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 * Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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package jdk.internal.management.remote.rest.http;

import jdk.internal.management.remote.rest.json.JSONArray;

import jdk.internal.management.remote.rest.json.JSONElement;

import jdk.internal.management.remote.rest.json.JSONObject;

import jdk.internal.management.remote.rest.json.JSONPrimitive;

import jdk.internal.management.remote.rest.json.parser.JSONParser;

import jdk.internal.management.remote.rest.json.parser.ParseException;

import jdk.internal.management.remote.rest.mapper.JSONMapper;

import jdk.internal.management.remote.rest.mapper.JSONMappingException;

import jdk.internal.management.remote.rest.mapper.JSONMappingFactory;

import com.sun.net.httpserver.HttpExchange;

import javax.management.*;

import jdk.internal.management.remote.rest.PlatformRestAdapter;

import java.io.IOException;

import java.io.UnsupportedEncodingException;

import java.net.URLDecoder;

import java.nio.charset.StandardCharsets;

import java.util.*;

import java.util.concurrent.ConcurrentHashMap;

import java.util.concurrent.CopyOnWriteArrayList;

import java.util.regex.Matcher;

import java.util.regex.Pattern;

import java.util.stream.Collectors;

public class MBeanCollectionResource implements RestResource, NotificationListener {

    private List<ObjectName> allowedMbeans;

    private final MBeanServer mBeanServer;

    private final Map<ObjectName, MBeanResource> mBeanResourceMap = new ConcurrentHashMap<>();

    private static final int pageSize = 10;

    private static final String pathPrefix = "^/?jmx/servers/[a-zA-Z0-9\\-\\.]+/mbeans";

    // Only MXBean or any other MBean that uses types

    // that have a valid mapper functions

    private boolean isMBeanAllowed(ObjectName objName) {

        try {

            MBeanInfo mInfo = mBeanServer.getMBeanInfo(objName);

            // Return true for MXbean

            Descriptor desc = mInfo.getDescriptor();

            String isMxBean = (String) desc.getFieldValue("mxbean");

            if (isMxBean != null && isMxBean.equalsIgnoreCase("true"))

                return true;

            // Check attribute types

            MBeanAttributeInfo[] attrsInfo = mInfo.getAttributes();

            for (MBeanAttributeInfo attrInfo : attrsInfo) {

                String type = attrInfo.getType();

                if (!JSONMappingFactory.INSTANCE.isTypeMapped(type)) {

                    return false;

                }

            }

            // Check operation parameters and return types

            MBeanOperationInfo[] operations = mInfo.getOperations();

            for (MBeanOperationInfo opInfo : operations) {

                MBeanParameterInfo[] signature = opInfo.getSignature();

                for (MBeanParameterInfo sig : signature) {

                    if (!JSONMappingFactory.INSTANCE.isTypeMapped(sig.getType())) {

                        return false;

                    }

                }

                if (!JSONMappingFactory.INSTANCE.isTypeMapped(opInfo.getReturnType())) {

                    return false;

                }

            }

            return true;

        } catch (InstanceNotFoundException | IntrospectionException |

                ReflectionException | ClassNotFoundException ex) {

            ex.printStackTrace();

            return false;

        }

    }

    private void introspectMBeanTypes(MBeanServer server) {

        if (allowedMbeans.isEmpty()) {

            Set<ObjectInstance> allMBeans = server.queryMBeans(null, null); // get all Mbeans

            allMBeans.stream().filter((objIns) -> (isMBeanAllowed(objIns.getObjectName())))

                    .forEachOrdered(objIns -> allowedMbeans.add(objIns.getObjectName()));

        }

    }

    @Override

    public void handleNotification(Notification notification, Object handback) {

        try {

            MBeanServerNotification mbs = (MBeanServerNotification) notification;

            if (MBeanServerNotification.REGISTRATION_NOTIFICATION.equals(mbs.getType())) {

                ObjectName mBeanName = mbs.getMBeanName();

                if (isMBeanAllowed(mBeanName)) {

                    allowedMbeans.add(mBeanName);

                }

            } else if (MBeanServerNotification.UNREGISTRATION_NOTIFICATION.equals(mbs.getType())) {

                if (allowedMbeans.contains(mbs.getMBeanName())) {

                    allowedMbeans.remove(mbs.getMBeanName());

                }

            }

        } catch (Exception e) {

        }

    }

    public MBeanCollectionResource(MBeanServer mBeanServer) {

        this.mBeanServer = mBeanServer;

        allowedMbeans = new ArrayList<>();

        introspectMBeanTypes(mBeanServer);

        allowedMbeans = new CopyOnWriteArrayList<>(allowedMbeans);

        // Create a REST handler for each MBean

        allowedMbeans.forEach(objectName -> mBeanResourceMap.put(objectName,

                new MBeanResource(mBeanServer, objectName)));

    }

    @Override

    public void handle(HttpExchange exchange) throws IOException {

        String path = URLDecoder.decode(exchange.getRequestURI().getPath(), StandardCharsets.UTF_8.name());

        if (path.matches(pathPrefix + "/?$")) {

            RestResource.super.handle(exchange);

        } else if (path.matches(pathPrefix + "/[^/]+/?.*")) {

            // Extract mbean name

            // Forward the request to its corresponding rest resource

            Pattern mbeans = Pattern.compile(pathPrefix + "/");

            Matcher matcher = mbeans.matcher(path);

            if (matcher.find()) {

                String ss = path.substring(matcher.end());

                String mBeanName = ss;

                if (ss.indexOf('/') != -1) {

                    mBeanName = ss.substring(0, ss.indexOf('/'));

                }

                try {

                    MBeanResource mBeanResource = mBeanResourceMap.get(new ObjectName(mBeanName));

                    if (mBeanResource == null) {

                        HttpUtil.sendResponse(exchange, HttpResponse.REQUEST_NOT_FOUND);

                        return;

                    }

                    mBeanResource.handle(exchange);

                } catch (MalformedObjectNameException e) {

                    HttpUtil.sendResponse(exchange, HttpResponse.BAD_REQUEST);

                }

            }

        }

    }

    @Override

    public HttpResponse doGet(HttpExchange exchange) {

        try {

            final String path = PlatformRestAdapter.getDomain()

                    + URLDecoder.decode(exchange.getRequestURI().getPath(), StandardCharsets.UTF_8.displayName())

                    .replaceAll("/$", "");

            List<ObjectName> filteredMBeans = allowedMbeans;

            Map<String, String> queryMap = HttpUtil.getGetRequestQueryMap(exchange);

            String query = exchange.getRequestURI().getQuery();

            if (query != null && queryMap.isEmpty()) {

                return new HttpResponse(HttpResponse.BAD_REQUEST,

                        "Invalid query params : Allowed query keys [objectname,page]");

            } else if (query != null && !queryMap.isEmpty()) {

                Map<String, String> newMap = new HashMap<>(queryMap);

                newMap.remove("objectname");

                newMap.remove("page");

                if (!newMap.isEmpty()) { // Invalid query params

                    return new HttpResponse(HttpResponse.BAD_REQUEST,

                            "Invalid query params : Allowed query keys [objectname,page]");

                }

            }

            if (queryMap.containsKey("objectname")) {        // Filter based on ObjectName query

                Set<ObjectName> queryMBeans = mBeanServer

                        .queryNames(new ObjectName(queryMap.get("objectname")), null);

                queryMBeans.retainAll(allowedMbeans);   // Intersection of two lists

                filteredMBeans = new ArrayList<>(queryMBeans);

            }

            JSONObject _links = HttpUtil.getPaginationLinks(exchange, filteredMBeans, pageSize);

            List<ObjectName> mbeanPage = HttpUtil.filterByPage(exchange, filteredMBeans, pageSize);

            List<Map<String, String>> items = new ArrayList<>(filteredMBeans.size());

            for (ObjectName objectName : mbeanPage) {

                Map<String, String> item = new LinkedHashMap<>();

                item.put("name", objectName.getCanonicalName());

                MBeanResource mBeanResource = mBeanResourceMap.get(objectName);

                try {

                    JSONObject mBeanInfo = mBeanResource.getMBeanInfo(mBeanServer, objectName);

                    JSONElement element = mBeanInfo.get("descriptor");

                    if (element != null) {

                        JSONElement element1 = ((JSONObject) element).get("interfaceClassName");

                        if (element1 != null) {

                            String intfName = (String) ((JSONPrimitive) element1).getValue();

                            item.put("interfaceClassName", intfName);

                        }

                    }

                    element = mBeanInfo.get("className");

                    if (element != null) {

                        String className = (String) ((JSONPrimitive) element).getValue();

                        item.put("className", className);

                    }

                    element = mBeanInfo.get("description");

                    if (element != null) {

                        String description = (String) ((JSONPrimitive) element).getValue();

                        item.put("description", description);

                    }

                    element = mBeanInfo.get("attributeInfo");

                    if (element != null) {

                        item.put("attributeCount", ((JSONArray) element).size() + "");

                    }

                    element = mBeanInfo.get("operationInfo");

                    if (element != null) {

                        item.put("operationCount", ((JSONArray) element).size() + "");

                    }

                } catch (InstanceNotFoundException | IntrospectionException | ReflectionException e) {

                }

                String href = path + "/" + objectName.toString();

                href = HttpUtil.escapeUrl(href);

                item.put("href", href);

                items.add(item);

            }

            Map<String, String> properties = new HashMap<>();

            properties.put("mbeanCount", Integer.toString(filteredMBeans.size()));

            JSONMapper typeMapper1 = JSONMappingFactory.INSTANCE.getTypeMapper(items);

            JSONMapper typeMapper2 = JSONMappingFactory.INSTANCE.getTypeMapper(properties);

            JSONElement linkElem = typeMapper1.toJsonValue(items);

            JSONElement propElem = typeMapper2.toJsonValue(properties);

            JSONObject jobj = new JSONObject();

            jobj.putAll((JSONObject) propElem);

            jobj.put("mbeans", linkElem);

            if (_links != null && !_links.isEmpty()) {

                jobj.put("_links", _links);

            }

            return new HttpResponse(jobj.toJsonString());

        } catch (JSONMappingException e) {

            return HttpResponse.SERVER_ERROR;

        } catch (UnsupportedEncodingException e) {

            return HttpResponse.BAD_REQUEST;

        } catch (MalformedObjectNameException e) {

            return new HttpResponse(HttpResponse.BAD_REQUEST, "Invalid query string");

        }

    }

    @Override

    public HttpResponse doPost(HttpExchange exchange) {

        try {

            String path = URLDecoder.decode(exchange.getRequestURI().getPath(),StandardCharsets.UTF_8.displayName());

            String reqBody = null;

            if (path.matches(pathPrefix + "/?$")) { // POST to current URL

                reqBody = HttpUtil.readRequestBody(exchange);

                if (reqBody == null || reqBody.isEmpty()) { // No Parameters

                    return HttpResponse.BAD_REQUEST;

                }

                JSONParser parser = new JSONParser(reqBody);

                JSONElement jsonElement = parser.parse();

                if (!(jsonElement instanceof JSONObject)) {

                    return new HttpResponse(HttpResponse.BAD_REQUEST,

                            "Invalid parameters : [" + reqBody + "]");

                }

                JSONObject jsonObject = (JSONObject) jsonElement;

                JSONObject normalizedObject = new JSONObject(jsonObject);

                // Normalize the input MBean names

                for (String objectNameString : jsonObject.keySet()) {

                    if (!objectNameString.startsWith("?")) { // Ignore object name patterns

                        JSONElement element = jsonObject.get(objectNameString);

                        normalizedObject.remove(objectNameString);

                        normalizedObject.put(new ObjectName(objectNameString).getCanonicalName(), element);

                    }

                }

                jsonObject.clear();

                jsonObject = normalizedObject;

                Set<String> objectNamePatterns = jsonObject.keySet()

                        .stream()

                        .filter(a -> a.startsWith("?"))

                        .collect(Collectors.toSet());

                if (!objectNamePatterns.isEmpty()) {

                    for (String pattern : objectNamePatterns) {

                        Set<ObjectName> queryMBeans = mBeanServer

                                .queryNames(new ObjectName(pattern.substring(1)), null);

                        queryMBeans.retainAll(allowedMbeans);

                        JSONElement patternNode = jsonObject.get(pattern);

                        jsonObject.remove(pattern);

                        for (ObjectName queryMBean : queryMBeans) {

                            String name = queryMBean.getCanonicalName();

                            if (jsonObject.containsKey(name)) {

                                JSONObject obj = new JSONObject();

                                obj.put(name, patternNode);

                                deepMerge(jsonObject, obj);

                            } else {

                                jsonObject.put(name, patternNode);

                            }

                        }

                    }

                }

                JSONObject result = new JSONObject();

                for (String mBeanName : jsonObject.keySet()) {

                    MBeanResource mBeanResource = mBeanResourceMap.get(new ObjectName(mBeanName));

                    if (mBeanResource != null) {

                        JSONElement element = jsonObject.get(mBeanName);

                        if (element instanceof JSONObject) {

                            JSONElement res = mBeanResource.handleBulkRequest

                                    ((JSONObject) element);

                            result.put(mBeanName, res);

                        } else {

                            result.put(mBeanName, "Invalid input");

                        }

                    } else {

                        result.put(mBeanName, "Invalid MBean");

                    }

                }

                return new HttpResponse(result.toJsonString());

            } else {

                return HttpResponse.METHOD_NOT_ALLOWED;

            }

        } catch (ParseException e) {

            return new HttpResponse(HttpResponse.BAD_REQUEST, "Invalid JSON String for request body");

        } catch (IOException e) {

            return HttpResponse.BAD_REQUEST;

        } catch (MalformedObjectNameException e) {

            return new HttpResponse(HttpResponse.BAD_REQUEST, "Invalid query string");

        }

    }

    private JSONObject deepMerge(JSONObject jsonObject1, JSONObject jsonObject2) {

        for (String key : jsonObject2.keySet()) {

            if (jsonObject1.containsKey(key)) {

                if (jsonObject2.get(key) instanceof JSONObject && jsonObject1.get(key) instanceof JSONObject) {

                    JSONObject jobj1 = (JSONObject) jsonObject1.get(key);

                    JSONObject jobj2 = (JSONObject) jsonObject2.get(key);

                    jsonObject1.put(key, deepMerge(jobj1, jobj2));

                } else if (jsonObject2.get(key) instanceof JSONArray && jsonObject1.get(key) instanceof JSONArray) {

                    JSONArray array1 = (JSONArray) jsonObject1.get(key);

                    JSONArray array2 = (JSONArray) jsonObject2.get(key);

                    for (JSONElement each : array2) {

                        if (!array1.contains(each)) {

                            array1.add(each);

                        }

                    }

                } else {

                    JSONArray array = new JSONArray();

                    array.add(jsonObject1.get(key));

                    array.add(jsonObject2.get(key));

                    jsonObject1.put(key, array);

                }

            } else {

                jsonObject1.put(key, jsonObject2.get(key));

            }

        }

        return jsonObject1;

    }

}