optimize the condition of enabling kcp (#1210)

easytier/src/peers/foreign_network_manager.rs

@@ -163,6 +163,10 @@ impl ForeignNetworkEntry {
         config.set_network_identity(network.clone());
         config.set_hostname(Some(format!("PublicServer_{}", global_ctx.get_hostname())));
 
+        let mut flags = config.get_flags();
+        flags.disable_relay_kcp = !global_ctx.get_flags().enable_relay_foreign_network_kcp;
+        config.set_flags(flags);
+
         let foreign_global_ctx = Arc::new(GlobalCtx::new(config));
         foreign_global_ctx
             .replace_stun_info_collector(Box::new(global_ctx.get_stun_info_collector().clone()));

easytier/src/peers/peer_manager.rs

@@ -1360,6 +1360,38 @@ impl PeerManager {
         tracing::info!("close_peer_conn in foreign network manager done: {:?}", ret);
         ret
     }
+
+    pub async fn check_allow_kcp_to_dst(&self, dst_ip: &IpAddr) -> bool {
+        let route = self.get_route();
+        let Some(dst_peer_id) = route.get_peer_id_by_ip(dst_ip).await else {
+            return false;
+        };
+        let Some(peer_info) = route.get_peer_info(dst_peer_id).await else {
+            return false;
+        };
+
+        // check dst allow kcp input
+        if !peer_info.feature_flag.map(|x| x.kcp_input).unwrap_or(false) {
+            return false;
+        }
+
+        let next_hop_policy = Self::get_next_hop_policy( self.global_ctx.get_flags().latency_first);
+        // check relay node allow relay kcp.
+        let Some(next_hop_id) = route.get_next_hop_with_policy(dst_peer_id, next_hop_policy).await else {
+            return false;
+        };
+
+        let Some(next_hop_info) = route.get_peer_info(next_hop_id).await else {
+            return false;
+        };
+
+        // check next hop allow kcp relay
+        if next_hop_info.feature_flag.map(|x| x.no_relay_kcp).unwrap_or(false) {
+            return false;
+        }
+
+        true
+    }
 }
 
 #[cfg(test)]

easytier/src/peers/route_trait.rs

@@ -86,6 +86,13 @@ pub trait Route {
         None
     }
 
+    async fn get_peer_id_by_ip(&self, ip: &std::net::IpAddr) -> Option<PeerId> {
+        match ip {
+            std::net::IpAddr::V4(v4) => self.get_peer_id_by_ipv4(v4).await,
+            std::net::IpAddr::V6(v6) => self.get_peer_id_by_ipv6(v6).await,
+        }
+    }
+
     async fn list_peers_own_foreign_network(
         &self,
         _network_identity: &NetworkIdentity,