source: branches/TaskRewrite/src/grails-app/controllers/LoginController.groovy @ 58

import org.codehaus.groovy.grails.plugins.springsecurity.RedirectUtils
import org.grails.plugins.springsecurity.service.AuthenticateService

import org.springframework.security.AuthenticationTrustResolverImpl
import org.springframework.security.DisabledException
import org.springframework.security.context.SecurityContextHolder as SCH
import org.springframework.security.ui.AbstractProcessingFilter
import org.springframework.security.ui.webapp.AuthenticationProcessingFilter

/**
 * Login Controller (Example).
 */
class LoginController {

        /**
         * Dependency injection for the authentication service.
         */
        def authenticateService

        /**
         * Dependency injection for OpenIDConsumer.
         */
        def openIDConsumer

        /**
         * Dependency injection for OpenIDAuthenticationProcessingFilter.
         */
        def openIDAuthenticationProcessingFilter

        private final authenticationTrustResolver = new AuthenticationTrustResolverImpl()

        def index = {
                if (isLoggedIn()) {
                        redirect uri: '/'
                }
                else {
                        redirect action: auth, params: params
                }
        }

        /**
         * Show the login page.
         */
        def auth = {

                nocache response

                if (isLoggedIn()) {
                        redirect uri: '/'
                        return
                }

                String view
                String postUrl
                def config = authenticateService.securityConfig.security
                if (config.useOpenId) {
                        view = 'openIdAuth'
                        postUrl = "${request.contextPath}/login/openIdAuthenticate"
                }
                else if (config.useFacebook) {
                        view = 'facebookAuth'
                        postUrl = "${request.contextPath}${config.facebook.filterProcessesUrl}"
                }
                else {
                        view = 'auth'
                        postUrl = "${request.contextPath}${config.filterProcessesUrl}"
                }

                render view: view, model: [postUrl: postUrl]
        }

        /**
         * Form submit action to start an OpenID authentication.
         */
        def openIdAuthenticate = {
                String openID = params['j_username']
                try {
                        String returnToURL = RedirectUtils.buildRedirectUrl(
                                        request, response, openIDAuthenticationProcessingFilter.filterProcessesUrl)
                        String redirectUrl = openIDConsumer.beginConsumption(request, openID, returnToURL)
                        redirect url: redirectUrl
                }
                catch (org.springframework.security.ui.openid.OpenIDConsumerException e) {
                        log.error "Consumer error: $e.message", e
                        redirect url: openIDAuthenticationProcessingFilter.authenticationFailureUrl
                }
        }

        // Login page (function|json) for Ajax access.
        def authAjax = {
                nocache(response)
                //this is example:
                render """
                <script type='text/javascript'>
                (function() {
                        loginForm();
                })();
                </script>
                """
        }

        /**
         * The Ajax success redirect url.
         */
        def ajaxSuccess = {
                nocache(response)
                render '{success: true}'
        }

        /**
         * Show denied page.
         */
        def denied = {
                if (isLoggedIn() && authenticationTrustResolver.isRememberMe(SCH.context?.authentication)) {
                        // have cookie but the page is guarded with IS_AUTHENTICATED_FULLY
                        redirect action: full, params: params
                }
        }

        /**
         * Login page for users with a remember-me cookie but accessing a IS_AUTHENTICATED_FULLY page.
         */
        def full = {
                render view: 'auth', params: params,
                        model: [hasCookie: authenticationTrustResolver.isRememberMe(SCH.context?.authentication)]
        }

        // Denial page (data|view|json) for Ajax access.
        def deniedAjax = {
                //this is example:
                render "{error: 'access denied'}"
        }

        /**
         * login failed
         */
        def authfail = {

                def username = session[AuthenticationProcessingFilter.SPRING_SECURITY_LAST_USERNAME_KEY]
                def msg = ''
                def exception = session[AbstractProcessingFilter.SPRING_SECURITY_LAST_EXCEPTION_KEY]
                if (exception) {
                        if (exception instanceof DisabledException) {
                                msg = "[$username] is disabled."
                        }
                        else {
                                msg = "[$username] wrong username/password."
                        }
                }

                if (isAjax()) {
                        render "{error: '${msg}'}"
                }
                else {
                        flash.message = msg
                        redirect action: auth, params: params
                }
        }

        /**
         * Check if logged in.
         */
        private boolean isLoggedIn() {
                return authenticateService.isLoggedIn()
        }

        private boolean isAjax() {
                return authenticateService.isAjax(request)
        }

        /** cache controls */
        private void nocache(response) {
                response.setHeader('Cache-Control', 'no-cache') // HTTP 1.1
                response.addDateHeader('Expires', 0)
                response.setDateHeader('max-age', 0)
                response.setIntHeader ('Expires', -1) //prevents caching at the proxy server
                response.addHeader('cache-Control', 'private') //IE5.x only
        }
}