CustomAuthenticationProvider.java

package com.blabadi.sec.oauth.provider;

import java.util.ArrayList;
import java.util.Collection;
import java.util.List;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.security.authentication.AuthenticationProvider;
import org.springframework.security.authentication.BadCredentialsException;
import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;
import org.springframework.security.core.Authentication;
import org.springframework.security.core.AuthenticationException;
import org.springframework.security.core.authority.SimpleGrantedAuthority;

public class CustomAuthenticationProvider implements AuthenticationProvider {
	
	/** LoginService service bean */
	@Autowired
	LoginService loginSvc;
	
	/** Logger */
	private final static Logger logger = LoggerFactory.getLogger(CustomAuthenticationProvider.class);
	
	/**
	 * Override the authenticate method to implement our custom authentication logic agains LoginService api.
	 */
	public Authentication authenticate(Authentication auth) throws AuthenticationException {
		logger.debug("entered CustomAuthenticationProvider.authenticate() with arguments: {}", auth.toString());
		//extract user name and password from Authentication instance
		String userName = (String) auth.getPrincipal();
		String password = (String) auth.getCredentials();
		//call LoginService login to authenticate the user name and password
		logger.debug("calling LoginService.login for user: {}", userName);
		String userId = loginSvc.login(userName, password);
		//check validity of the user Id returned, if it's valid => authentication successful. 
		if (loginSvc.validateUserId(userId)) {
			logger.info("user {} authentication with LoginService was successful, found userId : {}", userName, userId);
			logger.debug("getting user: {} roles from LoginService", userName);
			List<String> userRoles = loginSvc.getUserRoles(userId);
			logger.info("retrieved user roles from LoginService");
			//create GrantedAuthority collection from retrieved roles
			Collection<SimpleGrantedAuthority> authorties = fillUserAuthorities(userRoles);
			//create a fully populated authentication object
			Authentication filledAuthentication = new UsernamePasswordAuthenticationToken(userName, password, authorties);
			logger.info("created fully populated authentication object {}", filledAuthentication.toString());
			logger.debug("exiting authenticate()");
			return filledAuthentication;
		} else {
			logger.error("authentication failed against LoginService, invalid userId : {} , was returned", userId);
			//throw an exception to indicate failure of authentication process
			throw new BadCredentialsException("Invalid credentials");
		}
		
	}

	public boolean supports(Class<?> arg0) {
		return true;
	}
	
	/**
	 * utility method to convert the user roles to a Collection<GrantedAuthority> for spring security to deal with 
	 * @param roles the list of roles as string
	 * @return a collection of SimpleGrantedAuthority that represent user roles
	 */
	private Collection<SimpleGrantedAuthority> fillUserAuthorities(List<String> roles) {
		Collection<SimpleGrantedAuthority> authorties = new ArrayList<SimpleGrantedAuthority>();
		for(String role : roles) {
			authorties.add(new SimpleGrantedAuthority(role));
		}
		return authorties;
	}
}