Add SplitHTTP Browser Dialer support (#3484)

transport/internet/splithttp/client.go

@@ -0,0 +1,169 @@
+package splithttp
+
+import (
+	"bytes"
+	"context"
+	"io"
+	gonet "net"
+	"net/http"
+	"net/http/httptrace"
+	"sync"
+
+	"github.com/xtls/xray-core/common"
+	"github.com/xtls/xray-core/common/errors"
+	"github.com/xtls/xray-core/common/net"
+	"github.com/xtls/xray-core/common/signal/done"
+)
+
+// interface to abstract between use of browser dialer, vs net/http
+type DialerClient interface {
+	// (ctx, baseURL, payload) -> err
+	// baseURL already contains sessionId and seq
+	SendUploadRequest(context.Context, string, io.ReadWriteCloser, int64) error
+
+	// (ctx, baseURL) -> (downloadReader, remoteAddr, localAddr)
+	// baseURL already contains sessionId
+	OpenDownload(context.Context, string) (io.ReadCloser, net.Addr, net.Addr, error)
+}
+
+// implements splithttp.DialerClient in terms of direct network connections
+type DefaultDialerClient struct {
+	transportConfig *Config
+	download        *http.Client
+	upload          *http.Client
+	isH2            bool
+	// pool of net.Conn, created using dialUploadConn
+	uploadRawPool  *sync.Pool
+	dialUploadConn func(ctxInner context.Context) (net.Conn, error)
+}
+
+func (c *DefaultDialerClient) OpenDownload(ctx context.Context, baseURL string) (io.ReadCloser, gonet.Addr, gonet.Addr, error) {
+	var remoteAddr gonet.Addr
+	var localAddr gonet.Addr
+	// this is done when the TCP/UDP connection to the server was established,
+	// and we can unblock the Dial function and print correct net addresses in
+	// logs
+	gotConn := done.New()
+
+	var downResponse io.ReadCloser
+	gotDownResponse := done.New()
+
+	go func() {
+		trace := &httptrace.ClientTrace{
+			GotConn: func(connInfo httptrace.GotConnInfo) {
+				remoteAddr = connInfo.Conn.RemoteAddr()
+				localAddr = connInfo.Conn.LocalAddr()
+				gotConn.Close()
+			},
+		}
+
+		// in case we hit an error, we want to unblock this part
+		defer gotConn.Close()
+
+		req, err := http.NewRequestWithContext(
+			httptrace.WithClientTrace(ctx, trace),
+			"GET",
+			baseURL,
+			nil,
+		)
+		if err != nil {
+			errors.LogInfoInner(ctx, err, "failed to construct download http request")
+			gotDownResponse.Close()
+			return
+		}
+
+		req.Header = c.transportConfig.GetRequestHeader()
+
+		response, err := c.download.Do(req)
+		gotConn.Close()
+		if err != nil {
+			errors.LogInfoInner(ctx, err, "failed to send download http request")
+			gotDownResponse.Close()
+			return
+		}
+
+		if response.StatusCode != 200 {
+			response.Body.Close()
+			errors.LogInfo(ctx, "invalid status code on download:", response.Status)
+			gotDownResponse.Close()
+			return
+		}
+
+		downResponse = response.Body
+		gotDownResponse.Close()
+	}()
+
+	// we want to block Dial until we know the remote address of the server,
+	// for logging purposes
+	<-gotConn.Wait()
+
+	lazyDownload := &LazyReader{
+		CreateReader: func() (io.ReadCloser, error) {
+			<-gotDownResponse.Wait()
+			if downResponse == nil {
+				return nil, errors.New("downResponse failed")
+			}
+			return downResponse, nil
+		},
+	}
+
+	return lazyDownload, remoteAddr, localAddr, nil
+}
+
+func (c *DefaultDialerClient) SendUploadRequest(ctx context.Context, url string, payload io.ReadWriteCloser, contentLength int64) error {
+	req, err := http.NewRequest("POST", url, payload)
+	req.ContentLength = contentLength
+	if err != nil {
+		return err
+	}
+	req.Header = c.transportConfig.GetRequestHeader()
+
+	if c.isH2 {
+		resp, err := c.upload.Do(req)
+		if err != nil {
+			return err
+		}
+
+		defer resp.Body.Close()
+
+		if resp.StatusCode != 200 {
+			return errors.New("bad status code:", resp.Status)
+		}
+	} else {
+		// stringify the entire HTTP/1.1 request so it can be
+		// safely retried. if instead req.Write is called multiple
+		// times, the body is already drained after the first
+		// request
+		requestBytes := new(bytes.Buffer)
+		common.Must(req.Write(requestBytes))
+
+		var uploadConn any
+
+		for {
+			uploadConn = c.uploadRawPool.Get()
+			newConnection := uploadConn == nil
+			if newConnection {
+				uploadConn, err = c.dialUploadConn(context.WithoutCancel(ctx))
+				if err != nil {
+					return err
+				}
+			}
+
+			_, err = uploadConn.(net.Conn).Write(requestBytes.Bytes())
+
+			// if the write failed, we try another connection from
+			// the pool, until the write on a new connection fails.
+			// failed writes to a pooled connection are normal when
+			// the connection has been closed in the meantime.
+			if err == nil {
+				break
+			} else if newConnection {
+				return err
+			}
+		}
+
+		c.uploadRawPool.Put(uploadConn)
+	}
+
+	return nil
+}