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package websocket
import (
"bytes"
"crypto/rand"
"encoding/binary"
"math/big"
"math/bits"
"testing"
"github.com/coder/websocket/internal/test/assert"
)
func basicMask(b []byte, key uint32) uint32 {
for i := range b {
b[i] ^= byte(key)
key = bits.RotateLeft32(key, -8)
}
return key
}
func basicMask2(b []byte, key uint32) uint32 {
keyb := binary.LittleEndian.AppendUint32(nil, key)
pos := 0
for i := range b {
b[i] ^= keyb[pos&3]
pos++
}
return bits.RotateLeft32(key, (pos&3)*-8)
}
func TestMask(t *testing.T) {
t.Parallel()
testMask(t, "basicMask", basicMask)
testMask(t, "maskGo", maskGo)
testMask(t, "basicMask2", basicMask2)
}
func testMask(t *testing.T, name string, fn func(b []byte, key uint32) uint32) {
t.Run(name, func(t *testing.T) {
t.Parallel()
for i := 0; i < 9999; i++ {
keyb := make([]byte, 4)
_, err := rand.Read(keyb)
assert.Success(t, err)
key := binary.LittleEndian.Uint32(keyb)
n, err := rand.Int(rand.Reader, big.NewInt(1<<16))
assert.Success(t, err)
b := make([]byte, 1+n.Int64())
_, err = rand.Read(b)
assert.Success(t, err)
b2 := make([]byte, len(b))
copy(b2, b)
b3 := make([]byte, len(b))
copy(b3, b)
key2 := basicMask(b2, key)
key3 := fn(b3, key)
if key2 != key3 {
t.Errorf("expected key %X but got %X", key2, key3)
}
if !bytes.Equal(b2, b3) {
t.Error("bad bytes")
return
}
}
})
}
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