automatic discovery of nodes on the same LAN (fix #2)

src/main.rs

@@ -21,6 +21,8 @@ const TIMEOUT: Duration = Duration::from_secs(300);
 /// Interval at which to gossip last_seen info
 const GOSSIP_INTERVAL: Duration = Duration::from_secs(300);
 
+const LAN_BROADCAST_INTERVAL: Duration = Duration::from_secs(60);
+
 const IGD_INTERVAL: Duration = Duration::from_secs(60);
 const IGD_LEASE_DURATION: Duration = Duration::from_secs(300);
 
@@ -30,10 +32,16 @@ type Pubkey = String;
 struct Config {
     /// The Wireguard interface name
     interface: Pubkey,
-    /// Forward an external port to Wiregard using UPnP IGD
-    upnp_forward_external_port: Option<u16>,
     /// The port to use for gossip inside the Wireguard mesh (must be the same on all nodes)
     gossip_port: u16,
+
+    /// Enable LAN discovery
+    #[serde(default)]
+    lan_discovery: bool,
+
+    /// Forward an external port to Wiregard using UPnP IGD
+    upnp_forward_external_port: Option<u16>,
+
     /// The list of peers we try to connect to
     #[serde(default)]
     peers: Vec<Peer>,
@@ -134,6 +142,7 @@ struct Daemon {
 
 struct PeerInfo {
     endpoint: Option<SocketAddr>,
+    lan_endpoint: Option<(SocketAddr, u64)>,
     last_seen: u64,
     gossip_ip: IpAddr,
     gossip_prio: u64,
@@ -146,6 +155,10 @@ enum Gossip {
         endpoints: Vec<(SocketAddr, u64)>,
     },
     Request,
+    LanBroadcast {
+        pubkey: Pubkey,
+        listen_port: u16,
+    }
 }
 
 impl Daemon {
@@ -180,6 +193,7 @@ impl Daemon {
         thread::scope(|s| {
             s.spawn(|| self.wg_loop());
             s.spawn(|| self.recv_loop());
+            s.spawn(|| self.lan_broadcast_loop());
             s.spawn(|| self.igd_loop());
         });
         unreachable!()
@@ -197,34 +211,10 @@ impl Daemon {
     }
 
     fn wg_loop_iter(&self, i: usize) -> Result<()> {
-        let (_, _, wg_peers) = wg_dump(&self.config)?;
         let mut state = self.state.lock().unwrap();
 
         // 1. Update local peers info of peers
-        for (pk, endpoint, last_seen) in wg_peers {
-            match state.peers.get_mut(&pk) {
-                Some(i) => {
-                    i.endpoint = endpoint;
-                    i.last_seen = last_seen;
-                }
-                None => {
-                    let gossip_ip = match self.config.peers.iter().find(|x| x.pubkey == pk) {
-                        Some(x) => x.address,
-                        None => continue,
-                    };
-                    let gossip_prio = fasthash(format!("{}-{}", self.our_pubkey, pk).as_bytes());
-                    state.peers.insert(
-                        pk,
-                        PeerInfo {
-                            endpoint,
-                            gossip_prio,
-                            gossip_ip,
-                            last_seen,
-                        },
-                    );
-                }
-            }
-        }
+        state.read_wg_peers(self)?;
 
         // 2. Send gossip for peers where there is a big update
         let announces = state
@@ -247,7 +237,7 @@ impl Daemon {
         }
 
         // 3. Try new address for disconnected peers
-        state.setup_wg_peers(&self, i)?;
+        state.setup_wg_peers(self, i)?;
 
         Ok(())
     }
@@ -277,6 +267,13 @@ impl Daemon {
                     self.socket.send_to(&packet, from)?;
                 }
             }
+            Gossip::LanBroadcast{ pubkey, listen_port } => {
+                if self.config.lan_discovery {
+                    if let Some(peer) = state.peers.get_mut(&pubkey) {
+                        peer.lan_endpoint = Some((SocketAddr::new(from.ip(), listen_port), time()));
+                    }
+                }
+            }
         }
         Ok(())
     }
@@ -292,6 +289,27 @@ impl Daemon {
         Ok((src, gossip))
     }
 
+    fn lan_broadcast_loop(&self) {
+        if self.config.lan_discovery {
+            loop {
+                if let Err(e) = self.lan_broadcast_iter() {
+                    error!("LAN broadcast loop error: {}", e);
+                }
+                std::thread::sleep(LAN_BROADCAST_INTERVAL);
+            }
+        }
+    }
+
+    fn lan_broadcast_iter(&self) -> Result<()> {
+        let packet = bincode::serialize(&Gossip::LanBroadcast {
+            pubkey: self.our_pubkey.clone(),
+            listen_port: self.listen_port,
+        })?;
+        let addr = SocketAddr::new("255.255.255.255".parse().unwrap(), self.config.gossip_port);
+        self.socket.send_to(&packet, addr)?;
+        Ok(())
+    }
+
     fn igd_loop(&self) {
         if let Some(external_port) = self.config.upnp_forward_external_port {
             loop {
@@ -401,6 +419,7 @@ impl State {
                     }
                 }
                 None => {
+                    endpoints.sort_by_key(|(_, t)| -(*t as i64));
                     endpoints.truncate(KEEP_MAX_ADDRESSES);
                     self.gossip.insert(pubkey.clone(), endpoints.clone());
                     Some(Gossip::Announce { pubkey, endpoints })
@@ -414,6 +433,37 @@ impl State {
         Ok(())
     }
 
+    fn read_wg_peers(&mut self, daemon: &Daemon) -> Result<()> {
+        let (_, _, wg_peers) = wg_dump(&daemon.config)?;
+        for (pk, endpoint, last_seen) in wg_peers {
+            match self.peers.get_mut(&pk) {
+                Some(i) => {
+                    i.endpoint = endpoint;
+                    i.last_seen = last_seen;
+                }
+                None => {
+                    let gossip_ip = match daemon.config.peers.iter().find(|x| x.pubkey == pk) {
+                        Some(x) => x.address,
+                        None => continue,
+                    };
+                    let gossip_prio = fasthash(format!("{}-{}", daemon.our_pubkey, pk).as_bytes());
+                    self.peers.insert(
+                        pk,
+                        PeerInfo {
+                            endpoint,
+                            lan_endpoint: None,
+                            gossip_prio,
+                            gossip_ip,
+                            last_seen,
+                        },
+                    );
+                }
+            }
+        }
+
+        Ok(())
+    }
+
     fn setup_wg_peers(&self, daemon: &Daemon, i: usize) -> Result<()> {
         let now = time();
         for peer in daemon.config.peers.iter() {
@@ -442,6 +492,13 @@ impl State {
             }
 
             // For disconnected peers, cycle through the IP addresses that we know of
+            let lan_endpoint = self.peers.get(&peer.pubkey)
+                .and_then(|peer| peer.lan_endpoint)
+                .filter(|(_, t)| time() < t + TIMEOUT.as_secs());
+
+            let endpoints = match lan_endpoint {
+                Some(endpoint) => vec![endpoint],
+                None => {
                     let mut endpoints = self.gossip.get(&peer.pubkey).cloned().unwrap_or_default();
                     if let Some(endpoint) = &peer.endpoint {
                         match endpoint.to_socket_addrs() {
@@ -454,6 +511,9 @@ impl State {
                         }
                     }
                     endpoints.sort();
+                    endpoints
+                }
+            };
 
             if !endpoints.is_empty() {
                 let endpoint = endpoints[i % endpoints.len()];
@@ -486,6 +546,7 @@ impl State {
                     .output()?;
             }
         }
+
         Ok(())
     }
 }