fix: dns truncate not work

dns/client.go

@@ -78,7 +78,9 @@ func (c *client) ExchangeContext(ctx context.Context, m *D.Msg) (*D.Msg, error)
 		options = append(options, dialer.WithInterface(c.iface))
 	}
 
-	conn, err := getDialHandler(c.r, c.proxyAdapter, c.proxyName, options...)(ctx, network, net.JoinHostPort(ip.String(), c.port))
+	dialHandler := getDialHandler(c.r, c.proxyAdapter, c.proxyName, options...)
+	addr := net.JoinHostPort(ip.String(), c.port)
+	conn, err := dialHandler(ctx, network, addr)
 	if err != nil {
 		return nil, err
 	}
@@ -111,7 +113,16 @@ func (c *client) ExchangeContext(ctx context.Context, m *D.Msg) (*D.Msg, error)
 		if msg != nil && msg.Truncated && c.Client.Net == "" {
 			tcpClient := *c.Client // copy a client
 			tcpClient.Net = "tcp"
+			network = "tcp"
 			log.Debugln("[DNS] Truncated reply from %s:%s for %s over UDP, retrying over TCP", c.host, c.port, m.Question[0].String())
+			dConn.Conn, err = dialHandler(ctx, network, addr)
+			if err != nil {
+				ch <- result{msg, err}
+				return
+			}
+			defer func() {
+				_ = conn.Close()
+			}()
 			msg, _, err = tcpClient.ExchangeWithConn(m, dConn)
 		}