SplitHTTP client: Add minUploadInterval (#3592)

Author: mmmray

infra/conf/common.go

@@ -2,6 +2,7 @@ package conf
 
 import (
 	"encoding/json"
+	"strconv"
 	"strings"
 
 	"github.com/xtls/xray-core/common/errors"
@@ -242,3 +243,33 @@ func (v *User) Build() *protocol.User {
 		Level: uint32(v.LevelByte),
 	}
 }
+
+// Int32Range deserializes from "1-2" or 1, so can deserialize from both int and number.
+// Negative integers can be passed as sentinel values, but do not parse as ranges.
+type Int32Range struct {
+	From int32
+	To   int32
+}
+
+func (v *Int32Range) UnmarshalJSON(data []byte) error {
+	var stringrange string
+	var rawint int32
+	if err := json.Unmarshal(data, &stringrange); err == nil {
+		pair := strings.SplitN(stringrange, "-", 2)
+		if len(pair) == 2 {
+			from, err := strconv.Atoi(pair[0])
+			to, err2 := strconv.Atoi(pair[1])
+			if err == nil && err2 == nil {
+				v.From = int32(from)
+				v.To = int32(to)
+				return nil
+			}
+		}
+	} else if err := json.Unmarshal(data, &rawint); err == nil {
+		v.From = rawint
+		v.To = rawint
+		return nil
+	}
+
+	return errors.New("Invalid integer range, expected either string of form \"1-2\" or plain integer.")
+}

infra/conf/transport_internet.go

@@ -231,6 +231,7 @@ type SplitHTTPConfig struct {
 	Headers              map[string]string `json:"headers"`
 	MaxConcurrentUploads int32             `json:"maxConcurrentUploads"`
 	MaxUploadSize        int32             `json:"maxUploadSize"`
+	MinUploadIntervalMs  Int32Range        `json:"minUploadIntervalMs"`
 }
 
 // Build implements Buildable.
@@ -249,6 +250,10 @@ func (c *SplitHTTPConfig) Build() (proto.Message, error) {
 		Header:               c.Headers,
 		MaxConcurrentUploads: c.MaxConcurrentUploads,
 		MaxUploadSize:        c.MaxUploadSize,
+		MinUploadIntervalMs: &splithttp.RandRangeConfig{
+			From: c.MinUploadIntervalMs.From,
+			To:   c.MinUploadIntervalMs.To,
+		},
 	}
 	return config, nil
 }

transport/internet/splithttp/config.go

@@ -1,6 +1,8 @@
 package splithttp
 
 import (
+	"crypto/rand"
+	"math/big"
 	"net/http"
 
 	"github.com/xtls/xray-core/common"
@@ -45,8 +47,29 @@ func (c *Config) GetNormalizedMaxUploadSize() int32 {
 	return c.MaxUploadSize
 }
 
+func (c *Config) GetNormalizedMinUploadInterval() RandRangeConfig {
+	r := c.MinUploadIntervalMs
+
+	if r == nil {
+		r = &RandRangeConfig{
+			From: 30,
+			To:   30,
+		}
+	}
+
+	return *r
+}
+
 func init() {
 	common.Must(internet.RegisterProtocolConfigCreator(protocolName, func() interface{} {
 		return new(Config)
 	}))
 }
+
+func (c RandRangeConfig) roll() int32 {
+	if c.From == c.To {
+		return c.From
+	}
+	bigInt, _ := rand.Int(rand.Reader, big.NewInt(int64(c.To-c.From)))
+	return c.From + int32(bigInt.Int64())
+}

transport/internet/splithttp/config.pb.go

@@ -12,4 +12,10 @@ message Config {
   map<string, string> header = 3;
   int32 maxConcurrentUploads = 4;
   int32 maxUploadSize = 5;
+  RandRangeConfig minUploadIntervalMs = 6;
+}
+
+message RandRangeConfig {
+    int32 from = 1;
+    int32 to = 2;
 }

transport/internet/splithttp/config.proto

@@ -183,6 +183,7 @@ func Dial(ctx context.Context, dest net.Destination, streamSettings *internet.Me
 
 	maxConcurrentUploads := transportConfiguration.GetNormalizedMaxConcurrentUploads()
 	maxUploadSize := transportConfiguration.GetNormalizedMaxUploadSize()
+	minUploadInterval := transportConfiguration.GetNormalizedMinUploadInterval()
 
 	if tlsConfig != nil {
 		requestURL.Scheme = "https"
@@ -207,6 +208,8 @@ func Dial(ctx context.Context, dest net.Destination, streamSettings *internet.Me
 		requestsLimiter := semaphore.New(int(maxConcurrentUploads))
 		var requestCounter int64
 
+		lastWrite := time.Now()
+
 		// by offloading the uploads into a buffered pipe, multiple conn.Write
 		// calls get automatically batched together into larger POST requests.
 		// without batching, bandwidth is extremely limited.
@@ -237,6 +240,14 @@ func Dial(ctx context.Context, dest net.Destination, streamSettings *internet.Me
 				}
 			}()
 
+			if minUploadInterval.From > 0 {
+				roll := time.Duration(minUploadInterval.roll()) * time.Millisecond
+				if time.Since(lastWrite) < roll {
+					time.Sleep(roll)
+				}
+
+				lastWrite = time.Now()
+			}
 		}
 	}()