dns outbound proxy

app/dns/server.go

@@ -14,6 +14,7 @@ import (
 	"v2ray.com/core/common/net"
 	"v2ray.com/core/common/session"
 	"v2ray.com/core/common/strmatcher"
+	"v2ray.com/core/common/uuid"
 	"v2ray.com/core/features"
 	"v2ray.com/core/features/dns"
 	"v2ray.com/core/features/routing"
@@ -30,12 +31,20 @@ type Server struct {
 	tag            string
 }
 
+func generateRandomTag() string {
+	id := uuid.New()
+	return "v2ray.system." + id.String()
+}
+
 // New creates a new DNS server with given configuration.
 func New(ctx context.Context, config *Config) (*Server, error) {
 	server := &Server{
 		clients: make([]Client, 0, len(config.NameServers)+len(config.NameServer)),
 		tag:     config.Tag,
 	}
+	if len(server.tag) == 0 {
+		server.tag = generateRandomTag()
+	}
 	if len(config.ClientIp) > 0 {
 		if len(config.ClientIp) != 4 && len(config.ClientIp) != 16 {
 			return nil, newError("unexpected IP length", len(config.ClientIp))
@@ -121,6 +130,11 @@ func (s *Server) Close() error {
 	return nil
 }
 
+func (s *Server) IsOwnLink(ctx context.Context) bool {
+	inbound := session.InboundFromContext(ctx)
+	return inbound != nil && inbound.Tag == s.tag
+}
+
 func (s *Server) queryIPTimeout(client Client, domain string, option IPOption) ([]net.IP, error) {
 	ctx, cancel := context.WithTimeout(context.Background(), time.Second*4)
 	if len(s.tag) > 0 {

app/dns/server_test.go

@@ -5,6 +5,7 @@ import (
 	"time"
 
 	"github.com/google/go-cmp/cmp"
+	"github.com/miekg/dns"
 
 	"v2ray.com/core"
 	"v2ray.com/core/app/dispatcher"
@@ -18,8 +19,6 @@ import (
 	feature_dns "v2ray.com/core/features/dns"
 	"v2ray.com/core/proxy/freedom"
 	"v2ray.com/core/testing/servers/udp"
-
-	"github.com/miekg/dns"
 )
 
 type staticHandler struct {

common/protocol/dns/errors.generated.go

@@ -0,0 +1,9 @@
+package dns
+
+import "v2ray.com/core/common/errors"
+
+type errPathObjHolder struct{}
+
+func newError(values ...interface{}) *errors.Error {
+	return errors.New(values...).WithPathObj(errPathObjHolder{})
+}

common/protocol/dns/io.go

@@ -1,11 +1,13 @@
 package dns
 
 import (
+	"encoding/binary"
 	"sync"
 
 	"golang.org/x/net/dns/dnsmessage"
 	"v2ray.com/core/common"
 	"v2ray.com/core/common/buf"
+	"v2ray.com/core/common/serial"
 )
 
 func PackMessage(msg *dnsmessage.Message) (*buf.Buffer, error) {
@@ -75,3 +77,67 @@ func (r *UDPReader) Close() error {
 
 	return common.Close(r.Reader)
 }
+
+type TCPReader struct {
+	reader *buf.BufferedReader
+}
+
+func NewTCPReader(reader buf.Reader) *TCPReader {
+	return &TCPReader{
+		reader: &buf.BufferedReader{
+			Reader: reader,
+		},
+	}
+}
+
+func (r *TCPReader) ReadMessage() (*buf.Buffer, error) {
+	size, err := serial.ReadUint16(r.reader)
+	if err != nil {
+		return nil, err
+	}
+	if size > buf.Size {
+		return nil, newError("message size too large: ", size)
+	}
+	b := buf.New()
+	if _, err := b.ReadFullFrom(r.reader, int32(size)); err != nil {
+		return nil, err
+	}
+	return b, nil
+}
+
+func (r *TCPReader) Interrupt() {
+	common.Interrupt(r.reader)
+}
+
+func (r *TCPReader) Close() error {
+	return common.Close(r.reader)
+}
+
+type MessageWriter interface {
+	WriteMessage(msg *buf.Buffer) error
+}
+
+type UDPWriter struct {
+	buf.Writer
+}
+
+func (w *UDPWriter) WriteMessage(b *buf.Buffer) error {
+	return w.WriteMultiBuffer(buf.MultiBuffer{b})
+}
+
+type TCPWriter struct {
+	buf.Writer
+}
+
+func (w *TCPWriter) WriteMessage(b *buf.Buffer) error {
+	if b.IsEmpty() {
+		return nil
+	}
+
+	mb := make(buf.MultiBuffer, 0, 2)
+
+	size := buf.New()
+	binary.BigEndian.PutUint16(size.Extend(2), uint16(b.Len()))
+	mb = append(mb, size, b)
+	return w.WriteMultiBuffer(mb)
+}

proxy/dns/config.pb.go

@@ -0,0 +1,69 @@
+package dns
+
+import (
+	fmt "fmt"
+	proto "github.com/golang/protobuf/proto"
+	math "math"
+)
+
+// Reference imports to suppress errors if they are not otherwise used.
+var _ = proto.Marshal
+var _ = fmt.Errorf
+var _ = math.Inf
+
+// This is a compile-time assertion to ensure that this generated file
+// is compatible with the proto package it is being compiled against.
+// A compilation error at this line likely means your copy of the
+// proto package needs to be updated.
+const _ = proto.ProtoPackageIsVersion3 // please upgrade the proto package
+
+type Config struct {
+	XXX_NoUnkeyedLiteral struct{} `json:"-"`
+	XXX_unrecognized     []byte   `json:"-"`
+	XXX_sizecache        int32    `json:"-"`
+}
+
+func (m *Config) Reset()         { *m = Config{} }
+func (m *Config) String() string { return proto.CompactTextString(m) }
+func (*Config) ProtoMessage()    {}
+func (*Config) Descriptor() ([]byte, []int) {
+	return fileDescriptor_c49bb2d51e576d57, []int{0}
+}
+
+func (m *Config) XXX_Unmarshal(b []byte) error {
+	return xxx_messageInfo_Config.Unmarshal(m, b)
+}
+func (m *Config) XXX_Marshal(b []byte, deterministic bool) ([]byte, error) {
+	return xxx_messageInfo_Config.Marshal(b, m, deterministic)
+}
+func (m *Config) XXX_Merge(src proto.Message) {
+	xxx_messageInfo_Config.Merge(m, src)
+}
+func (m *Config) XXX_Size() int {
+	return xxx_messageInfo_Config.Size(m)
+}
+func (m *Config) XXX_DiscardUnknown() {
+	xxx_messageInfo_Config.DiscardUnknown(m)
+}
+
+var xxx_messageInfo_Config proto.InternalMessageInfo
+
+func init() {
+	proto.RegisterType((*Config)(nil), "v2ray.core.proxy.dns.Config")
+}
+
+func init() {
+	proto.RegisterFile("v2ray.com/core/proxy/dns/config.proto", fileDescriptor_c49bb2d51e576d57)
+}
+
+var fileDescriptor_c49bb2d51e576d57 = []byte{
+	// 123 bytes of a gzipped FileDescriptorProto
+	0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0xff, 0xe2, 0x52, 0x2d, 0x33, 0x2a, 0x4a,
+	0xac, 0xd4, 0x4b, 0xce, 0xcf, 0xd5, 0x4f, 0xce, 0x2f, 0x4a, 0xd5, 0x2f, 0x28, 0xca, 0xaf, 0xa8,
+	0xd4, 0x4f, 0xc9, 0x2b, 0xd6, 0x4f, 0xce, 0xcf, 0x4b, 0xcb, 0x4c, 0xd7, 0x2b, 0x28, 0xca, 0x2f,
+	0xc9, 0x17, 0x12, 0x81, 0x29, 0x2b, 0x4a, 0xd5, 0x03, 0x2b, 0xd1, 0x4b, 0xc9, 0x2b, 0x56, 0xe2,
+	0xe0, 0x62, 0x73, 0x06, 0xab, 0x72, 0xb2, 0xe0, 0x92, 0x48, 0xce, 0xcf, 0xd5, 0xc3, 0xa6, 0x2a,
+	0x80, 0x31, 0x8a, 0x39, 0x25, 0xaf, 0x78, 0x15, 0x93, 0x48, 0x98, 0x51, 0x50, 0x62, 0xa5, 0x9e,
+	0x33, 0x48, 0x36, 0x00, 0x2c, 0xeb, 0x92, 0x57, 0x9c, 0xc4, 0x06, 0xb6, 0xc0, 0x18, 0x10, 0x00,
+	0x00, 0xff, 0xff, 0xee, 0x22, 0xde, 0xc9, 0x89, 0x00, 0x00, 0x00,
+}

proxy/dns/config.proto

@@ -0,0 +1,10 @@
+syntax = "proto3";
+
+package v2ray.core.proxy.dns;
+option csharp_namespace = "V2Ray.Core.Proxy.Dns";
+option go_package = "dns";
+option java_package = "com.v2ray.core.proxy.dns";
+option java_multiple_files = true;
+
+message Config {
+}

proxy/dns/dns.go

@@ -0,0 +1,304 @@
+// +build !confonly
+
+package dns
+
+import (
+	"context"
+	"io"
+	"sync"
+
+	"golang.org/x/net/dns/dnsmessage"
+
+	"v2ray.com/core"
+	"v2ray.com/core/common"
+	"v2ray.com/core/common/buf"
+	"v2ray.com/core/common/net"
+	dns_proto "v2ray.com/core/common/protocol/dns"
+	"v2ray.com/core/common/session"
+	"v2ray.com/core/common/task"
+	"v2ray.com/core/features/dns"
+	"v2ray.com/core/transport"
+	"v2ray.com/core/transport/internet"
+)
+
+func init() {
+	common.Must(common.RegisterConfig((*Config)(nil), func(ctx context.Context, config interface{}) (interface{}, error) {
+		h := new(Handler)
+		if err := core.RequireFeatures(ctx, func(dnsClient dns.Client) error {
+			return h.Init(config.(*Config), dnsClient)
+		}); err != nil {
+			return nil, err
+		}
+		return h, nil
+	}))
+}
+
+type ownLinkVerifier interface {
+	IsOwnLink(ctx context.Context) bool
+}
+
+type Handler struct {
+	ipv4Lookup      dns.IPv4Lookup
+	ipv6Lookup      dns.IPv6Lookup
+	ownLinkVerifier ownLinkVerifier
+}
+
+func (h *Handler) Init(config *Config, dnsClient dns.Client) error {
+	ipv4lookup, ok := dnsClient.(dns.IPv4Lookup)
+	if !ok {
+		return newError("dns.Client doesn't implement IPv4Lookup")
+	}
+	h.ipv4Lookup = ipv4lookup
+
+	ipv6lookup, ok := dnsClient.(dns.IPv6Lookup)
+	if !ok {
+		return newError("dns.Client doesn't implement IPv6Lookup")
+	}
+	h.ipv6Lookup = ipv6lookup
+
+	if v, ok := dnsClient.(ownLinkVerifier); ok {
+		h.ownLinkVerifier = v
+	}
+	return nil
+}
+
+func (h *Handler) isOwnLink(ctx context.Context) bool {
+	return h.ownLinkVerifier != nil && h.ownLinkVerifier.IsOwnLink(ctx)
+}
+
+func parseIPQuery(b []byte) (r bool, domain string, id uint16, qType dnsmessage.Type) {
+	var parser dnsmessage.Parser
+	header, err := parser.Start(b)
+	if err != nil {
+		newError("parser start").Base(err).WriteToLog()
+		return
+	}
+
+	id = header.ID
+	q, err := parser.Question()
+	if err != nil {
+		newError("question").Base(err).WriteToLog()
+		return
+	}
+	qType = q.Type
+	if qType != dnsmessage.TypeA && qType != dnsmessage.TypeAAAA {
+		return
+	}
+
+	domain = q.Name.String()
+	r = true
+	return
+}
+
+// Process implements proxy.Outbound.
+func (h *Handler) Process(ctx context.Context, link *transport.Link, d internet.Dialer) error {
+	outbound := session.OutboundFromContext(ctx)
+	if outbound == nil || !outbound.Target.IsValid() {
+		return newError("invalid outbound")
+	}
+
+	dest := outbound.Target
+
+	conn := &outboundConn{
+		dialer: func() (internet.Connection, error) {
+			return d.Dial(ctx, dest)
+		},
+		connReady: make(chan struct{}, 1),
+	}
+
+	var reader dns_proto.MessageReader
+	var writer dns_proto.MessageWriter
+	if dest.Network == net.Network_TCP {
+		reader = dns_proto.NewTCPReader(link.Reader)
+		writer = &dns_proto.TCPWriter{
+			Writer: link.Writer,
+		}
+	} else {
+		reader = &dns_proto.UDPReader{
+			Reader: link.Reader,
+		}
+		writer = &dns_proto.UDPWriter{
+			Writer: link.Writer,
+		}
+	}
+
+	var connReader dns_proto.MessageReader
+	var connWriter dns_proto.MessageWriter
+	if dest.Network == net.Network_TCP {
+		connReader = dns_proto.NewTCPReader(buf.NewReader(conn))
+		connWriter = &dns_proto.TCPWriter{
+			Writer: buf.NewWriter(conn),
+		}
+	} else {
+		connReader = &dns_proto.UDPReader{
+			Reader: &buf.PacketReader{Reader: conn},
+		}
+		connWriter = &dns_proto.UDPWriter{
+			Writer: buf.NewWriter(conn),
+		}
+	}
+
+	request := func() error {
+		defer conn.Close()
+
+		for {
+			b, err := reader.ReadMessage()
+			if err == io.EOF {
+				return nil
+			}
+
+			if err != nil {
+				return err
+			}
+
+			if !h.isOwnLink(ctx) {
+				isIPQuery, domain, id, qType := parseIPQuery(b.Bytes())
+				if isIPQuery {
+					go h.handleIPQuery(id, qType, domain, writer)
+					continue
+				}
+			}
+
+			if err := connWriter.WriteMessage(b); err != nil {
+				return err
+			}
+		}
+	}
+
+	response := func() error {
+		for {
+			b, err := connReader.ReadMessage()
+			if err == io.EOF {
+				return nil
+			}
+
+			if err != nil {
+				return err
+			}
+
+			if err := writer.WriteMessage(b); err != nil {
+				return err
+			}
+		}
+	}
+
+	if err := task.Run(ctx, request, response); err != nil {
+		return newError("connection ends").Base(err)
+	}
+
+	return nil
+}
+
+func (h *Handler) handleIPQuery(id uint16, qType dnsmessage.Type, domain string, writer dns_proto.MessageWriter) {
+	var ips []net.IP
+	var err error
+
+	switch qType {
+	case dnsmessage.TypeA:
+		ips, err = h.ipv4Lookup.LookupIPv4(domain)
+	case dnsmessage.TypeAAAA:
+		ips, err = h.ipv6Lookup.LookupIPv6(domain)
+	}
+
+	if err != nil {
+		newError("ip query").Base(err).WriteToLog()
+		return
+	}
+
+	if len(ips) == 0 {
+		return
+	}
+
+	b := buf.New()
+	rawBytes := b.Extend(buf.Size)
+	builder := dnsmessage.NewBuilder(rawBytes[:0], dnsmessage.Header{
+		ID:    id,
+		RCode: dnsmessage.RCodeSuccess,
+	})
+	builder.StartAnswers()
+
+	rHeader := dnsmessage.ResourceHeader{Name: dnsmessage.MustNewName(domain), Class: dnsmessage.ClassINET, TTL: 600}
+	for _, ip := range ips {
+		if len(ip) == net.IPv4len {
+			var r dnsmessage.AResource
+			copy(r.A[:], ip)
+			builder.AResource(rHeader, r)
+		} else {
+			var r dnsmessage.AAAAResource
+			copy(r.AAAA[:], ip)
+			builder.AAAAResource(rHeader, r)
+		}
+	}
+	msgBytes, err := builder.Finish()
+	if err != nil {
+		newError("pack message").Base(err).WriteToLog()
+		b.Release()
+		return
+	}
+	b.Resize(0, int32(len(msgBytes)))
+
+	if err := writer.WriteMessage(b); err != nil {
+		newError("write IP answer").Base(err).WriteToLog()
+	}
+}
+
+type outboundConn struct {
+	access sync.Mutex
+	dialer func() (internet.Connection, error)
+
+	conn      net.Conn
+	connReady chan struct{}
+}
+
+func (c *outboundConn) dial() error {
+	conn, err := c.dialer()
+	if err != nil {
+		return err
+	}
+	c.conn = conn
+	c.connReady <- struct{}{}
+	return nil
+}
+
+func (c *outboundConn) Write(b []byte) (int, error) {
+	c.access.Lock()
+
+	if c.conn == nil {
+		if err := c.dial(); err != nil {
+			c.access.Unlock()
+			newError("failed to dial outbound connection").Base(err).AtWarning().WriteToLog()
+			return len(b), nil
+		}
+	}
+
+	c.access.Unlock()
+
+	return c.conn.Write(b)
+}
+
+func (c *outboundConn) Read(b []byte) (int, error) {
+	var conn net.Conn
+	c.access.Lock()
+	conn = c.conn
+	c.access.Unlock()
+
+	if conn == nil {
+		_, open := <-c.connReady
+		if !open {
+			return 0, io.EOF
+		}
+		conn = c.conn
+	}
+
+	return conn.Read(b)
+}
+
+func (c *outboundConn) Close() error {
+	c.access.Lock()
+	close(c.connReady)
+	if c.conn != nil {
+		c.conn.Close()
+	}
+	c.access.Unlock()
+	return nil
+}

proxy/dns/dns_test.go

@@ -0,0 +1,238 @@
+package dns_test
+
+import (
+	"strconv"
+	"testing"
+	"time"
+
+	"github.com/google/go-cmp/cmp"
+	"github.com/miekg/dns"
+
+	"v2ray.com/core"
+	"v2ray.com/core/app/dispatcher"
+	dnsapp "v2ray.com/core/app/dns"
+	"v2ray.com/core/app/policy"
+	"v2ray.com/core/app/proxyman"
+	_ "v2ray.com/core/app/proxyman/inbound"
+	_ "v2ray.com/core/app/proxyman/outbound"
+	"v2ray.com/core/common"
+	"v2ray.com/core/common/net"
+	"v2ray.com/core/common/serial"
+	dns_proxy "v2ray.com/core/proxy/dns"
+	"v2ray.com/core/proxy/dokodemo"
+	"v2ray.com/core/testing/servers/tcp"
+	"v2ray.com/core/testing/servers/udp"
+)
+
+type staticHandler struct {
+}
+
+func (*staticHandler) ServeDNS(w dns.ResponseWriter, r *dns.Msg) {
+	ans := new(dns.Msg)
+	ans.Id = r.Id
+
+	var clientIP net.IP
+
+	opt := r.IsEdns0()
+	if opt != nil {
+		for _, o := range opt.Option {
+			if o.Option() == dns.EDNS0SUBNET {
+				subnet := o.(*dns.EDNS0_SUBNET)
+				clientIP = subnet.Address
+			}
+		}
+	}
+
+	for _, q := range r.Question {
+		if q.Name == "google.com." && q.Qtype == dns.TypeA {
+			if clientIP == nil {
+				rr, _ := dns.NewRR("google.com. IN A 8.8.8.8")
+				ans.Answer = append(ans.Answer, rr)
+			} else {
+				rr, _ := dns.NewRR("google.com. IN A 8.8.4.4")
+				ans.Answer = append(ans.Answer, rr)
+			}
+		} else if q.Name == "facebook.com." && q.Qtype == dns.TypeA {
+			rr, _ := dns.NewRR("facebook.com. IN A 9.9.9.9")
+			ans.Answer = append(ans.Answer, rr)
+		} else if q.Name == "ipv6.google.com." && q.Qtype == dns.TypeA {
+			rr, err := dns.NewRR("ipv6.google.com. IN A 8.8.8.7")
+			common.Must(err)
+			ans.Answer = append(ans.Answer, rr)
+		} else if q.Name == "ipv6.google.com." && q.Qtype == dns.TypeAAAA {
+			rr, err := dns.NewRR("ipv6.google.com. IN AAAA 2001:4860:4860::8888")
+			common.Must(err)
+			ans.Answer = append(ans.Answer, rr)
+		}
+	}
+	w.WriteMsg(ans)
+}
+
+func TestUDPDNSTunnel(t *testing.T) {
+	port := udp.PickPort()
+
+	dnsServer := dns.Server{
+		Addr:    "127.0.0.1:" + port.String(),
+		Net:     "udp",
+		Handler: &staticHandler{},
+		UDPSize: 1200,
+	}
+	defer dnsServer.Shutdown()
+
+	go dnsServer.ListenAndServe()
+	time.Sleep(time.Second)
+
+	serverPort := udp.PickPort()
+	config := &core.Config{
+		App: []*serial.TypedMessage{
+			serial.ToTypedMessage(&dnsapp.Config{
+				NameServers: []*net.Endpoint{
+					{
+						Network: net.Network_UDP,
+						Address: &net.IPOrDomain{
+							Address: &net.IPOrDomain_Ip{
+								Ip: []byte{127, 0, 0, 1},
+							},
+						},
+						Port: uint32(port),
+					},
+				},
+			}),
+			serial.ToTypedMessage(&dispatcher.Config{}),
+			serial.ToTypedMessage(&proxyman.OutboundConfig{}),
+			serial.ToTypedMessage(&proxyman.InboundConfig{}),
+			serial.ToTypedMessage(&policy.Config{}),
+		},
+		Inbound: []*core.InboundHandlerConfig{
+			{
+				ProxySettings: serial.ToTypedMessage(&dokodemo.Config{
+					Address:  net.NewIPOrDomain(net.LocalHostIP),
+					Port:     uint32(port),
+					Networks: []net.Network{net.Network_UDP},
+				}),
+				ReceiverSettings: serial.ToTypedMessage(&proxyman.ReceiverConfig{
+					PortRange: net.SinglePortRange(serverPort),
+					Listen:    net.NewIPOrDomain(net.LocalHostIP),
+				}),
+			},
+		},
+		Outbound: []*core.OutboundHandlerConfig{
+			{
+				ProxySettings: serial.ToTypedMessage(&dns_proxy.Config{}),
+			},
+		},
+	}
+
+	v, err := core.New(config)
+	common.Must(err)
+	common.Must(v.Start())
+	defer v.Close()
+
+	m1 := new(dns.Msg)
+	m1.Id = dns.Id()
+	m1.RecursionDesired = true
+	m1.Question = make([]dns.Question, 1)
+	m1.Question[0] = dns.Question{"google.com.", dns.TypeA, dns.ClassINET}
+
+	c := new(dns.Client)
+	in, _, err := c.Exchange(m1, "127.0.0.1:"+strconv.Itoa(int(serverPort)))
+	common.Must(err)
+
+	if len(in.Answer) != 1 {
+		t.Fatal("len(answer): ", len(in.Answer))
+	}
+
+	rr, ok := in.Answer[0].(*dns.A)
+	if !ok {
+		t.Fatal("not A record")
+	}
+	if r := cmp.Diff(rr.A[:], net.IP{8, 8, 8, 8}); r != "" {
+		t.Error(r)
+	}
+}
+
+func TestTCPDNSTunnel(t *testing.T) {
+	port := udp.PickPort()
+
+	dnsServer := dns.Server{
+		Addr:    "127.0.0.1:" + port.String(),
+		Net:     "udp",
+		Handler: &staticHandler{},
+	}
+	defer dnsServer.Shutdown()
+
+	go dnsServer.ListenAndServe()
+	time.Sleep(time.Second)
+
+	serverPort := tcp.PickPort()
+	config := &core.Config{
+		App: []*serial.TypedMessage{
+			serial.ToTypedMessage(&dnsapp.Config{
+				NameServer: []*dnsapp.NameServer{
+					{
+						Address: &net.Endpoint{
+							Network: net.Network_UDP,
+							Address: &net.IPOrDomain{
+								Address: &net.IPOrDomain_Ip{
+									Ip: []byte{127, 0, 0, 1},
+								},
+							},
+							Port: uint32(port),
+						},
+					},
+				},
+			}),
+			serial.ToTypedMessage(&dispatcher.Config{}),
+			serial.ToTypedMessage(&proxyman.OutboundConfig{}),
+			serial.ToTypedMessage(&proxyman.InboundConfig{}),
+			serial.ToTypedMessage(&policy.Config{}),
+		},
+		Inbound: []*core.InboundHandlerConfig{
+			{
+				ProxySettings: serial.ToTypedMessage(&dokodemo.Config{
+					Address:  net.NewIPOrDomain(net.LocalHostIP),
+					Port:     uint32(port),
+					Networks: []net.Network{net.Network_TCP},
+				}),
+				ReceiverSettings: serial.ToTypedMessage(&proxyman.ReceiverConfig{
+					PortRange: net.SinglePortRange(serverPort),
+					Listen:    net.NewIPOrDomain(net.LocalHostIP),
+				}),
+			},
+		},
+		Outbound: []*core.OutboundHandlerConfig{
+			{
+				ProxySettings: serial.ToTypedMessage(&dns_proxy.Config{}),
+			},
+		},
+	}
+
+	v, err := core.New(config)
+	common.Must(err)
+	common.Must(v.Start())
+	defer v.Close()
+
+	m1 := new(dns.Msg)
+	m1.Id = dns.Id()
+	m1.RecursionDesired = true
+	m1.Question = make([]dns.Question, 1)
+	m1.Question[0] = dns.Question{"google.com.", dns.TypeA, dns.ClassINET}
+
+	c := &dns.Client{
+		Net: "tcp",
+	}
+	in, _, err := c.Exchange(m1, "127.0.0.1:"+serverPort.String())
+	common.Must(err)
+
+	if len(in.Answer) != 1 {
+		t.Fatal("len(answer): ", len(in.Answer))
+	}
+
+	rr, ok := in.Answer[0].(*dns.A)
+	if !ok {
+		t.Fatal("not A record")
+	}
+	if r := cmp.Diff(rr.A[:], net.IP{8, 8, 8, 8}); r != "" {
+		t.Error(r)
+	}
+}

proxy/dns/errors.generated.go

@@ -0,0 +1,9 @@
+package dns
+
+import "v2ray.com/core/common/errors"
+
+type errPathObjHolder struct{}
+
+func newError(values ...interface{}) *errors.Error {
+	return errors.New(values...).WithPathObj(errPathObjHolder{})
+}