Send shadowsocks handshake with payload if available

proxy/shadowsocks/client.go

@@ -5,6 +5,7 @@ package shadowsocks
 
 import (
 	"context"
+	"time"
 
 	core "github.com/v2fly/v2ray-core/v4"
 	"github.com/v2fly/v2ray-core/v4/common"
@@ -108,11 +109,14 @@ func (c *Client) Process(ctx context.Context, link *transport.Link, dialer inter
 			return newError("failed to write request").Base(err)
 		}
 
-		if err := bufferedWriter.SetBuffered(false); err != nil {
-			return err
-		}
-
 		requestDone := func() error {
+			if err = buf.CopyOnceTimeout(link.Reader, bodyWriter, time.Millisecond*100); err != nil && err != buf.ErrNotTimeoutReader && err != buf.ErrReadTimeout {
+				return newError("failed to write A request payload").Base(err).AtWarning()
+			}
+			if err := bufferedWriter.SetBuffered(false); err != nil {
+				return err
+			}
+
 			defer timer.SetTimeout(sessionPolicy.Timeouts.DownlinkOnly)
 			return buf.Copy(link.Reader, bodyWriter, buf.UpdateActivity(timer))
 		}