Chore: split component to transport

transport/ssr/tools/random.go

@@ -0,0 +1,57 @@
+package tools
+
+import (
+	"encoding/binary"
+
+	"github.com/Dreamacro/clash/common/pool"
+)
+
+// XorShift128Plus - a pseudorandom number generator
+type XorShift128Plus struct {
+	s [2]uint64
+}
+
+func (r *XorShift128Plus) Next() uint64 {
+	x := r.s[0]
+	y := r.s[1]
+	r.s[0] = y
+	x ^= x << 23
+	x ^= y ^ (x >> 17) ^ (y >> 26)
+	r.s[1] = x
+	return x + y
+}
+
+func (r *XorShift128Plus) InitFromBin(bin []byte) {
+	var full []byte
+	if len(bin) < 16 {
+		full := pool.Get(16)[:0]
+		defer pool.Put(full)
+		full = append(full, bin...)
+		for len(full) < 16 {
+			full = append(full, 0)
+		}
+	} else {
+		full = bin
+	}
+	r.s[0] = binary.LittleEndian.Uint64(full[:8])
+	r.s[1] = binary.LittleEndian.Uint64(full[8:16])
+}
+
+func (r *XorShift128Plus) InitFromBinAndLength(bin []byte, length int) {
+	var full []byte
+	if len(bin) < 16 {
+		full := pool.Get(16)[:0]
+		defer pool.Put(full)
+		full = append(full, bin...)
+		for len(full) < 16 {
+			full = append(full, 0)
+		}
+	}
+	full = bin
+	binary.LittleEndian.PutUint16(full, uint16(length))
+	r.s[0] = binary.LittleEndian.Uint64(full[:8])
+	r.s[1] = binary.LittleEndian.Uint64(full[8:16])
+	for i := 0; i < 4; i++ {
+		r.Next()
+	}
+}