mirror of https://github.com/gorilla/websocket.git
62 lines
1.2 KiB
Go
62 lines
1.2 KiB
Go
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// Copyright 2016 The Gorilla WebSocket Authors. All rights reserved. Use of
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// this source code is governed by a BSD-style license that can be found in the
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// LICENSE file.
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package websocket
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import (
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"math/rand"
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"unsafe"
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)
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const wordSize = int(unsafe.Sizeof(uintptr(0)))
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func newMaskKey() [4]byte {
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n := rand.Uint32()
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return [4]byte{byte(n), byte(n >> 8), byte(n >> 16), byte(n >> 24)}
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}
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func maskBytes(key [4]byte, pos int, b []byte) int {
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// Mask one byte at a time for small buffers.
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if len(b) < 2*wordSize {
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for i := range b {
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b[i] ^= key[pos&3]
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pos++
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}
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return pos & 3
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}
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// Mask one byte at a time to word boundary.
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if n := int(uintptr(unsafe.Pointer(&b))) % wordSize; n != 0 {
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n = wordSize - n
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for i := range b[:n] {
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b[i] ^= key[pos&3]
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pos++
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}
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b = b[n:]
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}
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// Create aligned word size key.
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var k [wordSize]byte
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for i := range k {
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k[i] = key[(pos+i)&3]
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}
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kw := *(*uintptr)(unsafe.Pointer(&k))
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// Mask one word at a time.
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n := (len(b) / wordSize) * wordSize
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for i := 0; i < n; i += wordSize {
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*(*uintptr)(unsafe.Pointer(uintptr(unsafe.Pointer(&b[0])) + uintptr(i))) ^= kw
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}
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// Mask one byte at a time for remaining bytes.
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b = b[n:]
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for i := range b {
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b[i] ^= key[pos&3]
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pos++
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}
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return pos & 3
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}
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