Using Programmatic Security with Web Applications (original) (raw)

Programmatic security is used by security-aware applications when declarative security alone is not sufficient to express the security model of the application.

The following topics are addressed here:

Authenticating Users Programmatically

You can use the SecurityContext and HttpServletRequest interfaces to authenticate users for a web application programmatically.

SecurityContext

The SecurityContext interface, as specified in the Java EE Security API specification, defines the following method to programmatically trigger the authentication process:

Programmatically triggering means that the container responds as if the caller had attempted to access a constrained resource. It causes the container to invoke the authentication mechanism configured for the application. If the configured authentication mechanism is an HttpAuthenticationMechanism, then the AuthenticationParameters argument is meaningful and extended capabilities ofHttpAuthenticationMechanism are available. If not, the behavior and result is as if HttpServletRequest.authenticate() were called.

HttpServletRequest

The HttpServletRequest interface defines the following methods that enable you to authenticate users for a web application programmatically.

The following example code shows how to use the login and logoutmethods:

package test;

import java.io.IOException;
import java.io.PrintWriter;
import java.math.BigDecimal;
import javax.ejb.EJB;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet(name="TutorialServlet", urlPatterns={"/TutorialServlet"})
public class TutorialServlet extends HttpServlet {
    @EJB
    private ConverterBean converterBean;

    /**
     * Processes requests for both HTTP <code>GET</code>
     *    and <code>POST</code> methods.
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    protected void processRequest(HttpServletRequest request,
            HttpServletResponse response)
    throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();
        try {

            out.println("<html>");
            out.println("<head>");
            out.println("<title>Servlet TutorialServlet</title>");
            out.println("</head>");
            out.println("<body>");
            request.login("TutorialUser", "TutorialUser");
            BigDecimal result =
                converterBean.dollarToYen(new BigDecimal("1.0"));
            out.println("<h1>Servlet TutorialServlet result of dollarToYen= "
                + result + "</h1>");
            out.println("</body>");
            out.println("</html>");
        } catch (Exception e) {
            throw new ServletException(e);
        } finally {
            request.logout();
            out.close();
        }
    }
}

The following example code shows how to use the authenticate method:

package com.example.test;

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;

public class TestServlet extends HttpServlet {

    protected void processRequest(HttpServletRequest request,
            HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();
        try {
            request.authenticate(response);
            out.println("Authenticate Successful");
        } finally {
            out.close();
        }
    }

Checking Caller Identity Programmatically

In general, the container enforces security management in a manner that is transparent to the web component. Use the security APIs described in this section only in the less frequent situations in which the web component methods need to access the security context information.

The Java EE Security API specification defines the following methods of theSecurityContext interface that allow the application to test aspects of the caller data:

Servlet 4.0 specifies the following methods that enable you to access security information about the component’s caller.

Your application can make business-logic decisions based on the information obtained using these APIs.

Testing Access to a Resource Programmatically

The SecurityContext interface, as specified in the Java EE Security API specification, defines the following method for programmatically testing access to a resource:

For example, consider the following Servlet definition:

@WebServlet("/protectedServlet")
@ServletSecurity(@HttpConstraint(rolesAllowed = "foo"))
public class ProtectedServlet extends HttpServlet { ... }

And the following call to hasAccessToWebResource():

securityContext.hasAccessToWebResource("/protectedServlet", GET)

The above hasAccessToWebResource() call returns true if, and only if, the caller is in role "foo".

Example Code for Programmatic Security

The following code demonstrates the use of programmatic security for the purposes of programmatic login. This servlet does the following.

  1. It displays information about the current user.
  2. It prompts the user to log in.
  3. It prints out the information again to demonstrate the effect of thelogin method.
  4. It logs the user out.
  5. It prints out the information again to demonstrate the effect of thelogout method.
package enterprise.programmatic_login;

import java.io.*;
import java.net.*;
import javax.annotation.security.DeclareRoles;
import javax.servlet.*;
import javax.servlet.http.*;

@DeclareRoles("javaeeuser")
public class LoginServlet extends HttpServlet {

    /**
     * Processes requests for both HTTP GET and POST methods.
     * @param request servlet request
     * @param response servlet response
     */
    protected void processRequest(HttpServletRequest request,
                 HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();
        try {
            String userName = request.getParameter("txtUserName");
            String password = request.getParameter("txtPassword");

            out.println("Before Login" + "<br><br>");
            out.println("IsUserInRole?.."
                        + request.isUserInRole("javaeeuser")+"<br>");
            out.println("getRemoteUser?.." + request.getRemoteUser()+"<br>");
            out.println("getUserPrincipal?.."
                        + request.getUserPrincipal()+"<br>");
            out.println("getAuthType?.." + request.getAuthType()+"<br><br>");

            try {
                request.login(userName, password);
            } catch(ServletException ex) {
                out.println("Login Failed with a ServletException.."
                    + ex.getMessage());
                return;
            }
            out.println("After Login..."+"<br><br>");
            out.println("IsUserInRole?.."
                        + request.isUserInRole("javaeeuser")+"<br>");
            out.println("getRemoteUser?.." + request.getRemoteUser()+"<br>");
            out.println("getUserPrincipal?.."
                        + request.getUserPrincipal()+"<br>");
            out.println("getAuthType?.." + request.getAuthType()+"<br><br>");

            request.logout();
            out.println("After Logout..."+"<br><br>");
            out.println("IsUserInRole?.."
                        + request.isUserInRole("javaeeuser")+"<br>");
            out.println("getRemoteUser?.." + request.getRemoteUser()+"<br>");
            out.println("getUserPrincipal?.."
                        + request.getUserPrincipal()+"<br>");
            out.println("getAuthType?.." + request.getAuthType()+"<br>");
        } finally {
            out.close();
        }
    }
    ...
}

Declaring and Linking Role References

A security role reference is a mapping between the name of a role that is called from a web component using isUserInRole(String role) and the name of a security role that has been defined for the application. If nosecurity-role-ref element is declared in a deployment descriptor and the isUserInRole method is called, the container defaults to checking the provided role name against the list of all security roles defined for the web application. Using the default method instead of using thesecurity-role-ref element limits your flexibility to change role names in an application without also recompiling the servlet making the call.

The security-role-ref element is used when an application uses theHttpServletRequest.isUserInRole(String role). The value passed to theisUserInRole method is a String representing the role name of the user. The value of the role-name element must be the String used as the parameter to the HttpServletRequest.isUserInRole(String role). Therole-link must contain the name of one of the security roles defined in the security-role elements. The container uses the mapping ofsecurity-role-ref to security-role when determining the return value of the call.

For example, to map the security role reference cust to the security role with role name bankCustomer, the elements would look like this:

<servlet>
...
    <security-role-ref>
        <role-name>cust</role-name>
        <role-link>bankCustomer</role-link>
    </security-role-ref>
...
</servlet>

If the servlet method is called by a user in the bankCustomer security role, isUserInRole("cust") returns true.

The role-link element in the security-role-ref element must match arole-name defined in the security-role element of the same web.xmldeployment descriptor, as shown here:

<security-role>
    <role-name>bankCustomer</role-name>
</security-role>

A security role reference, including the name defined by the reference, is scoped to the component whose deployment descriptor contains thesecurity-role-ref deployment descriptor element.