Add hysteria2 protocol

transport/hysteria2/internal/protocol/padding.go

@@ -0,0 +1,31 @@
+package protocol
+
+import (
+	"math/rand"
+)
+
+const (
+	paddingChars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
+)
+
+// padding specifies a half-open range [Min, Max).
+type padding struct {
+	Min int
+	Max int
+}
+
+func (p padding) String() string {
+	n := p.Min + rand.Intn(p.Max-p.Min)
+	bs := make([]byte, n)
+	for i := range bs {
+		bs[i] = paddingChars[rand.Intn(len(paddingChars))]
+	}
+	return string(bs)
+}
+
+var (
+	authRequestPadding  = padding{Min: 256, Max: 2048}
+	authResponsePadding = padding{Min: 256, Max: 2048}
+	tcpRequestPadding   = padding{Min: 64, Max: 512}
+	tcpResponsePadding  = padding{Min: 128, Max: 1024}
+)