XHTTP client: Fix a race condition and a data race (#6665)

https://github.com/XTLS/Xray-core/pull/6665#issuecomment-5429028477

---------

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

transport/internet/splithttp/client.go

@@ -8,6 +8,7 @@ import (
 	"net/http"
 	"net/http/httptrace"
 	"sync"
+	"sync/atomic"
 
 	"github.com/apernet/quic-go/http3"
 	"github.com/xtls/xray-core/common"
@@ -32,7 +33,7 @@ type DialerClient interface {
 type DefaultDialerClient struct {
 	transportConfig *Config
 	client          *http.Client
-	closed          bool
+	closed          atomic.Bool
 	httpVersion     string
 	// pool of net.Conn, created using dialUploadConn
 	uploadRawPool  *sync.Pool
@@ -40,7 +41,7 @@ type DefaultDialerClient struct {
 }
 
 func (c *DefaultDialerClient) IsClosed() bool {
-	return c.closed
+	return c.closed.Load()
 }
 
 func (c *DefaultDialerClient) OpenStream(ctx context.Context, url string, sessionId string, body io.Reader, uploadOnly bool) (wrc io.ReadCloser, remoteAddr, localAddr net.Addr, err error) {
@@ -72,7 +73,7 @@ func (c *DefaultDialerClient) OpenStream(ctx context.Context, url string, sessio
 		resp, err := c.client.Do(req)
 		if err != nil {
 			if !uploadOnly { // stream-down is enough
-				c.closed = true
+				c.closed.Store(true)
 				errors.LogInfoInner(ctx, err, "failed to "+method+" "+url)
 			}
 			gotConn.Close()
@@ -108,7 +109,7 @@ func (c *DefaultDialerClient) PostPacket(ctx context.Context, url string, sessio
 	if c.httpVersion != "1.1" {
 		resp, err := c.client.Do(req)
 		if err != nil {
-			c.closed = true
+			c.closed.Store(true)
 			return err
 		}
 
@@ -148,7 +149,7 @@ func (c *DefaultDialerClient) PostPacket(ctx context.Context, url string, sessio
 				if h1UploadConn.UnreadedResponsesCount > 0 {
 					resp, err := http.ReadResponse(h1UploadConn.RespBufReader, req)
 					if err != nil {
-						c.closed = true
+						c.closed.Store(true)
 						return fmt.Errorf("error while reading response: %s", err.Error())
 					}
 					io.Copy(io.Discard, resp.Body)

transport/internet/splithttp/dialer.go

@@ -595,11 +595,12 @@ func (w uploadWriter) Write(b []byte) (int, error) {
 
 	var writed int
 	for _, buff := range buffer.MultiBuffer {
+		n := int(buff.Len())
 		err := w.WriteMultiBuffer(buf.MultiBuffer{buff})
 		if err != nil {
 			return writed, err
 		}
-		writed += int(buff.Len())
+		writed += n
 	}
 	return writed, nil
 }