ReCaptchaHandler.java

/*
 * JSmart Framework - Java Web Development Framework
 * Copyright (c) 2015, Jeferson Albino da Silva, All rights reserved.
 * 
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 3.0 of the License, or (at your option) any later version.
 * 
 * This library 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
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library. If not, see <http://www.gnu.org/licenses/>.
*/

package com.jsmartframework.web.manager;

import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.InputStreamReader;
import java.net.URL;
import java.net.URLEncoder;

import javax.net.ssl.HttpsURLConnection;
import javax.servlet.http.HttpServletRequest;

public final class ReCaptchaHandler {

    public static final String RECAPTCHA_V1 = "1";

    public static final String RECAPTCHA_V2 = "2";


    public static final String RESPONSE_V1_FIELD_NAME = "recaptcha_response_field";

    public static final String RECAPTCHA_V1_CHALLENGE_URL = "https://www.google.com/recaptcha/api/challenge?k=%s";

    static final String CHALLENGE_V1_FIELD_NAME = "recaptcha_challenge_field";

    static final String RECAPTCHA_V1_VERIFY_URL = "https://www.google.com/recaptcha/api/verify";


    public static final String RESPONSE_V2_FIELD_NAME = "g-recaptcha-response";

    public static final String RECAPTCHA_CHALLENGE_V2_URL = "https://www.google.com/recaptcha/api.js?onload=%s&render=explicit&hl=%s";

    static final String RECAPTCHA_V2_VERIFY_URL = "https://www.google.com/recaptcha/api/siteverify";


    static boolean checkReCaptchaV1(String secretKey, String responseField) {
        return checkReCaptcha(secretKey, responseField, RECAPTCHA_V1);
    }

    static boolean checkReCaptchaV2(String secretKey, String responseField) {
        return checkReCaptcha(secretKey, responseField, RECAPTCHA_V2);
    }

    private static boolean checkReCaptcha(String secretKey, String responseField, String version) {

        HttpsURLConnection conn = null;
        HttpServletRequest request = WebContext.getRequest();

        try {
            if (version.equals(RECAPTCHA_V1)) {
                conn = (HttpsURLConnection) new URL(RECAPTCHA_V1_VERIFY_URL).openConnection();
            } else {
                conn = (HttpsURLConnection) new URL(RECAPTCHA_V2_VERIFY_URL).openConnection();
            }

            conn.setRequestMethod("POST");
            conn.setDoOutput(true);

            StringBuilder params = new StringBuilder();
            params.append("response=").append(URLEncoder.encode(responseField, "UTF-8"))
                .append("&remoteip=").append(request.getRemoteAddr());

            if (version.equals(RECAPTCHA_V1)) {
                String challengeField = request.getParameter(CHALLENGE_V1_FIELD_NAME);

                params.append("&privatekey=").append(URLEncoder.encode(secretKey, "UTF-8"))
                    .append("&challenge=").append(URLEncoder.encode(challengeField, "UTF-8"));
            } else {
                params.append("&secret=").append(URLEncoder.encode(secretKey, "UTF-8"));
            }

            DataOutputStream wr = new DataOutputStream(conn.getOutputStream());
            wr.writeBytes(params.toString());
            wr.close();

            if (conn.getResponseCode() != 200) {
                return false;
            }

            String line;
            StringBuilder builder = new StringBuilder();
            BufferedReader in = new BufferedReader(new InputStreamReader(conn.getInputStream()));

            while ((line = in.readLine()) != null) {
                builder.append(line);
            }
            in.close();

            return builder.toString().contains("true");

        } catch (Exception e) {
            throw new RuntimeException(e);

        } finally {
            if (conn != null) {
                conn.disconnect();
            }
        }
    }

    private ReCaptchaHandler() {
        // DO NOTHING
    }
}