chore: embed hysteria, clean irrelevant codes, code from https://github.com/HyNetwork/hysteria

transport/hysteria/obfs/xplus.go

@@ -0,0 +1,52 @@
+package obfs
+
+import (
+	"crypto/sha256"
+	"math/rand"
+	"sync"
+	"time"
+)
+
+// [salt][obfuscated payload]
+
+const saltLen = 16
+
+type XPlusObfuscator struct {
+	Key     []byte
+	RandSrc *rand.Rand
+
+	lk sync.Mutex
+}
+
+func NewXPlusObfuscator(key []byte) *XPlusObfuscator {
+	return &XPlusObfuscator{
+		Key:     key,
+		RandSrc: rand.New(rand.NewSource(time.Now().UnixNano())),
+	}
+}
+
+func (x *XPlusObfuscator) Deobfuscate(in []byte, out []byte) int {
+	pLen := len(in) - saltLen
+	if pLen <= 0 || len(out) < pLen {
+		// Invalid
+		return 0
+	}
+	key := sha256.Sum256(append(x.Key, in[:saltLen]...))
+	// Deobfuscate the payload
+	for i, c := range in[saltLen:] {
+		out[i] = c ^ key[i%sha256.Size]
+	}
+	return pLen
+}
+
+func (x *XPlusObfuscator) Obfuscate(in []byte, out []byte) int {
+	x.lk.Lock()
+	_, _ = x.RandSrc.Read(out[:saltLen]) // salt
+	x.lk.Unlock()
+	// Obfuscate the payload
+	key := sha256.Sum256(append(x.Key, out[:saltLen]...))
+	for i, c := range in {
+		out[i+saltLen] = c ^ key[i%sha256.Size]
+	}
+	return len(in) + saltLen
+}