Update vendor (mattermost)

vendor/github.com/mattermost/platform/vendor/github.com/gorilla/websocket/mask.go

@@ -0,0 +1,61 @@
+// 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.
+
+package websocket
+
+import (
+	"math/rand"
+	"unsafe"
+)
+
+const wordSize = int(unsafe.Sizeof(uintptr(0)))
+
+func newMaskKey() [4]byte {
+	n := rand.Uint32()
+	return [4]byte{byte(n), byte(n >> 8), byte(n >> 16), byte(n >> 24)}
+}
+
+func maskBytes(key [4]byte, pos int, b []byte) int {
+
+	// Mask one byte at a time for small buffers.
+	if len(b) < 2*wordSize {
+		for i := range b {
+			b[i] ^= key[pos&3]
+			pos++
+		}
+		return pos & 3
+	}
+
+	// Mask one byte at a time to word boundary.
+	if n := int(uintptr(unsafe.Pointer(&b[0]))) % wordSize; n != 0 {
+		n = wordSize - n
+		for i := range b[:n] {
+			b[i] ^= key[pos&3]
+			pos++
+		}
+		b = b[n:]
+	}
+
+	// Create aligned word size key.
+	var k [wordSize]byte
+	for i := range k {
+		k[i] = key[(pos+i)&3]
+	}
+	kw := *(*uintptr)(unsafe.Pointer(&k))
+
+	// Mask one word at a time.
+	n := (len(b) / wordSize) * wordSize
+	for i := 0; i < n; i += wordSize {
+		*(*uintptr)(unsafe.Pointer(uintptr(unsafe.Pointer(&b[0])) + uintptr(i))) ^= kw
+	}
+
+	// Mask one byte at a time for remaining bytes.
+	b = b[n:]
+	for i := range b {
+		b[i] ^= key[pos&3]
+		pos++
+	}
+
+	return pos & 3
+}