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

transport/hysteria/obfs/obfs.go

@@ -0,0 +1,6 @@
+package obfs
+
+type Obfuscator interface {
+	Deobfuscate(in []byte, out []byte) int
+	Obfuscate(in []byte, out []byte) int
+}

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
+}

transport/hysteria/obfs/xplus_test.go

@@ -0,0 +1,31 @@
+package obfs
+
+import (
+	"bytes"
+	"testing"
+)
+
+func TestXPlusObfuscator(t *testing.T) {
+	x := NewXPlusObfuscator([]byte("Vaundy"))
+	tests := []struct {
+		name string
+		p    []byte
+	}{
+		{name: "1", p: []byte("HelloWorld")},
+		{name: "2", p: []byte("Regret is just a horrible attempt at time travel that ends with you feeling like crap")},
+		{name: "3", p: []byte("To be, or not to be, that is the question:\nWhether 'tis nobler in the mind to suffer\n" +
+			"The slings and arrows of outrageous fortune,\nOr to take arms against a sea of troubles\n" +
+			"And by opposing end them. To die—to sleep,\nNo more; and by a sleep to say we end")},
+		{name: "empty", p: []byte("")},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			buf := make([]byte, 10240)
+			n := x.Obfuscate(tt.p, buf)
+			n2 := x.Deobfuscate(buf[:n], buf[n:])
+			if !bytes.Equal(tt.p, buf[n:n+n2]) {
+				t.Errorf("Inconsistent deobfuscate result: got %v, want %v", buf[n:n+n2], tt.p)
+			}
+		})
+	}
+}