XHTTP client: Define Request.GetBody() for packet-up so h2 can replay after GOAWAY (#6632)

https://github.com/XTLS/Xray-core/pull/6632#issuecomment-5430735467

---------

Co-authored-by: 风扇滑翔翼 <Fangliding.fshxy@outlook.com>

transport/internet/splithttp/config.go

@@ -1,6 +1,7 @@
 package splithttp
 
 import (
+	"bytes"
 	"encoding/base64"
 	"fmt"
 	"io"
@@ -330,14 +331,18 @@ func (c *Config) FillStreamRequest(request *http.Request, sessionId string, seqS
 func (c *Config) FillPacketRequest(request *http.Request, sessionId string, seqStr string, payload buf.MultiBuffer) error {
 	dataPlacement := c.GetNormalizedUplinkDataPlacement()
 
+	data := make([]byte, payload.Len())
+	payload.Copy(data)
+	buf.ReleaseMulti(payload)
+
 	if dataPlacement == PlacementBody || dataPlacement == PlacementAuto {
 		request.Header = c.GetRequestHeader()
-		request.Body = io.NopCloser(&buf.MultiBufferContainer{MultiBuffer: payload})
-		request.ContentLength = int64(payload.Len())
+		request.Body = io.NopCloser(bytes.NewReader(data))
+		request.ContentLength = int64(len(data))
+		request.GetBody = func() (io.ReadCloser, error) {
+			return io.NopCloser(bytes.NewReader(data)), nil
+		}
 	} else {
-		data := make([]byte, payload.Len())
-		payload.Copy(data)
-		buf.ReleaseMulti(payload)
 		switch dataPlacement {
 		case PlacementHeader:
 			request.Header = c.GetRequestHeaderWithPayload(data)

transport/internet/splithttp/config_test.go

@@ -1,9 +1,13 @@
 package splithttp_test
 
 import (
+	"io"
+	"net/http"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
+	"github.com/xtls/xray-core/common"
+	"github.com/xtls/xray-core/common/buf"
 	. "github.com/xtls/xray-core/transport/internet/splithttp"
 )
 
@@ -77,3 +81,35 @@ func Test_GetNormalizedPath(t *testing.T) {
 		})
 	}
 }
+
+func Test_FillPacketRequest_GetBody(t *testing.T) {
+	data := []byte("hello xray")
+	payload := buf.MergeBytes(nil, data)
+
+	req, err := http.NewRequest("POST", "https://example.com/", nil)
+	common.Must(err)
+
+	config := &Config{}
+	config.FillPacketRequest(req, "sess", "0", payload)
+
+	if req.GetBody == nil {
+		t.Fatalf("Expected GetBody to be set")
+	}
+
+	first, err := io.ReadAll(req.Body)
+	common.Must(err)
+
+	if string(data) != string(first) {
+		t.Fatalf("Body mismatch. Format %q and %q are not equal", data, first)
+	}
+
+	body2, err := req.GetBody()
+	common.Must(err)
+
+	second, err := io.ReadAll(body2)
+	common.Must(err)
+
+	if string(data) != string(second) {
+		t.Fatalf("Replayed body mismatch. Format %q and %q are not equal", data, second)
+	}
+}