Use vendoring for backward compatibility
The switch of the Madon library to Go modules breaks builds with
Go version < 1.11 since the import path now contains "v2".
This patch adds vendoring so that it can still build with those
versions.
Let's try to re-enable Travis builds with Go v1.8-1.11...
// Copyright 2016 The Gorilla WebSocket Authors. All rights reserved. Use of
// this source code is governed by a BSD-style license that can be found in the
// LICENSE file.
// +build appengine
package websocket
func maskBytes(key [4]byte, pos int, b []byte) int {
for i := range b {
b[i] ^= key[pos&3]
pos++
}
return pos & 3
}