SplitHTTP: Replace responseOkPadding with xPaddingBytes (#3643)

infra/conf/transport_internet.go

@@ -233,7 +233,7 @@ type SplitHTTPConfig struct {
 	ScMaxEachPostBytes   *Int32Range       `json:"scMaxEachPostBytes"`
 	ScMinPostsIntervalMs *Int32Range       `json:"scMinPostsIntervalMs"`
 	NoSSEHeader          bool              `json:"noSSEHeader"`
-	ResponseOkPadding    *Int32Range       `json:"responseOkPadding"`
+	XPaddingBytes        *Int32Range       `json:"xPaddingBytes"`
 }
 
 func splithttpNewRandRangeConfig(input *Int32Range) *splithttp.RandRangeConfig {
@@ -265,7 +265,7 @@ func (c *SplitHTTPConfig) Build() (proto.Message, error) {
 		ScMaxEachPostBytes:   splithttpNewRandRangeConfig(c.ScMaxEachPostBytes),
 		ScMinPostsIntervalMs: splithttpNewRandRangeConfig(c.ScMinPostsIntervalMs),
 		NoSSEHeader:          c.NoSSEHeader,
-		ResponseOkPadding:    splithttpNewRandRangeConfig(c.ResponseOkPadding),
+		XPaddingBytes:        splithttpNewRandRangeConfig(c.XPaddingBytes),
 	}
 	return config, nil
 }

transport/internet/splithttp/config.go

@@ -10,32 +10,57 @@ import (
 	"github.com/xtls/xray-core/transport/internet"
 )
 
-func (c *Config) GetNormalizedPath(addPath string, addQuery bool) string {
+func (c *Config) GetNormalizedPath() string {
 	pathAndQuery := strings.SplitN(c.Path, "?", 2)
 	path := pathAndQuery[0]
-	query := ""
-	if len(pathAndQuery) > 1 && addQuery {
-		query = "?" + pathAndQuery[1]
-	}
 
 	if path == "" || path[0] != '/' {
 		path = "/" + path
 	}
+
 	if path[len(path)-1] != '/' {
 		path = path + "/"
 	}
 
-	return path + addPath + query
+	return path
+}
+
+func (c *Config) GetNormalizedQuery() string {
+	pathAndQuery := strings.SplitN(c.Path, "?", 2)
+	query := ""
+
+	if len(pathAndQuery) > 1 {
+		query = pathAndQuery[1]
+	}
+
+	if query != "" {
+		query += "&"
+	}
+
+	paddingLen := c.GetNormalizedXPaddingBytes().roll()
+	if paddingLen > 0 {
+		query += "x_padding=" + strings.Repeat("0", int(paddingLen))
+	}
+
+	return query
 }
 
 func (c *Config) GetRequestHeader() http.Header {
 	header := http.Header{}
 	for k, v := range c.Header {
 		header.Add(k, v)
 	}
+
 	return header
 }
 
+func (c *Config) WriteResponseHeader(writer http.ResponseWriter) {
+	paddingLen := c.GetNormalizedXPaddingBytes().roll()
+	if paddingLen > 0 {
+		writer.Header().Set("X-Padding", strings.Repeat("0", int(paddingLen)))
+	}
+}
+
 func (c *Config) GetNormalizedScMaxConcurrentPosts() RandRangeConfig {
 	if c.ScMaxConcurrentPosts == nil || c.ScMaxConcurrentPosts.To == 0 {
 		return RandRangeConfig{
@@ -69,15 +94,15 @@ func (c *Config) GetNormalizedScMinPostsIntervalMs() RandRangeConfig {
 	return *c.ScMinPostsIntervalMs
 }
 
-func (c *Config) GetNormalizedResponseOkPadding() RandRangeConfig {
-	if c.ResponseOkPadding == nil || c.ResponseOkPadding.To == 0 {
+func (c *Config) GetNormalizedXPaddingBytes() RandRangeConfig {
+	if c.XPaddingBytes == nil || c.XPaddingBytes.To == 0 {
 		return RandRangeConfig{
 			From: 100,
 			To:   1000,
 		}
 	}
 
-	return *c.ResponseOkPadding
+	return *c.XPaddingBytes
 }
 
 func init() {

transport/internet/splithttp/config.proto

@@ -14,7 +14,7 @@ message Config {
   RandRangeConfig scMaxEachPostBytes = 5;
   RandRangeConfig scMinPostsIntervalMs = 6;
   bool noSSEHeader = 7;
-  RandRangeConfig responseOkPadding = 8;
+  RandRangeConfig xPaddingBytes = 8;
 }
 
 message RandRangeConfig {

transport/internet/splithttp/config_test.go

@@ -11,41 +11,8 @@ func Test_GetNormalizedPath(t *testing.T) {
 		Path: "/?world",
 	}
 
-	path := c.GetNormalizedPath("hello", true)
-	if path != "/hello?world" {
-		t.Error("Unexpected: ", path)
-	}
-}
-
-func Test_GetNormalizedPath2(t *testing.T) {
-	c := Config{
-		Path: "?world",
-	}
-
-	path := c.GetNormalizedPath("hello", true)
-	if path != "/hello?world" {
-		t.Error("Unexpected: ", path)
-	}
-}
-
-func Test_GetNormalizedPath3(t *testing.T) {
-	c := Config{
-		Path: "hello?world",
-	}
-
-	path := c.GetNormalizedPath("", true)
-	if path != "/hello/?world" {
-		t.Error("Unexpected: ", path)
-	}
-}
-
-func Test_GetNormalizedPath4(t *testing.T) {
-	c := Config{
-		Path: "hello?world",
-	}
-
-	path := c.GetNormalizedPath("", false)
-	if path != "/hello/" {
+	path := c.GetNormalizedPath()
+	if path != "/" {
 		t.Error("Unexpected: ", path)
 	}
 }

transport/internet/splithttp/dialer.go

@@ -1,6 +1,7 @@
 package splithttp
 
 import (
+	"bytes"
 	"context"
 	gotls "crypto/tls"
 	"io"
@@ -217,8 +218,8 @@ func Dial(ctx context.Context, dest net.Destination, streamSettings *internet.Me
 	}
 
 	sessionIdUuid := uuid.New()
-	requestURL.Path = transportConfiguration.GetNormalizedPath(sessionIdUuid.String(), true)
-	baseURL := requestURL.String()
+	requestURL.Path = transportConfiguration.GetNormalizedPath() + sessionIdUuid.String()
+	requestURL.RawQuery = transportConfiguration.GetNormalizedQuery()
 
 	httpClient := getHTTPClient(ctx, dest, streamSettings)
 
@@ -247,9 +248,16 @@ func Dial(ctx context.Context, dest net.Destination, streamSettings *internet.Me
 			go func() {
 				defer requestsLimiter.Signal()
 
+				// this intentionally makes a shallow-copy of the struct so we
+				// can reassign Path (potentially concurrently)
+				url := requestURL
+				url.Path += "/" + strconv.FormatInt(seq, 10)
+				// reassign query to get different padding
+				url.RawQuery = transportConfiguration.GetNormalizedQuery()
+
 				err := httpClient.SendUploadRequest(
 					context.WithoutCancel(ctx),
-					baseURL+"/"+strconv.FormatInt(seq, 10),
+					url.String(),
 					&buf.MultiBufferContainer{MultiBuffer: chunk},
 					int64(chunk.Len()),
 				)
@@ -271,26 +279,38 @@ func Dial(ctx context.Context, dest net.Destination, streamSettings *internet.Me
 		}
 	}()
 
-	lazyRawDownload, remoteAddr, localAddr, err := httpClient.OpenDownload(context.WithoutCancel(ctx), baseURL)
+	lazyRawDownload, remoteAddr, localAddr, err := httpClient.OpenDownload(context.WithoutCancel(ctx), requestURL.String())
 	if err != nil {
 		return nil, err
 	}
 
 	lazyDownload := &LazyReader{
 		CreateReader: func() (io.ReadCloser, error) {
-			// skip "ooooooooook" response
-			trashHeader := []byte{0}
-			for {
-				_, err := io.ReadFull(lazyRawDownload, trashHeader)
-				if err != nil {
-					return nil, errors.New("failed to read initial response").Base(err)
-				}
-				if trashHeader[0] == 'k' {
-					break
-				}
+			// skip "ok" response
+			trashHeader := []byte{0, 0}
+			_, err := io.ReadFull(lazyRawDownload, trashHeader)
+			if err != nil {
+				return nil, errors.New("failed to read initial response").Base(err)
+			}
+
+			if bytes.Equal(trashHeader, []byte("ok")) {
+				return lazyRawDownload, nil
 			}
 
-			return lazyRawDownload, nil
+			// we read some garbage byte that may not have been "ok" at
+			// all. return a reader that replays what we have read so far
+			reader := io.MultiReader(
+				bytes.NewReader(trashHeader),
+				lazyRawDownload,
+			)
+			readCloser := struct {
+				io.Reader
+				io.Closer
+			}{
+				Reader: reader,
+				Closer: lazyRawDownload,
+			}
+			return readCloser, nil
 		},
 	}
 

transport/internet/splithttp/hub.go

@@ -124,7 +124,6 @@ func (h *requestHandler) ServeHTTP(writer http.ResponseWriter, request *http.Req
 
 	currentSession := h.upsertSession(sessionId)
 	scMaxEachPostBytes := int(h.ln.config.GetNormalizedScMaxEachPostBytes().To)
-	responseOkPadding := h.ln.config.GetNormalizedResponseOkPadding()
 
 	if request.Method == "POST" {
 		seq := ""
@@ -170,6 +169,7 @@ func (h *requestHandler) ServeHTTP(writer http.ResponseWriter, request *http.Req
 			return
 		}
 
+		h.config.WriteResponseHeader(writer)
 		writer.WriteHeader(http.StatusOK)
 	} else if request.Method == "GET" {
 		responseFlusher, ok := writer.(http.Flusher)
@@ -189,14 +189,14 @@ func (h *requestHandler) ServeHTTP(writer http.ResponseWriter, request *http.Req
 			writer.Header().Set("Content-Type", "text/event-stream")
 		}
 
+		h.config.WriteResponseHeader(writer)
+
 		writer.WriteHeader(http.StatusOK)
-		// send a chunk immediately to enable CDN streaming.
-		// many CDN buffer the response headers until the origin starts sending
-		// the body, with no way to turn it off.
-		padding := int(responseOkPadding.roll())
-		for i := 0; i < padding; i++ {
-			writer.Write([]byte("o"))
-		}
+		// in earlier versions, this initial body data was used to immediately
+		// start a 200 OK on all CDN. but xray client since 1.8.16 does not
+		// actually require an immediate 200 OK, but now requires these
+		// additional bytes "ok". xray client 1.8.24+ doesn't require "ok"
+		// anymore, and so this line should be removed in later versions.
 		writer.Write([]byte("ok"))
 		responseFlusher.Flush()
 
@@ -277,7 +277,7 @@ func ListenSH(ctx context.Context, address net.Address, port net.Port, streamSet
 	handler := &requestHandler{
 		config:    shSettings,
 		host:      shSettings.Host,
-		path:      shSettings.GetNormalizedPath("", false),
+		path:      shSettings.GetNormalizedPath(),
 		ln:        l,
 		sessionMu: &sync.Mutex{},
 		sessions:  sync.Map{},