CsrfProtectionFilter.java

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package com.sun.jersey.api.client.filter;

import com.sun.jersey.api.client.ClientHandlerException;
import com.sun.jersey.api.client.ClientRequest;
import com.sun.jersey.api.client.ClientResponse;
import java.util.Collections;
import java.util.HashSet;
import java.util.Set;

/**
 * Simple client-side filter that adds X-Requested-By headers to all state-changing
 * request (i.e. request for methods other than GET, HEAD and OPTIONS).
 * This is to satisfy the requirements of the {@link com.sun.jersey.api.container.filter.CsrfProtectionFilter}
 * on the server side.
 *
 * @author Martin Matula
 */
public class CsrfProtectionFilter extends ClientFilter {

    private static final Set<String> METHODS_TO_IGNORE;
    private static final String HEADER_NAME = "X-Requested-By";

    static {
        HashSet<String> mti = new HashSet<String>();
        mti.add("GET");
        mti.add("OPTIONS");
        mti.add("HEAD");
        METHODS_TO_IGNORE = Collections.unmodifiableSet(mti);
    }
    private final String requestedBy;

    public CsrfProtectionFilter() {
        this("");
    }

    /**
     * Initialized the filter with a desired value of the X-Requested-By header.
     *
     * @param requestedBy Desired value of X-Requested-By header the filter
     * will be adding for all potentially state changing requests.
     */
    public CsrfProtectionFilter(String requestedBy) {
        this.requestedBy = requestedBy;
    }

    /**
     * Adds X-Requested-By header (if not present) to potentially state changing requests.
     *
     * @param cr Client request to be processed.
     * @return Response
     * @throws ClientHandlerException
     */
    @Override
    public ClientResponse handle(ClientRequest cr) throws ClientHandlerException {
        if (!METHODS_TO_IGNORE.contains(cr.getMethod()) && !cr.getHeaders().containsKey(HEADER_NAME)) {
            cr.getHeaders().add(HEADER_NAME, requestedBy);
        }
        return getNext().handle(cr);
    }
}