drivers/utilities/src/main/java/org/onosproject/drivers/utilities/XmlConfigParser.java

/*
 * Copyright 2016-present Open Networking Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.onosproject.drivers.utilities;

import org.apache.commons.configuration.ConfigurationException;
import org.apache.commons.configuration.HierarchicalConfiguration;
import org.apache.commons.configuration.XMLConfiguration;
import org.apache.commons.configuration.tree.ConfigurationNode;
import org.onlab.packet.IpAddress;
import org.onosproject.net.behaviour.ControllerInfo;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import java.io.ByteArrayInputStream;
import java.io.InputStream;
import java.io.StringWriter;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.List;

/**
 * Parser for Netconf XML configurations and replys.
 */
public final class XmlConfigParser {
    public static final Logger log = LoggerFactory
            .getLogger(XmlConfigParser.class);

    private static final String DISALLOW_DTD_FEATURE = "http://apache.org/xml/features/disallow-doctype-decl";
    private static final String DISALLOW_EXTERNAL_DTD =
            "http://apache.org/xml/features/nonvalidating/load-external-dtd";

    private XmlConfigParser() {
        //not called, preventing any allocation
    }

    private static HierarchicalConfiguration loadXmlCommonPart(XMLConfiguration cfg, InputStream xmlStream)
                   throws ParserConfigurationException, ConfigurationException {

        DocumentBuilderFactory dbfactory = DocumentBuilderFactory.newInstance();
        //Disabling DTDs in order to avoid XXE xml-based attacks.
        disableFeature(dbfactory, DISALLOW_DTD_FEATURE);
        disableFeature(dbfactory, DISALLOW_EXTERNAL_DTD);
        dbfactory.setXIncludeAware(false);
        dbfactory.setExpandEntityReferences(false);
        cfg.setDocumentBuilder(dbfactory.newDocumentBuilder());
        cfg.load(xmlStream);
        return cfg;
    }

    public static HierarchicalConfiguration loadXml(InputStream xmlStream) {
        try {
            XMLConfiguration cfg = new XMLConfiguration();
            return loadXmlCommonPart(cfg, xmlStream);
        } catch (ConfigurationException | ParserConfigurationException e) {
            throw new IllegalArgumentException("Cannot load xml from Stream", e);
        }
    }

    public static HierarchicalConfiguration loadXml(InputStream xmlStream, boolean withDelim) {
        try {
            XMLConfiguration cfg = new XMLConfiguration();
            //Optionally disable default comma-based parsing on config values to allow JSON strings to be used therein
            if (!withDelim) {
                cfg.setDelimiterParsingDisabled(true);
            }
            return loadXmlCommonPart(cfg, xmlStream);
        } catch (ConfigurationException | ParserConfigurationException e) {
            throw new IllegalArgumentException("Cannot load xml from Stream", e);
        }
    }

    public static HierarchicalConfiguration loadXmlString(String xmlStr) {
        return loadXml(new ByteArrayInputStream(xmlStr.getBytes(StandardCharsets.UTF_8)));
    }

    public static HierarchicalConfiguration loadXmlString(String xmlStr, boolean withDelim) {
        return loadXml(new ByteArrayInputStream(xmlStr.getBytes(StandardCharsets.UTF_8)), withDelim);
    }

    public static List<ControllerInfo> parseStreamControllers(HierarchicalConfiguration cfg) {
        List<ControllerInfo> controllers = new ArrayList<>();
        List<HierarchicalConfiguration> fields =
                cfg.configurationsAt("data.capable-switch." +
                        "logical-switches." +
                        "switch.controllers.controller");
        for (HierarchicalConfiguration sub : fields) {
            controllers.add(new ControllerInfo(
                    IpAddress.valueOf(sub.getString("ip-address")),
                    Integer.parseInt(sub.getString("port")),
                    sub.getString("protocol")));
        }
        return controllers;
    }


    protected static String parseSwitchId(HierarchicalConfiguration cfg) {
        HierarchicalConfiguration field =
                cfg.configurationAt("data.capable-switch." +
                        "logical-switches." +
                        "switch");
        return field.getProperty("id").toString();
    }

    public static String parseCapableSwitchId(HierarchicalConfiguration cfg) {
        HierarchicalConfiguration field =
                cfg.configurationAt("data.capable-switch");
        return field.getProperty("id").toString();
    }

    public static String createControllersConfig(HierarchicalConfiguration cfg,
                                                 HierarchicalConfiguration actualCfg,
                                                 String target, String netconfOperation,
                                                 String controllerOperation,
                                                 List<ControllerInfo> controllers) {
        //cfg.getKeys().forEachRemaining(key -> System.out.println(key));
        cfg.setProperty("edit-config.target", target);
        cfg.setProperty("edit-config.default-operation", netconfOperation);
        cfg.setProperty("edit-config.config.capable-switch.id",
                parseCapableSwitchId(actualCfg));
        cfg.setProperty("edit-config.config.capable-switch." +
                "logical-switches.switch.id", parseSwitchId(actualCfg));
        List<ConfigurationNode> newControllers = new ArrayList<>();
        for (ControllerInfo ci : controllers) {
            XMLConfiguration controller = new XMLConfiguration();
            controller.setRoot(new HierarchicalConfiguration.Node("controller"));
            String id = ci.type() + ":" + ci.ip() + ":" + ci.port();
            controller.setProperty("id", id);
            controller.setProperty("ip-address", ci.ip());
            controller.setProperty("port", ci.port());
            controller.setProperty("protocol", ci.type());
            newControllers.add(controller.getRootNode());
        }
        cfg.addNodes("edit-config.config.capable-switch.logical-switches." +
                "switch.controllers", newControllers);
        XMLConfiguration editcfg = (XMLConfiguration) cfg;
        StringWriter stringWriter = new StringWriter();
        try {
            editcfg.save(stringWriter);
        } catch (ConfigurationException e) {
            log.error("createControllersConfig()", e);
        }
        String s = stringWriter.toString()
                .replaceAll("<controller>",
                        "<controller nc:operation=\"" + controllerOperation + "\">");
        s = s.replace("<target>" + target + "</target>",
                "<target><" + target + "/></target>");
        return s;

    }

    //TODO implement mor methods for parsing configuration when you need them

    /**
     * Parses a config reply and returns the result.
     *
     * @param reply a tree-like source
     * @return the configuration result
     */
    public static boolean configSuccess(HierarchicalConfiguration reply) {
        if (reply != null) {
            if (reply.containsKey("ok")) {
                return true;
            }
        }
        return false;
    }

    private static void disableFeature(DocumentBuilderFactory dbfactory, String feature) {
        try {
            dbfactory.setFeature(feature, true);
        } catch (ParserConfigurationException e) {
            // This should catch a failed setFeature feature
            log.info("ParserConfigurationException was thrown. The feature '" +
                    feature + "' is probably not supported by your XML processor.");
        }
    }
}