My chief interest is software engineering, mainly dealing with Linux and Java projects, but also interested in teaching what I’ve learned, have published a couple of CBTs about programming in Persian (java/Android) and here I’ll share my thoughts and experiences in English as well.
If you are working in an enterprise infrastructures, chances are that you are using a centralized authentication system, most likely Active Directory or openLDAP. In this blog I’ll explore how to create a REST API using spring boot to authenticate against openLDAP and create a JWT token in return.
Before getting our hand dirty, we need to review the architecture of spring security and the way we want to utilise it, in a REST API endpoint. According to openLDAP, I’ve explained it’s concept briefly before, you can read more about it here. Also I’ll assume that you know how Spring Boot and JWT works.
Spring Security
In this example I will extend the WebSecurityConfigurerAdapter. This class will assist me to intercept security chain of spring security and insert openLDAP authentication adapter in between.
In fact this abstract class provides convenient methods for configuring spring security configuration using HTTPSecurity object.
First of all I injected three different beans as follows :
This will let us to override default behaviour of spring security authentication. In addition we need to override the configure(HttpSecurity httpSecurity):
@Override
protected void configure(HttpSecurity httpSecurity) throws Exception {
// We don't need CSRF for this example
httpSecurity
.csrf().disable()
.headers()
.frameOptions()
.deny()
.and()
// dont authenticate this particular request
.authorizeRequests().antMatchers("/api/login").permitAll().
// all other requests need to be authenticated
antMatchers("/api/**").authenticated().and().
// make sure we use stateless session; session won't be used to
// store user's state.
exceptionHandling().authenticationEntryPoint(jwtAuthenticationEntryPoint).and().sessionManagement()
.sessionCreationPolicy(SessionCreationPolicy.STATELESS);
// Add a filter to validate the tokens with every request
httpSecurity.addFilterBefore(jwtRequestFilter, UsernamePasswordAuthenticationFilter.class);
}
Also For the sake of manually authenticating a user in /api/login we will expose the authenticationManagerBean() :
After configuring WebSecurityConfig, I’ll provide my customer authentication adapter. This adapter will utilise spring’s LdapTemplate and let us to establish a connection to a LDAP server.
@Component
public class OpenLdapAuthenticationProvider implements AuthenticationProvider {
@Autowired
private LdapContextSource contextSource;
private LdapTemplate ldapTemplate;
@PostConstruct
private void initContext() {
contextSource.setUrl("ldap://1.1.1.1:389/ou=users,dc=www,dc=devcrutch,dc=com");
// I use anonymous binding so, no need to provide bind user/pass
contextSource.setAnonymousReadOnly(true);
contextSource.setUserDn("ou=users,");
contextSource.afterPropertiesSet();
ldapTemplate = new LdapTemplate(contextSource);
}
@Override
public Authentication authenticate(Authentication authentication) throws AuthenticationException {
Filter filter = new EqualsFilter("uid", authentication.getName());
Boolean authenticate = ldapTemplate.authenticate(LdapUtils.emptyLdapName(), filter.encode(),
authentication.getCredentials().toString());
if (authenticate) {
List<GrantedAuthority> grantedAuthorities = new ArrayList<>();
grantedAuthorities.add(new SimpleGrantedAuthority("ROLE_USER"));
UserDetails userDetails = new User(authentication.getName() ,authentication.getCredentials().toString()
,grantedAuthorities);
Authentication auth = new UsernamePasswordAuthenticationToken(userDetails,
authentication.getCredentials().toString() , grantedAuthorities);
return auth;
} else {
return null;
}
}
@Override
public boolean supports(Class<?> authentication) {
return authentication.equals(UsernamePasswordAuthenticationToken.class);
}
}
Another part that we have to take into consideration is, implementing user login controller. Since we haven’t provided any filter for controlling username and password we ought to implementing it manually as follows :
@RestController
@RequestMapping("/api/login")
public class LoginController {
@Autowired
private AuthenticationManager authenticationManager;
@Autowired
private JwtTokenUtil jwtTokenUtil;
@Autowired
private UserService userService;
@PostMapping
public ResponseEntity<?> createAuthenticationToken(@RequestBody JwtRequest authenticationRequest) throws Exception
{
authenticate(authenticationRequest.getUsername(), authenticationRequest.getPassword());
final User userDetails = userService.loadUserByUsername(authenticationRequest.getUsername());
final String token = jwtTokenUtil.generateToken(userDetails);
return ResponseEntity.ok(new JwtResponse(token));
}
private void authenticate(String username, String password) throws Exception {
try {
authenticationManager.authenticate(new UsernamePasswordAuthenticationToken(username, password));
} catch (DisabledException e) {
throw new Exception("USER_DISABLED", e);
} catch (BadCredentialsException e) {
throw new Exception("INVALID_CREDENTIALS", e);
}
}
}
These are the pillars of having a REST API + JWT + LDAP back-end using spring boot.
Now we can test the API using a REST client.
After getting the JWT token we can call authorized endpoints
My chief interest is software engineering, mainly dealing with Linux and Java projects, but also interested in teaching what I’ve learned, have published a couple of CBTs about programming in Persian (java/Android) and here I’ll share my thoughts and experiences in English as well.
In fact you can’t do it without knowing DN! There is an anonymous access in openLDAP which is enabled by default. The anonymous access let one to query(search filter) openLDAP without knowing bind username/password.
Run following command on your openLDAP server :
ldapwhoami -H ldap:// -x
If you get “anonymous” as result you are all set and your openLDAP is supporting anonymous query, otherwise this blog is not the one you are looking for!
So What’s the Deal?
Assume you know UID of the user in ldap directory but not his DN and assume the root directory hierarchy is : dc=devcrutch,dc=com . How do you want to get CN and then DN of such user in LDAP just by using UID? you might think of such query to get data out of openLDAP
uid=USERNAME,dc=devcrutch,dc=com
If you run this query, it’ll get you to nowhere.
Here Comes the Anonymous Query
First of all you have to query the whole directory for finding such user. You have to create a query similar to following:
(&(objectClass=*)(uid=USERNAME))
This query will search the entire Directory Information Tree (DIT) for such user name.
With such query you can get the DN. Using DN and password you can authenticate against LDAP.
Well this was the idea, applying a search filter using USERNAME via anonymous identity then find the DN and finally login using the retrieved DN.
Time for Some java
Now we have the rough idea it’s time to implement it in java. For finding DN you need to query the entire LDAP directory (note: in real world searching the entire directory is not a good idea, you have to narrow your query, otherwise your query might consume all the server’s resources)
My chief interest is software engineering, mainly dealing with Linux and Java projects, but also interested in teaching what I’ve learned, have published a couple of CBTs about programming in Persian (java/Android) and here I’ll share my thoughts and experiences in English as well.
In Spring Boot there is an annotation @Async to assist developers for developing concurrent applications. But using this feature is quite tricky. In this blog we will see how to use this feature along with CompletableFuture. I assumed you know the drill about CompletableFuture, so I won’t repeat the concept here.
First of all you need to annotate your application class with @EnableAsync, this annotation tells the Spring to look for methods that are annotated with @Async and run them in a separate executor.
@SpringBootApplication
@EnableAsync
public class App {
RestTemplate
public static void main(String[] args) {
SpringApplication.run(App.class, args);
}
}
If you take a look at Spring Boot example about @Async using CompletableFuture you’ll notice the way they’re using this feature is based on a REST request, in my opinion, I beleive, it’s kinda limited, it doesn’t give you a clue of how to use such feature in other situation. For an instance if you have a long running task what would you do about it?
// Source : https://spring.io/guides/gs/async-method/
package hello;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.boot.web.client.RestTemplateBuilder;
import org.springframework.scheduling.annotation.Async;
import org.springframework.stereotype.Service;
import org.springframework.web.client.RestTemplate;
import java.util.concurrent.CompletableFuture;
@Service
public class GitHubLookupService {
private static final Logger logger = LoggerFactory.getLogger(GitHubLookupService.class);
private final RestTemplate restTemplate;
public GitHubLookupService(RestTemplateBuilder restTemplateBuilder) {
this.restTemplate = restTemplateBuilder.build();
}
@Async
public CompletableFuture<User> findUser(String user) throws InterruptedException {
logger.info("Looking up " + user);
String url = String.format("https://api.github.com/users/%s", user);
User results = restTemplate.getForObject(url, User.class);
// Artificial delay of 1s for demonstration purposes
Thread.sleep(1000L);
return CompletableFuture.completedFuture(results);
}
}
In FindUser(String user), it uses a synthetic delay in the main thread also the main task of this method is fetching data from github using RestTemplate, this class is a “Synchronous client to perform HTTP requests”. How about using a long running task such as calling a network function, like ping a server from your REST endpoint? In that case you need to tailor the CompletableFuture. You can’t simply call following line and carry on.
For using @Async in your code, your method has to return Future or CompletableFuture for more information you can refer to its document. Take a look at following example :
In this example I override the get() method and return the CompletableFuture without any thread executor, in fact with this method we ask Spring to execute the @Async method in a different thread, but we don’t provide any thread executor, only body of a background-worker will suffice.
P.S : In this example I decided to use a network function inside Spring Boot just for the sake of argument. But it’s better to not to use network functions directly in a REST endpoint. Specially when you expect to get an immediate result out of it. The reason: network functions are blocking which means, if you call this REST endpoint. You’ll have to wait to get the result from the endpoint. It’s highly advised to use other methods such as queue or push method(e.g. websocket) for calling blocking functions.
My chief interest is software engineering, mainly dealing with Linux and Java projects, but also interested in teaching what I’ve learned, have published a couple of CBTs about programming in Persian (java/Android) and here I’ll share my thoughts and experiences in English as well.
For installing Maven on Ubuntu you have two ways the easy way and the manual method. The easy way is just execute following command :
sudo apt-get install maven
Or if you use Ubuntu 16+ you can use following command too :
sudo apt install maven
Just remember you need to have root privileges.
The manual way
If you want to have the latest version of Maven on your Ubuntu go to the Maven website and download the latest binary package then you can extract it in /opt/ using command :
tar xvf apache-maven-3.5.2-bin.tar.gz -C /opt/
make sure you have set your JAVA_HOME if you don’t know how you can read this post
then open up your /etc/environment add following to your path
My chief interest is software engineering, mainly dealing with Linux and Java projects, but also interested in teaching what I’ve learned, have published a couple of CBTs about programming in Persian (java/Android) and here I’ll share my thoughts and experiences in English as well.
Installing Java JDK is easy and straightforward in Windows and OSX but not in Ubuntu. Here is how I am installing JDK on Ubuntu.
Download the latest JDK package from Oracle website. If you don’t know which file to choose you ought to select .tar.gz files whether 32bit or 64bit depends on your requirements.
after download the right package you need to extract it using following command you can extract it :
tar xvf jdk-8u161-linux-x64.tar.gz -C /opt/
Note : In this example I am using JDK version 8 revision 161
The /opt directory is where I chose to extract my JDK.
After extracting my JDK it is time to let Ubuntu know where to look after the Java Development Kit and Java Run Time.
Suppose you want to install your java and javac and javaws executable files in /usr/bin directory :
My chief interest is software engineering, mainly dealing with Linux and Java projects, but also interested in teaching what I’ve learned, have published a couple of CBTs about programming in Persian (java/Android) and here I’ll share my thoughts and experiences in English as well.