Apache – HTTP Basic Auth with ActiveDirectory user/pass lookup

You could take a look at this example here and change the source e.g. from here to use the code from the first link.

Link#1 content:

public class ADAuthenticator 
{
  private String domain;
  private String ldapHost;
  private String searchBase;

  public ADAuthenticator()
  {
    this.domain = "<your domain>";
    this.ldapHost = "ldap://<your AD controller>";
    this.searchBase = "your AD root e.g. dc=abbl,dc=org";
  }

  public ADAuthenticator(String domain, String host, String dn)
  {
    this.domain = domain;
    this.ldapHost = host;
    this.searchBase = dn;
  }

  public Map authenticate(String user, String pass)
  {
    String returnedAtts[] ={ "sn", "givenName", "mail" };
    String searchFilter = "(&(objectClass=user)(sAMAccountName=" + user + "))";

    //Create the search controls
    SearchControls searchCtls = new SearchControls();
    searchCtls.setReturningAttributes(returnedAtts);

    //Specify the search scope
    searchCtls.setSearchScope(SearchControls.SUBTREE_SCOPE);

    Hashtable env = new Hashtable();
    env.put(Context.INITIAL_CONTEXT_FACTORY, "com.sun.jndi.ldap.LdapCtxFactory");
    env.put(Context.PROVIDER_URL, ldapHost);
    env.put(Context.SECURITY_AUTHENTICATION, "simple");
    env.put(Context.SECURITY_PRINCIPAL, user + "@" + domain);
    env.put(Context.SECURITY_CREDENTIALS, pass);

    LdapContext ctxGC = null;

    try
    {
      ctxGC = new InitialLdapContext(env, null);
      //Search objects in GC using filters
      NamingEnumeration answer = ctxGC.search(searchBase, searchFilter, searchCtls);
      while (answer.hasMoreElements())
      {
        SearchResult sr = (SearchResult) answer.next();
        Attributes attrs = sr.getAttributes();
        Map amap = null;
        if (attrs != null)
        {
          amap = new HashMap();
          NamingEnumeration ne = attrs.getAll();
          while (ne.hasMore())
          {
            Attribute attr = (Attribute) ne.next();
            amap.put(attr.getID(), attr.get());
          }
          ne.close();
        }
          return amap;
      }
    }
    catch (NamingException ex)
    {
      ex.printStackTrace();
    }

    return null;
  }
}

Link#2 content:

public class BasicAuthenticationFilter implements Filter {

  /** Logger */
  private static final Logger LOG = LoggerFactory.getLogger(BasicAuthenticationFilter.class);

  private String username = "";

  private String password = "";

  private String realm = "Protected";

  @Override
  public void init(FilterConfig filterConfig) throws ServletException {
    username = filterConfig.getInitParameter("username");
    password = filterConfig.getInitParameter("password");
    String paramRealm = filterConfig.getInitParameter("realm");
    if (StringUtils.isNotBlank(paramRealm)) {
      realm = paramRealm;
    }
  }

  @Override
  public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain)
      throws IOException, ServletException {

    HttpServletRequest request = (HttpServletRequest) servletRequest;
    HttpServletResponse response = (HttpServletResponse) servletResponse;

    String authHeader = request.getHeader("Authorization");
    if (authHeader != null) {
      StringTokenizer st = new StringTokenizer(authHeader);
      if (st.hasMoreTokens()) {
        String basic = st.nextToken();

        if (basic.equalsIgnoreCase("Basic")) {
          try {
            String credentials = new String(Base64.decodeBase64(st.nextToken()), "UTF-8");
            LOG.debug("Credentials: " + credentials);
            int p = credentials.indexOf(":");
            if (p != -1) {
              String _username = credentials.substring(0, p).trim();
              String _password = credentials.substring(p + 1).trim();

              if (!username.equals(_username) || !password.equals(_password)) {
                unauthorized(response, "Bad credentials");
              }

              filterChain.doFilter(servletRequest, servletResponse);
            } else {
              unauthorized(response, "Invalid authentication token");
            }
          } catch (UnsupportedEncodingException e) {
            throw new Error("Couldn't retrieve authentication", e);
          }
        }
      }
    } else {
      unauthorized(response);
    }
  }

  @Override
  public void destroy() {
  }

  private void unauthorized(HttpServletResponse response, String message) throws IOException {
    response.setHeader("WWW-Authenticate", "Basic realm="" + realm + """);
    response.sendError(401, message);
  }

  private void unauthorized(HttpServletResponse response) throws IOException {
    unauthorized(response, "Unauthorized");
  }

}