Fix tcptls and udp bug; Improve code

Author: shawn1m

core/outbound/clients/resolver/base_resolver.go

@@ -25,20 +25,26 @@ type BaseResolver struct {
 	dnsUpstream *common.DNSUpstream
 }
 
-func (r *BaseResolver) Exchange(*dns.Msg) (*dns.Msg, error) {
-	return nil, nil
-}
-
-func (r *BaseResolver) ExchangeByBaseConn(q *dns.Msg) (*dns.Msg, error) {
+func (r *BaseResolver) Exchange(q *dns.Msg) (*dns.Msg, error) {
 	conn, err := r.CreateBaseConn()
+	defer conn.Close()
 	if err != nil {
 		return nil, err
 	}
+	return r.exchangeByConnWithoutClose(q, conn)
+}
+
+func (r *BaseResolver) exchangeByConnWithoutClose(q *dns.Msg, conn net.Conn) (msg *dns.Msg, err error) {
+	if conn == nil {
+		log.Fatal("Conn not initialized for exchangeByDNSClient")
+		return nil, err
+	}
+
 	r.setTimeout(conn)
 	dc := &dns.Conn{Conn: conn, UDPSize: 65535}
-	defer dc.Close()
 	err = dc.WriteMsg(q)
 	if err != nil {
+		log.Warnf("%s Fail: Send question message failed", r.dnsUpstream.Name)
 		return nil, err
 	}
 	return dc.ReadMsg()
@@ -147,17 +153,18 @@ func (r *BaseResolver) createConnectionPool(connCreate func() (interface{}, erro
 	return pool.NewChannelPool(poolConfig)
 }
 
-func (r *BaseResolver) exchangeByDNSClient(q *dns.Msg, conn net.Conn) (msg *dns.Msg, err error) {
-	if conn == nil {
-		log.Fatal("Conn not initialized for exchangeByDNSClient")
+func (r *BaseResolver) exchangeByPool(q *dns.Msg, poolConn pool.Pool) (msg *dns.Msg, err error) {
+	_conn, err := poolConn.Get()
+	if err != nil {
 		return nil, err
 	}
-
-	dc := &dns.Conn{Conn: conn, UDPSize: 65535}
-	err = dc.WriteMsg(q)
+	conn := _conn.(net.Conn)
+	ret, err := r.exchangeByConnWithoutClose(q, conn)
 	if err != nil {
-		log.Warnf("%s Fail: Send question message failed", r.dnsUpstream.Name)
-		return nil, err
+		poolConn.Close(conn)
+	} else {
+		r.setIdleTimeout(conn)
+		poolConn.Put(conn)
 	}
-	return dc.ReadMsg()
+	return ret, err
 }

core/outbound/clients/resolver/tcp_resolver.go

@@ -14,24 +14,11 @@ type TCPResolver struct {
 }
 
 func (r *TCPResolver) Exchange(q *dns.Msg) (*dns.Msg, error) {
-	if !r.dnsUpstream.TCPPoolConfig.Enable {
-		return r.ExchangeByBaseConn(q)
-	}
-
-	_conn, err := r.poolConn.Get()
-	if err != nil {
-		return nil, err
-	}
-	conn := _conn.(net.Conn)
-	r.setTimeout(conn)
-	ret, err := r.exchangeByDNSClient(q, conn)
-	if err != nil {
-		r.poolConn.Close(conn)
+	if r.dnsUpstream.TCPPoolConfig.Enable {
+		return r.BaseResolver.exchangeByPool(q, r.poolConn)
 	} else {
-		r.setIdleTimeout(conn)
-		r.poolConn.Put(conn)
+		return r.BaseResolver.Exchange(q)
 	}
-	return ret, err
 }
 
 func (r *TCPResolver) Init() error {

core/outbound/clients/resolver/tcptls_resolver.go

@@ -15,23 +15,16 @@ type TCPTLSResolver struct {
 }
 
 func (r *TCPTLSResolver) Exchange(q *dns.Msg) (*dns.Msg, error) {
-	if !r.dnsUpstream.TCPPoolConfig.Enable {
-		return r.ExchangeByBaseConn(q)
-	}
-	_conn, err := r.poolConn.Get()
-	if err != nil {
-		return nil, err
-	}
-	conn := _conn.(net.Conn)
-	r.setTimeout(conn)
-	ret, err := r.exchangeByDNSClient(q, conn)
-	if err != nil {
-		r.poolConn.Close(conn)
+	if r.dnsUpstream.TCPPoolConfig.Enable {
+		return r.BaseResolver.exchangeByPool(q, r.poolConn)
 	} else {
-		r.setIdleTimeout(conn)
-		r.poolConn.Put(conn)
+		conn, err := r.createTlsConn()
+		if err != nil {
+			return nil, err
+		}
+		defer conn.Close()
+		return r.exchangeByConnWithoutClose(q, conn)
 	}
-	return ret, err
 }
 
 func (r *TCPTLSResolver) createTlsConn() (conn net.Conn, err error) {

core/outbound/clients/resolver/udp_resolver.go

@@ -9,14 +9,7 @@ type UDPResolver struct {
 }
 
 func (r *UDPResolver) Exchange(q *dns.Msg) (*dns.Msg, error) {
-	conn, err := r.CreateBaseConn()
-	if err != nil {
-		return nil, err
-	}
-	defer conn.Close()
-	r.setTimeout(conn)
-	ret, err := r.exchangeByDNSClient(q, conn)
-	return ret, err
+	return r.BaseResolver.Exchange(q)
 }
 
 func (r *UDPResolver) Init() error {