fix: limit AMF decoder nesting depth

tests/test_amf.cpp

@@ -0,0 +1,52 @@
+/*
+ * Copyright (c) 2016-present The ZLMediaKit project authors. All Rights Reserved.
+ *
+ * This file is part of ZLMediaKit(https://github.com/ZLMediaKit/ZLMediaKit).
+ *
+ * Use of this source code is governed by MIT-like license that can be found in the
+ * LICENSE file in the root of the source tree. All contributing project authors
+ * may be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include <cassert>
+#include <stdexcept>
+#include <string>
+
+#include "Network/Buffer.h"
+#include "Rtmp/amf.h"
+
+using namespace std;
+using namespace toolkit;
+
+static string make_nested_object(size_t depth) {
+    string result;
+    for (size_t i = 0; i < depth; ++i) {
+        result.append("\x03\x00\x01x", 4);
+    }
+    result.append("\x05", 1);
+    for (size_t i = 0; i < depth; ++i) {
+        result.append("\x00\x00\x09", 3);
+    }
+    return result;
+}
+
+int main() {
+    {
+        BufferLikeString input(make_nested_object(64));
+        AMFDecoder decoder(input, 0);
+        assert(decoder.load<AMFValue>().type() == AMF_OBJECT);
+    }
+
+    {
+        BufferLikeString input(make_nested_object(65));
+        AMFDecoder decoder(input, 0);
+        try {
+            decoder.load<AMFValue>();
+            assert(false);
+        } catch (const runtime_error &ex) {
+            assert(string(ex.what()) == "Maximum AMF nesting depth exceeded");
+        }
+    }
+
+    return 0;
+}