Custom sessionID

infra/conf/transport_internet.go

@@ -6,6 +6,7 @@ import (
 	"encoding/hex"
 	"encoding/json"
 	"math"
+	"math/big"
 	"net/netip"
 	"net/url"
 	"os"
@@ -233,6 +234,8 @@ type SplitHTTPConfig struct {
 	ScMaxBufferedPosts   int64             `json:"scMaxBufferedPosts"`
 	ScStreamUpServerSecs Int32Range        `json:"scStreamUpServerSecs"`
 	ServerMaxHeaderBytes int32             `json:"serverMaxHeaderBytes"`
+	SessionIDTable       string            `json:"sessionIDTable"`
+	SessionIDLength      Int32Range        `json:"sessionIDLength"`
 	Xmux                 XmuxConfig        `json:"xmux"`
 	DownloadSettings     *StreamConfig     `json:"downloadSettings"`
 	Extra                json.RawMessage   `json:"extra"`
@@ -378,6 +381,25 @@ func (c *SplitHTTPConfig) Build() (proto.Message, error) {
 		return nil, errors.New("invalid negative value of maxHeaderBytes")
 	}
 
+	if c.SessionIDTable != "" {
+		if predefined, ok := splithttp.PredefinedTable[c.SessionIDTable]; ok {
+			c.SessionIDTable = predefined
+		}
+		room := roomSize(len(c.SessionIDTable), c.SessionIDLength.From, c.SessionIDLength.To)
+		// 2.1B possiblities should be enough
+		if room.Cmp(big.NewInt(2<<30)) < 0 {
+			return nil, errors.New("sessionIDTable or sessionIDLength is too small")
+		}
+		if c.SessionIDLength.From <= 0 {
+			return nil, errors.New("sessionIDLength.from must be greater than 0")
+		}
+		for i := 0; i < len(c.SessionIDTable); i++ {
+			if c.SessionIDTable[i] >= 0x80 {
+				return nil, errors.New("sessionIDTable must contain only ASCII characters")
+			}
+		}
+	}
+
 	if c.Xmux.MaxConnections.To > 0 && c.Xmux.MaxConcurrency.To > 0 {
 		return nil, errors.New("maxConnections cannot be specified together with maxConcurrency")
 	}
@@ -416,6 +438,8 @@ func (c *SplitHTTPConfig) Build() (proto.Message, error) {
 		ScMaxBufferedPosts:   c.ScMaxBufferedPosts,
 		ScStreamUpServerSecs: newRangeConfig(c.ScStreamUpServerSecs),
 		ServerMaxHeaderBytes: c.ServerMaxHeaderBytes,
+		SessionIDTable:       c.SessionIDTable,
+		SessionIDLength:      newRangeConfig(c.SessionIDLength),
 		Xmux: &splithttp.XmuxConfig{
 			MaxConcurrency:   newRangeConfig(c.Xmux.MaxConcurrency),
 			MaxConnections:   newRangeConfig(c.Xmux.MaxConnections),
@@ -439,6 +463,17 @@ func (c *SplitHTTPConfig) Build() (proto.Message, error) {
 	return config, nil
 }
 
+func roomSize(tableSize int, min, max int32) *big.Int {
+	base := big.NewInt(int64(tableSize))
+	sum := new(big.Int)
+	term := new(big.Int)
+	for k := min; k <= max; k++ {
+		term.Exp(base, big.NewInt(int64(k)), nil)
+		sum.Add(sum, term)
+	}
+	return sum
+}
+
 const (
 	Byte     = 1
 	Kilobyte = 1024 * Byte

transport/internet/splithttp/config.go

@@ -4,13 +4,15 @@ import (
 	"encoding/base64"
 	"fmt"
 	"io"
+	"math/rand/v2"
 	"net/http"
 	"strings"
 
 	"github.com/xtls/xray-core/common"
 	"github.com/xtls/xray-core/common/buf"
 	"github.com/xtls/xray-core/common/crypto"
 	"github.com/xtls/xray-core/common/utils"
+	"github.com/xtls/xray-core/common/uuid"
 	"github.com/xtls/xray-core/transport/internet"
 )
 
@@ -131,26 +133,26 @@ func (c *Config) GetNormalizedUplinkHTTPMethod() string {
 	return c.UplinkHTTPMethod
 }
 
-func (c *Config) GetNormalizedScMaxEachPostBytes() RangeConfig {
+func (c *Config) GetNormalizedScMaxEachPostBytes() *RangeConfig {
 	if c.ScMaxEachPostBytes == nil || c.ScMaxEachPostBytes.To == 0 {
-		return RangeConfig{
+		return &RangeConfig{
 			From: 1000000,
 			To:   1000000,
 		}
 	}
 
-	return *c.ScMaxEachPostBytes
+	return c.ScMaxEachPostBytes
 }
 
-func (c *Config) GetNormalizedScMinPostsIntervalMs() RangeConfig {
+func (c *Config) GetNormalizedScMinPostsIntervalMs() *RangeConfig {
 	if c.ScMinPostsIntervalMs == nil || c.ScMinPostsIntervalMs.To == 0 {
-		return RangeConfig{
+		return &RangeConfig{
 			From: 30,
 			To:   30,
 		}
 	}
 
-	return *c.ScMinPostsIntervalMs
+	return c.ScMinPostsIntervalMs
 }
 
 func (c *Config) GetNormalizedScMaxBufferedPosts() int {
@@ -161,41 +163,41 @@ func (c *Config) GetNormalizedScMaxBufferedPosts() int {
 	return int(c.ScMaxBufferedPosts)
 }
 
-func (c *Config) GetNormalizedScStreamUpServerSecs() RangeConfig {
+func (c *Config) GetNormalizedScStreamUpServerSecs() *RangeConfig {
 	if c.ScStreamUpServerSecs == nil || c.ScStreamUpServerSecs.To == 0 {
-		return RangeConfig{
+		return &RangeConfig{
 			From: 20,
 			To:   80,
 		}
 	}
 
-	return *c.ScStreamUpServerSecs
+	return c.ScStreamUpServerSecs
 }
 
-func (c *Config) GetNormalizedUplinkChunkSize() RangeConfig {
+func (c *Config) GetNormalizedUplinkChunkSize() *RangeConfig {
 	if c.UplinkChunkSize == nil || c.UplinkChunkSize.To == 0 {
 		switch c.UplinkDataPlacement {
 		case PlacementCookie:
-			return RangeConfig{
+			return &RangeConfig{
 				From: 2 * 1024, // 2 KiB
 				To:   3 * 1024, // 3 KiB
 			}
 		case PlacementHeader:
-			return RangeConfig{
+			return &RangeConfig{
 				From: 3 * 1000, // 3 KB
 				To:   4 * 1000, // 4 KB
 			}
 		default:
 			return c.GetNormalizedScMaxEachPostBytes()
 		}
 	} else if c.UplinkChunkSize.From < 64 {
-		return RangeConfig{
+		return &RangeConfig{
 			From: 64,
 			To:   max(64, c.UplinkChunkSize.To),
 		}
 	}
 
-	return *c.UplinkChunkSize
+	return c.UplinkChunkSize
 }
 
 func (c *Config) GetNormalizedServerMaxHeaderBytes() int {
@@ -417,59 +419,59 @@ func (c *Config) ExtractMetaFromRequest(req *http.Request, path string) (session
 	return sessionId, seqStr
 }
 
-func (m *XmuxConfig) GetNormalizedMaxConcurrency() RangeConfig {
+func (m *XmuxConfig) GetNormalizedMaxConcurrency() *RangeConfig {
 	if m.MaxConcurrency == nil {
-		return RangeConfig{
+		return &RangeConfig{
 			From: 0,
 			To:   0,
 		}
 	}
 
-	return *m.MaxConcurrency
+	return m.MaxConcurrency
 }
 
-func (m *XmuxConfig) GetNormalizedMaxConnections() RangeConfig {
+func (m *XmuxConfig) GetNormalizedMaxConnections() *RangeConfig {
 	if m.MaxConnections == nil {
-		return RangeConfig{
+		return &RangeConfig{
 			From: 0,
 			To:   0,
 		}
 	}
 
-	return *m.MaxConnections
+	return m.MaxConnections
 }
 
-func (m *XmuxConfig) GetNormalizedCMaxReuseTimes() RangeConfig {
+func (m *XmuxConfig) GetNormalizedCMaxReuseTimes() *RangeConfig {
 	if m.CMaxReuseTimes == nil {
-		return RangeConfig{
+		return &RangeConfig{
 			From: 0,
 			To:   0,
 		}
 	}
 
-	return *m.CMaxReuseTimes
+	return m.CMaxReuseTimes
 }
 
-func (m *XmuxConfig) GetNormalizedHMaxRequestTimes() RangeConfig {
+func (m *XmuxConfig) GetNormalizedHMaxRequestTimes() *RangeConfig {
 	if m.HMaxRequestTimes == nil {
-		return RangeConfig{
+		return &RangeConfig{
 			From: 0,
 			To:   0,
 		}
 	}
 
-	return *m.HMaxRequestTimes
+	return m.HMaxRequestTimes
 }
 
-func (m *XmuxConfig) GetNormalizedHMaxReusableSecs() RangeConfig {
+func (m *XmuxConfig) GetNormalizedHMaxReusableSecs() *RangeConfig {
 	if m.HMaxReusableSecs == nil {
-		return RangeConfig{
+		return &RangeConfig{
 			From: 0,
 			To:   0,
 		}
 	}
 
-	return *m.HMaxReusableSecs
+	return m.HMaxReusableSecs
 }
 
 func init() {
@@ -478,10 +480,44 @@ func init() {
 	}))
 }
 
-func (c RangeConfig) rand() int32 {
+func (c *RangeConfig) rand() int32 {
+	if c == nil {
+		return 0
+	}
 	return int32(crypto.RandBetween(int64(c.From), int64(c.To)))
 }
 
+// predefined
+var PredefinedTable = map[string]string{
+	"ALPHABET": "ABCDEFGHIJKLMNOPQRSTUVWXYZ",
+	"Alphabet": "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz",
+	"BASE36":   "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ",
+	"Base62":   "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz",
+	"HEX":      "0123456789ABCDEF",
+	"alphabet": "abcdefghijklmnopqrstuvwxyz",
+	"base36":   "0123456789abcdefghijklmnopqrstuvwxyz",
+	"hex":      "0123456789abcdef",
+	"number":   "0123456789",
+}
+
+func (c *Config) GenerateSessionID() string {
+	length := c.SessionIDLength.rand()
+	table := c.SessionIDTable
+	if predefined, ok := PredefinedTable[table]; ok {
+		table = predefined
+	}
+	if table != "" && length > 0 {
+		id := make([]byte, length)
+		for i := range id {
+			id[i] = table[rand.N(len(table))]
+		}
+		return string(id)
+	} else {
+		uuid := uuid.New()
+		return uuid.String()
+	}
+}
+
 func appendToPath(path, value string) string {
 	if strings.HasSuffix(path, "/") {
 		return path + value

transport/internet/splithttp/config.proto

@@ -50,4 +50,6 @@ message Config {
   string uplinkDataKey = 25;
   RangeConfig uplinkChunkSize = 26;
   int32 serverMaxHeaderBytes = 27;
+  string sessionIDTable = 28;
+  RangeConfig sessionIDLength = 29;
 }

transport/internet/splithttp/dialer.go

@@ -24,7 +24,6 @@ import (
 	"github.com/xtls/xray-core/common/net"
 	"github.com/xtls/xray-core/common/net/cnc"
 	"github.com/xtls/xray-core/common/signal/done"
-	"github.com/xtls/xray-core/common/uuid"
 	"github.com/xtls/xray-core/transport/internet"
 	"github.com/xtls/xray-core/transport/internet/browser_dialer"
 	"github.com/xtls/xray-core/transport/internet/hysteria/congestion"
@@ -376,8 +375,7 @@ func Dial(ctx context.Context, dest net.Destination, streamSettings *internet.Me
 
 	sessionId := ""
 	if mode != "stream-one" {
-		sessionIdUuid := uuid.New()
-		sessionId = sessionIdUuid.String()
+		sessionId = transportConfiguration.GenerateSessionID()
 	}
 
 	errors.LogInfo(ctx, fmt.Sprintf("XHTTP is dialing to %s, mode %s, HTTP version %s, host %s", dest, mode, httpVersion, requestURL.Host))