feat(rosenpass): Add wireguard-broker interface in AppServer (#303)

Dynamically dispatch WireguardBrokerMio trait in AppServer. Also allows for mio event registration and poll processing, logic from dev/broker-architecture branch

Co-authored-by: Prabhpreet Dua <615318+prabhpreet@users.noreply.github.com>
Co-authored-by: Karolin Varner <karo@cupdev.net>

wireguard-broker/src/brokers/netlink.rs

@@ -0,0 +1,112 @@
+use std::fmt::Debug;
+
+use wireguard_uapi::linux as wg;
+
+use crate::api::config::NetworkBrokerConfig;
+use crate::api::msgs;
+use crate::{SerializedBrokerConfig, WireGuardBroker};
+
+#[derive(thiserror::Error, Debug)]
+pub enum ConnectError {
+    #[error(transparent)]
+    ConnectError(#[from] wg::err::ConnectError),
+}
+
+#[derive(thiserror::Error, Debug)]
+pub enum NetlinkError {
+    #[error(transparent)]
+    SetDevice(#[from] wg::err::SetDeviceError),
+    #[error(transparent)]
+    GetDevice(#[from] wg::err::GetDeviceError),
+}
+
+#[derive(thiserror::Error, Debug)]
+pub enum SetPskError {
+    #[error("The indicated wireguard interface does not exist")]
+    NoSuchInterface,
+    #[error("The indicated peer does not exist on the wireguard interface")]
+    NoSuchPeer,
+    #[error(transparent)]
+    NetlinkError(#[from] NetlinkError),
+}
+
+impl From<wg::err::SetDeviceError> for SetPskError {
+    fn from(err: wg::err::SetDeviceError) -> Self {
+        NetlinkError::from(err).into()
+    }
+}
+
+impl From<wg::err::GetDeviceError> for SetPskError {
+    fn from(err: wg::err::GetDeviceError) -> Self {
+        NetlinkError::from(err).into()
+    }
+}
+
+use msgs::SetPskError as SetPskMsgsError;
+use SetPskError as SetPskNetlinkError;
+impl From<SetPskNetlinkError> for SetPskMsgsError {
+    fn from(err: SetPskError) -> Self {
+        match err {
+            SetPskNetlinkError::NoSuchPeer => SetPskMsgsError::NoSuchPeer,
+            _ => SetPskMsgsError::InternalError,
+        }
+    }
+}
+
+pub struct NetlinkWireGuardBroker {
+    sock: wg::WgSocket,
+}
+
+impl NetlinkWireGuardBroker {
+    pub fn new() -> Result<Self, ConnectError> {
+        let sock = wg::WgSocket::connect()?;
+        Ok(Self { sock })
+    }
+}
+
+impl Debug for NetlinkWireGuardBroker {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        //TODO: Add useful info in Debug
+        f.debug_struct("NetlinkWireGuardBroker").finish()
+    }
+}
+
+impl WireGuardBroker for NetlinkWireGuardBroker {
+    type Error = SetPskError;
+
+    fn set_psk(&mut self, config: SerializedBrokerConfig) -> Result<(), Self::Error> {
+        let config: NetworkBrokerConfig = config
+            .try_into()
+            .map_err(|e| SetPskError::NoSuchInterface)?;
+        // Ensure that the peer exists by querying the device configuration
+        // TODO: Use InvalidInterfaceError
+
+        let state = self
+            .sock
+            .get_device(wg::DeviceInterface::from_name(config.iface))?;
+
+        if state
+            .peers
+            .iter()
+            .find(|p| &p.public_key == &config.peer_id.value)
+            .is_none()
+        {
+            return Err(SetPskError::NoSuchPeer);
+        }
+
+        // Peer update description
+        let mut set_peer = wireguard_uapi::set::Peer::from_public_key(&config.peer_id);
+        set_peer
+            .flags
+            .push(wireguard_uapi::linux::set::WgPeerF::UpdateOnly);
+        set_peer.preshared_key = Some(&config.psk.secret());
+
+        // Device update description
+        let mut set_dev = wireguard_uapi::set::Device::from_ifname(config.iface);
+        set_dev.peers.push(set_peer);
+
+        self.sock.set_device(set_dev)?;
+
+        Ok(())
+    }
+}