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/lib.rs

@@ -1,19 +1,40 @@
-#[cfg(feature = "enable_broker")]
-use std::result::Result;
+use rosenpass_secret_memory::{Public, Secret};
+use std::{fmt::Debug, result::Result};
 
-#[cfg(feature = "enable_broker")]
-pub trait WireGuardBroker {
+pub const WG_KEY_LEN: usize = 32;
+pub const WG_PEER_LEN: usize = 32;
+pub trait WireGuardBroker: Debug {
     type Error;
-
-    fn set_psk(
-        &mut self,
-        interface: &str,
-        peer_id: [u8; 32],
-        psk: [u8; 32],
-    ) -> Result<(), Self::Error>;
+    fn set_psk(&mut self, config: SerializedBrokerConfig<'_>) -> Result<(), Self::Error>;
 }
 
-#[cfg(feature = "enable_broker")]
+pub trait WireguardBrokerCfg: Debug {
+    fn create_config<'a>(&'a self, psk: &'a Secret<WG_KEY_LEN>) -> SerializedBrokerConfig<'a>;
+}
+
+#[derive(Debug)]
+pub struct SerializedBrokerConfig<'a> {
+    pub interface: &'a [u8],
+    pub peer_id: &'a Public<WG_PEER_LEN>,
+    pub psk: &'a Secret<WG_KEY_LEN>,
+    pub additional_params: &'a [u8],
+}
+
+pub trait WireguardBrokerMio: WireGuardBroker {
+    type MioError;
+    /// Register interested events for mio::Registry
+    fn register(
+        &mut self,
+        registry: &mio::Registry,
+        token: mio::Token,
+    ) -> Result<(), Self::MioError>;
+    /// Run after a mio::poll operation
+    fn process_poll(&mut self) -> Result<(), Self::MioError>;
+
+    fn unregister(&mut self, registry: &mio::Registry) -> Result<(), Self::MioError>;
+}
+
+#[cfg(feature = "enable_broker_api")]
 pub mod api;
-#[cfg(feature = "enable_broker")]
-pub mod netlink;
+
+pub mod brokers;