add sni connector

pkg/handler/sni/conn.go

@@ -0,0 +1,20 @@
+package sni
+
+import (
+	"net"
+)
+
+type cacheConn struct {
+	net.Conn
+	buf []byte
+}
+
+func (c *cacheConn) Read(b []byte) (n int, err error) {
+	if len(c.buf) > 0 {
+		n = copy(b, c.buf)
+		c.buf = c.buf[n:]
+		return
+	}
+
+	return c.Conn.Read(b)
+}