computing

/*

 * First create the keystore (to allow SSL protection) by importing the LDAP

 * certificate (cert.pem) with:

 *   keytool -import -keystore keystore -storepass changeit -noprompt -file cert.pem

 *

 * You can get the certificate with OpenSSL:

 *   openssl s_client -connect ldap.server.com:636 </dev/null 2>/dev/null | sed -n '/-----BEGIN/,/-----END/ { p }' > cert.pem

 *  

 * Then compile this class with:

 *   javac LdapAuth.java

 *

 * Finally execute it with:

 *   java -Djavax.net.ssl.trustStore=keystore -Djavax.net.ssl.keyStorePassword=changeit LdapAuth <username> <password>

 */

package pt.up.fe;

import java.util.*;

import javax.naming.*;

import java.util.regex.*;

import javax.naming.directory.*;

public class LdapAuth {

        private final static String ldapURI = "ldaps://ldap.fe.up.pt/dc=fe,dc=up,dc=pt";

        private final static String contextFactory = "com.sun.jndi.ldap.LdapCtxFactory";

        private static DirContext ldapContext () throws Exception {

                Hashtable<String,String> env = new Hashtable <String,String>();

                return ldapContext(env);

        }

        private static DirContext ldapContext (Hashtable <String,String>env) throws Exception {

                env.put(Context.INITIAL_CONTEXT_FACTORY, contextFactory);

                env.put(Context.PROVIDER_URL, ldapURI);

                DirContext ctx = new InitialDirContext(env);

                return ctx;

        }

        private static String getUid (String user) throws Exception {

                DirContext ctx = ldapContext();

                String filter = "(uid=" + user + ")";

                SearchControls ctrl = new SearchControls();

                ctrl.setSearchScope(SearchControls.SUBTREE_SCOPE);

                NamingEnumeration answer = ctx.search("", filter, ctrl);

                String dn;

                if (answer.hasMore()) {

                        SearchResult result = (SearchResult) answer.next();

                        dn = result.getNameInNamespace();

                }

                else {

                        dn = null;

                }

                answer.close();

                return dn;

        }

        private static boolean testBind (String dn, String password) throws Exception {

                Hashtable<String,String> env = new Hashtable <String,String>();

                env.put(Context.SECURITY_AUTHENTICATION, "simple");

                env.put(Context.SECURITY_PRINCIPAL, dn);

                env.put(Context.SECURITY_CREDENTIALS, password);

                try {

                        ldapContext(env);

                }

                catch (javax.naming.AuthenticationException e) {

                        return false;

                }

                return true;

        }

        public static boolean authenticate (String user, String password) throws Exception {

                String dn = getUid( user );

                if (dn != null) {

                        System.out.println( "user '" + user + "' not found" );

                        if ( testBind( dn, password ) ) {

                                return true;

                        }

                }

                return false;

        }

        public static void main(String args[]) throws Exception {

                if (args.length != 2) {

                        System.out.println( "missing requried username and password" );

                        System.exit(1);

                }

                String user = args[0];

                String password = args[1];

                String dn = getUid( user );

                if (dn != null) {

                        /* Found user - test password */

                        if ( testBind( dn, password ) ) {

                                System.out.println( "user '" + user + "' authentication succeeded" );

                                System.exit(0);

                        }

                        else {

                                System.out.println( "user '" + user + "' authentication failed" );

                                System.exit(1);

                        }

                }

                else {

                        System.out.println( "user '" + user + "' not found" );

                        System.exit(1);

                }

        }

}