Fix: resolver dial context udp

dns/client.go

@@ -49,14 +49,14 @@ func (c *client) ExchangeContext(ctx context.Context, m *D.Msg) (*D.Msg, error)
 	}
 
 	var conn net.Conn
-	if c.proxyAdapter != "" && network == "tcp" {
-		conn, err = dialContextWithProxyAdapter(ctx, c.proxyAdapter, ip, c.port)
-	} else {
+	if c.proxyAdapter == "" {
 		options := []dialer.Option{}
 		if c.iface != "" {
 			options = append(options, dialer.WithInterface(c.iface))
 		}
-		conn, err = dialer.DialContext(ctx, network, net.JoinHostPort(c.host, c.port), options...)
+		conn, err = dialer.DialContext(ctx, network, net.JoinHostPort(ip.String(), c.port), options...)
+	} else {
+		conn, err = dialContextWithProxyAdapter(ctx, c.proxyAdapter, network, ip, c.port)
 	}
 
 	if err != nil {

dns/doh.go

@@ -100,7 +100,7 @@ func newDoHClient(url string, r *Resolver, proxyAdapter string) *dohClient {
 				if proxyAdapter == "" {
 					return dialer.DialContext(ctx, "tcp", net.JoinHostPort(ip.String(), port))
 				} else {
-					return dialContextWithProxyAdapter(ctx, proxyAdapter, ip, port)
+					return dialContextWithProxyAdapter(ctx, proxyAdapter, "tcp", ip, port)
 				}
 			},
 		},

dns/resolver.go

@@ -379,6 +379,7 @@ func NewMainResolver(old *Resolver) *Resolver {
 		main:     old.main,
 		lruCache: old.lruCache,
 		hosts:    old.hosts,
+		policy:   old.policy,
 	}
 	return r
 }

dns/util.go

@@ -110,25 +110,62 @@ func msgToIP(msg *D.Msg) []net.IP {
 	return ips
 }
 
-func dialContextWithProxyAdapter(ctx context.Context, adapterName string, dstIP net.IP, port string) (net.Conn, error) {
+type wrapPacketConn struct {
+	net.PacketConn
+	rAddr net.Addr
+}
+
+func (wpc *wrapPacketConn) Read(b []byte) (n int, err error) {
+	n, _, err = wpc.PacketConn.ReadFrom(b)
+	return n, err
+}
+
+func (wpc *wrapPacketConn) Write(b []byte) (n int, err error) {
+	return wpc.PacketConn.WriteTo(b, wpc.rAddr)
+}
+
+func (wpc *wrapPacketConn) RemoteAddr() net.Addr {
+	return wpc.rAddr
+}
+
+func dialContextWithProxyAdapter(ctx context.Context, adapterName string, network string, dstIP net.IP, port string) (net.Conn, error) {
 	adapter, ok := tunnel.Proxies()[adapterName]
 	if !ok {
-		return nil, fmt.Errorf("proxy dapter [%s] not found", adapterName)
+		return nil, fmt.Errorf("proxy adapter [%s] not found", adapterName)
+	}
+
+	networkType := C.TCP
+	if network == "udp" {
+		if !adapter.SupportUDP() {
+			return nil, fmt.Errorf("proxy adapter [%s] UDP is not supported", adapterName)
+		}
+		networkType = C.UDP
 	}
 
 	addrType := C.AtypIPv4
-
 	if dstIP.To4() == nil {
 		addrType = C.AtypIPv6
 	}
 
 	metadata := &C.Metadata{
-		NetWork:  C.TCP,
+		NetWork:  networkType,
 		AddrType: addrType,
 		Host:     "",
 		DstIP:    dstIP,
 		DstPort:  port,
 	}
 
+	if networkType == C.UDP {
+		packetConn, err := adapter.ListenPacketContext(ctx, metadata)
+		if err != nil {
+			return nil, err
+		}
+
+		return &wrapPacketConn{
+			PacketConn: packetConn,
+			rAddr:      metadata.UDPAddr(),
+		}, nil
+	}
+
 	return adapter.DialContext(ctx, metadata)
 }