2012年10月17日 星期三

JCaptcha integration with CAS

說明Jasig CAS登入頁增加圖形驗證碼的功能，圖形驗證碼採用JCaptcha來實做，這部份參與的不多只有做一些小修改，因此大部份是同事的努力，這邊只是單純的詳實記錄下來，如同事有blogger也會提供相關連結以利參考。

CAS Server的相關設定請參考文章末的參考連結，這裡只著重在Jasig CAS跟JCaptcha的整合。

準備執行環境

Maven是為 build JCaptcha integration with CAS 做準備
  • JDK (Java Development Kit) version 1.6+
  • Apache Maven 2.2.1+
  • Apache Tomcat 6+
  • JA-SIG CAS 3.4.2.1+
  • JCaptcha 1.0

下載JA-SIG CAS Server
  • 下載CAS Server版本為3.4.2.1，並將下載檔案cas-server-3.4.3-release.zip解壓縮。



Build & Running JCaptcha integration with CAS

  1. 修改pom.xml，可在cas-server-3.4.3-release.zip解壓縮後的路徑cas-server-3.4.3\cas-server-core\pom.xml下找到，新增下列幾行
    2.         <!-- jCaptcha -->
        <dependency>
            <groupId>com.octo.captcha</groupId>
            <artifactId>jcaptcha-all</artifactId>
            <version>1.0-RC6</version>
        </dependency>

  2. 新增cas-server-3.4.3\cas-server-core\src\main\java\org\jasig\cas\captcha\CaptchaServiceSingleton.java 檔案，以產生圖形驗證的圖檔。
    3. package org.jasig.cas.captcha;

import com.octo.captcha.service.image.ImageCaptchaService;
import com.octo.captcha.service.image.DefaultManageableImageCaptchaService;
import com.octo.captcha.engine.image.ListImageCaptchaEngine;
import com.octo.captcha.component.word.wordgenerator.WordGenerator;
import com.octo.captcha.component.word.wordgenerator.RandomWordGenerator;
import com.octo.captcha.component.image.color.RandomRangeColorGenerator;
import com.octo.captcha.component.image.textpaster.TextPaster;
import com.octo.captcha.component.image.textpaster.RandomTextPaster;
import com.octo.captcha.component.image.backgroundgenerator.BackgroundGenerator;
import com.octo.captcha.component.image.backgroundgenerator.UniColorBackgroundGenerator;
import com.octo.captcha.component.image.fontgenerator.FontGenerator;
import com.octo.captcha.component.image.fontgenerator.RandomFontGenerator;
import com.octo.captcha.component.image.wordtoimage.WordToImage;
import com.octo.captcha.component.image.wordtoimage.ComposedWordToImage;
import com.octo.captcha.image.gimpy.GimpyFactory;
import java.awt.Font;
import com.octo.captcha.service.captchastore.FastHashMapCaptchaStore;
import java.awt.Color;

public class CaptchaServiceSingleton {
 private static ImageCaptchaService instance =
    new DefaultManageableImageCaptchaService(new FastHashMapCaptchaStore(),
                  new MyImageCaptchaEngine(),
                  180,
                  1000,
                  750);

 public static ImageCaptchaService getInstance() {
  return instance;
 }

 private static class MyImageCaptchaEngine extends ListImageCaptchaEngine {
  protected void buildInitialFactories() {
   WordGenerator wgen = new RandomWordGenerator("abcdefghijklmnopqrstuvwxyz0123456789");
   RandomRangeColorGenerator cgen = new RandomRangeColorGenerator(
     new int[] {0, 100},
     new int[] {0, 100},
     new int[] {0, 100});
   TextPaster textPaster = new RandomTextPaster(new Integer(7), new Integer(7), cgen, true);

   BackgroundGenerator backgroundGenerator = new UniColorBackgroundGenerator(new Integer(200), new Integer(100), new Color(204, 204, 204));

   Font[] fontsList = new Font[] {
    new Font("Arial", 0, 10),
    new Font("Tahoma", 0, 10),
    new Font("Verdana", 0, 10),
   };

   FontGenerator fontGenerator = new RandomFontGenerator(new Integer(20), new Integer(35), fontsList);

   WordToImage wordToImage = new ComposedWordToImage(fontGenerator, backgroundGenerator, textPaster);
   this.addFactory(new GimpyFactory(wgen, wordToImage));
  }
 }
}

  3. 新增cas-server-3.4.3\cas-server-core\src\main\java\org\jasig\cas\captcha\ImageCaptchaServlet.java 檔案，以利CAS Server Login Page Request。
    4. package org.jasig.cas.captcha;

import com.octo.captcha.service.CaptchaServiceException;
import com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGImageEncoder;

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.awt.image.BufferedImage;
import java.io.ByteArrayOutputStream;
import java.io.IOException;


public class ImageCaptchaServlet extends HttpServlet {

 public void init(ServletConfig servletConfig) throws ServletException {
  super.init(servletConfig);
 }

 protected void doGet(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse) throws ServletException, IOException {

  byte[] captchaChallengeAsJpeg = null;
  // the output stream to render the captcha image as jpeg into
  ByteArrayOutputStream jpegOutputStream = new ByteArrayOutputStream();
  try {
   // get the session id that will identify the generated captcha.
   //the same id must be used to validate the response, the session id is a good candidate!
   String captchaId = httpServletRequest.getSession().getId();
   // call the ImageCaptchaService getChallenge method
   BufferedImage challenge =
   CaptchaServiceSingleton.getInstance().getImageChallengeForID(captchaId,
   httpServletRequest.getLocale());

   // a jpeg encoder
   JPEGImageEncoder jpegEncoder =
   JPEGCodec.createJPEGEncoder(jpegOutputStream);
   jpegEncoder.encode(challenge);
  } catch (IllegalArgumentException e) {
   httpServletResponse.sendError(HttpServletResponse.SC_NOT_FOUND);
   return;
  } catch (CaptchaServiceException e) {
   httpServletResponse.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
   return;
  }

  captchaChallengeAsJpeg = jpegOutputStream.toByteArray();

  // flush it in the response
  httpServletResponse.setHeader("Cache-Control", "no-store");
  httpServletResponse.setHeader("Pragma", "no-cache");
  httpServletResponse.setDateHeader("Expires", 0);
  httpServletResponse.setContentType("image/jpeg");
  ServletOutputStream responseOutputStream =
    httpServletResponse.getOutputStream();
  responseOutputStream.write(captchaChallengeAsJpeg);
  responseOutputStream.flush();
  responseOutputStream.close();
 }
}

  4. 於 Login Page submit 時增加圖形驗證碼的判斷，接著找出 submit 時執行的程式，cas\WEB-INF\login-webflow.xml片段如下，登入成功與否的控制在authenticationViaFormAction.submit() method。
    5.  
    <view-state id="viewLoginForm" view="casLoginView" model="credentials">
        <var name="credentials" class="org.jasig.cas.authentication.principal.UsernamePasswordCredentials" />
        <binder>
            <binding property="username" />
            <binding property="password" />
        </binder>
        <on-entry>
            <set name="viewScope.commandName" value="'credentials'" />
        </on-entry>
        <transition on="submit" bind="true" validate="true" to="realSubmit">
            <set name="flowScope.credentials" value="credentials" />
            <evaluate expression="authenticationViaFormAction.doBind(flowRequestContext, flowScope.credentials)" />
        </transition>
    </view-state>
    

    <action-state id="realSubmit">
        <evaluate expression="authenticationViaFormAction.submit(flowRequestContext, flowScope.credentials, messageContext)" />
        <transition on="warn" to="warn" />
        <transition on="success" to="sendTicketGrantingTicket" />
        <transition on="error" to="viewLoginForm" />
    </action-state>

    接著從cas\WEB-INF\cas-servlet.xml(如下)可看到authenticationViaFormAction的路徑，相對路徑為cas-server-3.4.3\cas-server-core\src\main\java\org\jasig\cas\web\flow。 
         <bean id="authenticationViaFormAction" class="org.jasig.cas.web.flow.AuthenticationViaFormAction"
        p:centralAuthenticationService-ref="centralAuthenticationService"
        p:warnCookieGenerator-ref="warnCookieGenerator" />

    修改cas-server-3.4.3\cas-server-core\src\main\java\org\jasig\cas\web\flow\AuthenticationViaFormAction.java，加上圖形驗證碼的判斷，僅列出修改的submit() method，新增 line-8 ~ 20 取得 User 輸入的驗證碼並比對是否輸入正確，將 line-42 ~ 43 置換成 line-46 ~ 55 加上驗證碼輸入正確與否的流程判斷，。 
    import com.octo.captcha.service.CaptchaServiceException;
import org.jasig.cas.captcha.CaptchaServiceSingleton;
....

    public final String submit(final RequestContext context, final Credentials credentials, final MessageContext messageContext) throws Exception {
        final String ticketGrantingTicketId = WebUtils.getTicketGrantingTicketId(context);
        final Service service = WebUtils.getService(context);

        // for captcha check input and expect value begin
        final HttpServletRequest request = WebUtils.getHttpServletRequest(context);
        Boolean isResponseCorrect = Boolean.FALSE;
        String enterCaptchaId = request.getParameter( "j_captcha_response" );
        String captchaId = request.getSession().getId();

        try {
            isResponseCorrect = CaptchaServiceSingleton.getInstance().validateResponseForID(captchaId, enterCaptchaId);
        } catch (CaptchaServiceException e) {
            //should not happen, may be thrown if the id is not valid
            logger.error( "Captcha Code Validation Failed", e );
        }
        // for captcah input and expect value end

        if (StringUtils.hasText(context.getRequestParameters().get("renew")) && ticketGrantingTicketId != null && service != null) {

            try {
                final String serviceTicketId = this.centralAuthenticationService.grantServiceTicket(ticketGrantingTicketId, service, credentials);
                WebUtils.putServiceTicketInRequestScope(context, serviceTicketId);
                putWarnCookieIfRequestParameterPresent(context);
                return "warn";
            } catch (final TicketException e) {
                if (e.getCause() != null && AuthenticationException.class.isAssignableFrom(e.getCause().getClass())) {
                    populateErrorsInstance(e, messageContext);
                    return "error";
                }
                this.centralAuthenticationService.destroyTicketGrantingTicket(ticketGrantingTicketId);
                if (logger.isDebugEnabled()) {
                    logger.debug("Attempted to generate a ServiceTicket using renew=true with different credentials", e);
                }
            }
        }

        try {
            //WebUtils.putTicketGrantingTicketInRequestScope(context, this.centralAuthenticationService.createTicketGrantingTicket(credentials));
            //putWarnCookieIfRequestParameterPresent(context);
            //return "success";

            // for captcha
            if( Boolean.TRUE.equals(isResponseCorrect) ) { 
                WebUtils.putTicketGrantingTicketInRequestScope(context, this.centralAuthenticationService.createTicketGrantingTicket(credentials));
                putWarnCookieIfRequestParameterPresent(context);
                return "success";
            } else {
                // for captcha, captcha validate failed
                messageContext.addMessage( new MessageBuilder().error().code( "captcha.input.error" ).defaultText( "captcha.input.error" ).build() );
                return "error"; 
            }// for captcha 

        } catch (final TicketException e) {
            populateErrorsInstance(e, messageContext);
            return "error";
        }
    }

  5. build cas-server-core-3.4.3.jar，切換到 cas-server-3.4.3\cas-server-core 路徑執行下列指令，將產出的cas-server-core-3.4.3.jar複製到cas\WEB-INF\lib此路徑下。
    6. mvn clean package -Dmaven.test.skip=true

  6. 下載jcaptcha-1.0-bin.zip，解壓縮後將 jcaptcha-1.0-all.jar 複製到cas\WEB-INF\lib此路徑下。

  7. 修改 cas\WEB-INF\web.xml 加上 JCaptcha Servlet mapping。
    8.     <!-- jCaptcha Servlet -->
    <servlet>
        <servlet-name>jcaptcha</servlet-name>
        <servlet-class>org.jasig.cas.captcha.ImageCaptchaServlet</servlet-class>
        <load-on-startup>0</load-on-startup>
    </servlet>

    <servlet-mapping>
        <servlet-name>jcaptcha</servlet-name>
        <url-pattern>/jcaptcha</url-pattern>
    </servlet-mapping>

  8. 修改登入頁 cas\WEB-INF\view\jsp\default\ui\casLoginView.jsp 加上圖形驗證碼的顯示。
    9.     <div class="row fl-controls-left">
        <img src="jcaptcha" />
        <input type="text" name="j_captcha_response" cssClass="required" cssErrorClass="error" size="25" />
    </div>

  9. 啟動 Tomcat ，連結至CAS Login Page，可看到如下畫面，經測試須正確輸入圖形驗證碼才可登入成功。

下一節依需求修改驗證碼的干擾方式，JCaptcha 官網有提供很多種方式以下所述只是其中一種，單看需求而訂。

Modify JCaptcha Background

  • cas-server-3.4.3\cas-server-core\src\main\java\org\jasig\cas\captcha\CaptchaServiceSingleton.java 修改如下，照之前的步驟 build & copy cas-server-core-3.4.3.jar。
    • package org.jasig.cas.captcha;

import com.octo.captcha.service.image.ImageCaptchaService;
import com.octo.captcha.service.image.DefaultManageableImageCaptchaService;
import com.octo.captcha.engine.image.ListImageCaptchaEngine;
import com.octo.captcha.component.word.wordgenerator.WordGenerator;
import com.octo.captcha.component.word.wordgenerator.RandomWordGenerator;
import com.octo.captcha.component.image.color.RandomRangeColorGenerator;
import com.octo.captcha.component.image.color.SingleColorGenerator;
import com.octo.captcha.component.image.textpaster.TextPaster;
import com.octo.captcha.component.image.textpaster.RandomTextPaster;
import com.octo.captcha.component.image.backgroundgenerator.FileReaderRandomBackgroundGenerator;
import com.octo.captcha.component.image.fontgenerator.FontGenerator;
import com.octo.captcha.component.image.fontgenerator.RandomFontGenerator;
import com.octo.captcha.component.image.wordtoimage.WordToImage;
import com.octo.captcha.component.image.wordtoimage.ComposedWordToImage;
import com.octo.captcha.image.gimpy.GimpyFactory;

import java.awt.Font;
import com.octo.captcha.service.captchastore.FastHashMapCaptchaStore;
import java.awt.Color;


public class CaptchaServiceSingleton {
 private static ImageCaptchaService instance =
       new DefaultManageableImageCaptchaService(new FastHashMapCaptchaStore(),
                                                new MyImageCaptchaEngine(), 
                                                180,
                                                1000,
                                                750);

 public static ImageCaptchaService getInstance() {
  return instance;
 }
    
 private static class MyImageCaptchaEngine extends ListImageCaptchaEngine {
  protected void buildInitialFactories() {
   WordGenerator wgen = new RandomWordGenerator("abcdefghijklmnopqrstuvwxyz0123456789");
   RandomRangeColorGenerator cgen = new RandomRangeColorGenerator(
   new int[] {0, 100},
   new int[] {0, 100},
   new int[] {0, 100});
   SingleColorGenerator wordColor = new SingleColorGenerator(Color.BLACK);
   TextPaster textPaster = new RandomTextPaster(new Integer(6), new Integer(6), wordColor, true);

   FileReaderRandomBackgroundGenerator background = new FileReaderRandomBackgroundGenerator(new Integer(180), new Integer(50),"../webapps/cas/images/backgrounds/");

   Font[] fontsList = new Font[] {
    new Font("Arial", 0, 10),
    new Font("Tahoma", 0, 10),
    new Font("Verdana", 0, 10),
   };
   FontGenerator fontGenerator = new RandomFontGenerator(new Integer(30), new Integer(30), fontsList);

   WordToImage wordToImage = new ComposedWordToImage(fontGenerator, background, textPaster);
   this.addFactory(new GimpyFactory(wgen, wordToImage));
 
  }
 }
}
  • 產出圖形驗證碼的背景圖(jpg)，放置於CaptchaServiceSingleton.java所設定的路徑%TOMCAT_HOME%/webapps/cas/images/backgrounds/，此 sample 只產出二張圖，一張黑色直條紋，一張紫色橫條紋

  • 啟動 Tomcat ，連結至CAS Login Page，可看到如下畫面，背景圖可自行放置數量不限，會依亂數顯示，如有放置新的圖 Tomcat 須重啟才能顯示新的背景圖。



相關設定可參考：
JA-SIG CAS Single-Sign On - 1
SSO demonstration for a quick start with CAS
CAS on Windows Quick Setup Guide
JA-SIG CAS - 3-1: 增加Captcha功能
JCAPTCHA integration with CAS

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