Fix: CounterConnection with ReadV/WriteV (#720)

Co-authored-by: JimhHan <50871214+JimhHan@users.noreply.github.com>

transport/internet/stat/connection.go

@@ -0,0 +1,34 @@
+package stat
+
+import (
+	"net"
+
+	"github.com/xtls/xray-core/features/stats"
+)
+
+type Connection interface {
+	net.Conn
+}
+
+type CounterConnection struct {
+	Connection
+	ReadCounter  stats.Counter
+	WriteCounter stats.Counter
+}
+
+func (c *CounterConnection) Read(b []byte) (int, error) {
+	nBytes, err := c.Connection.Read(b)
+	if c.ReadCounter != nil {
+		c.ReadCounter.Add(int64(nBytes))
+	}
+
+	return nBytes, err
+}
+
+func (c *CounterConnection) Write(b []byte) (int, error) {
+	nBytes, err := c.Connection.Write(b)
+	if c.WriteCounter != nil {
+		c.WriteCounter.Add(int64(nBytes))
+	}
+	return nBytes, err
+}