From eddad37c69114e5ca31564a3ba5b093781f78cab Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=D0=96=D0=BE=D1=80=D0=B0=20=D0=97=D0=BC=D0=B5=D0=B9=D0=BA?=
 =?UTF-8?q?=D0=B8=D0=BD?= <48821354+Katze-942@users.noreply.github.com>
Date: Mon, 5 Oct 2026 07:31:46 +0400
Subject: [PATCH] XDNS finalmask: Fix resolver close deadlock and socket leaks
 (#7089)

https://github.com/XTLS/Xray-core/pull/7089#issuecomment-5987521972
---
 transport/internet/finalmask/xdns/client.go       | 3 +++
 transport/internet/finalmask/xdns/resolver_tcp.go | 8 +++++---
 transport/internet/finalmask/xdns/resolver_udp.go | 8 +++++---
 3 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/transport/internet/finalmask/xdns/client.go b/transport/internet/finalmask/xdns/client.go
index b976f154f..d454a8ccd 100644
--- a/transport/internet/finalmask/xdns/client.go
+++ b/transport/internet/finalmask/xdns/client.go
@@ -80,6 +80,9 @@ func NewClient(c *Config, dialer *finalmask.Dialer) (net.PacketConn, error) {
 	for i := range c.Resolvers {
 		resolver, err := NewResolver(c.Resolvers[i], dialer)
 		if err != nil {
+			for _, resolver := range resolvers {
+				resolver.Close()
+			}
 			return nil, err
 		}
 		resolvers = append(resolvers, resolver)
diff --git a/transport/internet/finalmask/xdns/resolver_tcp.go b/transport/internet/finalmask/xdns/resolver_tcp.go
index 89f2b0ea6..0d0d2d845 100644
--- a/transport/internet/finalmask/xdns/resolver_tcp.go
+++ b/transport/internet/finalmask/xdns/resolver_tcp.go
@@ -130,13 +130,15 @@ func (r *TCPResolver) Send(p []byte) {
 
 func (r *TCPResolver) Close() {
 	r.mu.Lock()
-	defer r.mu.Unlock()
 	if r.closed() {
+		r.mu.Unlock()
 		return
 	}
 	close(r.closeCh)
-	if r.conn != nil {
-		_ = r.conn.Close()
+	conn := r.conn
+	r.mu.Unlock()
+	if conn != nil {
+		_ = conn.Close()
 	}
 	r.wg.Wait()
 	close(r.readCh)
diff --git a/transport/internet/finalmask/xdns/resolver_udp.go b/transport/internet/finalmask/xdns/resolver_udp.go
index e8d97ba29..43c35007c 100644
--- a/transport/internet/finalmask/xdns/resolver_udp.go
+++ b/transport/internet/finalmask/xdns/resolver_udp.go
@@ -117,13 +117,15 @@ func (r *UDPResolver) Send(p []byte) {
 
 func (r *UDPResolver) Close() {
 	r.mu.Lock()
-	defer r.mu.Unlock()
 	if r.closed() {
+		r.mu.Unlock()
 		return
 	}
 	close(r.closeCh)
-	if r.conn != nil {
-		_ = r.conn.Close()
+	conn := r.conn
+	r.mu.Unlock()
+	if conn != nil {
+		_ = conn.Close()
 	}
 	r.wg.Wait()
 	close(r.readCh)