QRCodeResource.java

/*
 * Copyright 2016 Red Hat, Inc. and/or its affiliates
 * and other contributors as indicated by the @author tags.
 *
 * 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.keycloak.services.resources;

import com.google.zxing.BarcodeFormat;
import com.google.zxing.WriterException;
import com.google.zxing.client.j2se.MatrixToImageWriter;
import com.google.zxing.common.BitMatrix;
import com.google.zxing.qrcode.QRCodeWriter;
import org.keycloak.services.util.CacheControlUtil;

import javax.servlet.ServletException;
import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.QueryParam;
import javax.ws.rs.WebApplicationException;
import javax.ws.rs.core.CacheControl;
import javax.ws.rs.core.Response;
import javax.ws.rs.core.StreamingOutput;
import java.io.IOException;
import java.io.OutputStream;

/**
 * Create a barcode image
 *
 * @author <a href="mailto:sthorger@redhat.com">Stian Thorgersen</a>
 */
@Path("/qrcode")
public class QRCodeResource {

    /**
     * Create a bar code image
     *
     * @param contents
     * @param size
     * @return
     * @throws ServletException
     * @throws IOException
     * @throws WriterException
     */
    @GET
    @Produces("image/png")
    public Response createQrCode(@QueryParam("contents") String contents, @QueryParam("size") String size) throws ServletException, IOException, WriterException {
        int width = 256;
        int height = 256;

        if (size != null) {
            String[] s = size.split("x");
            try {
                width = Integer.parseInt(s[0]);
                height = Integer.parseInt(s[1]);
            } catch (Throwable t) {
                return Response.status(Response.Status.BAD_REQUEST).build();
            }
        }

        if (contents == null) {
            return Response.status(Response.Status.BAD_REQUEST).build();
        }

        if (width > 1000 || height > 1000 || contents.length() > 1000) {
            return Response.status(Response.Status.BAD_REQUEST).build();
        }

        QRCodeWriter writer = new QRCodeWriter();
        final BitMatrix bitMatrix = writer.encode(contents, BarcodeFormat.QR_CODE, width, height);

        StreamingOutput stream = new StreamingOutput() {
            @Override
            public void write(OutputStream os) throws IOException,
                    WebApplicationException {
                MatrixToImageWriter.writeToStream(bitMatrix, "png", os);
            }
        };

        /*
         * This response is served with extra headers that tell the browser to not do any caching.
         * The reason is that this page will include a QR code that can give an attacker access to
         * the time based tokens, so it's best to take precautions and make sure there are no copies
         * of the QR code lost in a cache.
         */
        CacheControl cacheControl = CacheControlUtil.noCache();

        return Response.ok(stream) //
                .cacheControl(cacheControl) //
                .header("Pragma","no-cache") //
                .header("Expires", "0") //
                .build();
    }
}