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105 lines
2.2 KiB
Go
105 lines
2.2 KiB
Go
// Copyright (c) 2020, The Garble Authors.
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// See LICENSE for licensing information.
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package literals
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import (
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"fmt"
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"go/ast"
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"go/token"
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mathrand "math/rand"
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)
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// obfuscator takes a byte slice and converts it to a ast.BlockStmt
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type obfuscator interface {
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obfuscate(obfRand *mathrand.Rand, data []byte) *ast.BlockStmt
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}
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var (
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simpleObfuscator = simple{}
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// Obfuscators contains all types which implement the obfuscator Interface
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Obfuscators = []obfuscator{
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simpleObfuscator,
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swap{},
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split{},
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shuffle{},
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seed{},
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}
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// LinearTimeObfuscators contains all types which implement the obfuscator Interface and can safely be used on large literals
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LinearTimeObfuscators = []obfuscator{
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simpleObfuscator,
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}
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TestObfuscator string
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testPkgToObfuscatorMap map[string]obfuscator
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)
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func genRandIntSlice(obfRand *mathrand.Rand, max, count int) []int {
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indexes := make([]int, count)
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for i := 0; i < count; i++ {
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indexes[i] = obfRand.Intn(max)
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}
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return indexes
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}
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func randOperator(obfRand *mathrand.Rand) token.Token {
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operatorTokens := [...]token.Token{token.XOR, token.ADD, token.SUB}
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return operatorTokens[obfRand.Intn(len(operatorTokens))]
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}
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func evalOperator(t token.Token, x, y byte) byte {
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switch t {
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case token.XOR:
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return x ^ y
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case token.ADD:
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return x + y
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case token.SUB:
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return x - y
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default:
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panic(fmt.Sprintf("unknown operator: %s", t))
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}
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}
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func operatorToReversedBinaryExpr(t token.Token, x, y ast.Expr) *ast.BinaryExpr {
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expr := &ast.BinaryExpr{X: x, Y: y}
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switch t {
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case token.XOR:
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expr.Op = token.XOR
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case token.ADD:
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expr.Op = token.SUB
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case token.SUB:
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expr.Op = token.ADD
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default:
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panic(fmt.Sprintf("unknown operator: %s", t))
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}
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return expr
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}
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type obfRand struct {
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*mathrand.Rand
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testObfuscator obfuscator
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}
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func (r *obfRand) nextObfuscator() obfuscator {
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if r.testObfuscator != nil {
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return r.testObfuscator
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}
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return Obfuscators[r.Intn(len(Obfuscators))]
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}
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func (r *obfRand) nextLinearTimeObfuscator() obfuscator {
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if r.testObfuscator != nil {
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return r.testObfuscator
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}
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return Obfuscators[r.Intn(len(LinearTimeObfuscators))]
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}
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func newObfRand(rand *mathrand.Rand, file *ast.File) *obfRand {
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testObf := testPkgToObfuscatorMap[file.Name.Name]
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return &obfRand{rand, testObf}
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}
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