Epoll (#20)

major update:
- remove threading overhead by resorting to an event driven design with mio as a backend for epoll
- Clients can now have an arbitrary amount of ip adresses and lan-mouse will automatically choose the correct one
- -> seemless switching between ethernet and wifi
- cli frontend + frontend adapter for future frontends

src/frontend.rs

@@ -0,0 +1,115 @@
+use std::io::{Read, Result};
+use std::{str, net::SocketAddr};
+
+#[cfg(unix)]
+use std::{env, path::{Path, PathBuf}};
+
+use mio::{Registry, Token, event::Source};
+
+#[cfg(unix)]
+use mio::net::UnixListener;
+#[cfg(windows)]
+use mio::net::TcpListener;
+
+use serde::{Serialize, Deserialize};
+
+use crate::client::{Client, Position};
+
+/// cli frontend
+pub mod cli;
+
+/// gtk frontend
+#[cfg(all(unix, feature = "gtk"))]
+pub mod gtk;
+
+#[derive(Debug, Eq, PartialEq, Clone, Serialize, Deserialize)]
+pub enum FrontendEvent {
+    RequestPortChange(u16),
+    RequestClientAdd(SocketAddr, Position),
+    RequestClientDelete(Client),
+    RequestClientUpdate(Client),
+    RequestShutdown(),
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub enum FrontendNotify {
+    NotifyClientCreate(Client),
+    NotifyError(String),
+}
+
+pub struct FrontendAdapter {
+    #[cfg(windows)]
+    listener: TcpListener,
+    #[cfg(unix)]
+    listener: UnixListener,
+    #[cfg(unix)]
+    socket_path: PathBuf,
+}
+
+impl FrontendAdapter {
+    pub fn new() -> std::result::Result<Self, Box<dyn std::error::Error>> {
+        #[cfg(unix)]
+        let socket_path = Path::new(env::var("XDG_RUNTIME_DIR")?.as_str()).join("lan-mouse-socket.sock");
+        #[cfg(unix)]
+        let listener = UnixListener::bind(&socket_path)?;
+
+        #[cfg(windows)]
+        let listener = TcpListener::bind("127.0.0.1:5252".parse().unwrap())?; // abuse tcp
+
+        let adapter = Self {
+            listener,
+            #[cfg(unix)]
+            socket_path,
+        };
+
+        Ok(adapter)
+    }
+
+    pub fn read_event(&mut self) -> Result<FrontendEvent>{
+        let (mut stream, _) = self.listener.accept()?;
+        let mut buf = [0u8; 128]; // FIXME
+        stream.read(&mut buf)?;
+        let json = str::from_utf8(&buf)
+            .unwrap()
+            .trim_end_matches(char::from(0)); // remove trailing 0-bytes
+        let event = serde_json::from_str(json).unwrap();
+        log::debug!("{:?}", event);
+        Ok(event)
+    }
+
+    pub fn notify(&self, _event: FrontendNotify) { }
+}
+
+impl Source for FrontendAdapter {
+    fn register(
+        &mut self,
+        registry: &Registry,
+        token: Token,
+        interests: mio::Interest,
+    ) -> Result<()> {
+        self.listener.register(registry, token, interests)
+    }
+
+    fn reregister(
+        &mut self,
+        registry: &Registry,
+        token: Token,
+        interests: mio::Interest,
+    ) -> Result<()> {
+        self.listener.reregister(registry, token, interests)
+    }
+
+    fn deregister(&mut self, registry: &Registry) -> Result<()> {
+        self.listener.deregister(registry)
+    }
+}
+
+#[cfg(unix)]
+impl Drop for FrontendAdapter {
+    fn drop(&mut self) {
+        log::debug!("remove socket: {:?}", self.socket_path);
+        std::fs::remove_file(&self.socket_path).unwrap();
+    }
+}
+
+pub trait Frontend { }