fix: refactor processing of junk packets (#103)

- fix the bug that transport packet interprets as init/resp/cookie with the same size
- cleanup error responses
- reduce buffer allocations

device/obf_data.go

@@ -0,0 +1,25 @@
+package device
+
+func newDataObf(val string) (obf, error) {
+	return &dataObf{}, nil
+}
+
+type dataObf struct {
+}
+
+func (obf *dataObf) Obfuscate(dst, src []byte) {
+	copy(dst, src)
+}
+
+func (obf *dataObf) Deobfuscate(dst, src []byte) bool {
+	copy(dst, src)
+	return true
+}
+
+func (o *dataObf) ObfuscatedLen(n int) int {
+	return n
+}
+
+func (o *dataObf) DeobfuscatedLen(n int) int {
+	return n
+}