edu.umass.cs.msocket.common.policies.RandomProxyPolicy.java Source code

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Here is the source code for edu.umass.cs.msocket.common.policies.RandomProxyPolicy.java

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/*******************************************************************************
 *
 * Mobility First - mSocket library
 * Copyright (C) 2013, 2014 - University of Massachusetts Amherst
 * Contact: arun@cs.umass.edu
 *
 * 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. 
 *
 * Initial developer(s): Arun Venkataramani, Aditya Yadav, Emmanuel Cecchet.
 * Contributor(s): ______________________.
 *
 *******************************************************************************/

package edu.umass.cs.msocket.common.policies;

import java.net.InetSocketAddress;
import java.net.Socket;
import java.util.LinkedList;
import java.util.List;

import org.json.JSONArray;

import edu.umass.cs.gns.client.GuidEntry;
import edu.umass.cs.gns.client.UniversalGnsClient;
import edu.umass.cs.msocket.common.GnsConstants;
import edu.umass.cs.msocket.gns.GnsCredentials;
import edu.umass.cs.msocket.proxy.location.ProxyStatusInfo;

/**
 * This class defines a RandomProxyPolicy
 * 
 * @author <a href="mailto:cecchet@cs.umass.edu">Emmanuel Cecchet</a>
 * @version 1.0
 */
public class RandomProxyPolicy extends ProxySelectionPolicy {
    private static final long serialVersionUID = 2559217814049687908L;
    private String proxyGroupName;
    private int numProxy;
    private GnsCredentials gnsCredentials;

    /**
     * Creates a new <code>RandomProxyPolicy</code> object that picks up one
     * random proxy out of the given proxy group name.
     * 
     * @param proxyGroupName the proxy group name as registered in the GNS
     * @throws Exception if default GNS credentials can't be found
     */
    public RandomProxyPolicy(String proxyGroupName) throws Exception {
        this(proxyGroupName, 1, GnsCredentials.getDefaultCredentials());
    }

    /**
     * Creates a new <code>RandomProxyPolicy</code> object that picks up
     * numProxies random proxies out of the given proxy group name.
     * 
     * @param proxyGroupName the proxy group name as registered in the GNS
     * @param numProxy number of proxies to pick randomly (must be >=1)
     * @param gnsCredentials GNS credentials to use
     */
    public RandomProxyPolicy(String proxyGroupName, int numProxy, GnsCredentials gnsCredentials) {
        this.proxyGroupName = proxyGroupName;
        this.numProxy = numProxy;
        this.gnsCredentials = gnsCredentials;
        if (numProxy < 1)
            throw new IllegalArgumentException("Number of proxies must at least be 1");
        if (gnsCredentials == null)
            throw new IllegalArgumentException("GNS credentials cannot be null");
    }

    @Override
    public List<InetSocketAddress> getNewProxy() throws Exception {
        List<InetSocketAddress> result = new LinkedList<InetSocketAddress>();
        final GuidEntry guidEntry = gnsCredentials.getGuidEntry();

        // Lookup proxies in proxy group list
        UniversalGnsClient gnsClient = gnsCredentials.getGnsClient();
        String groupGuid = gnsClient.lookupGuid(proxyGroupName);
        JSONArray members = gnsClient.groupGetMembers(groupGuid, gnsCredentials.getGuidEntry());

        for (int i = 0; i < members.length(); i++) { // Add each proxy to the list
            String proxyGuid = members.getString(i);

            // Check first that this member is a proxy and not another service
            String serviceType = gnsClient.fieldRead(proxyGuid, GnsConstants.SERVICE_TYPE_FIELD, guidEntry)
                    .getString(0);
            if (!GnsConstants.PROXY_SERVICE.equals(serviceType))
                continue; // This is not a proxy, ignore

            // Grab the proxy IP address
            String proxyIp = gnsClient.fieldRead(proxyGuid, GnsConstants.PROXY_EXTERNAL_IP_FIELD, guidEntry)
                    .getString(0);
            String[] parsed = proxyIp.split(":");
            InetSocketAddress addr = new InetSocketAddress(parsed[0], Integer.parseInt(parsed[1]));
            result.add(addr);

            // Did we get enough proxies?
            if (result.size() == numProxy)
                break;
        }

        return result;
    }

    @Override
    public boolean hasAvailableProxies() {
        try {
            return getNewProxy() != null;
        } catch (Exception e) {
            return false;
        }
    }

    @Override
    public List<String> getProxyIPs(List<ProxyStatusInfo> proxies, Socket acceptedSocket) {
        throw new IllegalAccessError("Random proxy policies should not be sent to the location service");
    }

}