LDAP Authentication and Search

LDAP is a very widespread way for authentication. In this post I would like to show you how to connect to LDAP server, authenticate user and perform search.

We will use only standard Java classes. So we don't need any dependency. In the example you can see my configurations. Yours may differ (pay attention to Context.SECURITY_PRINCIPAL). Here is the code:

import java.util.Properties;

import javax.naming.Context;
import javax.naming.NamingEnumeration;
import javax.naming.NamingException;
import javax.naming.directory.Attribute;
import javax.naming.directory.Attributes;
import javax.naming.directory.SearchControls;
import javax.naming.directory.SearchResult;
import javax.naming.ldap.InitialLdapContext;

public class LdapTest {
    
    public static void processRequest(InitialLdapContext ctx, String userContext, String filter, String attribute) {
        SearchControls searchControls = new SearchControls();
        searchControls.setSearchScope(SearchControls.SUBTREE_SCOPE);

        NamingEnumeration<SearchResult> searchResults;
        try {
            searchResults = ctx.search(userContext, filter, searchControls);
            
            while (searchResults.hasMoreElements()) {
                SearchResult sr = searchResults.next();
                Attributes attributes = sr.getAttributes();
                Attribute a = attributes.get(attribute);
                if (a != null) {
                    String attrValue = (a.get().toString());
                    System.out.println(attrValue);
                } else {
                    System.out.println("Cannot get data");
                }
            }
        } catch (NamingException e) {
            e.printStackTrace();
        }
    }
        
    private static InitialLdapContext initialiaseLdapContext(String server, int port, String username, String password, String contextDN) {
        boolean initialised = false; 
        Properties properties = new Properties();
        properties.put(Context.INITIAL_CONTEXT_FACTORY, "com.sun.jndi.ldap.LdapCtxFactory");
        properties.put(Context.PROVIDER_URL, "ldap://" + server + ":"+ port);
        properties.put(Context.SECURITY_AUTHENTICATION, "simple");
        properties.put(Context.SECURITY_PRINCIPAL, "uid=" + username + "," + contextDN); //YOU MAY NEED TO CHANGE CODE HERE
        properties.put(Context.SECURITY_CREDENTIALS, password);

        InitialLdapContext ctx = null;
        try {
            // Create initial context
            ctx = new InitialLdapContext(properties, null);
            initialised = true;
        } catch (NamingException e) {
            initialised = false;
        } finally {
            if (initialised) {
                System.out.println("Initialization success");
            } else {
                System.out.println("Initialization fail");
            }
        }
        return ctx;
    }

    public static void main(String[] args) {
        String contextDN = "dc=test,dc=com";
        InitialLdapContext ctx = initialiaseLdapContext("localhost", 389, "test@test.com", "test" , contextDN);
        try {
            if (ctx != null) {
                processRequest(ctx, contextDN, "(uid=qwertTest@test.com)", "street");
                ctx.close();
            }
        } catch (NamingException e) {
            e.printStackTrace();
        }
    }
}