temp2, &[0x03]);
+        // responder.hash = HASH(responder.hash || temp2)
+        hash = b2s_hash(&hash, &temp2);
+        // msg.encrypted_nothing = AEAD(key, 0, [empty], responder.hash)
+        aead_chacha20_open(&mut [], &key, 0, packet.encrypted_nothing, &hash)?;
+
+        // responder.hash = HASH(responder.hash || msg.encrypted_nothing)
+        // hash = b2s_hash(hash, buf[ENC_NOTHING_OFF..ENC_NOTHING_OFF + ENC_NOTHING_SZ]);
+
+        // Derive keys
+        // temp1 = HMAC(initiator.chaining_key, [empty])
+        // temp2 = HMAC(temp1, 0x1)
+        // temp3 = HMAC(temp1, temp2 || 0x2)
+        // initiator.sending_key = temp2
+        // initiator.receiving_key = temp3
+        // initiator.sending_key_counter = 0
+        // initiator.receiving_key_counter = 0
+        let temp1 = b2s_hmac(&chaining_key, &[]);
+        let temp2 = b2s_hmac(&temp1, &[0x01]);
+        let temp3 = b2s_hmac2(&temp1, &temp2, &[0x02]);
+
+        let rtt_time = Instant::now().duration_since(state.time_sent);
+        self.last_rtt = Some(rtt_time.as_millis() as u32);
+
+        if is_previous {
+            self.previous = HandshakeState::None;
+        } else {
+            self.state = HandshakeState::None;
+        }
+        Ok(Session::new(local_index, peer_index, temp3, temp2))
+    }
+
+    pub(super) fn receive_cookie_reply(
+        &mut self,
+        packet: PacketCookieReply,
+    ) -> Result<(), WireGuardError> {
+        let mac1 = match self.cookies.last_mac1 {
+            Some(mac) => mac,
+            None => {
+                return Err(WireGuardError::UnexpectedPacket);
+            }
+        };
+
+        let local_index = self.cookies.index;
+        if packet.receiver_idx != local_index {
+            return Err(WireGuardError::WrongIndex);
+        }
+        // msg.encrypted_cookie = XAEAD(HASH(LABEL_COOKIE || responder.static_public), msg.nonce, cookie, last_received_msg.mac1)
+        let key = b2s_hash(LABEL_COOKIE, self.params.peer_static_public.as_bytes()); // TODO: pre-compute
+
+        let payload = Payload {
+            aad: &mac1[0..16],
+            msg: packet.encrypted_cookie,
+        };
+        let plaintext = XChaCha20Poly1305::new_from_slice(&key)
+            .unwrap()
+            .decrypt(packet.nonce.into(), payload)
+            .map_err(|_| WireGuardError::InvalidAeadTag)?;
+
+        let cookie = plaintext
+            .try_into()
+            .map_err(|_| WireGuardError::InvalidPacket)?;
+        self.cookies.write_cookie = Some(cookie);
+        Ok(())
+    }
+
+    // Compute and append mac1 and mac2 to a handshake message
+    fn append_mac1_and_mac2<'a>(
+        &mut self,
+        local_index: u32,
+        dst: &'a mut [u8],
+    ) -> Result<&'a mut [u8], WireGuardError> {
+        let mac1_off = dst.len() - 32;
+        let mac2_off = dst.len() - 16;
+
+        // msg.mac1 = MAC(HASH(LABEL_MAC1 || responder.static_public), msg[0:offsetof(msg.mac1)])
+        let msg_mac1 = b2s_keyed_mac_16(&self.params.sending_mac1_key, &dst[..mac1_off]);
+
+        dst[mac1_off..mac2_off].copy_from_slice(&msg_mac1[..]);
+
+        //msg.mac2 = MAC(initiator.last_received_cookie, msg[0:offsetof(msg.mac2)])
+        let msg_mac2: [u8; 16] = if let Some(cookie) = self.cookies.write_cookie {
+            b2s_keyed_mac_16(&cookie, &dst[..mac2_off])
+        } else {
+            [0u8; 16]
+        };
+
+        dst[mac2_off..].copy_from_slice(&msg_mac2[..]);
+
+        self.cookies.index = local_index;
+        self.cookies.last_mac1 = Some(msg_mac1);
+        Ok(dst)
+    }
+
+    pub(super) fn format_handshake_initiation<'a>(
+        &mut self,
+        dst: &'a mut [u8],
+    ) -> Result<&'a mut [u8], WireGuardError> {
+        if dst.len() < super::HANDSHAKE_INIT_SZ {
+            return Err(WireGuardError::DestinationBufferTooSmall);
+        }
+
+        let (message_type, rest) = dst.split_at_mut(4);
+        let (sender_index, rest) = rest.split_at_mut(4);
+        let (unencrypted_ephemeral, rest) = rest.split_at_mut(32);
+        let (encrypted_static, rest) = rest.split_at_mut(32 + 16);
+        let (encrypted_timestamp, _) = rest.split_at_mut(12 + 16);
+
+        let local_index = self.inc_index();
+
+        // initiator.chaining_key = HASH(CONSTRUCTION)
+        let mut chaining_key = INITIAL_CHAIN_KEY;
+        // initiator.hash = HASH(HASH(initiator.chaining_key || IDENTIFIER) || responder.static_public)
+        let mut hash = INITIAL_CHAIN_HASH;
+        hash = b2s_hash(&hash, self.params.peer_static_public.as_bytes());
+        // initiator.ephemeral_private = DH_GENERATE()
+        let ephemeral_private = x25519::ReusableSecret::random_from_rng(OsRng);
+        // msg.message_type = 1
+        // msg.reserved_zero = { 0, 0, 0 }
+        message_type.copy_from_slice(&super::HANDSHAKE_INIT.to_le_bytes());
+        // msg.sender_index = little_endian(initiator.sender_index)
+        sender_index.copy_from_slice(&local_index.to_le_bytes());
+        // msg.unencrypted_ephemeral = DH_PUBKEY(initiator.ephemeral_private)
+        unencrypted_ephemeral
+            .copy_from_slice(x25519::PublicKey::from(&ephemeral_private).as_bytes());
+        // initiator.hash = HASH(initiator.hash || msg.unencrypted_ephemeral)
+        hash = b2s_hash(&hash, unencrypted_ephemeral);
+        // temp = HMAC(initiator.chaining_key, msg.unencrypted_ephemeral)
+        // initiator.chaining_key = HMAC(temp, 0x1)
+        chaining_key = b2s_hmac(&b2s_hmac(&chaining_key, unencrypted_ephemeral), &[0x01]);
+        // temp = HMAC(initiator.chaining_key, DH(initiator.ephemeral_private, responder.static_public))
+        let ephemeral_shared = ephemeral_private.diffie_hellman(&self.params.peer_static_public);
+        let temp = b2s_hmac(&chaining_key, &ephemeral_shared.to_bytes());
+        // initiator.chaining_key = HMAC(temp, 0x1)
+        chaining_key = b2s_hmac(&temp, &[0x01]);
+        // key = HMAC(temp, initiator.chaining_key || 0x2)
+        let key = b2s_hmac2(&temp, &chaining_key, &[0x02]);
+        // msg.encrypted_static = AEAD(key, 0, initiator.static_public, initiator.hash)
+        aead_chacha20_seal(
+            encrypted_static,
+            &key,
+            0,
+            self.params.static_public.as_bytes(),
+            &hash,
+        );
+        // initiator.hash = HASH(initiator.hash || msg.encrypted_static)
+        hash = b2s_hash(&hash, encrypted_static);
+        // temp = HMAC(initiator.chaining_key, DH(initiator.static_private, responder.static_public))
+        let temp = b2s_hmac(&chaining_key, self.params.static_shared.as_bytes());
+        // initiator.chaining_key = HMAC(temp, 0x1)
+        chaining_key = b2s_hmac(&temp, &[0x01]);
+        // key = HMAC(temp, initiator.chaining_key || 0x2)
+        let key = b2s_hmac2(&temp, &chaining_key, &[0x02]);
+        // msg.encrypted_timestamp = AEAD(key, 0, TAI64N(), initiator.hash)
+        let timestamp = self.stamper.stamp();
+        aead_chacha20_seal(encrypted_timestamp, &key, 0, &timestamp, &hash);
+        // initiator.hash = HASH(initiator.hash || msg.encrypted_timestamp)
+        hash = b2s_hash(&hash, encrypted_timestamp);
+
+        let time_now = Instant::now();
+        self.previous = std::mem::replace(
+            &mut self.state,
+            HandshakeState::InitSent(HandshakeInitSentState {
+                local_index,
+                chaining_key,
+                hash,
+                ephemeral_private,
+                time_sent: time_now,
+            }),
+        );
+
+        self.append_mac1_and_mac2(local_index, &mut dst[..super::HANDSHAKE_INIT_SZ])
+    }
+
+    fn format_handshake_response<'a>(
+        &mut self,
+        dst: &'a mut [u8],
+    ) -> Result<(&'a mut [u8], Session), WireGuardError> {
+        if dst.len() < super::HANDSHAKE_RESP_SZ {
+            return Err(WireGuardError::DestinationBufferTooSmall);
+        }
+
+        let state = std::mem::replace(&mut self.state, HandshakeState::None);
+        let (mut chaining_key, mut hash, peer_ephemeral_public, peer_index) = match state {
+            HandshakeState::InitReceived {
+                chaining_key,
+                hash,
+                peer_ephemeral_public,
+                peer_index,
+            } => (chaining_key, hash, peer_ephemeral_public, peer_index),
+            _ => {
+                panic!("Unexpected attempt to call send_handshake_response");
+            }
+        };
+
+        let (message_type, rest) = dst.split_at_mut(4);
+        let (sender_index, rest) = rest.split_at_mut(4);
+        let (receiver_index, rest) = rest.split_at_mut(4);
+        let (unencrypted_ephemeral, rest) = rest.split_at_mut(32);
+        let (encrypted_nothing, _) = rest.split_at_mut(16);
+
+        // responder.ephemeral_private = DH_GENERATE()
+        let ephemeral_private = x25519::ReusableSecret::random_from_rng(OsRng);
+        let local_index = self.inc_index();
+        // msg.message_type = 2
+        // msg.reserved_zero = { 0, 0, 0 }
+        message_type.copy_from_slice(&super::HANDSHAKE_RESP.to_le_bytes());
+        // msg.sender_index = little_endian(responder.sender_index)
+        sender_index.copy_from_slice(&local_index.to_le_bytes());
+        // msg.receiver_index = little_endian(initiator.sender_index)
+        receiver_index.copy_from_slice(&peer_index.to_le_bytes());
+        // msg.unencrypted_ephemeral = DH_PUBKEY(initiator.ephemeral_private)
+        unencrypted_ephemeral
+            .copy_from_slice(x25519::PublicKey::from(&ephemeral_private).as_bytes());
+        // responder.hash = HASH(responder.hash || msg.unencrypted_ephemeral)
+        hash = b2s_hash(&hash, unencrypted_ephemeral);
+        // temp = HMAC(responder.chaining_key, msg.unencrypted_ephemeral)
+        let temp = b2s_hmac(&chaining_key, unencrypted_ephemeral);
+        // responder.chaining_key = HMAC(temp, 0x1)
+        chaining_key = b2s_hmac(&temp, &[0x01]);
+        // temp = HMAC(responder.chaining_key, DH(responder.ephemeral_private, initiator.ephemeral_public))
+        let ephemeral_shared = ephemeral_private.diffie_hellman(&peer_ephemeral_public);
+        let temp = b2s_hmac(&chaining_key, &ephemeral_shared.to_bytes());
+        // responder.chaining_key = HMAC(temp, 0x1)
+        chaining_key = b2s_hmac(&temp, &[0x01]);
+        // temp = HMAC(responder.chaining_key, DH(responder.ephemeral_private, initiator.static_public))
+        let temp = b2s_hmac(
+            &chaining_key,
+            &ephemeral_private
+                .diffie_hellman(&self.params.peer_static_public)
+                .to_bytes(),
+        );
+        // responder.chaining_key = HMAC(temp, 0x1)
+        chaining_key = b2s_hmac(&temp, &[0x01]);
+        // temp = HMAC(responder.chaining_key, preshared_key)
+        let temp = b2s_hmac(
+            &chaining_key,
+            &self.params.preshared_key.unwrap_or([0u8; 32])[..],
+        );
+        // responder.chaining_key = HMAC(temp, 0x1)
+        chaining_key = b2s_hmac(&temp, &[0x01]);
+        // temp2 = HMAC(temp, responder.chaining_key || 0x2)
+        let temp2 = b2s_hmac2(&temp, &chaining_key, &[0x02]);
+        // key = HMAC(temp, temp2 || 0x3)
+        let key = b2s_hmac2(&temp, &temp2, &[0x03]);
+        // responder.hash = HASH(responder.hash || temp2)
+        hash = b2s_hash(&hash, &temp2);
+        // msg.encrypted_nothing = AEAD(key, 0, [empty], responder.hash)
+        aead_chacha20_seal(encrypted_nothing, &key, 0, &[], &hash);
+
+        // Derive keys
+        // temp1 = HMAC(initiator.chaining_key, [empty])
+        // temp2 = HMAC(temp1, 0x1)
+        // temp3 = HMAC(temp1, temp2 || 0x2)
+        // initiator.sending_key = temp2
+        // initiator.receiving_key = temp3
+        // initiator.sending_key_counter = 0
+        // initiator.receiving_key_counter = 0
+        let temp1 = b2s_hmac(&chaining_key, &[]);
+        let temp2 = b2s_hmac(&temp1, &[0x01]);
+        let temp3 = b2s_hmac2(&temp1, &temp2, &[0x02]);
+
+        let dst = self.append_mac1_and_mac2(local_index, &mut dst[..super::HANDSHAKE_RESP_SZ])?;
+
+        Ok((dst, Session::new(local_index, peer_index, temp2, temp3)))
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn chacha20_seal_rfc7530_test_vector() {
+        let plaintext = b"Ladies and Gentlemen of the class of '99: If I could offer you only one tip for the future, sunscreen would be it.";
+        let aad: [u8; 12] = [
+            0x50, 0x51, 0x52, 0x53, 0xc0, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7,
+        ];
+        let key: [u8; 32] = [
+            0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87, 0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d,
+            0x8e, 0x8f, 0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 0x98, 0x99, 0x9a, 0x9b,
+            0x9c, 0x9d, 0x9e, 0x9f,
+        ];
+        let nonce: [u8; 12] = [
+            0x07, 0x00, 0x00, 0x00, 0x40, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47,
+        ];
+        let mut buffer = vec![0; plaintext.len() + 16];
+
+        aead_chacha20_seal_inner(&mut buffer, &key, nonce, plaintext, &aad);
+
+        const EXPECTED_CIPHERTEXT: [u8; 114] = [
+            0xd3, 0x1a, 0x8d, 0x34, 0x64, 0x8e, 0x60, 0xdb, 0x7b, 0x86, 0xaf, 0xbc, 0x53, 0xef,
+            0x7e, 0xc2, 0xa4, 0xad, 0xed, 0x51, 0x29, 0x6e, 0x08, 0xfe, 0xa9, 0xe2, 0xb5, 0xa7,
+            0x36, 0xee, 0x62, 0xd6, 0x3d, 0xbe, 0xa4, 0x5e, 0x8c, 0xa9, 0x67, 0x12, 0x82, 0xfa,
+            0xfb, 0x69, 0xda, 0x92, 0x72, 0x8b, 0x1a, 0x71, 0xde, 0x0a, 0x9e, 0x06, 0x0b, 0x29,
+            0x05, 0xd6, 0xa5, 0xb6, 0x7e, 0xcd, 0x3b, 0x36, 0x92, 0xdd, 0xbd, 0x7f, 0x2d, 0x77,
+            0x8b, 0x8c, 0x98, 0x03, 0xae, 0xe3, 0x28, 0x09, 0x1b, 0x58, 0xfa, 0xb3, 0x24, 0xe4,
+            0xfa, 0xd6, 0x75, 0x94, 0x55, 0x85, 0x80, 0x8b, 0x48, 0x31, 0xd7, 0xbc, 0x3f, 0xf4,
+            0xde, 0xf0, 0x8e, 0x4b, 0x7a, 0x9d, 0xe5, 0x76, 0xd2, 0x65, 0x86, 0xce, 0xc6, 0x4b,
+            0x61, 0x16,
+        ];
+        const EXPECTED_TAG: [u8; 16] = [
+            0x1a, 0xe1, 0x0b, 0x59, 0x4f, 0x09, 0xe2, 0x6a, 0x7e, 0x90, 0x2e, 0xcb, 0xd0, 0x60,
+            0x06, 0x91,
+        ];
+
+        assert_eq!(buffer[..plaintext.len()], EXPECTED_CIPHERTEXT);
+        assert_eq!(buffer[plaintext.len()..], EXPECTED_TAG);
+    }
+
+    #[test]
+    fn symmetric_chacha20_seal_open() {
+        let aad: [u8; 32] = Default::default();
+        let key: [u8; 32] = Default::default();
+        let counter = 0;
+
+        let mut encrypted_nothing: [u8; 16] = Default::default();
+
+        aead_chacha20_seal(&mut encrypted_nothing, &key, counter, &[], &aad);
+
+        eprintln!("encrypted_nothing: {:?}", encrypted_nothing);
+
+        aead_chacha20_open(&mut [], &key, counter, &encrypted_nothing, &aad)
+            .expect("Should open what we just sealed");
+    }
+}

burrow/src/boringtun/src/noise/mod.rs

@@ -0,0 +1,799 @@
+// Copyright (c) 2019 Cloudflare, Inc. All rights reserved.
+// SPDX-License-Identifier: BSD-3-Clause
+
+pub mod errors;
+pub mod handshake;
+pub mod rate_limiter;
+
+mod session;
+mod timers;
+
+use crate::noise::errors::WireGuardError;
+use crate::noise::handshake::Handshake;
+use crate::noise::rate_limiter::RateLimiter;
+use crate::noise::timers::{TimerName, Timers};
+use crate::x25519;
+
+use std::collections::VecDeque;
+use std::convert::{TryFrom, TryInto};
+use std::net::{IpAddr, Ipv4Addr, Ipv6Addr};
+use std::sync::Arc;
+use std::time::Duration;
+
+/// The default value to use for rate limiting, when no other rate limiter is defined
+const PEER_HANDSHAKE_RATE_LIMIT: u64 = 10;
+
+const IPV4_MIN_HEADER_SIZE: usize = 20;
+const IPV4_LEN_OFF: usize = 2;
+const IPV4_SRC_IP_OFF: usize = 12;
+const IPV4_DST_IP_OFF: usize = 16;
+const IPV4_IP_SZ: usize = 4;
+
+const IPV6_MIN_HEADER_SIZE: usize = 40;
+const IPV6_LEN_OFF: usize = 4;
+const IPV6_SRC_IP_OFF: usize = 8;
+const IPV6_DST_IP_OFF: usize = 24;
+const IPV6_IP_SZ: usize = 16;
+
+const IP_LEN_SZ: usize = 2;
+
+const MAX_QUEUE_DEPTH: usize = 256;
+/// number of sessions in the ring, better keep a PoT
+const N_SESSIONS: usize = 8;
+
+#[derive(Debug)]
+pub enum TunnResult<'a> {
+    Done,
+    Err(WireGuardError),
+    WriteToNetwork(&'a mut [u8]),
+    WriteToTunnelV4(&'a mut [u8], Ipv4Addr),
+    WriteToTunnelV6(&'a mut [u8], Ipv6Addr),
+}
+
+impl<'a> From<WireGuardError> for TunnResult<'a> {
+    fn from(err: WireGuardError) -> TunnResult<'a> {
+        TunnResult::Err(err)
+    }
+}
+
+/// Tunnel represents a point-to-point WireGuard connection
+pub struct Tunn {
+    /// The handshake currently in progress
+    handshake: handshake::Handshake,
+    /// The N_SESSIONS most recent sessions, index is session id modulo N_SESSIONS
+    sessions: [Option<session::Session>; N_SESSIONS],
+    /// Index of most recently used session
+    current: usize,
+    /// Queue to store blocked packets
+    packet_queue: VecDeque<Vec<u8>>,
+    /// Keeps tabs on the expiring timers
+    timers: timers::Timers,
+    tx_bytes: usize,
+    rx_bytes: usize,
+    rate_limiter: Arc<RateLimiter>,
+}
+
+type MessageType = u32;
+const HANDSHAKE_INIT: MessageType = 1;
+const HANDSHAKE_RESP: MessageType = 2;
+const COOKIE_REPLY: MessageType = 3;
+const DATA: MessageType = 4;
+
+const HANDSHAKE_INIT_SZ: usize = 148;
+const HANDSHAKE_RESP_SZ: usize = 92;
+const COOKIE_REPLY_SZ: usize = 64;
+const DATA_OVERHEAD_SZ: usize = 32;
+
+#[derive(Debug)]
+pub struct HandshakeInit<'a> {
+    sender_idx: u32,
+    unencrypted_ephemeral: &'a [u8; 32],
+    encrypted_static: &'a [u8],
+    encrypted_timestamp: &'a [u8],
+}
+
+#[derive(Debug)]
+pub struct HandshakeResponse<'a> {
+    sender_idx: u32,
+    pub receiver_idx: u32,
+    unencrypted_ephemeral: &'a [u8; 32],
+    encrypted_nothing: &'a [u8],
+}
+
+#[derive(Debug)]
+pub struct PacketCookieReply<'a> {
+    pub receiver_idx: u32,
+    nonce: &'a [u8],
+    encrypted_cookie: &'a [u8],
+}
+
+#[derive(Debug)]
+pub struct PacketData<'a> {
+    pub receiver_idx: u32,
+    counter: u64,
+    encrypted_encapsulated_packet: &'a [u8],
+}
+
+/// Describes a packet from network
+#[derive(Debug)]
+pub enum Packet<'a> {
+    HandshakeInit(HandshakeInit<'a>),
+    HandshakeResponse(HandshakeResponse<'a>),
+    PacketCookieReply(PacketCookieReply<'a>),
+    PacketData(PacketData<'a>),
+}
+
+impl Tunn {
+    #[inline(always)]
+    pub fn parse_incoming_packet(src: &[u8]) -> Result<Packet, WireGuardError> {
+        if src.len() < 4 {
+            return Err(WireGuardError::InvalidPacket);
+        }
+
+        // Checks the type, as well as the reserved zero fields
+        let packet_type = u32::from_le_bytes(src[0..4].try_into().unwrap());
+
+        Ok(match (packet_type, src.len()) {
+            (HANDSHAKE_INIT, HANDSHAKE_INIT_SZ) => Packet::HandshakeInit(HandshakeInit {
+                sender_idx: u32::from_le_bytes(src[4..8].try_into().unwrap()),
+                unencrypted_ephemeral: <&[u8; 32] as TryFrom<&[u8]>>::try_from(&src[8..40])
+                    .expect("length already checked above"),
+                encrypted_static: &src[40..88],
+                encrypted_timestamp: &src[88..116],
+            }),
+            (HANDSHAKE_RESP, HANDSHAKE_RESP_SZ) => Packet::HandshakeResponse(HandshakeResponse {
+                sender_idx: u32::from_le_bytes(src[4..8].try_into().unwrap()),
+                receiver_idx: u32::from_le_bytes(src[8..12].try_into().unwrap()),
+                unencrypted_ephemeral: <&[u8; 32] as TryFrom<&[u8]>>::try_from(&src[12..44])
+                    .expect("length already checked above"),
+                encrypted_nothing: &src[44..60],
+            }),
+            (COOKIE_REPLY, COOKIE_REPLY_SZ) => Packet::PacketCookieReply(PacketCookieReply {
+                receiver_idx: u32::from_le_bytes(src[4..8].try_into().unwrap()),
+                nonce: &src[8..32],
+                encrypted_cookie: &src[32..64],
+            }),
+            (DATA, DATA_OVERHEAD_SZ..=std::usize::MAX) => Packet::PacketData(PacketData {
+                receiver_idx: u32::from_le_bytes(src[4..8].try_into().unwrap()),
+                counter: u64::from_le_bytes(src[8..16].try_into().unwrap()),
+                encrypted_encapsulated_packet: &src[16..],
+            }),
+            _ => return Err(WireGuardError::InvalidPacket),
+        })
+    }
+
+    pub fn is_expired(&self) -> bool {
+        self.handshake.is_expired()
+    }
+
+    pub fn dst_address(packet: &[u8]) -> Option<IpAddr> {
+        if packet.is_empty() {
+            return None;
+        }
+
+        match packet[0] >> 4 {
+            4 if packet.len() >= IPV4_MIN_HEADER_SIZE => {
+                let addr_bytes: [u8; IPV4_IP_SZ] = packet
+                    [IPV4_DST_IP_OFF..IPV4_DST_IP_OFF + IPV4_IP_SZ]
+                    .try_into()
+                    .unwrap();
+                Some(IpAddr::from(addr_bytes))
+            }
+            6 if packet.len() >= IPV6_MIN_HEADER_SIZE => {
+                let addr_bytes: [u8; IPV6_IP_SZ] = packet
+                    [IPV6_DST_IP_OFF..IPV6_DST_IP_OFF + IPV6_IP_SZ]
+                    .try_into()
+                    .unwrap();
+                Some(IpAddr::from(addr_bytes))
+            }
+            _ => None,
+        }
+    }
+
+    /// Create a new tunnel using own private key and the peer public key
+    pub fn new(
+        static_private: x25519::StaticSecret,
+        peer_static_public: x25519::PublicKey,
+        preshared_key: Option<[u8; 32]>,
+        persistent_keepalive: Option<u16>,
+        index: u32,
+        rate_limiter: Option<Arc<RateLimiter>>,
+    ) -> Result<Self, &'static str> {
+        let static_public = x25519::PublicKey::from(&static_private);
+
+        let tunn = Tunn {
+            handshake: Handshake::new(
+                static_private,
+                static_public,
+                peer_static_public,
+                index << 8,
+                preshared_key,
+            )
+            .map_err(|_| "Invalid parameters")?,
+            sessions: Default::default(),
+            current: Default::default(),
+            tx_bytes: Default::default(),
+            rx_bytes: Default::default(),
+
+            packet_queue: VecDeque::new(),
+            timers: Timers::new(persistent_keepalive, rate_limiter.is_none()),
+
+            rate_limiter: rate_limiter.unwrap_or_else(|| {
+                Arc::new(RateLimiter::new(&static_public, PEER_HANDSHAKE_RATE_LIMIT))
+            }),
+        };
+
+        Ok(tunn)
+    }
+
+    /// Update the private key and clear existing sessions
+    pub fn set_static_private(
+        &mut self,
+        static_private: x25519::StaticSecret,
+        static_public: x25519::PublicKey,
+        rate_limiter: Option<Arc<RateLimiter>>,
+    ) -> Result<(), WireGuardError> {
+        self.timers.should_reset_rr = rate_limiter.is_none();
+        self.rate_limiter = rate_limiter.unwrap_or_else(|| {
+            Arc::new(RateLimiter::new(&static_public, PEER_HANDSHAKE_RATE_LIMIT))
+        });
+        self.handshake
+            .set_static_private(static_private, static_public)?;
+        for s in &mut self.sessions {
+            *s = None;
+        }
+        Ok(())
+    }
+
+    /// Encapsulate a single packet from the tunnel interface.
+    /// Returns TunnResult.
+    ///
+    /// # Panics
+    /// Panics if dst buffer is too small.
+    /// Size of dst should be at least src.len() + 32, and no less than 148 bytes.
+    pub fn encapsulate<'a>(&mut self, src: &[u8], dst: &'a mut [u8]) -> TunnResult<'a> {
+        let current = self.current;
+        if let Some(ref session) = self.sessions[current % N_SESSIONS] {
+            // Send the packet using an established session
+            let packet = session.format_packet_data(src, dst);
+            self.timer_tick(TimerName::TimeLastPacketSent);
+            // Exclude Keepalive packets from timer update.
+            if !src.is_empty() {
+                self.timer_tick(TimerName::TimeLastDataPacketSent);
+            }
+            self.tx_bytes += src.len();
+            return TunnResult::WriteToNetwork(packet);
+        }
+
+        // If there is no session, queue the packet for future retry
+        self.queue_packet(src);
+        // Initiate a new handshake if none is in progress
+        self.format_handshake_initiation(dst, false)
+    }
+
+    /// Receives a UDP datagram from the network and parses it.
+    /// Returns TunnResult.
+    ///
+    /// If the result is of type TunnResult::WriteToNetwork, should repeat the call with empty datagram,
+    /// until TunnResult::Done is returned. If batch processing packets, it is OK to defer until last
+    /// packet is processed.
+    pub fn decapsulate<'a>(
+        &mut self,
+        src_addr: Option<IpAddr>,
+        datagram: &[u8],
+        dst: &'a mut [u8],
+    ) -> TunnResult<'a> {
+        if datagram.is_empty() {
+            // Indicates a repeated call
+            return self.send_queued_packet(dst);
+        }
+
+        let mut cookie = [0u8; COOKIE_REPLY_SZ];
+        let packet = match self
+            .rate_limiter
+            .verify_packet(src_addr, datagram, &mut cookie)
+        {
+            Ok(packet) => packet,
+            Err(TunnResult::WriteToNetwork(cookie)) => {
+                dst[..cookie.len()].copy_from_slice(cookie);
+                return TunnResult::WriteToNetwork(&mut dst[..cookie.len()]);
+            }
+            Err(TunnResult::Err(e)) => return TunnResult::Err(e),
+            _ => unreachable!(),
+        };
+
+        self.handle_verified_packet(packet, dst)
+    }
+
+    pub(crate) fn handle_verified_packet<'a>(
+        &mut self,
+        packet: Packet,
+        dst: &'a mut [u8],
+    ) -> TunnResult<'a> {
+        match packet {
+            Packet::HandshakeInit(p) => self.handle_handshake_init(p, dst),
+            Packet::HandshakeResponse(p) => self.handle_handshake_response(p, dst),
+            Packet::PacketCookieReply(p) => self.handle_cookie_reply(p),
+            Packet::PacketData(p) => self.handle_data(p, dst),
+        }
+        .unwrap_or_else(TunnResult::from)
+    }
+
+    fn handle_handshake_init<'a>(
+        &mut self,
+        p: HandshakeInit,
+        dst: &'a mut [u8],
+    ) -> Result<TunnResult<'a>, WireGuardError> {
+        tracing::debug!(
+            message = "Received handshake_initiation",
+            remote_idx = p.sender_idx
+        );
+
+        let (packet, session) = self.handshake.receive_handshake_initialization(p, dst)?;
+
+        // Store new session in ring buffer
+        let index = session.local_index();
+        self.sessions[index % N_SESSIONS] = Some(session);
+
+        self.timer_tick(TimerName::TimeLastPacketReceived);
+        self.timer_tick(TimerName::TimeLastPacketSent);
+        self.timer_tick_session_established(false, index); // New session established, we are not the initiator
+
+        tracing::debug!(message = "Sending handshake_response", local_idx = index);
+
+        Ok(TunnResult::WriteToNetwork(packet))
+    }
+
+    fn handle_handshake_response<'a>(
+        &mut self,
+        p: HandshakeResponse,
+        dst: &'a mut [u8],
+    ) -> Result<TunnResult<'a>, WireGuardError> {
+        tracing::debug!(
+            message = "Received handshake_response",
+            local_idx = p.receiver_idx,
+            remote_idx = p.sender_idx
+        );
+
+        let session = self.handshake.receive_handshake_response(p)?;
+
+        let keepalive_packet = session.format_packet_data(&[], dst);
+        // Store new session in ring buffer
+        let l_idx = session.local_index();
+        let index = l_idx % N_SESSIONS;
+        self.sessions[index] = Some(session);
+
+        self.timer_tick(TimerName::TimeLastPacketReceived);
+        self.timer_tick_session_established(true, index); // New session established, we are the initiator
+        self.set_current_session(l_idx);
+
+        tracing::debug!("Sending keepalive");
+
+        Ok(TunnResult::WriteToNetwork(keepalive_packet)) // Send a keepalive as a response
+    }
+
+    fn handle_cookie_reply<'a>(
+        &mut self,
+        p: PacketCookieReply,
+    ) -> Result<TunnResult<'a>, WireGuardError> {
+        tracing::debug!(
+            message = "Received cookie_reply",
+            local_idx = p.receiver_idx
+        );
+
+        self.handshake.receive_cookie_reply(p)?;
+        self.timer_tick(TimerName::TimeLastPacketReceived);
+        self.timer_tick(TimerName::TimeCookieReceived);
+
+        tracing::debug!("Did set cookie");
+
+        Ok(TunnResult::Done)
+    }
+
+    /// Update the index of the currently used session, if needed
+    fn set_current_session(&mut self, new_idx: usize) {
+        let cur_idx = self.current;
+        if cur_idx == new_idx {
+            // There is nothing to do, already using this session, this is the common case
+            return;
+        }
+        if self.sessions[cur_idx % N_SESSIONS].is_none()
+            || self.timers.session_timers[new_idx % N_SESSIONS]
+                >= self.timers.session_timers[cur_idx % N_SESSIONS]
+        {
+            self.current = new_idx;
+            tracing::debug!(message = "New session", session = new_idx);
+        }
+    }
+
+    /// Decrypts a data packet, and stores the decapsulated packet in dst.
+    fn handle_data<'a>(
+        &mut self,
+        packet: PacketData,
+        dst: &'a mut [u8],
+    ) -> Result<TunnResult<'a>, WireGuardError> {
+        let r_idx = packet.receiver_idx as usize;
+        let idx = r_idx % N_SESSIONS;
+
+        // Get the (probably) right session
+        let decapsulated_packet = {
+            let session = self.sessions[idx].as_ref();
+            let session = session.ok_or_else(|| {
+                tracing::trace!(message = "No current session available", remote_idx = r_idx);
+                WireGuardError::NoCurrentSession
+            })?;
+            session.receive_packet_data(packet, dst)?
+        };
+
+        self.set_current_session(r_idx);
+
+        self.timer_tick(TimerName::TimeLastPacketReceived);
+
+        Ok(self.validate_decapsulated_packet(decapsulated_packet))
+    }
+
+    /// Formats a new handshake initiation message and store it in dst. If force_resend is true will send
+    /// a new handshake, even if a handshake is already in progress (for example when a handshake times out)
+    pub fn format_handshake_initiation<'a>(
+        &mut self,
+        dst: &'a mut [u8],
+        force_resend: bool,
+    ) -> TunnResult<'a> {
+        if self.handshake.is_in_progress() && !force_resend {
+            return TunnResult::Done;
+        }
+
+        if self.handshake.is_expired() {
+            self.timers.clear();
+        }
+
+        let starting_new_handshake = !self.handshake.is_in_progress();
+
+        match self.handshake.format_handshake_initiation(dst) {
+            Ok(packet) => {
+                tracing::debug!("Sending handshake_initiation");
+
+                if starting_new_handshake {
+                    self.timer_tick(TimerName::TimeLastHandshakeStarted);
+                }
+                self.timer_tick(TimerName::TimeLastPacketSent);
+                TunnResult::WriteToNetwork(packet)
+            }
+            Err(e) => TunnResult::Err(e),
+        }
+    }
+
+    /// Check if an IP packet is v4 or v6, truncate to the length indicated by the length field
+    /// Returns the truncated packet and the source IP as TunnResult
+    fn validate_decapsulated_packet<'a>(&mut self, packet: &'a mut [u8]) -> TunnResult<'a> {
+        let (computed_len, src_ip_address) = match packet.len() {
+            0 => return TunnResult::Done, // This is keepalive, and not an error
+            _ if packet[0] >> 4 == 4 && packet.len() >= IPV4_MIN_HEADER_SIZE => {
+                let len_bytes: [u8; IP_LEN_SZ] = packet[IPV4_LEN_OFF..IPV4_LEN_OFF + IP_LEN_SZ]
+                    .try_into()
+                    .unwrap();
+                let addr_bytes: [u8; IPV4_IP_SZ] = packet
+                    [IPV4_SRC_IP_OFF..IPV4_SRC_IP_OFF + IPV4_IP_SZ]
+                    .try_into()
+                    .unwrap();
+                (
+                    u16::from_be_bytes(len_bytes) as usize,
+                    IpAddr::from(addr_bytes),
+                )
+            }
+            _ if packet[0] >> 4 == 6 && packet.len() >= IPV6_MIN_HEADER_SIZE => {
+                let len_bytes: [u8; IP_LEN_SZ] = packet[IPV6_LEN_OFF..IPV6_LEN_OFF + IP_LEN_SZ]
+                    .try_into()
+                    .unwrap();
+                let addr_bytes: [u8; IPV6_IP_SZ] = packet
+                    [IPV6_SRC_IP_OFF..IPV6_SRC_IP_OFF + IPV6_IP_SZ]
+                    .try_into()
+                    .unwrap();
+                (
+                    u16::from_be_bytes(len_bytes) as usize + IPV6_MIN_HEADER_SIZE,
+                    IpAddr::from(addr_bytes),
+                )
+            }
+            _ => return TunnResult::Err(WireGuardError::InvalidPacket),
+        };
+
+        if computed_len > packet.len() {
+            return TunnResult::Err(WireGuardError::InvalidPacket);
+        }
+
+        self.timer_tick(TimerName::TimeLastDataPacketReceived);
+        self.rx_bytes += computed_len;
+
+        match src_ip_address {
+            IpAddr::V4(addr) => TunnResult::WriteToTunnelV4(&mut packet[..computed_len], addr),
+            IpAddr::V6(addr) => TunnResult::WriteToTunnelV6(&mut packet[..computed_len], addr),
+        }
+    }
+
+    /// Get a packet from the queue, and try to encapsulate it
+    fn send_queued_packet<'a>(&mut self, dst: &'a mut [u8]) -> TunnResult<'a> {
+        if let Some(packet) = self.dequeue_packet() {
+            match self.encapsulate(&packet, dst) {
+                TunnResult::Err(_) => {
+                    // On error, return packet to the queue
+                    self.requeue_packet(packet);
+                }
+                r => return r,
+            }
+        }
+        TunnResult::Done
+    }
+
+    /// Push packet to the back of the queue
+    fn queue_packet(&mut self, packet: &[u8]) {
+        if self.packet_queue.len() < MAX_QUEUE_DEPTH {
+            // Drop if too many are already in queue
+            self.packet_queue.push_back(packet.to_vec());
+        }
+    }
+
+    /// Push packet to the front of the queue
+    fn requeue_packet(&mut self, packet: Vec<u8>) {
+        if self.packet_queue.len() < MAX_QUEUE_DEPTH {
+            // Drop if too many are already in queue
+            self.packet_queue.push_front(packet);
+        }
+    }
+
+    fn dequeue_packet(&mut self) -> Option<Vec<u8>> {
+        self.packet_queue.pop_front()
+    }
+
+    fn estimate_loss(&self) -> f32 {
+        let session_idx = self.current;
+
+        let mut weight = 9.0;
+        let mut cur_avg = 0.0;
+        let mut total_weight = 0.0;
+
+        for i in 0..N_SESSIONS {
+            if let Some(ref session) = self.sessions[(session_idx.wrapping_sub(i)) % N_SESSIONS] {
+                let (expected, received) = session.current_packet_cnt();
+
+                let loss = if expected == 0 {
+                    0.0
+                } else {
+                    1.0 - received as f32 / expected as f32
+                };
+
+                cur_avg += loss * weight;
+                total_weight += weight;
+                weight /= 3.0;
+            }
+        }
+
+        if total_weight == 0.0 {
+            0.0
+        } else {
+            cur_avg / total_weight
+        }
+    }
+
+    /// Return stats from the tunnel:
+    /// * Time since last handshake in seconds
+    /// * Data bytes sent
+    /// * Data bytes received
+    pub fn stats(&self) -> (Option<Duration>, usize, usize, f32, Option<u32>) {
+        let time = self.time_since_last_handshake();
+        let tx_bytes = self.tx_bytes;
+        let rx_bytes = self.rx_bytes;
+        let loss = self.estimate_loss();
+        let rtt = self.handshake.last_rtt;
+
+        (time, tx_bytes, rx_bytes, loss, rtt)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    #[cfg(feature = "mock-instant")]
+    use crate::noise::timers::{REKEY_AFTER_TIME, REKEY_TIMEOUT};
+
+    use super::*;
+    use rand_core::{OsRng, RngCore};
+
+    fn create_two_tuns() -> (Tunn, Tunn) {
+        let my_secret_key = x25519_dalek::StaticSecret::random_from_rng(OsRng);
+        let my_public_key = x25519_dalek::PublicKey::from(&my_secret_key);
+        let my_idx = OsRng.next_u32();
+
+        let their_secret_key = x25519_dalek::StaticSecret::random_from_rng(OsRng);
+        let their_public_key = x25519_dalek::PublicKey::from(&their_secret_key);
+        let their_idx = OsRng.next_u32();
+
+        let my_tun = Tunn::new(my_secret_key, their_public_key, None, None, my_idx, None).unwrap();
+
+        let their_tun =
+            Tunn::new(their_secret_key, my_public_key, None, None, their_idx, None).unwrap();
+
+        (my_tun, their_tun)
+    }
+
+    fn create_handshake_init(tun: &mut Tunn) -> Vec<u8> {
+        let mut dst = vec![0u8; 2048];
+        let handshake_init = tun.format_handshake_initiation(&mut dst, false);
+        assert!(matches!(handshake_init, TunnResult::WriteToNetwork(_)));
+        let handshake_init = if let TunnResult::WriteToNetwork(sent) = handshake_init {
+            sent
+        } else {
+            unreachable!();
+        };
+
+        handshake_init.into()
+    }
+
+    fn create_handshake_response(tun: &mut Tunn, handshake_init: &[u8]) -> Vec<u8> {
+        let mut dst = vec![0u8; 2048];
+        let handshake_resp = tun.decapsulate(None, handshake_init, &mut dst);
+        assert!(matches!(handshake_resp, TunnResult::WriteToNetwork(_)));
+
+        let handshake_resp = if let TunnResult::WriteToNetwork(sent) = handshake_resp {
+            sent
+        } else {
+            unreachable!();
+        };
+
+        handshake_resp.into()
+    }
+
+    fn parse_handshake_resp(tun: &mut Tunn, handshake_resp: &[u8]) -> Vec<u8> {
+        let mut dst = vec![0u8; 2048];
+        let keepalive = tun.decapsulate(None, handshake_resp, &mut dst);
+        assert!(matches!(keepalive, TunnResult::WriteToNetwork(_)));
+
+        let keepalive = if let TunnResult::WriteToNetwork(sent) = keepalive {
+            sent
+        } else {
+            unreachable!();
+        };
+
+        keepalive.into()
+    }
+
+    fn parse_keepalive(tun: &mut Tunn, keepalive: &[u8]) {
+        let mut dst = vec![0u8; 2048];
+        let keepalive = tun.decapsulate(None, keepalive, &mut dst);
+        assert!(matches!(keepalive, TunnResult::Done));
+    }
+
+    fn create_two_tuns_and_handshake() -> (Tunn, Tunn) {
+        let (mut my_tun, mut their_tun) = create_two_tuns();
+        let init = create_handshake_init(&mut my_tun);
+        let resp = create_handshake_response(&mut their_tun, &init);
+        let keepalive = parse_handshake_resp(&mut my_tun, &resp);
+        parse_keepalive(&mut their_tun, &keepalive);
+
+        (my_tun, their_tun)
+    }
+
+    fn create_ipv4_udp_packet() -> Vec<u8> {
+        let header =
+            etherparse::PacketBuilder::ipv4([192, 168, 1, 2], [192, 168, 1, 3], 5).udp(5678, 23);
+        let payload = [0, 1, 2, 3];
+        let mut packet = Vec::<u8>::with_capacity(header.size(payload.len()));
+        header.write(&mut packet, &payload).unwrap();
+        packet
+    }
+
+    #[cfg(feature = "mock-instant")]
+    fn update_timer_results_in_handshake(tun: &mut Tunn) {
+        let mut dst = vec![0u8; 2048];
+        let result = tun.update_timers(&mut dst);
+        assert!(matches!(result, TunnResult::WriteToNetwork(_)));
+        let packet_data = if let TunnResult::WriteToNetwork(data) = result {
+            data
+        } else {
+            unreachable!();
+        };
+        let packet = Tunn::parse_incoming_packet(packet_data).unwrap();
+        assert!(matches!(packet, Packet::HandshakeInit(_)));
+    }
+
+    #[test]
+    fn create_two_tunnels_linked_to_eachother() {
+        let (_my_tun, _their_tun) = create_two_tuns();
+    }
+
+    #[test]
+    fn handshake_init() {
+        let (mut my_tun, _their_tun) = create_two_tuns();
+        let init = create_handshake_init(&mut my_tun);
+        let packet = Tunn::parse_incoming_packet(&init).unwrap();
+        assert!(matches!(packet, Packet::HandshakeInit(_)));
+    }
+
+    #[test]
+    fn handshake_init_and_response() {
+        let (mut my_tun, mut their_tun) = create_two_tuns();
+        let init = create_handshake_init(&mut my_tun);
+        let resp = create_handshake_response(&mut their_tun, &init);
+        let packet = Tunn::parse_incoming_packet(&resp).unwrap();
+        assert!(matches!(packet, Packet::HandshakeResponse(_)));
+    }
+
+    #[test]
+    fn full_handshake() {
+        let (mut my_tun, mut their_tun) = create_two_tuns();
+        let init = create_handshake_init(&mut my_tun);
+        let resp = create_handshake_response(&mut their_tun, &init);
+        let keepalive = parse_handshake_resp(&mut my_tun, &resp);
+        let packet = Tunn::parse_incoming_packet(&keepalive).unwrap();
+        assert!(matches!(packet, Packet::PacketData(_)));
+    }
+
+    #[test]
+    fn full_handshake_plus_timers() {
+        let (mut my_tun, mut their_tun) = create_two_tuns_and_handshake();
+        // Time has not yet advanced so their is nothing to do
+        assert!(matches!(my_tun.update_timers(&mut []), TunnResult::Done));
+        assert!(matches!(their_tun.update_timers(&mut []), TunnResult::Done));
+    }
+
+    #[test]
+    #[cfg(feature = "mock-instant")]
+    fn new_handshake_after_two_mins() {
+        let (mut my_tun, mut their_tun) = create_two_tuns_and_handshake();
+        let mut my_dst = [0u8; 1024];
+
+        // Advance time 1 second and "send" 1 packet so that we send a handshake
+        // after the timeout
+        mock_instant::MockClock::advance(Duration::from_secs(1));
+        assert!(matches!(their_tun.update_timers(&mut []), TunnResult::Done));
+        assert!(matches!(
+            my_tun.update_timers(&mut my_dst),
+            TunnResult::Done
+        ));
+        let sent_packet_buf = create_ipv4_udp_packet();
+        let data = my_tun.encapsulate(&sent_packet_buf, &mut my_dst);
+        assert!(matches!(data, TunnResult::WriteToNetwork(_)));
+
+        //Advance to timeout
+        mock_instant::MockClock::advance(REKEY_AFTER_TIME);
+        assert!(matches!(their_tun.update_timers(&mut []), TunnResult::Done));
+        update_timer_results_in_handshake(&mut my_tun);
+    }
+
+    #[test]
+    #[cfg(feature = "mock-instant")]
+    fn handshake_no_resp_rekey_timeout() {
+        let (mut my_tun, _their_tun) = create_two_tuns();
+
+        let init = create_handshake_init(&mut my_tun);
+        let packet = Tunn::parse_incoming_packet(&init).unwrap();
+        assert!(matches!(packet, Packet::HandshakeInit(_)));
+
+        mock_instant::MockClock::advance(REKEY_TIMEOUT);
+        update_timer_results_in_handshake(&mut my_tun)
+    }
+
+    #[test]
+    fn one_ip_packet() {
+        let (mut my_tun, mut their_tun) = create_two_tuns_and_handshake();
+        let mut my_dst = [0u8; 1024];
+        let mut their_dst = [0u8; 1024];
+
+        let sent_packet_buf = create_ipv4_udp_packet();
+
+        let data = my_tun.encapsulate(&sent_packet_buf, &mut my_dst);
+        assert!(matches!(data, TunnResult::WriteToNetwork(_)));
+        let data = if let TunnResult::WriteToNetwork(sent) = data {
+            sent
+        } else {
+            unreachable!();
+        };
+
+        let data = their_tun.decapsulate(None, data, &mut their_dst);
+        assert!(matches!(data, TunnResult::WriteToTunnelV4(..)));
+        let recv_packet_buf = if let TunnResult::WriteToTunnelV4(recv, _addr) = data {
+            recv
+        } else {
+            unreachable!();
+        };
+        assert_eq!(sent_packet_buf, recv_packet_buf);
+    }
+}

burrow/src/boringtun/src/noise/rate_limiter.rs

@@ -0,0 +1,193 @@
+use super::handshake::{b2s_hash, b2s_keyed_mac_16, b2s_keyed_mac_16_2, b2s_mac_24};
+use crate::noise::handshake::{LABEL_COOKIE, LABEL_MAC1};
+use crate::noise::{HandshakeInit, HandshakeResponse, Packet, Tunn, TunnResult, WireGuardError};
+
+#[cfg(feature = "mock-instant")]
+use mock_instant::Instant;
+use std::net::IpAddr;
+use std::sync::atomic::{AtomicU64, Ordering};
+
+#[cfg(not(feature = "mock-instant"))]
+use crate::sleepyinstant::Instant;
+
+use aead::generic_array::GenericArray;
+use aead::{AeadInPlace, KeyInit};
+use chacha20poly1305::{Key, XChaCha20Poly1305};
+use parking_lot::Mutex;
+use rand_core::{OsRng, RngCore};
+use ring::constant_time::verify_slices_are_equal;
+
+const COOKIE_REFRESH: u64 = 128; // Use 128 and not 120 so the compiler can optimize out the division
+const COOKIE_SIZE: usize = 16;
+const COOKIE_NONCE_SIZE: usize = 24;
+
+/// How often should reset count in seconds
+const RESET_PERIOD: u64 = 1;
+
+type Cookie = [u8; COOKIE_SIZE];
+
+/// There are two places where WireGuard requires "randomness" for cookies
+/// * The 24 byte nonce in the cookie massage - here the only goal is to avoid nonce reuse
+/// * A secret value that changes every two minutes
+/// Because the main goal of the cookie is simply for a party to prove ownership of an IP address
+/// we can relax the randomness definition a bit, in order to avoid locking, because using less
+/// resources is the main goal of any DoS prevention mechanism.
+/// In order to avoid locking and calls to rand we derive pseudo random values using the AEAD and
+/// some counters.
+pub struct RateLimiter {
+    /// The key we use to derive the nonce
+    nonce_key: [u8; 32],
+    /// The key we use to derive the cookie
+    secret_key: [u8; 16],
+    start_time: Instant,
+    /// A single 64 bit counter (should suffice for many years)
+    nonce_ctr: AtomicU64,
+    mac1_key: [u8; 32],
+    cookie_key: Key,
+    limit: u64,
+    /// The counter since last reset
+    count: AtomicU64,
+    /// The time last reset was performed on this rate limiter
+    last_reset: Mutex<Instant>,
+}
+
+impl RateLimiter {
+    pub fn new(public_key: &crate::x25519::PublicKey, limit: u64) -> Self {
+        let mut secret_key = [0u8; 16];
+        OsRng.fill_bytes(&mut secret_key);
+        RateLimiter {
+            nonce_key: Self::rand_bytes(),
+            secret_key,
+            start_time: Instant::now(),
+            nonce_ctr: AtomicU64::new(0),
+            mac1_key: b2s_hash(LABEL_MAC1, public_key.as_bytes()),
+            cookie_key: b2s_hash(LABEL_COOKIE, public_key.as_bytes()).into(),
+            limit,
+            count: AtomicU64::new(0),
+            last_reset: Mutex::new(Instant::now()),
+        }
+    }
+
+    fn rand_bytes() -> [u8; 32] {
+        let mut key = [0u8; 32];
+        OsRng.fill_bytes(&mut key);
+        key
+    }
+
+    /// Reset packet count (ideally should be called with a period of 1 second)
+    pub fn reset_count(&self) {
+        // The rate limiter is not very accurate, but at the scale we care about it doesn't matter much
+        let current_time = Instant::now();
+        let mut last_reset_time = self.last_reset.lock();
+        if current_time.duration_since(*last_reset_time).as_secs() >= RESET_PERIOD {
+            self.count.store(0, Ordering::SeqCst);
+            *last_reset_time = current_time;
+        }
+    }
+
+    /// Compute the correct cookie value based on the current secret value and the source IP
+    fn current_cookie(&self, addr: IpAddr) -> Cookie {
+        let mut addr_bytes = [0u8; 16];
+
+        match addr {
+            IpAddr::V4(a) => addr_bytes[..4].copy_from_slice(&a.octets()[..]),
+            IpAddr::V6(a) => addr_bytes[..].copy_from_slice(&a.octets()[..]),
+        }
+
+        // The current cookie for a given IP is the MAC(responder.changing_secret_every_two_minutes, initiator.ip_address)
+        // First we derive the secret from the current time, the value of cur_counter would change with time.
+        let cur_counter = Instant::now().duration_since(self.start_time).as_secs() / COOKIE_REFRESH;
+
+        // Next we derive the cookie
+        b2s_keyed_mac_16_2(&self.secret_key, &cur_counter.to_le_bytes(), &addr_bytes)
+    }
+
+    fn nonce(&self) -> [u8; COOKIE_NONCE_SIZE] {
+        let ctr = self.nonce_ctr.fetch_add(1, Ordering::Relaxed);
+
+        b2s_mac_24(&self.nonce_key, &ctr.to_le_bytes())
+    }
+
+    fn is_under_load(&self) -> bool {
+        self.count.fetch_add(1, Ordering::SeqCst) >= self.limit
+    }
+
+    pub(crate) fn format_cookie_reply<'a>(
+        &self,
+        idx: u32,
+        cookie: Cookie,
+        mac1: &[u8],
+        dst: &'a mut [u8],
+    ) -> Result<&'a mut [u8], WireGuardError> {
+        if dst.len() < super::COOKIE_REPLY_SZ {
+            return Err(WireGuardError::DestinationBufferTooSmall);
+        }
+
+        let (message_type, rest) = dst.split_at_mut(4);
+        let (receiver_index, rest) = rest.split_at_mut(4);
+        let (nonce, rest) = rest.split_at_mut(24);
+        let (encrypted_cookie, _) = rest.split_at_mut(16 + 16);
+
+        // msg.message_type = 3
+        // msg.reserved_zero = { 0, 0, 0 }
+        message_type.copy_from_slice(&super::COOKIE_REPLY.to_le_bytes());
+        // msg.receiver_index = little_endian(initiator.sender_index)
+        receiver_index.copy_from_slice(&idx.to_le_bytes());
+        nonce.copy_from_slice(&self.nonce()[..]);
+
+        let cipher = XChaCha20Poly1305::new(&self.cookie_key);
+
+        let iv = GenericArray::from_slice(nonce);
+
+        encrypted_cookie[..16].copy_from_slice(&cookie);
+        let tag = cipher
+            .encrypt_in_place_detached(iv, mac1, &mut encrypted_cookie[..16])
+            .map_err(|_| WireGuardError::DestinationBufferTooSmall)?;
+
+        encrypted_cookie[16..].copy_from_slice(&tag);
+
+        Ok(&mut dst[..super::COOKIE_REPLY_SZ])
+    }
+
+    /// Verify the MAC fields on the datagram, and apply rate limiting if needed
+    pub fn verify_packet<'a, 'b>(
+        &self,
+        src_addr: Option<IpAddr>,
+        src: &'a [u8],
+        dst: &'b mut [u8],
+    ) -> Result<Packet<'a>, TunnResult<'b>> {
+        let packet = Tunn::parse_incoming_packet(src)?;
+
+        // Verify and rate limit handshake messages only
+        if let Packet::HandshakeInit(HandshakeInit { sender_idx, .. })
+        | Packet::HandshakeResponse(HandshakeResponse { sender_idx, .. }) = packet
+        {
+            let (msg, macs) = src.split_at(src.len() - 32);
+            let (mac1, mac2) = macs.split_at(16);
+
+            let computed_mac1 = b2s_keyed_mac_16(&self.mac1_key, msg);
+            verify_slices_are_equal(&computed_mac1[..16], mac1)
+                .map_err(|_| TunnResult::Err(WireGuardError::InvalidMac))?;
+
+            if self.is_under_load() {
+                let addr = match src_addr {
+                    None => return Err(TunnResult::Err(WireGuardError::UnderLoad)),
+                    Some(addr) => addr,
+                };
+
+                // Only given an address can we validate mac2
+                let cookie = self.current_cookie(addr);
+                let computed_mac2 = b2s_keyed_mac_16_2(&cookie, msg, mac1);
+
+                if verify_slices_are_equal(&computed_mac2[..16], mac2).is_err() {
+                    let cookie_packet = self
+                        .format_cookie_reply(sender_idx, cookie, mac1, dst)
+                        .map_err(TunnResult::Err)?;
+                    return Err(TunnResult::WriteToNetwork(cookie_packet));
+                }
+            }
+        }
+
+        Ok(packet)
+    }
+}

burrow/src/boringtun/src/noise/session.rs

@@ -0,0 +1,329 @@
+// Copyright (c) 2019 Cloudflare, Inc. All rights reserved.
+// SPDX-License-Identifier: BSD-3-Clause
+
+use super::PacketData;
+use crate::noise::errors::WireGuardError;
+use parking_lot::Mutex;
+use ring::aead::{Aad, LessSafeKey, Nonce, UnboundKey, CHACHA20_POLY1305};
+use std::sync::atomic::{AtomicUsize, Ordering};
+
+pub struct Session {
+    pub(crate) receiving_index: u32,
+    sending_index: u32,
+    receiver: LessSafeKey,
+    sender: LessSafeKey,
+    sending_key_counter: AtomicUsize,
+    receiving_key_counter: Mutex<ReceivingKeyCounterValidator>,
+}
+
+impl std::fmt::Debug for Session {
+    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+        write!(
+            f,
+            "Session: {}<- ->{}",
+            self.receiving_index, self.sending_index
+        )
+    }
+}
+
+/// Where encrypted data resides in a data packet
+const DATA_OFFSET: usize = 16;
+/// The overhead of the AEAD
+const AEAD_SIZE: usize = 16;
+
+// Receiving buffer constants
+const WORD_SIZE: u64 = 64;
+const N_WORDS: u64 = 16; // Suffice to reorder 64*16 = 1024 packets; can be increased at will
+const N_BITS: u64 = WORD_SIZE * N_WORDS;
+
+#[derive(Debug, Clone, Default)]
+struct ReceivingKeyCounterValidator {
+    /// In order to avoid replays while allowing for some reordering of the packets, we keep a
+    /// bitmap of received packets, and the value of the highest counter
+    next: u64,
+    /// Used to estimate packet loss
+    receive_cnt: u64,
+    bitmap: [u64; N_WORDS as usize],
+}
+
+impl ReceivingKeyCounterValidator {
+    #[inline(always)]
+    fn set_bit(&mut self, idx: u64) {
+        let bit_idx = idx % N_BITS;
+        let word = (bit_idx / WORD_SIZE) as usize;
+        let bit = (bit_idx % WORD_SIZE) as usize;
+        self.bitmap[word] |= 1 << bit;
+    }
+
+    #[inline(always)]
+    fn clear_bit(&mut self, idx: u64) {
+        let bit_idx = idx % N_BITS;
+        let word = (bit_idx / WORD_SIZE) as usize;
+        let bit = (bit_idx % WORD_SIZE) as usize;
+        self.bitmap[word] &= !(1u64 << bit);
+    }
+
+    /// Clear the word that contains idx
+    #[inline(always)]
+    fn clear_word(&mut self, idx: u64) {
+        let bit_idx = idx % N_BITS;
+        let word = (bit_idx / WORD_SIZE) as usize;
+        self.bitmap[word] = 0;
+    }
+
+    /// Returns true if bit is set, false otherwise
+    #[inline(always)]
+    fn check_bit(&self, idx: u64) -> bool {
+        let bit_idx = idx % N_BITS;
+        let word = (bit_idx / WORD_SIZE) as usize;
+        let bit = (bit_idx % WORD_SIZE) as usize;
+        ((self.bitmap[word] >> bit) & 1) == 1
+    }
+
+    /// Returns true if the counter was not yet received, and is not too far back
+    #[inline(always)]
+    fn will_accept(&self, counter: u64) -> Result<(), WireGuardError> {
+        if counter >= self.next {
+            // As long as the counter is growing no replay took place for sure
+            return Ok(());
+        }
+        if counter + N_BITS < self.next {
+            // Drop if too far back
+            return Err(WireGuardError::InvalidCounter);
+        }
+        if !self.check_bit(counter) {
+            Ok(())
+        } else {
+            Err(WireGuardError::DuplicateCounter)
+        }
+    }
+
+    /// Marks the counter as received, and returns true if it is still good (in case during
+    /// decryption something changed)
+    #[inline(always)]
+    fn mark_did_receive(&mut self, counter: u64) -> Result<(), WireGuardError> {
+        if counter + N_BITS < self.next {
+            // Drop if too far back
+            return Err(WireGuardError::InvalidCounter);
+        }
+        if counter == self.next {
+            // Usually the packets arrive in order, in that case we simply mark the bit and
+            // increment the counter
+            self.set_bit(counter);
+            self.next += 1;
+            return Ok(());
+        }
+        if counter < self.next {
+            // A packet arrived out of order, check if it is valid, and mark
+            if self.check_bit(counter) {
+                return Err(WireGuardError::InvalidCounter);
+            }
+            self.set_bit(counter);
+            return Ok(());
+        }
+        // Packets where dropped, or maybe reordered, skip them and mark unused
+        if counter - self.next >= N_BITS {
+            // Too far ahead, clear all the bits
+            for c in self.bitmap.iter_mut() {
+                *c = 0;
+            }
+        } else {
+            let mut i = self.next;
+            while i % WORD_SIZE != 0 && i < counter {
+                // Clear until i aligned to word size
+                self.clear_bit(i);
+                i += 1;
+            }
+            while i + WORD_SIZE < counter {
+                // Clear whole word at a time
+                self.clear_word(i);
+                i = (i + WORD_SIZE) & 0u64.wrapping_sub(WORD_SIZE);
+            }
+            while i < counter {
+                // Clear any remaining bits
+                self.clear_bit(i);
+                i += 1;
+            }
+        }
+        self.set_bit(counter);
+        self.next = counter + 1;
+        Ok(())
+    }
+}
+
+impl Session {
+    pub(super) fn new(
+        local_index: u32,
+        peer_index: u32,
+        receiving_key: [u8; 32],
+        sending_key: [u8; 32],
+    ) -> Session {
+        Session {
+            receiving_index: local_index,
+            sending_index: peer_index,
+            receiver: LessSafeKey::new(
+                UnboundKey::new(&CHACHA20_POLY1305, &receiving_key).unwrap(),
+            ),
+            sender: LessSafeKey::new(UnboundKey::new(&CHACHA20_POLY1305, &sending_key).unwrap()),
+            sending_key_counter: AtomicUsize::new(0),
+            receiving_key_counter: Mutex::new(Default::default()),
+        }
+    }
+
+    pub(super) fn local_index(&self) -> usize {
+        self.receiving_index as usize
+    }
+
+    /// Returns true if receiving counter is good to use
+    fn receiving_counter_quick_check(&self, counter: u64) -> Result<(), WireGuardError> {
+        let counter_validator = self.receiving_key_counter.lock();
+        counter_validator.will_accept(counter)
+    }
+
+    /// Returns true if receiving counter is good to use, and marks it as used {
+    fn receiving_counter_mark(&self, counter: u64) -> Result<(), WireGuardError> {
+        let mut counter_validator = self.receiving_key_counter.lock();
+        let ret = counter_validator.mark_did_receive(counter);
+        if ret.is_ok() {
+            counter_validator.receive_cnt += 1;
+        }
+        ret
+    }
+
+    /// src - an IP packet from the interface
+    /// dst - pre-allocated space to hold the encapsulating UDP packet to send over the network
+    /// returns the size of the formatted packet
+    pub(super) fn format_packet_data<'a>(&self, src: &[u8], dst: &'a mut [u8]) -> &'a mut [u8] {
+        if dst.len() < src.len() + super::DATA_OVERHEAD_SZ {
+            panic!("The destination buffer is too small");
+        }
+
+        let sending_key_counter = self.sending_key_counter.fetch_add(1, Ordering::Relaxed) as u64;
+
+        let (message_type, rest) = dst.split_at_mut(4);
+        let (receiver_index, rest) = rest.split_at_mut(4);
+        let (counter, data) = rest.split_at_mut(8);
+
+        message_type.copy_from_slice(&super::DATA.to_le_bytes());
+        receiver_index.copy_from_slice(&self.sending_index.to_le_bytes());
+        counter.copy_from_slice(&sending_key_counter.to_le_bytes());
+
+        // TODO: spec requires padding to 16 bytes, but actually works fine without it
+        let n = {
+            let mut nonce = [0u8; 12];
+            nonce[4..12].copy_from_slice(&sending_key_counter.to_le_bytes());
+            data[..src.len()].copy_from_slice(src);
+            self.sender
+                .seal_in_place_separate_tag(
+                    Nonce::assume_unique_for_key(nonce),
+                    Aad::from(&[]),
+                    &mut data[..src.len()],
+                )
+                .map(|tag| {
+                    data[src.len()..src.len() + AEAD_SIZE].copy_from_slice(tag.as_ref());
+                    src.len() + AEAD_SIZE
+                })
+                .unwrap()
+        };
+
+        &mut dst[..DATA_OFFSET + n]
+    }
+
+    /// packet - a data packet we received from the network
+    /// dst - pre-allocated space to hold the encapsulated IP packet, to send to the interface
+    ///       dst will always take less space than src
+    /// return the size of the encapsulated packet on success
+    pub(super) fn receive_packet_data<'a>(
+        &self,
+        packet: PacketData,
+        dst: &'a mut [u8],
+    ) -> Result<&'a mut [u8], WireGuardError> {
+        let ct_len = packet.encrypted_encapsulated_packet.len();
+        if dst.len() < ct_len {
+            // This is a very incorrect use of the library, therefore panic and not error
+            panic!("The destination buffer is too small");
+        }
+        if packet.receiver_idx != self.receiving_index {
+            return Err(WireGuardError::WrongIndex);
+        }
+        // Don't reuse counters, in case this is a replay attack we want to quickly check the counter without running expensive decryption
+        self.receiving_counter_quick_check(packet.counter)?;
+
+        let ret = {
+            let mut nonce = [0u8; 12];
+            nonce[4..12].copy_from_slice(&packet.counter.to_le_bytes());
+            dst[..ct_len].copy_from_slice(packet.encrypted_encapsulated_packet);
+            self.receiver
+                .open_in_place(
+                    Nonce::assume_unique_for_key(nonce),
+                    Aad::from(&[]),
+                    &mut dst[..ct_len],
+                )
+                .map_err(|_| WireGuardError::InvalidAeadTag)?
+        };
+
+        // After decryption is done, check counter again, and mark as received
+        self.receiving_counter_mark(packet.counter)?;
+        Ok(ret)
+    }
+
+    /// Returns the estimated downstream packet loss for this session
+    pub(super) fn current_packet_cnt(&self) -> (u64, u64) {
+        let counter_validator = self.receiving_key_counter.lock();
+        (counter_validator.next, counter_validator.receive_cnt)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn test_replay_counter() {
+        let mut c: ReceivingKeyCounterValidator = Default::default();
+
+        assert!(c.mark_did_receive(0).is_ok());
+        assert!(c.mark_did_receive(0).is_err());
+        assert!(c.mark_did_receive(1).is_ok());
+        assert!(c.mark_did_receive(1).is_err());
+        assert!(c.mark_did_receive(63).is_ok());
+        assert!(c.mark_did_receive(63).is_err());
+        assert!(c.mark_did_receive(15).is_ok());
+        assert!(c.mark_did_receive(15).is_err());
+
+        for i in 64..N_BITS + 128 {
+            assert!(c.mark_did_receive(i).is_ok());
+            assert!(c.mark_did_receive(i).is_err());
+        }
+
+        assert!(c.mark_did_receive(N_BITS * 3).is_ok());
+        for i in 0..=N_BITS * 2 {
+            assert!(matches!(
+                c.will_accept(i),
+                Err(WireGuardError::InvalidCounter)
+            ));
+            assert!(c.mark_did_receive(i).is_err());
+        }
+        for i in N_BITS * 2 + 1..N_BITS * 3 {
+            assert!(c.will_accept(i).is_ok());
+        }
+        assert!(matches!(
+            c.will_accept(N_BITS * 3),
+            Err(WireGuardError::DuplicateCounter)
+        ));
+
+        for i in (N_BITS * 2 + 1..N_BITS * 3).rev() {
+            assert!(c.mark_did_receive(i).is_ok());
+            assert!(c.mark_did_receive(i).is_err());
+        }
+
+        assert!(c.mark_did_receive(N_BITS * 3 + 70).is_ok());
+        assert!(c.mark_did_receive(N_BITS * 3 + 71).is_ok());
+        assert!(c.mark_did_receive(N_BITS * 3 + 72).is_ok());
+        assert!(c.mark_did_receive(N_BITS * 3 + 72 + 125).is_ok());
+        assert!(c.mark_did_receive(N_BITS * 3 + 63).is_ok());
+
+        assert!(c.mark_did_receive(N_BITS * 3 + 70).is_err());
+        assert!(c.mark_did_receive(N_BITS * 3 + 71).is_err());
+        assert!(c.mark_did_receive(N_BITS * 3 + 72).is_err());
+    }
+}

burrow/src/boringtun/src/noise/timers.rs

@@ -0,0 +1,335 @@
+// Copyright (c) 2019 Cloudflare, Inc. All rights reserved.
+// SPDX-License-Identifier: BSD-3-Clause
+
+use super::errors::WireGuardError;
+use crate::noise::{Tunn, TunnResult};
+use std::mem;
+use std::ops::{Index, IndexMut};
+
+use std::time::Duration;
+
+#[cfg(feature = "mock-instant")]
+use mock_instant::Instant;
+
+#[cfg(not(feature = "mock-instant"))]
+use crate::sleepyinstant::Instant;
+
+// Some constants, represent time in seconds
+// https://www.wireguard.com/papers/wireguard.pdf#page=14
+pub(crate) const REKEY_AFTER_TIME: Duration = Duration::from_secs(120);
+const REJECT_AFTER_TIME: Duration = Duration::from_secs(180);
+const REKEY_ATTEMPT_TIME: Duration = Duration::from_secs(90);
+pub(crate) const REKEY_TIMEOUT: Duration = Duration::from_secs(5);
+const KEEPALIVE_TIMEOUT: Duration = Duration::from_secs(10);
+const COOKIE_EXPIRATION_TIME: Duration = Duration::from_secs(120);
+
+#[derive(Debug)]
+pub enum TimerName {
+    /// Current time, updated each call to `update_timers`
+    TimeCurrent,
+    /// Time when last handshake was completed
+    TimeSessionEstablished,
+    /// Time the last attempt for a new handshake began
+    TimeLastHandshakeStarted,
+    /// Time we last received and authenticated a packet
+    TimeLastPacketReceived,
+    /// Time we last send a packet
+    TimeLastPacketSent,
+    /// Time we last received and authenticated a DATA packet
+    TimeLastDataPacketReceived,
+    /// Time we last send a DATA packet
+    TimeLastDataPacketSent,
+    /// Time we last received a cookie
+    TimeCookieReceived,
+    /// Time we last sent persistent keepalive
+    TimePersistentKeepalive,
+    Top,
+}
+
+use self::TimerName::*;
+
+#[derive(Debug)]
+pub struct Timers {
+    /// Is the owner of the timer the initiator or the responder for the last handshake?
+    is_initiator: bool,
+    /// Start time of the tunnel
+    time_started: Instant,
+    timers: [Duration; TimerName::Top as usize],
+    pub(super) session_timers: [Duration; super::N_SESSIONS],
+    /// Did we receive data without sending anything back?
+    want_keepalive: bool,
+    /// Did we send data without hearing back?
+    want_handshake: bool,
+    persistent_keepalive: usize,
+    /// Should this timer call reset rr function (if not a shared rr instance)
+    pub(super) should_reset_rr: bool,
+}
+
+impl Timers {
+    pub(super) fn new(persistent_keepalive: Option<u16>, reset_rr: bool) -> Timers {
+        Timers {
+            is_initiator: false,
+            time_started: Instant::now(),
+            timers: Default::default(),
+            session_timers: Default::default(),
+            want_keepalive: Default::default(),
+            want_handshake: Default::default(),
+            persistent_keepalive: usize::from(persistent_keepalive.unwrap_or(0)),
+            should_reset_rr: reset_rr,
+        }
+    }
+
+    fn is_initiator(&self) -> bool {
+        self.is_initiator
+    }
+
+    // We don't really clear the timers, but we set them to the current time to
+    // so the reference time frame is the same
+    pub(super) fn clear(&mut self) {
+        let now = Instant::now().duration_since(self.time_started);
+        for t in &mut self.timers[..] {
+            *t = now;
+        }
+        self.want_handshake = false;
+        self.want_keepalive = false;
+    }
+}
+
+impl Index<TimerName> for Timers {
+    type Output = Duration;
+    fn index(&self, index: TimerName) -> &Duration {
+        &self.timers[index as usize]
+    }
+}
+
+impl IndexMut<TimerName> for Timers {
+    fn index_mut(&mut self, index: TimerName) -> &mut Duration {
+        &mut self.timers[index as usize]
+    }
+}
+
+impl Tunn {
+    pub(super) fn timer_tick(&mut self, timer_name: TimerName) {
+        match timer_name {
+            TimeLastPacketReceived => {
+                self.timers.want_keepalive = true;
+                self.timers.want_handshake = false;
+            }
+            TimeLastPacketSent => {
+                self.timers.want_handshake = true;
+                self.timers.want_keepalive = false;
+            }
+            _ => {}
+        }
+
+        let time = self.timers[TimeCurrent];
+        self.timers[timer_name] = time;
+    }
+
+    pub(super) fn timer_tick_session_established(
+        &mut self,
+        is_initiator: bool,
+        session_idx: usize,
+    ) {
+        self.timer_tick(TimeSessionEstablished);
+        self.timers.session_timers[session_idx % crate::noise::N_SESSIONS] =
+            self.timers[TimeCurrent];
+        self.timers.is_initiator = is_initiator;
+    }
+
+    // We don't really clear the timers, but we set them to the current time to
+    // so the reference time frame is the same
+    fn clear_all(&mut self) {
+        for session in &mut self.sessions {
+            *session = None;
+        }
+
+        self.packet_queue.clear();
+
+        self.timers.clear();
+    }
+
+    fn update_session_timers(&mut self, time_now: Duration) {
+        let timers = &mut self.timers;
+
+        for (i, t) in timers.session_timers.iter_mut().enumerate() {
+            if time_now - *t > REJECT_AFTER_TIME {
+                if let Some(session) = self.sessions[i].take() {
+                    tracing::debug!(
+                        message = "SESSION_EXPIRED(REJECT_AFTER_TIME)",
+                        session = session.receiving_index
+                    );
+                }
+                *t = time_now;
+            }
+        }
+    }
+
+    pub fn update_timers<'a>(&mut self, dst: &'a mut [u8]) -> TunnResult<'a> {
+        let mut handshake_initiation_required = false;
+        let mut keepalive_required = false;
+
+        let time = Instant::now();
+
+        if self.timers.should_reset_rr {
+            self.rate_limiter.reset_count();
+        }
+
+        // All the times are counted from tunnel initiation, for efficiency our timers are rounded
+        // to a second, as there is no real benefit to having highly accurate timers.
+        let now = time.duration_since(self.timers.time_started);
+        self.timers[TimeCurrent] = now;
+
+        self.update_session_timers(now);
+
+        // Load timers only once:
+        let session_established = self.timers[TimeSessionEstablished];
+        let handshake_started = self.timers[TimeLastHandshakeStarted];
+        let aut_packet_received = self.timers[TimeLastPacketReceived];
+        let aut_packet_sent = self.timers[TimeLastPacketSent];
+        let data_packet_received = self.timers[TimeLastDataPacketReceived];
+        let data_packet_sent = self.timers[TimeLastDataPacketSent];
+        let persistent_keepalive = self.timers.persistent_keepalive;
+
+        {
+            if self.handshake.is_expired() {
+                return TunnResult::Err(WireGuardError::ConnectionExpired);
+            }
+
+            // Clear cookie after COOKIE_EXPIRATION_TIME
+            if self.handshake.has_cookie()
+                && now - self.timers[TimeCookieReceived] >= COOKIE_EXPIRATION_TIME
+            {
+                self.handshake.clear_cookie();
+            }
+
+            // All ephemeral private keys and symmetric session keys are zeroed out after
+            // (REJECT_AFTER_TIME * 3) ms if no new keys have been exchanged.
+            if now - session_established >= REJECT_AFTER_TIME * 3 {
+                tracing::error!("CONNECTION_EXPIRED(REJECT_AFTER_TIME * 3)");
+                self.handshake.set_expired();
+                self.clear_all();
+                return TunnResult::Err(WireGuardError::ConnectionExpired);
+            }
+
+            if let Some(time_init_sent) = self.handshake.timer() {
+                // Handshake Initiation Retransmission
+                if now - handshake_started >= REKEY_ATTEMPT_TIME {
+                    // After REKEY_ATTEMPT_TIME ms of trying to initiate a new handshake,
+                    // the retries give up and cease, and clear all existing packets queued
+                    // up to be sent. If a packet is explicitly queued up to be sent, then
+                    // this timer is reset.
+                    tracing::error!("CONNECTION_EXPIRED(REKEY_ATTEMPT_TIME)");
+                    self.handshake.set_expired();
+                    self.clear_all();
+                    return TunnResult::Err(WireGuardError::ConnectionExpired);
+                }
+
+                if time_init_sent.elapsed() >= REKEY_TIMEOUT {
+                    // We avoid using `time` here, because it can be earlier than `time_init_sent`.
+                    // Once `checked_duration_since` is stable we can use that.
+                    // A handshake initiation is retried after REKEY_TIMEOUT + jitter ms,
+                    // if a response has not been received, where jitter is some random
+                    // value between 0 and 333 ms.
+                    tracing::warn!("HANDSHAKE(REKEY_TIMEOUT)");
+                    handshake_initiation_required = true;
+                }
+            } else {
+                if self.timers.is_initiator() {
+                    // After sending a packet, if the sender was the original initiator
+                    // of the handshake and if the current session key is REKEY_AFTER_TIME
+                    // ms old, we initiate a new handshake. If the sender was the original
+                    // responder of the handshake, it does not re-initiate a new handshake
+                    // after REKEY_AFTER_TIME ms like the original initiator does.
+                    if session_established < data_packet_sent
+                        && now - session_established >= REKEY_AFTER_TIME
+                    {
+                        tracing::debug!("HANDSHAKE(REKEY_AFTER_TIME (on send))");
+                        handshake_initiation_required = true;
+                    }
+
+                    // After receiving a packet, if the receiver was the original initiator
+                    // of the handshake and if the current session key is REJECT_AFTER_TIME
+                    // - KEEPALIVE_TIMEOUT - REKEY_TIMEOUT ms old, we initiate a new
+                    // handshake.
+                    if session_established < data_packet_received
+                        && now - session_established
+                            >= REJECT_AFTER_TIME - KEEPALIVE_TIMEOUT - REKEY_TIMEOUT
+                    {
+                        tracing::warn!(
+                            "HANDSHAKE(REJECT_AFTER_TIME - KEEPALIVE_TIMEOUT - \
+                        REKEY_TIMEOUT \
+                        (on receive))"
+                        );
+                        handshake_initiation_required = true;
+                    }
+                }
+
+                // If we have sent a packet to a given peer but have not received a
+                // packet after from that peer for (KEEPALIVE + REKEY_TIMEOUT) ms,
+                // we initiate a new handshake.
+                if data_packet_sent > aut_packet_received
+                    && now - aut_packet_received >= KEEPALIVE_TIMEOUT + REKEY_TIMEOUT
+                    && mem::replace(&mut self.timers.want_handshake, false)
+                {
+                    tracing::warn!("HANDSHAKE(KEEPALIVE + REKEY_TIMEOUT)");
+                    handshake_initiation_required = true;
+                }
+
+                if !handshake_initiation_required {
+                    // If a packet has been received from a given peer, but we have not sent one back
+                    // to the given peer in KEEPALIVE ms, we send an empty packet.
+                    if data_packet_received > aut_packet_sent
+                        && now - aut_packet_sent >= KEEPALIVE_TIMEOUT
+                        && mem::replace(&mut self.timers.want_keepalive, false)
+                    {
+                        tracing::debug!("KEEPALIVE(KEEPALIVE_TIMEOUT)");
+                        keepalive_required = true;
+                    }
+
+                    // Persistent KEEPALIVE
+                    if persistent_keepalive > 0
+                        && (now - self.timers[TimePersistentKeepalive]
+                            >= Duration::from_secs(persistent_keepalive as _))
+                    {
+                        tracing::debug!("KEEPALIVE(PERSISTENT_KEEPALIVE)");
+                        self.timer_tick(TimePersistentKeepalive);
+                        keepalive_required = true;
+                    }
+                }
+            }
+        }
+
+        if handshake_initiation_required {
+            return self.format_handshake_initiation(dst, true);
+        }
+
+        if keepalive_required {
+            return self.encapsulate(&[], dst);
+        }
+
+        TunnResult::Done
+    }
+
+    pub fn time_since_last_handshake(&self) -> Option<Duration> {
+        let current_session = self.current;
+        if self.sessions[current_session % super::N_SESSIONS].is_some() {
+            let duration_since_tun_start = Instant::now().duration_since(self.timers.time_started);
+            let duration_since_session_established = self.timers[TimeSessionEstablished];
+
+            Some(duration_since_tun_start - duration_since_session_established)
+        } else {
+            None
+        }
+    }
+
+    pub fn persistent_keepalive(&self) -> Option<u16> {
+        let keepalive = self.timers.persistent_keepalive;
+
+        if keepalive > 0 {
+            Some(keepalive as u16)
+        } else {
+            None
+        }
+    }
+}

burrow/src/boringtun/src/serialization.rs

@@ -0,0 +1,33 @@
+pub(crate) struct KeyBytes(pub [u8; 32]);
+
+impl std::str::FromStr for KeyBytes {
+    type Err = &'static str;
+
+    /// Can parse a secret key from a hex or base64 encoded string.
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        let mut internal = [0u8; 32];
+
+        match s.len() {
+            64 => {
+                // Try to parse as hex
+                for i in 0..32 {
+                    internal[i] = u8::from_str_radix(&s[i * 2..=i * 2 + 1], 16)
+                        .map_err(|_| "Illegal character in key")?;
+                }
+            }
+            43 | 44 => {
+                // Try to parse as base64
+                if let Ok(decoded_key) = base64::decode(s) {
+                    if decoded_key.len() == internal.len() {
+                        internal[..].copy_from_slice(&decoded_key);
+                    } else {
+                        return Err("Illegal character in key");
+                    }
+                }
+            }
+            _ => return Err("Illegal key size"),
+        }
+
+        Ok(KeyBytes(internal))
+    }
+}

burrow/src/daemon/command.rs

@@ -0,0 +1,13 @@
+use serde::{Deserialize, Serialize};
+use tun::TunOptions;
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub enum DaemonCommand {
+    Start(DaemonStartOptions),
+    Stop,
+}
+
+#[derive(Debug, Clone, Default, Serialize, Deserialize)]
+pub struct DaemonStartOptions {
+    pub(super) tun: TunOptions,
+}

burrow/src/daemon/instance.rs

@@ -0,0 +1,40 @@
+use super::*;
+
+pub struct DaemonInstance {
+    rx: mpsc::Receiver<DaemonCommand>,
+    tun_interface: Option<TunInterface>,
+}
+
+impl DaemonInstance {
+    pub fn new(rx: mpsc::Receiver<DaemonCommand>) -> Self {
+        Self {
+            rx,
+            tun_interface: None,
+        }
+    }
+
+    pub async fn run(&mut self) -> Result<()> {
+        while let Some(command) = self.rx.recv().await {
+            match command {
+                DaemonCommand::Start(options) => {
+                    if self.tun_interface.is_none() {
+                        self.tun_interface = Some(options.tun.open()?);
+                        eprintln!("Daemon starting tun interface.");
+                    } else {
+                        eprintln!("Got start, but tun interface already up.");
+                    }
+                }
+                DaemonCommand::Stop => {
+                    if self.tun_interface.is_some() {
+                        self.tun_interface = None;
+                        eprintln!("Daemon stopping tun interface.");
+                    } else {
+                        eprintln!("Got stop, but tun interface is not up.")
+                    }
+                }
+            }
+        }
+
+        Ok(())
+    }
+}

burrow/src/daemon/mod.rs

@@ -0,0 +1,19 @@
+use super::*;
+use tokio::sync::mpsc;
+
+mod command;
+mod instance;
+mod net;
+
+use instance::DaemonInstance;
+use net::listen;
+
+pub use command::{DaemonCommand, DaemonStartOptions};
+pub use net::DaemonClient;
+
+pub async fn daemon_main() -> Result<()> {
+    let (tx, rx) = mpsc::channel(2);
+    let mut inst = DaemonInstance::new(rx);
+
+    tokio::try_join!(inst.run(), listen(tx)).map(|_| ())
+}

burrow/src/daemon/net/mod.rs

@@ -0,0 +1,29 @@
+use super::*;
+use serde::{Deserialize, Serialize};
+
+#[cfg(target_family = "unix")]
+mod unix;
+#[cfg(all(target_family = "unix", not(target_os = "linux")))]
+pub use unix::{listen, DaemonClient};
+
+#[cfg(target_os = "linux")]
+mod systemd;
+#[cfg(target_os = "linux")]
+pub use systemd::{listen, DaemonClient};
+
+#[cfg(target_os = "windows")]
+mod windows;
+#[cfg(target_os = "windows")]
+pub use windows::{listen, DaemonClient};
+
+#[derive(Clone, Serialize, Deserialize)]
+pub struct DaemonRequest {
+    pub id: u32,
+    pub command: DaemonCommand,
+}
+
+#[derive(Clone, Serialize, Deserialize)]
+pub struct DaemonResponse {
+    //  Error types can't be serialized, so this is the second best option.
+    result: std::result::Result<(), String>,
+}

burrow/src/daemon/net/systemd.rs

@@ -0,0 +1,16 @@
+use super::*;
+use std::os::fd::IntoRawFd;
+
+pub async fn listen(cmd_tx: mpsc::Sender<DaemonCommand>) -> Result<()> {
+    if !libsystemd::daemon::booted() || listen_with_systemd(cmd_tx.clone()).await.is_err() {
+        unix::listen(cmd_tx).await?;
+    }
+    Ok(())
+}
+
+async fn listen_with_systemd(cmd_tx: mpsc::Sender<DaemonCommand>) -> Result<()> {
+    let fds = libsystemd::activation::receive_descriptors(false).unwrap();
+    super::unix::listen_with_optional_fd(cmd_tx, Some(fds[0].clone().into_raw_fd())).await
+}
+
+pub type DaemonClient = unix::DaemonClient;

burrow/src/daemon/net/unix.rs

@@ -0,0 +1,102 @@
+use super::*;
+use std::{
+    os::fd::{FromRawFd, RawFd},
+    os::unix::net::UnixListener as StdUnixListener,
+    path::Path,
+};
+use tokio::{
+    io::{AsyncBufReadExt, AsyncWriteExt, BufReader},
+    net::{UnixListener, UnixStream},
+};
+
+const UNIX_SOCKET_PATH: &str = "/run/burrow.sock";
+
+pub async fn listen(cmd_tx: mpsc::Sender<DaemonCommand>) -> Result<()> {
+    listen_with_optional_fd(cmd_tx, None).await
+}
+
+pub(crate) async fn listen_with_optional_fd(
+    cmd_tx: mpsc::Sender<DaemonCommand>,
+    raw_fd: Option<RawFd>,
+) -> Result<()> {
+    let path = Path::new(UNIX_SOCKET_PATH);
+
+    let listener = if let Some(raw_fd) = raw_fd {
+        let listener = unsafe { StdUnixListener::from_raw_fd(raw_fd) };
+        listener.set_nonblocking(true)?;
+        UnixListener::from_std(listener)
+    } else {
+        UnixListener::bind(path)
+    };
+    let listener = if let Ok(listener) = listener {
+        listener
+    } else {
+        //  Won't help all that much, if we use the async version of fs.
+        std::fs::remove_file(path)?;
+        UnixListener::bind(path)?
+    };
+    loop {
+        let (stream, _) = listener.accept().await?;
+        let cmd_tx = cmd_tx.clone();
+
+        //  I'm pretty sure we won't need to manually join / shut this down,
+        //  `lines` will return Err during dropping, and this task should exit gracefully.
+        tokio::task::spawn(async {
+            let cmd_tx = cmd_tx;
+            let mut stream = stream;
+            let (mut read_stream, mut write_stream) = stream.split();
+            let buf_reader = BufReader::new(&mut read_stream);
+            let mut lines = buf_reader.lines();
+            while let Ok(Some(line)) = lines.next_line().await {
+                let mut res = DaemonResponse { result: Ok(()) };
+                let command = match serde_json::from_str::<DaemonRequest>(&line) {
+                    Ok(req) => Some(req.command),
+                    Err(e) => {
+                        res.result = Err(format!("{}", e));
+                        None
+                    }
+                };
+                let mut res = serde_json::to_string(&res).unwrap();
+                res.push('\n');
+
+                write_stream.write_all(res.as_bytes()).await.unwrap();
+
+                //  I want this to come at the very end so that we always send a reponse back.
+                if let Some(command) = command {
+                    cmd_tx.send(command).await.unwrap();
+                }
+            }
+        });
+    }
+}
+
+pub struct DaemonClient {
+    connection: UnixStream,
+}
+
+impl DaemonClient {
+    pub async fn new() -> Result<Self> {
+        Self::new_with_path(UNIX_SOCKET_PATH).await
+    }
+
+    pub async fn new_with_path(path: &str) -> Result<Self> {
+        let path = Path::new(path);
+        let connection = UnixStream::connect(path).await?;
+
+        Ok(Self { connection })
+    }
+
+    pub async fn send_command(&mut self, command: DaemonCommand) -> Result<()> {
+        let mut command = serde_json::to_string(&DaemonRequest { id: 0, command })?;
+        command.push('\n');
+
+        self.connection.write_all(command.as_bytes()).await?;
+        let buf_reader = BufReader::new(&mut self.connection);
+        let mut lines = buf_reader.lines();
+        //  This unwrap *should* never cause issues.
+        let response = lines.next_line().await?.unwrap();
+        let res: DaemonResponse = serde_json::from_str(&response)?;
+        res.result.unwrap();
+        Ok(())
+    }
+}

burrow/src/daemon/net/windows.rs

@@ -0,0 +1,17 @@
+use super::*;
+
+pub async fn listen(_: mpsc::Sender<DaemonCommand>) -> Result<()> {
+    unimplemented!("This platform does not currently support daemon mode.")
+}
+
+pub struct DaemonClient;
+
+impl DaemonClient {
+    pub async fn new() -> Result<Self> {
+        unimplemented!("This platform does not currently support daemon mode.")
+    }
+
+    pub async fn send_command(&mut self, _: DaemonCommand) -> Result<()> {
+        unimplemented!("This platform does not currently support daemon mode.")
+    }
+}

burrow/src/ensureroot.rs

@@ -1,5 +1,8 @@
+use tracing::instrument;
+
 // Check capabilities on Linux
 #[cfg(target_os = "linux")]
+#[instrument]
 pub fn ensure_root() {
     use caps::{has_cap, CapSet, Capability};
 
@@ -19,6 +22,7 @@ pub fn ensure_root() {
 
 // Check for root user on macOS
 #[cfg(target_vendor = "apple")]
+#[instrument]
 pub fn ensure_root() {
     use nix::unistd::Uid;
 
@@ -30,6 +34,7 @@ pub fn ensure_root() {
 }
 
 #[cfg(target_family = "windows")]
+#[instrument]
 pub fn ensure_root() {
     todo!()
 }

burrow/src/lib.rs

@@ -1 +1,33 @@
+#![deny(missing_debug_implementations)]
 pub mod ensureroot;
+
+#[cfg(any(target_os = "linux", target_vendor = "apple"))]
+use std::{
+    mem,
+    os::fd::{AsRawFd, FromRawFd},
+};
+
+use tun::TunInterface;
+
+// TODO Separate start and retrieve functions
+
+#[cfg(any(target_os = "linux", target_vendor = "apple"))]
+#[no_mangle]
+pub extern "C" fn retrieve() -> i32 {
+    let iface2 = (1..100)
+        .filter_map(|i| {
+            let iface = unsafe { TunInterface::from_raw_fd(i) };
+            match iface.name() {
+                Ok(_name) => Some(iface),
+                Err(_) => {
+                    mem::forget(iface);
+                    None
+                }
+            }
+        })
+        .next();
+    match iface2 {
+        Some(iface) => iface.as_raw_fd(),
+        None => -1,
+    }
+}

burrow/src/main.rs

@@ -1,7 +1,23 @@
+use anyhow::Context;
+use std::mem;
+#[cfg(any(target_os = "linux", target_vendor = "apple"))]
+use std::os::fd::FromRawFd;
+
 use clap::{Args, Parser, Subcommand};
+use tracing::instrument;
+
+use tracing_log::LogTracer;
+use tracing_oslog::OsLogger;
+use tracing_subscriber::{prelude::*, FmtSubscriber};
 use tokio::io::Result;
+#[cfg(any(target_os = "linux", target_vendor = "apple"))]
+use burrow::retrieve;
 use tun::TunInterface;
 
+mod daemon;
+
+use daemon::{DaemonClient, DaemonCommand, DaemonStartOptions};
+
 #[derive(Parser)]
 #[command(name = "Burrow")]
 #[command(author = "Hack Club <team@hackclub.com>")]
@@ -22,28 +38,108 @@ struct Cli {
 enum Commands {
     /// Start Burrow
     Start(StartArgs),
+    /// Retrieve the file descriptor of the tun interface
+    Retrieve(RetrieveArgs),
+    /// Stop Burrow daemon
+    Stop,
+    /// Start Burrow daemon
+    Daemon(DaemonArgs),
 }
 
 #[derive(Args)]
 struct StartArgs {}
 
-async fn try_main() -> Result<()> {
+#[derive(Args)]
+struct RetrieveArgs {}
+
+#[derive(Args)]
+struct DaemonArgs {}
+
+#[cfg(any(target_os = "linux", target_vendor = "apple"))]
+async fn try_start() -> Result<()> {
+    let mut client = DaemonClient::new().await?;
+    client
+        .send_command(DaemonCommand::Start(DaemonStartOptions::default()))
+        .await
+}
+
+#[cfg(any(target_os = "linux", target_vendor = "apple"))]
+#[instrument]
+async fn try_retrieve() -> Result<()> {
+    LogTracer::init().context("Failed to initialize LogTracer").unwrap();
+
+    if cfg!(target_os = "linux") || cfg!(target_vendor = "apple") {
+        let maybe_layer = system_log().unwrap();
+        if let Some(layer) = maybe_layer {
+            let logger = layer.with_subscriber(FmtSubscriber::new());
+            tracing::subscriber::set_global_default(logger).context("Failed to set the global tracing subscriber").unwrap();
+        }
+    }
+
     burrow::ensureroot::ensure_root();
+    let iface2 = retrieve();
+    tracing::info!("{}", iface2);
+    Ok(())
+}
 
-    let iface = TunInterface::new()?;
-    println!("{:?}", iface.name());
+#[cfg(any(target_os = "linux", target_vendor = "apple"))]
+async fn try_stop() -> Result<()> {
+    let mut client = DaemonClient::new().await?;
+    client.send_command(DaemonCommand::Stop).await?;
+    Ok(())
+}
 
+#[cfg(not(any(target_os = "linux", target_vendor = "apple")))]
+async fn try_start() -> Result<()> {
+    Ok(())
+}
+
+#[cfg(not(any(target_os = "linux", target_vendor = "apple")))]
+async fn try_retrieve() -> Result<()> {
+    Ok(())
+}
+
+#[cfg(not(any(target_os = "linux", target_vendor = "apple")))]
+async fn try_stop() -> Result<()> {
     Ok(())
 }
 
 #[tokio::main(flavor = "current_thread")]
-async fn main() {
-    println!("Platform: {}", std::env::consts::OS);
+async fn main() -> Result<()> {
+    tracing::info!("Platform: {}", std::env::consts::OS);
 
     let cli = Cli::parse();
     match &cli.command {
         Commands::Start(..) => {
-            try_main().await.unwrap();
+            try_start().await.unwrap();
+            tracing::info!("FINISHED");
+        }
+        Commands::Retrieve(..) => {
+            try_retrieve().await.unwrap();
+            tracing::info!("FINISHED");
+        }
+        Commands::Stop => {
+            try_stop().await.unwrap();
+        }
+        Commands::Daemon(_) => daemon::daemon_main().await?,
+    }
+
+    Ok(())
+}
+
+#[cfg(target_os = "linux")]
+fn system_log() -> anyhow::Result<Option<tracing_journald::Layer>> {
+    let maybe_journald = tracing_journald::layer();
+    match maybe_journald {
+        Err(e) if e.kind() == std::io::ErrorKind::NotFound => {
+            tracing::trace!("journald not found");
+            Ok(None)
+        },
+        _ => Ok(Some(maybe_journald?))
     }
 }
+
+#[cfg(target_vendor = "apple")]
+fn system_log() -> anyhow::Result<Option<OsLogger>> {
+    Ok(Some(OsLogger::new("com.hackclub.burrow", "default")))
 }

systemd/burrow.service

@@ -0,0 +1,9 @@
+[Unit]
+Description=Burrow
+After=burrow.socket
+
+[Service]
+ExecStart=/usr/local/bin/burrow daemon
+
+[Install]
+WantedBy=multi-user.target

systemd/burrow.socket

@@ -0,0 +1,8 @@
+[Unit]
+Description=Burrow Socket
+
+[Socket]
+ListenStream=/run/burrow.sock
+
+[Install]
+WantedBy=sockets.target

tun/Cargo.toml

@@ -10,11 +10,14 @@ nix = { version = "0.26", features = ["ioctl"] }
 socket2 = "0.4"
 tokio = { version = "1.28", features = [] }
 byteorder = "1.4"
+tracing = "0.1"
 log = "0.4"
+serde = { version = "1", features = ["derive"], optional = true }
 
 futures = { version = "0.3.28", optional = true }
 
 [features]
+serde = ["dep:serde"]
 tokio = ["tokio/net", "dep:futures"]
 
 [target.'cfg(feature = "tokio")'.dev-dependencies]

tun/src/lib.rs

@@ -1,3 +1,5 @@
+#![deny(missing_debug_implementations)]
+
 #[cfg(target_os = "windows")]
 #[path = "windows/mod.rs"]
 mod imp;

tun/src/options.rs

@@ -3,7 +3,8 @@ use std::io::Error;
 
 use super::TunInterface;
 
-#[derive(Default)]
+#[derive(Debug, Clone, Default)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 pub struct TunOptions {
     /// (Windows + Linux) Name the tun interface.
     pub(crate) name: Option<String>,

tun/src/tokio/mod.rs

@@ -1,17 +1,21 @@
 use std::io;
 use tokio::io::unix::AsyncFd;
+use tracing::instrument;
 
+#[derive(Debug)]
 pub struct TunInterface {
     inner: AsyncFd<crate::TunInterface>,
 }
 
 impl TunInterface {
+    #[instrument]
     pub fn new(tun: crate::TunInterface) -> io::Result<Self> {
         Ok(Self {
             inner: AsyncFd::new(tun)?,
         })
     }
 
+    #[instrument]
     pub async fn write(&self, buf: &[u8]) -> io::Result<usize> {
         loop {
             let mut guard = self.inner.writable().await?;
@@ -22,6 +26,7 @@ impl TunInterface {
         }
     }
 
+    #[instrument]
     pub async fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
         loop {
             let mut guard = self.inner.readable_mut().await?;
@@ -32,27 +37,3 @@ impl TunInterface {
         }
     }
 }
-
-#[cfg(test)]
-mod tests {
-    use std::net::Ipv4Addr;
-
-    use super::*;
-    #[tokio::test]
-    async fn test_create() {
-        let tun = crate::TunInterface::new().unwrap();
-        let _async_tun = TunInterface::new(tun).unwrap();
-    }
-
-    #[tokio::test]
-    async fn test_write() {
-        let tun = crate::TunInterface::new().unwrap();
-        tun.set_ipv4_addr(Ipv4Addr::from([192, 168, 1, 10]))
-            .unwrap();
-        let async_tun = TunInterface::new(tun).unwrap();
-        let mut buf = [0u8; 1500];
-        buf[0] = 6 << 4;
-        let bytes_written = async_tun.write(&buf).await.unwrap();
-        assert!(bytes_written > 0);
-    }
-}

tun/src/unix/apple/mod.rs

@@ -1,12 +1,13 @@
 use byteorder::{ByteOrder, NetworkEndian};
 use fehler::throws;
 use libc::{c_char, iovec, writev, AF_INET, AF_INET6};
-use log::info;
+use tracing::info;
 use socket2::{Domain, SockAddr, Socket, Type};
 use std::io::IoSlice;
 use std::net::{Ipv4Addr, SocketAddrV4};
 use std::os::fd::{AsRawFd, RawFd};
 use std::{io::Error, mem};
+use tracing::instrument;
 
 mod kern_control;
 mod sys;
@@ -23,16 +24,19 @@ pub struct TunInterface {
 
 impl TunInterface {
     #[throws]
+    #[instrument]
     pub fn new() -> TunInterface {
         Self::new_with_options(TunOptions::new())?
     }
 
     #[throws]
+    #[instrument]
     pub fn new_with_options(_: TunOptions) -> TunInterface {
         TunInterface::connect(0)?
     }
 
     #[throws]
+    #[instrument]
     fn connect(index: u32) -> TunInterface {
         use socket2::{Domain, Protocol, Socket, Type};
 
@@ -48,6 +52,7 @@ impl TunInterface {
     }
 
     #[throws]
+    #[instrument]
     pub fn name(&self) -> String {
         let mut buf = [0 as c_char; sys::IFNAMSIZ];
         let mut len = buf.len() as sys::socklen_t;
@@ -62,6 +67,7 @@ impl TunInterface {
     }
 
     #[throws]
+    #[instrument]
     fn ifreq(&self) -> sys::ifreq {
         let mut iff: sys::ifreq = unsafe { mem::zeroed() };
         iff.ifr_name = string_to_ifname(&self.name()?);
@@ -69,6 +75,7 @@ impl TunInterface {
     }
 
     #[throws]
+    #[instrument]
     pub fn set_ipv4_addr(&self, addr: Ipv4Addr) {
         let addr = SockAddr::from(SocketAddrV4::new(addr, 0));
         let mut iff = self.ifreq()?;
@@ -78,6 +85,7 @@ impl TunInterface {
     }
 
     #[throws]
+    #[instrument]
     pub fn ipv4_addr(&self) -> Ipv4Addr {
         let mut iff = self.ifreq()?;
         self.perform(|fd| unsafe { sys::if_get_addr(fd, &mut iff) })?;
@@ -87,11 +95,15 @@ impl TunInterface {
 
     #[throws]
     fn perform<R>(&self, perform: impl FnOnce(RawFd) -> Result<R, nix::Error>) -> R {
+        let span = tracing::info_span!("perform", fd = self.as_raw_fd());
+        let _enter = span.enter();
+
         let socket = Socket::new(Domain::IPV4, Type::DGRAM, None)?;
         perform(socket.as_raw_fd())?
     }
 
     #[throws]
+    #[instrument]
     pub fn mtu(&self) -> i32 {
         let mut iff = self.ifreq()?;
         self.perform(|fd| unsafe { sys::if_get_mtu(fd, &mut iff) })?;
@@ -101,6 +113,7 @@ impl TunInterface {
     }
 
     #[throws]
+    #[instrument]
     pub fn set_mtu(&self, mtu: i32) {
         let mut iff = self.ifreq()?;
         iff.ifr_ifru.ifru_mtu = mtu;
@@ -109,6 +122,7 @@ impl TunInterface {
     }
 
     #[throws]
+    #[instrument]
     pub fn netmask(&self) -> Ipv4Addr {
         let mut iff = self.ifreq()?;
         self.perform(|fd| unsafe { sys::if_get_netmask(fd, &mut iff) })?;
@@ -120,6 +134,7 @@ impl TunInterface {
     }
 
     #[throws]
+    #[instrument]
     pub fn set_netmask(&self, addr: Ipv4Addr) {
         let addr = SockAddr::from(SocketAddrV4::new(addr, 0));
         let mut iff = self.ifreq()?;
@@ -133,6 +148,7 @@ impl TunInterface {
     }
 
     #[throws]
+    #[instrument]
     pub fn send(&self, buf: &[u8]) -> usize {
         use std::io::ErrorKind;
         let proto = match buf[0] >> 4 {
@@ -156,32 +172,3 @@ impl TunInterface {
             .map_err(|_| Error::new(ErrorKind::Other, "Conversion error"))?
     }
 }
-
-#[cfg(test)]
-mod test {
-    use super::*;
-    use std::net::Ipv4Addr;
-
-    #[test]
-    fn mtu() {
-        let interf = TunInterface::new().unwrap();
-
-        interf.set_mtu(500).unwrap();
-
-        assert_eq!(interf.mtu().unwrap(), 500);
-    }
-
-    #[test]
-    #[throws]
-    fn netmask() {
-        let interf = TunInterface::new()?;
-
-        let netmask = Ipv4Addr::new(255, 0, 0, 0);
-        let addr = Ipv4Addr::new(192, 168, 1, 1);
-
-        interf.set_ipv4_addr(addr)?;
-        interf.set_netmask(netmask)?;
-
-        assert_eq!(interf.netmask()?, netmask);
-    }
-}

tun/src/unix/linux/mod.rs

@@ -8,7 +8,7 @@ use std::net::{Ipv4Addr, Ipv6Addr, SocketAddrV4};
 use std::os::fd::RawFd;
 use std::os::unix::io::{AsRawFd, FromRawFd, IntoRawFd};
 
-use log::info;
+use tracing::{info, instrument};
 
 use libc::in6_ifreq;
 
@@ -23,11 +23,13 @@ pub struct TunInterface {
 
 impl TunInterface {
     #[throws]
+    #[instrument]
     pub fn new() -> TunInterface {
         Self::new_with_options(TunOptions::new())?
     }
 
     #[throws]
+    #[instrument]
     pub(crate) fn new_with_options(options: TunOptions) -> TunInterface {
         let file = OpenOptions::new()
             .read(true)
@@ -59,6 +61,7 @@ impl TunInterface {
     }
 
     #[throws]
+    #[instrument]
     pub fn name(&self) -> String {
         let mut iff = unsafe { mem::zeroed() };
         unsafe { sys::tun_get_iff(self.socket.as_raw_fd(), &mut iff)? };
@@ -66,6 +69,7 @@ impl TunInterface {
     }
 
     #[throws]
+    #[instrument]
     fn ifreq(&self) -> sys::ifreq {
         let mut iff: sys::ifreq = unsafe { mem::zeroed() };
         iff.ifr_name = string_to_ifname(&self.name()?);
@@ -73,6 +77,7 @@ impl TunInterface {
     }
 
     #[throws]
+    #[instrument]
     fn in6_ifreq(&self) -> in6_ifreq {
         let mut iff: in6_ifreq = unsafe { mem::zeroed() };
         iff.ifr6_ifindex = self.index()?;
@@ -80,6 +85,7 @@ impl TunInterface {
     }
 
     #[throws]
+    #[instrument]
     pub fn index(&self) -> i32 {
         let mut iff = self.ifreq()?;
         self.perform(|fd| unsafe { sys::if_get_index(fd, &mut iff) })?;
@@ -87,6 +93,7 @@ impl TunInterface {
     }
 
     #[throws]
+    #[instrument]
     pub fn set_ipv4_addr(&self, addr: Ipv4Addr) {
         let addr = SockAddr::from(SocketAddrV4::new(addr, 0));
         let mut iff = self.ifreq()?;
@@ -96,6 +103,7 @@ impl TunInterface {
     }
 
     #[throws]
+    #[instrument]
     pub fn ipv4_addr(&self) -> Ipv4Addr {
         let mut iff = self.ifreq()?;
         self.perform(|fd| unsafe { sys::if_get_addr(fd, &mut iff) })?;
@@ -104,6 +112,31 @@ impl TunInterface {
     }
 
     #[throws]
+    #[instrument]
+    pub fn set_broadcast_addr(&self, addr: Ipv4Addr) {
+        let addr = SockAddr::from(SocketAddrV4::new(addr, 0));
+        let mut iff = self.ifreq()?;
+        iff.ifr_ifru.ifru_broadaddr = unsafe { *addr.as_ptr() };
+        self.perform(|fd| unsafe { sys::if_set_brdaddr(fd, &iff) })?;
+        info!(
+            "broadcast_addr_set: {:?} (fd: {:?})",
+            addr,
+            self.as_raw_fd()
+        )
+    }
+
+    #[throws]
+    #[instrument]
+    pub fn broadcast_addr(&self) -> Ipv4Addr {
+        let mut iff = self.ifreq()?;
+        self.perform(|fd| unsafe { sys::if_get_brdaddr(fd, &mut iff) })?;
+        let addr =
+            unsafe { *(&iff.ifr_ifru.ifru_broadaddr as *const _ as *const sys::sockaddr_in) };
+        Ipv4Addr::from(u32::from_be(addr.sin_addr.s_addr))
+    }
+
+    #[throws]
+    #[instrument]
     pub fn set_ipv6_addr(&self, addr: Ipv6Addr) {
         let mut iff = self.in6_ifreq()?;
         iff.ifr6_addr.s6_addr = addr.octets();
@@ -112,6 +145,7 @@ impl TunInterface {
     }
 
     #[throws]
+    #[instrument]
     pub fn set_mtu(&self, mtu: i32) {
         let mut iff = self.ifreq()?;
         iff.ifr_ifru.ifru_mtu = mtu;
@@ -120,6 +154,7 @@ impl TunInterface {
     }
 
     #[throws]
+    #[instrument]
     pub fn mtu(&self) -> i32 {
         let mut iff = self.ifreq()?;
         self.perform(|fd| unsafe { sys::if_get_mtu(fd, &mut iff) })?;
@@ -129,6 +164,7 @@ impl TunInterface {
     }
 
     #[throws]
+    #[instrument]
     pub fn set_netmask(&self, addr: Ipv4Addr) {
         let addr = SockAddr::from(SocketAddrV4::new(addr, 0));
 
@@ -145,6 +181,7 @@ impl TunInterface {
     }
 
     #[throws]
+    #[instrument]
     pub fn netmask(&self) -> Ipv4Addr {
         let mut iff = self.ifreq()?;
         self.perform(|fd| unsafe { sys::if_get_netmask(fd, &mut iff) })?;
@@ -157,47 +194,25 @@ impl TunInterface {
 
     #[throws]
     fn perform<R>(&self, perform: impl FnOnce(RawFd) -> Result<R, nix::Error>) -> R {
+        let span = tracing::info_span!("perform");
+        let _enter = span.enter();
+
         let socket = Socket::new(Domain::IPV4, Type::DGRAM, None)?;
         perform(socket.as_raw_fd())?
     }
 
     #[throws]
     fn perform6<R>(&self, perform: impl FnOnce(RawFd) -> Result<R, nix::Error>) -> R {
+        let span = tracing::info_span!("perform");
+        let _enter = span.enter();
+
         let socket = Socket::new(Domain::IPV6, Type::DGRAM, None)?;
         perform(socket.as_raw_fd())?
     }
 
     #[throws]
+    #[instrument]
     pub fn send(&self, buf: &[u8]) -> usize {
         self.socket.send(buf)?
     }
 }
-
-#[cfg(test)]
-mod test {
-    use super::TunInterface;
-    use std::net::Ipv4Addr;
-
-    #[test]
-    fn mtu() {
-        let interf = TunInterface::new().unwrap();
-
-        interf.set_mtu(500).unwrap();
-
-        assert_eq!(interf.mtu().unwrap(), 500);
-    }
-
-    #[test]
-    #[throws]
-    fn netmask() {
-        let interf = TunInterface::new()?;
-
-        let netmask = Ipv4Addr::new(255, 0, 0, 0);
-        let addr = Ipv4Addr::new(192, 168, 1, 1);
-
-        interf.set_ipv4_addr(addr)?;
-        interf.set_netmask(netmask)?;
-
-        assert_eq!(interf.netmask()?, netmask);
-    }
-}

tun/src/unix/linux/sys.rs

@@ -18,10 +18,12 @@ ioctl_read_bad!(
 );
 ioctl_read_bad!(if_get_index, libc::SIOCGIFINDEX, libc::ifreq);
 ioctl_read_bad!(if_get_addr, libc::SIOCGIFADDR, libc::ifreq);
+ioctl_read_bad!(if_get_brdaddr, libc::SIOCGIFBRDADDR, libc::ifreq);
 ioctl_read_bad!(if_get_mtu, libc::SIOCGIFMTU, libc::ifreq);
 ioctl_read_bad!(if_get_netmask, libc::SIOCGIFNETMASK, libc::ifreq);
 
 ioctl_write_ptr_bad!(if_set_addr, libc::SIOCSIFADDR, libc::ifreq);
 ioctl_write_ptr_bad!(if_set_addr6, libc::SIOCSIFADDR, libc::in6_ifreq);
+ioctl_write_ptr_bad!(if_set_brdaddr, libc::SIOCSIFBRDADDR, libc::ifreq);
 ioctl_write_ptr_bad!(if_set_mtu, libc::SIOCSIFMTU, libc::ifreq);
 ioctl_write_ptr_bad!(if_set_netmask, libc::SIOCSIFNETMASK, libc::ifreq);

tun/src/unix/mod.rs

@@ -2,6 +2,7 @@ use std::{
     io::{Error, Read},
     os::fd::{AsRawFd, FromRawFd, IntoRawFd, RawFd},
 };
+use tracing::instrument;
 
 use super::TunOptions;
 
@@ -41,11 +42,13 @@ impl IntoRawFd for TunInterface {
 
 impl TunInterface {
     #[throws]
+    #[instrument]
     pub fn recv(&mut self, buf: &mut [u8]) -> usize {
         self.socket.read(buf)?
     }
 }
 
+#[instrument]
 pub fn ifname_to_string(buf: [libc::c_char; libc::IFNAMSIZ]) -> String {
     // TODO: Switch to `CStr::from_bytes_until_nul` when stabilized
     unsafe {
@@ -56,44 +59,10 @@ pub fn ifname_to_string(buf: [libc::c_char; libc::IFNAMSIZ]) -> String {
     }
 }
 
+#[instrument]
 pub fn string_to_ifname(name: &str) -> [libc::c_char; libc::IFNAMSIZ] {
     let mut buf = [0 as libc::c_char; libc::IFNAMSIZ];
     let len = name.len().min(buf.len());
     buf[..len].copy_from_slice(unsafe { &*(name.as_bytes() as *const _ as *const [libc::c_char]) });
     buf
 }
-
-#[cfg(test)]
-mod test {
-
-    use super::*;
-
-    use std::net::Ipv4Addr;
-
-    #[throws]
-    #[test]
-    fn tst_read() {
-        // This test is interactive, you need to send a packet to any server through 192.168.1.10
-        // EG. `sudo route add 8.8.8.8 192.168.1.10`,
-        //`dig @8.8.8.8 hackclub.com`
-        let mut tun = TunInterface::new()?;
-        println!("tun name: {:?}", tun.name()?);
-        tun.set_ipv4_addr(Ipv4Addr::from([192, 168, 1, 10]))?;
-        println!("tun ip: {:?}", tun.ipv4_addr()?);
-        println!("Waiting for a packet...");
-        let buf = &mut [0u8; 1500];
-        let res = tun.recv(buf);
-        println!("Received!");
-        assert!(res.is_ok());
-    }
-
-    #[test]
-    #[throws]
-    fn write_packets() {
-        let tun = TunInterface::new()?;
-        let mut buf = [0u8; 1500];
-        buf[0] = 6 << 4;
-        let bytes_written = tun.send(&buf)?;
-        assert_eq!(bytes_written, 1504);
-    }
-}

tun/src/unix/queue.rs

@@ -5,15 +5,18 @@ use std::{
     mem::MaybeUninit,
     os::unix::io::{AsRawFd, IntoRawFd, RawFd},
 };
+use tracing::instrument;
 
 use crate::TunInterface;
 
+#[derive(Debug)]
 pub struct TunQueue {
     socket: socket2::Socket,
 }
 
 impl TunQueue {
     #[throws]
+    #[instrument]
     pub fn recv(&self, buf: &mut [MaybeUninit<u8>]) -> usize {
         self.socket.recv(buf)?
     }

tun/src/windows/mod.rs

@@ -1,3 +1,4 @@
+use std::fmt::Debug;
 use fehler::throws;
 use std::io::Error;
 use std::ptr;
@@ -14,6 +15,15 @@ pub struct TunInterface {
     name: String,
 }
 
+impl Debug for TunInterface {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("TunInterface")
+            .field("handle", &"SYS_WINTUN_ADAPTER_HANDLE".to_string())
+            .field("name", &self.name)
+            .finish()
+    }
+}
+
 impl TunInterface {
     #[throws]
     pub fn new() -> TunInterface {

tun/src/windows/queue.rs

@@ -1 +1,2 @@
+#[derive(Debug)]
 pub struct TunQueue;

tun/tests/configure.rs

@@ -1,6 +1,6 @@
 use fehler::throws;
 use std::io::Error;
-use std::net::{Ipv4Addr};
+use std::net::Ipv4Addr;
 use tun::TunInterface;
 
 #[test]
@@ -11,6 +11,22 @@ fn test_create() {
 
 #[test]
 #[throws]
+#[cfg(not(any(target_os = "windows", target_vendor = "apple")))]
+fn test_set_get_broadcast_addr() {
+    let tun = TunInterface::new()?;
+    let addr = Ipv4Addr::new(10, 0, 0, 1);
+    tun.set_ipv4_addr(addr)?;
+
+    let broadcast_addr = Ipv4Addr::new(255, 255, 255, 0);
+    tun.set_broadcast_addr(broadcast_addr)?;
+    let result = tun.broadcast_addr()?;
+
+    assert_eq!(broadcast_addr, result);
+}
+
+#[test]
+#[throws]
+#[cfg(not(target_os = "windows"))]
 fn test_set_get_ipv4() {
     let tun = TunInterface::new()?;
 
@@ -23,8 +39,10 @@ fn test_set_get_ipv4() {
 
 #[test]
 #[throws]
-#[cfg(target_os = "linux")]
+#[cfg(not(any(target_os = "windows", target_vendor = "apple")))]
 fn test_set_get_ipv6() {
+    use std::net::Ipv6Addr;
+
     let tun = TunInterface::new()?;
 
     let addr = Ipv6Addr::new(1, 1, 1, 1, 1, 1, 1, 1);
@@ -33,3 +51,29 @@ fn test_set_get_ipv6() {
     // let result = tun.ipv6_addr()?;
     // assert_eq!(addr, result);
 }
+
+#[test]
+#[throws]
+#[cfg(not(target_os = "windows"))]
+fn test_set_get_mtu() {
+    let interf = TunInterface::new()?;
+
+    interf.set_mtu(500)?;
+
+    assert_eq!(interf.mtu().unwrap(), 500);
+}
+
+#[test]
+#[throws]
+#[cfg(not(target_os = "windows"))]
+fn test_set_get_netmask() {
+    let interf = TunInterface::new()?;
+
+    let netmask = Ipv4Addr::new(255, 0, 0, 0);
+    let addr = Ipv4Addr::new(192, 168, 1, 1);
+
+    interf.set_ipv4_addr(addr)?;
+    interf.set_netmask(netmask)?;
+
+    assert_eq!(interf.netmask()?, netmask);
+}

tun/tests/packets.rs

@@ -0,0 +1,36 @@
+use fehler::throws;
+use std::io::Error;
+
+use std::net::Ipv4Addr;
+use tun::TunInterface;
+
+#[throws]
+#[test]
+#[ignore = "requires interactivity"]
+#[cfg(not(target_os = "windows"))]
+fn tst_read() {
+    // This test is interactive, you need to send a packet to any server through 192.168.1.10
+    // EG. `sudo route add 8.8.8.8 192.168.1.10`,
+    //`dig @8.8.8.8 hackclub.com`
+    let mut tun = TunInterface::new()?;
+    println!("tun name: {:?}", tun.name()?);
+    tun.set_ipv4_addr(Ipv4Addr::from([192, 168, 1, 10]))?;
+    println!("tun ip: {:?}", tun.ipv4_addr()?);
+    println!("Waiting for a packet...");
+    let buf = &mut [0u8; 1500];
+    let res = tun.recv(buf);
+    println!("Received!");
+    assert!(res.is_ok());
+}
+
+#[test]
+#[throws]
+#[ignore = "requires interactivity"]
+#[cfg(not(target_os = "windows"))]
+fn write_packets() {
+    let tun = TunInterface::new()?;
+    let mut buf = [0u8; 1500];
+    buf[0] = 6 << 4;
+    let bytes_written = tun.send(&buf)?;
+    assert_eq!(bytes_written, 1504);
+}

tun/tests/tokio.rs

@@ -0,0 +1,22 @@
+use std::net::Ipv4Addr;
+
+#[tokio::test]
+#[cfg(all(feature = "tokio", not(target_os = "windows")))]
+async fn test_create() {
+    let tun = tun::TunInterface::new().unwrap();
+    let async_tun = tun::tokio::TunInterface::new(tun).unwrap();
+}
+
+#[tokio::test]
+#[ignore = "requires interactivity"]
+#[cfg(all(feature = "tokio", not(target_os = "windows")))]
+async fn test_write() {
+    let tun = tun::TunInterface::new().unwrap();
+    tun.set_ipv4_addr(Ipv4Addr::from([192, 168, 1, 10]))
+        .unwrap();
+    let async_tun = tun::tokio::TunInterface::new(tun).unwrap();
+    let mut buf = [0u8; 1500];
+    buf[0] = 6 << 4;
+    let bytes_written = async_tun.write(&buf).await.unwrap();
+    assert!(bytes_written > 0);
+}