XDNS finalmask: Support resolvers (client) and domains (server) instead of domain (#5872)

https://github.com/XTLS/Xray-core/pull/5872#issuecomment-4192730898

Example: https://github.com/XTLS/Xray-core/pull/5872#issuecomment-4196172391

---------

Co-authored-by: LjhAUMEM <llnu14702@gmail.com>

infra/conf/transport_internet.go

@@ -1662,16 +1662,30 @@ func (c *Sudoku) Build() (proto.Message, error) {
 }
 
 type Xdns struct {
-	Domain string `json:"domain"`
+	Domain json.RawMessage `json:"domain"`
+
+	Domains   []string `json:"domains"`
+	Resolvers []string `json:"resolvers"`
 }
 
 func (c *Xdns) Build() (proto.Message, error) {
-	if c.Domain == "" {
-		return nil, errors.New("empty domain")
+	if c.Domain != nil {
+		return nil, errors.PrintRemovedFeatureError("domain", "domains(server) & resolvers(client)")
+	}
+
+	if len(c.Domains) == 0 && len(c.Resolvers) == 0 {
+		return nil, errors.New("empty domains & empty resolvers")
+	}
+
+	for _, r := range c.Resolvers {
+		if !strings.Contains(r, "+udp://") {
+			return nil, errors.New("invalid resolver ", r)
+		}
 	}
 
 	return &xdns.Config{
-		Domain: c.Domain,
+		Domains:   c.Domains,
+		Resolvers: c.Resolvers,
 	}, nil
 }
 

transport/internet/finalmask/xdns/client.go

@@ -9,7 +9,10 @@ import (
 	go_errors "errors"
 	"io"
 	"net"
+	"strconv"
+	"strings"
 	"sync"
+	"sync/atomic"
 	"time"
 
 	"github.com/xtls/xray-core/common"
@@ -34,10 +37,14 @@ type packet struct {
 }
 
 type xdnsConnClient struct {
-	net.PacketConn
+	conn          net.PacketConn
+	resolverConns []net.PacketConn
+	resolverAddrs []*net.UDPAddr
+	resolverIdx   uint32
+	resolverSend  []atomic.Uint32
 
 	clientID []byte
-	domain   Name
+	domains  []Name
 
 	pollChan   chan struct{}
 	readQueue  chan *packet
@@ -48,16 +55,66 @@ type xdnsConnClient struct {
 }
 
 func NewConnClient(c *Config, raw net.PacketConn) (net.PacketConn, error) {
-	domain, err := ParseName(c.Domain)
-	if err != nil {
-		return nil, err
+	if len(c.Resolvers) == 0 {
+		return nil, errors.New("empty resolvers")
 	}
 
+	var domains []Name
+	var servers []string
+	for _, rs := range c.Resolvers {
+		parts := strings.Split(rs, "+udp://")
+		if len(parts) != 2 {
+			return nil, errors.New("invalid resolvers")
+		}
+		domain, err := ParseName(parts[0])
+		if err != nil {
+			return nil, err
+		}
+		domains = append(domains, domain)
+		servers = append(servers, parts[1])
+	}
+
+	var resolverConns []net.PacketConn
+	var resolverAddrs []*net.UDPAddr
+	var resolverSend []atomic.Uint32
+	for _, rs := range servers {
+		h, p, err := net.SplitHostPort(rs)
+		if err != nil {
+			return nil, err
+		}
+		ip := net.ParseIP(h)
+		if ip == nil {
+			return nil, errors.New("invalid ip address")
+		}
+		port, _ := strconv.Atoi(p)
+		if port == 0 {
+			return nil, errors.New("invalid port")
+		}
+		var uc net.PacketConn
+		if ip.To4() != nil {
+			uc, err = net.ListenPacket("udp4", ":0")
+		} else {
+			uc, err = net.ListenPacket("udp6", ":0")
+		}
+		if err != nil {
+			for _, rc := range resolverConns {
+				rc.Close()
+			}
+			return nil, errors.New("failed to create resolver socket: ", err)
+		}
+		resolverConns = append(resolverConns, uc)
+		resolverAddrs = append(resolverAddrs, &net.UDPAddr{IP: ip, Port: port})
+	}
+	resolverSend = make([]atomic.Uint32, len(resolverConns))
+
 	conn := &xdnsConnClient{
-		PacketConn: raw,
+		conn:          raw,
+		resolverConns: resolverConns,
+		resolverAddrs: resolverAddrs,
+		resolverSend:  resolverSend,
 
 		clientID: make([]byte, 8),
-		domain:   domain,
+		domains:  domains,
 
 		pollChan:   make(chan struct{}, pollLimit),
 		readQueue:  make(chan *packet, 256),
@@ -73,58 +130,70 @@ func NewConnClient(c *Config, raw net.PacketConn) (net.PacketConn, error) {
 }
 
 func (c *xdnsConnClient) recvLoop() {
-	var buf [finalmask.UDPSize]byte
+	var wg sync.WaitGroup
 
-	for {
-		if c.closed {
-			break
-		}
+	for i, rc := range c.resolverConns {
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
 
-		n, addr, err := c.PacketConn.ReadFrom(buf[:])
-		if err != nil || n == 0 {
-			if go_errors.Is(err, net.ErrClosed) || go_errors.Is(err, io.EOF) {
-				break
+			var buf [finalmask.UDPSize]byte
+
+			for {
+				if c.closed {
+					break
+				}
+
+				n, addr, err := rc.ReadFrom(buf[:])
+				if err != nil {
+					if go_errors.Is(err, net.ErrClosed) {
+						break
+					}
+					continue
+				}
+
+				resp, err := MessageFromWireFormat(buf[:n])
+				if err != nil {
+					errors.LogDebug(context.Background(), addr, " xdns from wireformat err ", err)
+					continue
+				}
+
+				payload := dnsResponsePayload(&resp, c.domains)
+
+				r := bytes.NewReader(payload)
+				anyPacket := false
+				for {
+					p, err := nextPacket(r)
+					if err != nil {
+						break
+					}
+					anyPacket = true
+
+					buf := make([]byte, len(p))
+					copy(buf, p)
+					select {
+					case c.readQueue <- &packet{
+						p:    buf,
+						addr: addr,
+					}:
+					default:
+						errors.LogDebug(context.Background(), addr, " mask read err queue full")
+					}
+				}
+
+				if anyPacket {
+					c.resolverSend[i].Store(0)
+					select {
+					case c.pollChan <- struct{}{}:
+					default:
+					}
+				}
 			}
-			continue
-		}
-
-		resp, err := MessageFromWireFormat(buf[:n])
-		if err != nil {
-			errors.LogDebug(context.Background(), addr, " xdns from wireformat err ", err)
-			continue
-		}
-
-		payload := dnsResponsePayload(&resp, c.domain)
-
-		r := bytes.NewReader(payload)
-		anyPacket := false
-		for {
-			p, err := nextPacket(r)
-			if err != nil {
-				break
-			}
-			anyPacket = true
-
-			buf := make([]byte, len(p))
-			copy(buf, p)
-			select {
-			case c.readQueue <- &packet{
-				p:    buf,
-				addr: addr,
-			}:
-			default:
-				errors.LogDebug(context.Background(), addr, " mask read err queue full")
-			}
-		}
-
-		if anyPacket {
-			select {
-			case c.pollChan <- struct{}{}:
-			default:
-			}
-		}
+		}()
 	}
 
+	wg.Wait()
+
 	errors.LogDebug(context.Background(), "xdns closed")
 
 	close(c.pollChan)
@@ -138,8 +207,6 @@ func (c *xdnsConnClient) recvLoop() {
 }
 
 func (c *xdnsConnClient) sendLoop() {
-	var addr net.Addr
-
 	pollDelay := initPollDelay
 	pollTimer := time.NewTimer(pollDelay)
 	for {
@@ -158,17 +225,14 @@ func (c *xdnsConnClient) sendLoop() {
 		}
 
 		if p != nil {
-			addr = p.addr
-
 			select {
 			case <-c.pollChan:
 			default:
 			}
-		} else if addr != nil {
-			encoded, _ := encode(nil, c.clientID, c.domain)
+		} else {
+			encoded, _ := encode(nil, c.clientID, c.domains[c.resolverIdx])
 			p = &packet{
-				p:    encoded,
-				addr: addr,
+				p: encoded,
 			}
 		}
 
@@ -189,10 +253,16 @@ func (c *xdnsConnClient) sendLoop() {
 			return
 		}
 
-		if p != nil {
-			_, err := c.PacketConn.WriteTo(p.p, p.addr)
-			if go_errors.Is(err, net.ErrClosed) || go_errors.Is(err, io.ErrClosedPipe) {
-				c.closed = true
+		cur := c.resolverIdx
+		curSend := c.resolverSend[c.resolverIdx].Add(1)
+		_, _ = c.resolverConns[c.resolverIdx].WriteTo(p.p, c.resolverAddrs[c.resolverIdx])
+		for {
+			c.resolverIdx += 1
+			c.resolverIdx %= uint32(len(c.resolverConns))
+			if c.resolverIdx == cur {
+				break
+			}
+			if c.resolverSend[c.resolverIdx].Load() < curSend {
 				break
 			}
 		}
@@ -220,7 +290,7 @@ func (c *xdnsConnClient) WriteTo(p []byte, addr net.Addr) (n int, err error) {
 		return 0, io.ErrClosedPipe
 	}
 
-	encoded, err := encode(p, c.clientID, c.domain)
+	encoded, err := encode(p, c.clientID, c.domains[c.resolverIdx%uint32(len(c.resolverConns))])
 	if err != nil {
 		errors.LogDebug(context.Background(), addr, " xdns wireformat err ", err, " ", len(p))
 		return 0, nil
@@ -240,7 +310,35 @@ func (c *xdnsConnClient) WriteTo(p []byte, addr net.Addr) (n int, err error) {
 
 func (c *xdnsConnClient) Close() error {
 	c.closed = true
-	return c.PacketConn.Close()
+	for _, rc := range c.resolverConns {
+		rc.Close()
+	}
+	return c.conn.Close()
+}
+
+func (c *xdnsConnClient) LocalAddr() net.Addr {
+	return c.conn.LocalAddr()
+}
+
+func (c *xdnsConnClient) SetDeadline(t time.Time) error {
+	for _, rc := range c.resolverConns {
+		rc.SetDeadline(t)
+	}
+	return c.conn.SetDeadline(t)
+}
+
+func (c *xdnsConnClient) SetReadDeadline(t time.Time) error {
+	for _, rc := range c.resolverConns {
+		rc.SetReadDeadline(t)
+	}
+	return c.conn.SetReadDeadline(t)
+}
+
+func (c *xdnsConnClient) SetWriteDeadline(t time.Time) error {
+	for _, rc := range c.resolverConns {
+		rc.SetWriteDeadline(t)
+	}
+	return c.conn.SetWriteDeadline(t)
 }
 
 func encode(p []byte, clientID []byte, domain Name) ([]byte, error) {
@@ -332,7 +430,7 @@ func nextPacket(r *bytes.Reader) ([]byte, error) {
 	return p, err
 }
 
-func dnsResponsePayload(resp *Message, domain Name) []byte {
+func dnsResponsePayload(resp *Message, domains []Name) []byte {
 	if resp.Flags&0x8000 != 0x8000 {
 		return nil
 	}
@@ -345,7 +443,13 @@ func dnsResponsePayload(resp *Message, domain Name) []byte {
 	}
 	answer := resp.Answer[0]
 
-	_, ok := answer.Name.TrimSuffix(domain)
+	var ok bool
+	for _, domain := range domains {
+		_, ok = answer.Name.TrimSuffix(domain)
+		if ok {
+			break
+		}
+	}
 	if !ok {
 		return nil
 	}

transport/internet/finalmask/xdns/config.go

@@ -2,15 +2,27 @@ package xdns
 
 import (
 	"net"
+
+	"github.com/xtls/xray-core/common/errors"
+	"github.com/xtls/xray-core/transport/internet"
+	"github.com/xtls/xray-core/transport/internet/hysteria/udphop"
 )
 
 func (c *Config) UDP() {
 }
 
 func (c *Config) WrapPacketConnClient(raw net.PacketConn, level int, levelCount int) (net.PacketConn, error) {
+	_, ok1 := raw.(*internet.FakePacketConn)
+	_, ok2 := raw.(*udphop.UdpHopPacketConn)
+	if level != 0 || ok1 || ok2 {
+		return nil, errors.New("xdns requires being at the outermost level")
+	}
 	return NewConnClient(c, raw)
 }
 
 func (c *Config) WrapPacketConnServer(raw net.PacketConn, level int, levelCount int) (net.PacketConn, error) {
+	if level != 0 {
+		return nil, errors.New("xdns requires being at the outermost level")
+	}
 	return NewConnServer(c, raw)
 }

transport/internet/finalmask/xdns/config.pb.go

@@ -23,7 +23,8 @@ const (
 
 type Config struct {
 	state         protoimpl.MessageState `protogen:"open.v1"`
-	Domain        string                 `protobuf:"bytes,1,opt,name=domain,proto3" json:"domain,omitempty"`
+	Domains       []string               `protobuf:"bytes,1,rep,name=domains,proto3" json:"domains,omitempty"`
+	Resolvers     []string               `protobuf:"bytes,2,rep,name=resolvers,proto3" json:"resolvers,omitempty"`
 	unknownFields protoimpl.UnknownFields
 	sizeCache     protoimpl.SizeCache
 }
@@ -58,20 +59,28 @@ func (*Config) Descriptor() ([]byte, []int) {
 	return file_transport_internet_finalmask_xdns_config_proto_rawDescGZIP(), []int{0}
 }
 
-func (x *Config) GetDomain() string {
+func (x *Config) GetDomains() []string {
 	if x != nil {
-		return x.Domain
+		return x.Domains
 	}
-	return ""
+	return nil
+}
+
+func (x *Config) GetResolvers() []string {
+	if x != nil {
+		return x.Resolvers
+	}
+	return nil
 }
 
 var File_transport_internet_finalmask_xdns_config_proto protoreflect.FileDescriptor
 
 const file_transport_internet_finalmask_xdns_config_proto_rawDesc = "" +
 	"\n" +
-	".transport/internet/finalmask/xdns/config.proto\x12&xray.transport.internet.finalmask.xdns\" \n" +
-	"\x06Config\x12\x16\n" +
-	"\x06domain\x18\x01 \x01(\tR\x06domainB\x94\x01\n" +
+	".transport/internet/finalmask/xdns/config.proto\x12&xray.transport.internet.finalmask.xdns\"@\n" +
+	"\x06Config\x12\x18\n" +
+	"\adomains\x18\x01 \x03(\tR\adomains\x12\x1c\n" +
+	"\tresolvers\x18\x02 \x03(\tR\tresolversB\x94\x01\n" +
 	"*com.xray.transport.internet.finalmask.xdnsP\x01Z;github.com/xtls/xray-core/transport/internet/finalmask/xdns\xaa\x02&Xray.Transport.Internet.Finalmask.Xdnsb\x06proto3"
 
 var (

transport/internet/finalmask/xdns/config.proto

@@ -7,6 +7,6 @@ option java_package = "com.xray.transport.internet.finalmask.xdns";
 option java_multiple_files = true;
 
 message Config {
-  string domain = 1;
-}
-
+  repeated string domains = 1;
+  repeated string resolvers = 2;
+}

transport/internet/finalmask/xdns/dns_test.go

@@ -559,6 +559,7 @@ func TestEncodeRDataTXT(t *testing.T) {
 	}
 
 	fmt.Println(EncodeRDataTXT(nil))
+	fmt.Println(computeMaxEncodedPayload(maxUDPPayload))
 }
 
 func TestRDataTXTRoundTrip(t *testing.T) {

transport/internet/finalmask/xdns/server.go

@@ -52,7 +52,7 @@ type queue struct {
 type xdnsConnServer struct {
 	net.PacketConn
 
-	domain Name
+	domains []Name
 
 	ch            chan *record
 	readQueue     chan *packet
@@ -63,15 +63,22 @@ type xdnsConnServer struct {
 }
 
 func NewConnServer(c *Config, raw net.PacketConn) (net.PacketConn, error) {
-	domain, err := ParseName(c.Domain)
-	if err != nil {
-		return nil, err
+	if len(c.Domains) == 0 {
+		return nil, errors.New("empty domains")
+	}
+	domains := make([]Name, 0, len(c.Domains))
+	for _, domain := range c.Domains {
+		domain, err := ParseName(domain)
+		if err != nil {
+			return nil, err
+		}
+		domains = append(domains, domain)
 	}
 
 	conn := &xdnsConnServer{
 		PacketConn: raw,
 
-		domain: domain,
+		domains: domains,
 
 		ch:            make(chan *record, 500),
 		readQueue:     make(chan *packet, 512),
@@ -156,8 +163,8 @@ func (c *xdnsConnServer) recvLoop() {
 		}
 
 		n, addr, err := c.PacketConn.ReadFrom(buf[:])
-		if err != nil || n == 0 {
-			if go_errors.Is(err, net.ErrClosed) || go_errors.Is(err, io.EOF) {
+		if err != nil {
+			if go_errors.Is(err, net.ErrClosed) {
 				break
 			}
 			continue
@@ -169,7 +176,7 @@ func (c *xdnsConnServer) recvLoop() {
 			continue
 		}
 
-		resp, payload := responseFor(&query, c.domain)
+		resp, payload := responseFor(&query, c.domains)
 
 		var clientID [8]byte
 		n = copy(clientID[:], payload)
@@ -321,7 +328,7 @@ func (c *xdnsConnServer) sendLoop() {
 		}
 
 		_, err = c.PacketConn.WriteTo(buf, rec.Addr)
-		if go_errors.Is(err, net.ErrClosed) || go_errors.Is(err, io.ErrClosedPipe) {
+		if go_errors.Is(err, net.ErrClosed) {
 			c.closed = true
 			break
 		}
@@ -399,7 +406,7 @@ func nextPacketServer(r *bytes.Reader) ([]byte, error) {
 	}
 }
 
-func responseFor(query *Message, domain Name) (*Message, []byte) {
+func responseFor(query *Message, domains []Name) (*Message, []byte) {
 	resp := &Message{
 		ID:       query.ID,
 		Flags:    0x8000,
@@ -447,7 +454,14 @@ func responseFor(query *Message, domain Name) (*Message, []byte) {
 	}
 	question := query.Question[0]
 
-	prefix, ok := question.Name.TrimSuffix(domain)
+	var prefix Name
+	var ok bool
+	for _, domain := range domains {
+		prefix, ok = question.Name.TrimSuffix(domain)
+		if ok {
+			break
+		}
+	}
 	if !ok {
 		resp.Flags |= RcodeNameError
 		return resp, nil
@@ -525,7 +539,7 @@ func computeMaxEncodedPayload(limit int) int {
 			},
 		},
 	}
-	resp, _ := responseFor(query, [][]byte{})
+	resp, _ := responseFor(query, []Name{[][]byte{}})
 
 	resp.Answer = []RR{
 		{

transport/internet/finalmask/xicmp/client.go

@@ -10,9 +10,7 @@ import (
 
 	"github.com/xtls/xray-core/common/crypto"
 	"github.com/xtls/xray-core/common/errors"
-	"github.com/xtls/xray-core/transport/internet"
 	"github.com/xtls/xray-core/transport/internet/finalmask"
-	"github.com/xtls/xray-core/transport/internet/hysteria/udphop"
 	"golang.org/x/net/icmp"
 	"golang.org/x/net/ipv4"
 	"golang.org/x/net/ipv6"
@@ -54,13 +52,7 @@ type xicmpConnClient struct {
 	mutex  sync.Mutex
 }
 
-func NewConnClient(c *Config, raw net.PacketConn, level int) (net.PacketConn, error) {
-	_, ok1 := raw.(*internet.FakePacketConn)
-	_, ok2 := raw.(*udphop.UdpHopPacketConn)
-	if level != 0 || ok1 || ok2 {
-		return nil, errors.New("xicmp requires being at the outermost level")
-	}
-
+func NewConnClient(c *Config, raw net.PacketConn) (net.PacketConn, error) {
 	network := "ip4:icmp"
 	typ := icmp.Type(ipv4.ICMPTypeEcho)
 	proto := 1

transport/internet/finalmask/xicmp/config.go

@@ -2,15 +2,27 @@ package xicmp
 
 import (
 	"net"
+
+	"github.com/xtls/xray-core/common/errors"
+	"github.com/xtls/xray-core/transport/internet"
+	"github.com/xtls/xray-core/transport/internet/hysteria/udphop"
 )
 
 func (c *Config) UDP() {
 }
 
 func (c *Config) WrapPacketConnClient(raw net.PacketConn, level int, levelCount int) (net.PacketConn, error) {
-	return NewConnClient(c, raw, level)
+	_, ok1 := raw.(*internet.FakePacketConn)
+	_, ok2 := raw.(*udphop.UdpHopPacketConn)
+	if level != 0 || ok1 || ok2 {
+		return nil, errors.New("xicmp requires being at the outermost level")
+	}
+	return NewConnClient(c, raw)
 }
 
 func (c *Config) WrapPacketConnServer(raw net.PacketConn, level int, levelCount int) (net.PacketConn, error) {
-	return NewConnServer(c, raw, level)
+	if level != 0 {
+		return nil, errors.New("xicmp requires being at the outermost level")
+	}
+	return NewConnServer(c, raw)
 }

transport/internet/finalmask/xicmp/server.go

@@ -50,11 +50,7 @@ type xicmpConnServer struct {
 	mutex  sync.Mutex
 }
 
-func NewConnServer(c *Config, raw net.PacketConn, level int) (net.PacketConn, error) {
-	if level != 0 {
-		return nil, errors.New("xicmp requires being at the outermost level")
-	}
-
+func NewConnServer(c *Config, raw net.PacketConn) (net.PacketConn, error) {
 	network := "ip4:icmp"
 	typ := icmp.Type(ipv4.ICMPTypeEchoReply)
 	proto := 1