refactor: handle quic proxy internally instead of use external udp port (#1743)

* deprecate quic_listen_port, add disable_relay_quic and enable_relay_foreign_network_quic
* add set_src_modified to TcpProxyForWrappedSrcTrait
* prioritize quic over kcp

easytier/src/peers/peer_manager.rs

@@ -1489,6 +1489,54 @@ impl PeerManager {
         true
     }
 
+    pub async fn check_allow_quic_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 quic input
+        if !peer_info
+            .feature_flag
+            .map(|x| x.quic_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 quic.
+        let Some(next_hop_id) = route
+            .get_next_hop_with_policy(dst_peer_id, next_hop_policy)
+            .await
+        else {
+            return false;
+        };
+
+        if next_hop_id == dst_peer_id {
+            // dst p2p, no need to relay
+            return true;
+        }
+
+        let Some(next_hop_info) = route.get_peer_info(next_hop_id).await else {
+            return false;
+        };
+
+        // check next hop allow quic relay
+        if next_hop_info
+            .feature_flag
+            .map(|x| x.no_relay_quic)
+            .unwrap_or(false)
+        {
+            return false;
+        }
+
+        true
+    }
+
     pub async fn update_exit_nodes(&self) {
         let exit_nodes = self.global_ctx.config.get_exit_nodes();
         *self.exit_nodes.write().await = exit_nodes;