Nrthugu

I'm using a very simple httpServer in Java for an api rest with GET, POST, PUT and DELETE. I'm using Basic Authentication and I have a couple classes Authentication.java and Authorisation.java which I use to authenticate and check permissions for the users.

So, the thing is that I want all users (authenticated) to be able to GET information from my api rest, but only users with certain privileges to be able to POST, PUT and DELETE. So how can I do that?

This is what I got

public class Server {



  private static HttpServer server;



  public static void start() throws IOException {



    server = HttpServer.create(new InetSocketAddress(8000), 0);

    HttpContext ctx = server.createContext("/users", new UserHandler());

    ctx.setAuthenticator(new ApiRestBasicAuthentication("users"));



    server.start();

  }



}

And this is my ApiRestBasicAuthentication

public class ApiRestBasicAuthentication extends BasicAuthenticator {



  private UserAuthentication authentication = new UserAuthentication();



  public ApiRestBasicAuthentication(String realm) {

    super(realm);

  }



  @Override

  public boolean checkCredentials(String user, String pwd) {

    int authCode = authentication.authenticate(user, pwd);

    return authCode == UserAuthentication.USER_AUTHENTICATED;

  }



}

As this is now, check credentials is only checking if the user is authenticated.
But I'd like to check, if the method is POST, DELETE or PUT I should also check the specific credentials. But how can I get the method in my ApiRestBasicAuthentication? I'm doing that in my handler class

public void handle(HttpExchange httpExchange) throws IOException {

    String method = httpExchange.getRequestMethod();

    if ("post".equalsIgnoreCase(method)) {

      createUser(httpExchange);

    } else if ("get".equalsIgnoreCase(method)) {

      readUsers(httpExchange);

    } else if ("put".equalsIgnoreCase(method)) {

      updateUser(httpExchange);

    } else if ("delete".equalsIgnoreCase(method)) {

      deleteUser(httpExchange);

    }

  }

Maybe this is supposed to be done some other way.
Any ideas?

Many thanks.

A simple way to do it would be to change your
ApiRestBasicAuthentication like:

public class ApiRestBasicAuthentication extends BasicAuthenticator {



  private UserAuthentication authentication = new UserAuthentication();



  public ApiRestBasicAuthentication(String realm) {

    super(realm);

  }



  @Override

  public Authenticator.Result authenticate(HttpExchange exch) {

      Authenticator.Result result=super.authenticate(exch);

      if(result instanceof Authenticator.Success) {

          HttpPrincipal principal=((Authenticator.Success)result).getPrincipal();

          String requestMethod=exch.getRequestMethod();       

          if( ADD SOME LOGIC HERE FOR PRINCIPAL AND REQUEST METHOD) {

              return new return new Authenticator.Failure(401);

          }

          return result;



      }

  }



  @Override

  public boolean checkCredentials(String user, String pwd) {

    int authCode = authentication.authenticate(user, pwd);

    return authCode == UserAuthentication.USER_AUTHENTICATED;

  }



}

And add some logic there for requests/users that you want to fail the authenticator. I have shown you here how to get the method in the authenticate method but you need to specify the types of credentials.

Another solution would be if you check the source code of BasicAuthenticator you can see how it implements authenticate method and you can create your own implementation in a similar way instead of extending BasicAuthenticator and use the get method instead of just the username and password. You can see the source code here and I am sure you will be able to find your way around ;)

Usually in enterprise application you can use some external security management system - for example if you use Spring (the de facto standard in the current java web apps) you can use spring security and do such security patterns and filters in a more declarative way

While the above answers might be valid for you, I think you should also consider using defined roles and security-constraints which can be defined in your web.xml and used in the REST Resource using @RolesAllowed annotation. This then allows you to specifically allow permissions for methods individually or at the REST resource/class level.

In web.xml, this looks something like this:-

<security-role>

        <role-name>SERVERTOSERVER</role-name>

    </security-role>

    <security-constraint>

        <web-resource-collection>

            <web-resource-name>REST API description</web-resource-name>

            <url-pattern>/<path name>/*</url-pattern>

            <http-method>GET</http-method>

        </web-resource-collection>

        <auth-constraint>

            <description>Only allow users 

        from following roles</description>

            <role-name>SERVERTOSERVER</role-name>

        </auth-constraint>

    </security-constraint>

The following links have some examples: Purpose of roles tags in tomcat-users.xml? ,
https://www.thecoderscorner.com/team-blog/hosting-servers/17-setting-up-role-based-security-in-tomcat/

In case helpful, here is another type of solution for a Jersey based application: https://howtodoinjava.com/jersey/jersey-rest-security/

There might be many ways to solve this issue. Here is one of my proposal:

1. Create a User Object with fields that you want and one field called something like "role". Lets say only "admins" are allowed to do make Http requests other than "GET" while "regular" users can only do "GET". Many ways to do this but one way is to make the "role" field String and assign values to it using an ENUM, so that it's easy to change later and only specific terms are used. But you don't have to do that. Write get and set method for the fields you create and that you might need later, and definitely for role.




2. You need to make sure that class containing the handle(HttpExchange httpExchange) is able to see the currently logged in user, and refer to the User object associated with them. Then you need to modify the method so that

if(loggedInUser.getRole().equals("admin")){

  //allow whatever method 

} else {

  // allow "GET" or give some denied permission error

}

Since other implementations have not been provided, I can't give a more detailed answer or be sure that this will work for you.

I think what you should create an AuthenticationInterceptor and by-pass GET the requests there and correspondingly apply authentication mechanism for rest non-GET requests.

public class AuthenticationInterceptor extends HandlerInterceptorAdapter {



  @Autowired

  private ApiRestBasicAuthentication apiRestBasicAuthentication;



  public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {

    switch (request.getMethod()) {

      case "GET" :

        // by-passing all GET requests

        return true;



      default :

        return apiRestBasicAuthentication.checkCredentials(username, password);

    }

  }



}