3 basic auth

Authentication and Authorization

Grails provides a series of built-in authentication solutions, such as Form, Basic, Digest etc. And there are several additional plugins which provides CAS, OAuth authentication, please search them from the official Grails.org website.

For API centric applications, Basic is the simplest authentication.

Configure Basic authentication

By default, Form based authentication is enabled, it is easy to configure Basic authentication in Grails application.

Includes the following line in the Config.groovy file.

grails.plugin.springsecurity.useBasicAuth = true

Basic authentication includes a specific basicExceptionTranslationFilter, so the general-purpose exceptionTranslationFilter can be excluded.

grails.plugin.springsecurity.filterChain.chainMap = [
	'/api/**':'JOINED_FILTERS,-exceptionTranslationFilter',
	'/**':JOINED_FILTERS,-basicAuthenticationFilter,-basicExceptionTranslationFilter'
 ]

All resources matched /api/** will be protected and require authentication.

Try access the a protected resource, for example, http://localhost:8080/angularjs-grails-sample/api/books.json. There is a browser prompt popup for requiring username and password.

Stateless API

By default, Grails will create session to store the client principle, it is useful for a web application. For a REST API, it is usually designated as stateless.

Spring security provides a stateless option in http element. In Grails, you could have to configure it yourself.

In the resources.groovy file, declare a SecurityContextRepository and SecurityContextPersistenceFilter bean.

statelessSecurityContextRepository(NullSecurityContextRepository) {}

statelessSecurityContextPersistenceFilter(SecurityContextPersistenceFilter, ref('statelessSecurityContextRepository')) {	}

The SecurityContextPersistenceFilter is responsible for session creation, and it delegates the real work to SecurityContextRepository bean. NullSecurityContextRepository is an implementation of SecurityContextRepository which does not create the user data in HttpSession, it is suitable for stateless case.

Apply it in Config.groovy.

grails.plugin.springsecurity.filterChain.chainMap = [
	'/api/**': 'statelessSecurityContextPersistenceFilter,logoutFilter,authenticationProcessingFilter,customBasicAuthenticationFilter,securityContextHolderAwareRequestFilter,rememberMeAuthenticationFilter,anonymousAuthenticationFilter,basicExceptionTranslationFilter,filterInvocationInterceptor',
 ]

In the above, all filters used for /api/ url pattern are listed one by one.

There are some options for the configuration of the filters.

• If the value includes a JOINED_FILTERS, it is indicates it will includes all default filters. You can append -filterName to exclude the filter from the default filter list. For example,

   JOINED_FILTERS,-basicExceptionTranslationFilter

  It will include all filters but excludes basicExceptionTranslationFilter.

• If the value is none, security will skip the url pattern.

• You can specify the filters one by one.

Note: The exclusion can be used only with JOINED_FILTERS option.

I also create a custom BasicAuthenticationEntryPoint.

public class CustomBasicAuthenticationEntryPoint extends
		BasicAuthenticationEntryPoint {

	private static Logger log = LoggerFactory
			.getLogger(CustomBasicAuthenticationEntryPoint.class);

	@Override
	public void commence(HttpServletRequest request,
			HttpServletResponse response, AuthenticationException authException)
			throws IOException, ServletException {
		// TODO Auto-generated method stub
		// super.commence(request, response, authException);
		log.debug("call @ commence...");
		response.sendError(HttpServletResponse.SC_UNAUTHORIZED);
	}

}

The purpose is simple, it maps all authentication and authorization exception to 401 status. This will simplify the frontend AngluarJS processing work.

Configure this AuthenticationEntryPoint in resources.groovy.

customBasicAuthenticationEntryPoint(CustomBasicAuthenticationEntryPoint) {
	realmName = SpringSecurityUtils.securityConfig.basic.realmName // 'Grails Realm'
}

customBasicAuthenticationFilter(BasicAuthenticationFilter, ref('authenticationManager'), ref('customBasicAuthenticationEntryPoint')) {
	authenticationDetailsSource = ref('authenticationDetailsSource')
	rememberMeServices = ref('rememberMeServices')
	credentialsCharset = SpringSecurityUtils.securityConfig.basic.credentialsCharset // 'UTF-8'
}

basicAccessDeniedHandler(AccessDeniedHandlerImpl)

basicRequestCache(NullRequestCache)

basicExceptionTranslationFilter(ExceptionTranslationFilter, ref('customBasicAuthenticationEntryPoint'), ref('basicRequestCache')) {
	accessDeniedHandler = ref('basicAccessDeniedHandler')
	authenticationTrustResolver = ref('authenticationTrustResolver')
	throwableAnalyzer = ref('throwableAnalyzer')
}

Sample codes

The code is hosted on https://github.com/hantsy/angularjs-grails-sample/.