Finalmask: Add mkcp-legacy (UDP) to replace mkcp-* and legacy header-* (#6201)

https://github.com/XTLS/Xray-core/pull/6193#issuecomment-4543737699

https://github.com/XTLS/Xray-core/pull/6201#issuecomment-4574213827

Example: https://github.com/XTLS/Xray-core/pull/6201#issue-4525483699

transport/internet/finalmask/mkcp/header/config.go

@@ -0,0 +1,17 @@
+package header
+
+import (
+	"net"
+)
+
+func (c *Config) UDP() {}
+
+func (c *Config) HeaderConn() {}
+
+func (c *Config) WrapPacketConnClient(raw net.PacketConn, level int, levelCount int) (net.PacketConn, error) {
+	return NewConnClient(c, raw)
+}
+
+func (c *Config) WrapPacketConnServer(raw net.PacketConn, level int, levelCount int) (net.PacketConn, error) {
+	return NewConnServer(c, raw)
+}

transport/internet/finalmask/mkcp/header/config.pb.go

@@ -0,0 +1,132 @@
+// Code generated by protoc-gen-go. DO NOT EDIT.
+// versions:
+// 	protoc-gen-go v1.36.11
+// 	protoc        v6.33.5
+// source: transport/internet/finalmask/mkcp/header/config.proto
+
+package header
+
+import (
+	protoreflect "google.golang.org/protobuf/reflect/protoreflect"
+	protoimpl "google.golang.org/protobuf/runtime/protoimpl"
+	reflect "reflect"
+	sync "sync"
+	unsafe "unsafe"
+)
+
+const (
+	// Verify that this generated code is sufficiently up-to-date.
+	_ = protoimpl.EnforceVersion(20 - protoimpl.MinVersion)
+	// Verify that runtime/protoimpl is sufficiently up-to-date.
+	_ = protoimpl.EnforceVersion(protoimpl.MaxVersion - 20)
+)
+
+type Config struct {
+	state         protoimpl.MessageState `protogen:"open.v1"`
+	ID            int32                  `protobuf:"varint,1,opt,name=ID,proto3" json:"ID,omitempty"`
+	Domain        string                 `protobuf:"bytes,2,opt,name=domain,proto3" json:"domain,omitempty"`
+	unknownFields protoimpl.UnknownFields
+	sizeCache     protoimpl.SizeCache
+}
+
+func (x *Config) Reset() {
+	*x = Config{}
+	mi := &file_transport_internet_finalmask_mkcp_header_config_proto_msgTypes[0]
+	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+	ms.StoreMessageInfo(mi)
+}
+
+func (x *Config) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*Config) ProtoMessage() {}
+
+func (x *Config) ProtoReflect() protoreflect.Message {
+	mi := &file_transport_internet_finalmask_mkcp_header_config_proto_msgTypes[0]
+	if x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use Config.ProtoReflect.Descriptor instead.
+func (*Config) Descriptor() ([]byte, []int) {
+	return file_transport_internet_finalmask_mkcp_header_config_proto_rawDescGZIP(), []int{0}
+}
+
+func (x *Config) GetID() int32 {
+	if x != nil {
+		return x.ID
+	}
+	return 0
+}
+
+func (x *Config) GetDomain() string {
+	if x != nil {
+		return x.Domain
+	}
+	return ""
+}
+
+var File_transport_internet_finalmask_mkcp_header_config_proto protoreflect.FileDescriptor
+
+const file_transport_internet_finalmask_mkcp_header_config_proto_rawDesc = "" +
+	"\n" +
+	"5transport/internet/finalmask/mkcp/header/config.proto\x12-xray.transport.internet.finalmask.mkcp.header\"0\n" +
+	"\x06Config\x12\x0e\n" +
+	"\x02ID\x18\x01 \x01(\x05R\x02ID\x12\x16\n" +
+	"\x06domain\x18\x02 \x01(\tR\x06domainB\xa9\x01\n" +
+	"1com.xray.transport.internet.finalmask.mkcp.headerP\x01ZBgithub.com/xtls/xray-core/transport/internet/finalmask/mkcp/header\xaa\x02-Xray.Transport.Internet.Finalmask.Mkcp.Headerb\x06proto3"
+
+var (
+	file_transport_internet_finalmask_mkcp_header_config_proto_rawDescOnce sync.Once
+	file_transport_internet_finalmask_mkcp_header_config_proto_rawDescData []byte
+)
+
+func file_transport_internet_finalmask_mkcp_header_config_proto_rawDescGZIP() []byte {
+	file_transport_internet_finalmask_mkcp_header_config_proto_rawDescOnce.Do(func() {
+		file_transport_internet_finalmask_mkcp_header_config_proto_rawDescData = protoimpl.X.CompressGZIP(unsafe.Slice(unsafe.StringData(file_transport_internet_finalmask_mkcp_header_config_proto_rawDesc), len(file_transport_internet_finalmask_mkcp_header_config_proto_rawDesc)))
+	})
+	return file_transport_internet_finalmask_mkcp_header_config_proto_rawDescData
+}
+
+var file_transport_internet_finalmask_mkcp_header_config_proto_msgTypes = make([]protoimpl.MessageInfo, 1)
+var file_transport_internet_finalmask_mkcp_header_config_proto_goTypes = []any{
+	(*Config)(nil), // 0: xray.transport.internet.finalmask.mkcp.header.Config
+}
+var file_transport_internet_finalmask_mkcp_header_config_proto_depIdxs = []int32{
+	0, // [0:0] is the sub-list for method output_type
+	0, // [0:0] is the sub-list for method input_type
+	0, // [0:0] is the sub-list for extension type_name
+	0, // [0:0] is the sub-list for extension extendee
+	0, // [0:0] is the sub-list for field type_name
+}
+
+func init() { file_transport_internet_finalmask_mkcp_header_config_proto_init() }
+func file_transport_internet_finalmask_mkcp_header_config_proto_init() {
+	if File_transport_internet_finalmask_mkcp_header_config_proto != nil {
+		return
+	}
+	type x struct{}
+	out := protoimpl.TypeBuilder{
+		File: protoimpl.DescBuilder{
+			GoPackagePath: reflect.TypeOf(x{}).PkgPath(),
+			RawDescriptor: unsafe.Slice(unsafe.StringData(file_transport_internet_finalmask_mkcp_header_config_proto_rawDesc), len(file_transport_internet_finalmask_mkcp_header_config_proto_rawDesc)),
+			NumEnums:      0,
+			NumMessages:   1,
+			NumExtensions: 0,
+			NumServices:   0,
+		},
+		GoTypes:           file_transport_internet_finalmask_mkcp_header_config_proto_goTypes,
+		DependencyIndexes: file_transport_internet_finalmask_mkcp_header_config_proto_depIdxs,
+		MessageInfos:      file_transport_internet_finalmask_mkcp_header_config_proto_msgTypes,
+	}.Build()
+	File_transport_internet_finalmask_mkcp_header_config_proto = out.File
+	file_transport_internet_finalmask_mkcp_header_config_proto_goTypes = nil
+	file_transport_internet_finalmask_mkcp_header_config_proto_depIdxs = nil
+}

transport/internet/finalmask/mkcp/header/config.proto

@@ -0,0 +1,12 @@
+syntax = "proto3";
+
+package xray.transport.internet.finalmask.mkcp.header;
+option csharp_namespace = "Xray.Transport.Internet.Finalmask.Mkcp.Header";
+option go_package = "github.com/xtls/xray-core/transport/internet/finalmask/mkcp/header";
+option java_package = "com.xray.transport.internet.finalmask.mkcp.header";
+option java_multiple_files = true;
+
+message Config {
+    int32 ID = 1;
+    string domain = 2;
+}

transport/internet/finalmask/mkcp/header/conn.go

@@ -0,0 +1,57 @@
+package header
+
+import (
+	"net"
+
+	"github.com/xtls/xray-core/common/errors"
+)
+
+type headerConn struct {
+	net.PacketConn
+	header Header
+}
+
+func NewConnClient(c *Config, raw net.PacketConn) (net.PacketConn, error) {
+	var header Header
+	switch HeaderID(c.ID) {
+	case DNS:
+		var err error
+		header, err = NewHeaderDNS(c.Domain)
+		if err != nil {
+			return nil, err
+		}
+	case DTLS:
+		header = &dtls{}
+	case SRTP:
+		header = &srtp{}
+	case UTP:
+		header = &utp{}
+	case WECHAT:
+		header = &wechat{}
+	case WIREGUARD:
+		header = &wireguard{}
+	default:
+		return nil, errors.New("invalid id ", c.ID)
+	}
+	return &headerConn{
+		PacketConn: raw,
+		header:     header,
+	}, nil
+}
+
+func NewConnServer(c *Config, raw net.PacketConn) (net.PacketConn, error) {
+	return NewConnClient(c, raw)
+}
+
+func (c *headerConn) Size() int {
+	return c.header.Size()
+}
+
+func (c *headerConn) ReadFrom(p []byte) (n int, addr net.Addr, err error) {
+	return len(p) - c.header.Size(), nil, nil
+}
+
+func (c *headerConn) WriteTo(p []byte, addr net.Addr) (n int, err error) {
+	c.header.Serialize(p)
+	return len(p), nil
+}

transport/internet/finalmask/mkcp/header/header.go

@@ -0,0 +1,17 @@
+package header
+
+type Header interface {
+	Size() int
+	Serialize(b []byte)
+}
+
+type HeaderID int
+
+const (
+	DNS HeaderID = iota
+	DTLS
+	SRTP
+	UTP
+	WECHAT
+	WIREGUARD
+)

transport/internet/finalmask/mkcp/header/header_dns.go

@@ -0,0 +1,106 @@
+package header
+
+import (
+	"encoding/binary"
+	"errors"
+
+	"github.com/xtls/xray-core/common/dice"
+)
+
+type dns struct {
+	header []byte
+}
+
+func (h *dns) Size() int {
+	return len(h.header)
+}
+
+func (h *dns) Serialize(b []byte) {
+	copy(b, h.header)
+	binary.BigEndian.PutUint16(b[0:], dice.RollUint16())
+}
+
+func NewHeaderDNS(domain string) (*dns, error) {
+	var header []byte
+	header = binary.BigEndian.AppendUint16(header, 0x0000) // Transaction ID
+	header = binary.BigEndian.AppendUint16(header, 0x0100) // Flags: Standard query
+	header = binary.BigEndian.AppendUint16(header, 0x0001) // Questions
+	header = binary.BigEndian.AppendUint16(header, 0x0000) // Answer RRs
+	header = binary.BigEndian.AppendUint16(header, 0x0000) // Authority RRs
+	header = binary.BigEndian.AppendUint16(header, 0x0000) // Additional RRs
+	buf := make([]byte, 0x100)
+	off1, err := packDomainName(domain+".", buf)
+	if err != nil {
+		return nil, err
+	}
+	header = append(header, buf[:off1]...)
+	header = binary.BigEndian.AppendUint16(header, 0x0001) // Type: A
+	header = binary.BigEndian.AppendUint16(header, 0x0001) // Class: IN
+	return &dns{header: header}, nil
+}
+
+func packDomainName(s string, msg []byte) (off1 int, err error) {
+	off := 0
+	ls := len(s)
+	// Each dot ends a segment of the name.
+	// We trade each dot byte for a length byte.
+	// Except for escaped dots (\.), which are normal dots.
+	// There is also a trailing zero.
+
+	// Emit sequence of counted strings, chopping at dots.
+	var (
+		begin int
+		bs    []byte
+	)
+	for i := 0; i < ls; i++ {
+		var c byte
+		if bs == nil {
+			c = s[i]
+		} else {
+			c = bs[i]
+		}
+
+		switch c {
+		case '\\':
+			if off+1 > len(msg) {
+				return len(msg), errors.New("buffer size too small")
+			}
+
+			if bs == nil {
+				bs = []byte(s)
+			}
+
+			copy(bs[i:ls-1], bs[i+1:])
+			ls--
+		case '.':
+			labelLen := i - begin
+			if labelLen >= 1<<6 { // top two bits of length must be clear
+				return len(msg), errors.New("bad rdata")
+			}
+
+			// off can already (we're in a loop) be bigger than len(msg)
+			// this happens when a name isn't fully qualified
+			if off+1+labelLen > len(msg) {
+				return len(msg), errors.New("buffer size too small")
+			}
+
+			// The following is covered by the length check above.
+			msg[off] = byte(labelLen)
+
+			if bs == nil {
+				copy(msg[off+1:], s[begin:i])
+			} else {
+				copy(msg[off+1:], bs[begin:i])
+			}
+			off += 1 + labelLen
+			begin = i + 1
+		default:
+		}
+	}
+
+	if off < len(msg) {
+		msg[off] = 0
+	}
+
+	return off + 1, nil
+}

transport/internet/finalmask/mkcp/header/header_dtls.go

@@ -0,0 +1,32 @@
+package header
+
+type dtls struct {
+	epoch    uint16
+	length   uint16
+	sequence uint32
+}
+
+func (*dtls) Size() int {
+	return 1 + 2 + 2 + 6 + 2
+}
+
+func (h *dtls) Serialize(b []byte) {
+	b[0] = 23
+	b[1] = 254
+	b[2] = 253
+	b[3] = byte(h.epoch >> 8)
+	b[4] = byte(h.epoch)
+	b[5] = 0
+	b[6] = 0
+	b[7] = byte(h.sequence >> 24)
+	b[8] = byte(h.sequence >> 16)
+	b[9] = byte(h.sequence >> 8)
+	b[10] = byte(h.sequence)
+	h.sequence++
+	b[11] = byte(h.length >> 8)
+	b[12] = byte(h.length)
+	h.length += 17
+	if h.length > 100 {
+		h.length -= 50
+	}
+}

transport/internet/finalmask/mkcp/header/header_srtp.go

@@ -0,0 +1,18 @@
+package header
+
+import "encoding/binary"
+
+type srtp struct {
+	header uint16
+	number uint16
+}
+
+func (*srtp) Size() int {
+	return 4
+}
+
+func (h *srtp) Serialize(b []byte) {
+	h.number++
+	binary.BigEndian.PutUint16(b, h.header)
+	binary.BigEndian.PutUint16(b[2:], h.number)
+}

transport/internet/finalmask/mkcp/header/header_utp.go

@@ -0,0 +1,19 @@
+package header
+
+import "encoding/binary"
+
+type utp struct {
+	header       byte
+	extension    byte
+	connectionID uint16
+}
+
+func (*utp) Size() int {
+	return 4
+}
+
+func (h *utp) Serialize(b []byte) {
+	binary.BigEndian.PutUint16(b, h.connectionID)
+	b[2] = h.header
+	b[3] = h.extension
+}

transport/internet/finalmask/mkcp/header/header_wechat.go

@@ -0,0 +1,25 @@
+package header
+
+import "encoding/binary"
+
+type wechat struct {
+	sn uint32
+}
+
+func (*wechat) Size() int {
+	return 13
+}
+
+func (h *wechat) Serialize(b []byte) {
+	h.sn++
+	b[0] = 0xa1
+	b[1] = 0x08
+	binary.BigEndian.PutUint32(b[2:], h.sn)
+	b[6] = 0x00
+	b[7] = 0x10
+	b[8] = 0x11
+	b[9] = 0x18
+	b[10] = 0x30
+	b[11] = 0x22
+	b[12] = 0x30
+}

transport/internet/finalmask/mkcp/header/header_wireguard.go

@@ -0,0 +1,14 @@
+package header
+
+type wireguard struct{}
+
+func (*wireguard) Size() int {
+	return 4
+}
+
+func (h *wireguard) Serialize(b []byte) {
+	b[0] = 0x04
+	b[1] = 0x00
+	b[2] = 0x00
+	b[3] = 0x00
+}