Add the ability to define multiple authentication services

src/main/java/de/sebastianvonhelmersen/authentication/Authenticator.java

@@ -0,0 +1,8 @@
+package de.sebastianvonhelmersen.authentication;
+
+import de.sebastianvonhelmersen.User;
+
+public interface Authenticator {
+    public boolean authenticate(String username, String token);
+    public User getUser(String username);
+}

src/main/java/de/sebastianvonhelmersen/authentication/FetSite.java

@@ -0,0 +1,55 @@
+package de.sebastianvonhelmersen.authentication;
+
+import de.sebastianvonhelmersen.User;
+
+import java.nio.charset.StandardCharsets;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+import java.util.Arrays;
+import java.util.Base64;
+
+public class FetSite implements Authenticator {
+    private final byte[] masterPassword;
+    private final MessageDigest digest;
+    public FetSite(String masterPassword) {
+        this.masterPassword = masterPassword.getBytes(StandardCharsets.UTF_8);
+
+        // Setup hashing Class
+        try {
+            this.digest = MessageDigest.getInstance("SHA-256");
+        }
+        catch (NoSuchAlgorithmException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    /*
+    Token: base64(hash(<username>) XOR <masterpasswd>)
+     */
+    public boolean authenticate(String username, String token) {
+        byte[] byteToken = token.getBytes(StandardCharsets.UTF_8);
+
+
+        // Hash username to make comparison
+        byte[] userNameHash = digest.digest(username.getBytes(StandardCharsets.UTF_8));
+
+        // Decode token
+        // Ensure both have the same length
+        int length = Math.min(byteToken.length, userNameHash.length);
+        byte[] result = new byte[length];
+
+        // XOR each byte
+        for (int i = 0; i < length; i++) {
+            result[i] = (byte) (byteToken[i] ^ this.masterPassword[i]);
+        }
+
+        byte[] dec_token = Base64.getDecoder().decode(result);
+
+        // Compare hash and decoded token
+       return Arrays.equals(dec_token, userNameHash);
+    }
+
+    public User getUser(String username) {
+        return new User("", "", "", 0, 0, username);
+    }
+}

src/main/java/de/sebastianvonhelmersen/authentication/Ldap.java

@@ -0,0 +1,104 @@
+package de.sebastianvonhelmersen.authentication;
+
+import de.sebastianvonhelmersen.User;
+import de.sebastianvonhelmersen.user;
+
+import javax.naming.Context;
+import javax.naming.NamingEnumeration;
+import javax.naming.directory.*;
+import java.util.Hashtable;
+
+public class Ldap {
+
+    /*
+    private static final String LDAP_URL = "ldap://192.168.1.11:389";
+    private static final String BASE_DN = "dc=authentik,dc=vonhelmersen,dc=online";
+    private static final String ADMIN_DN = "cn=akadmin,ou=users,dc=authentik,dc=vonhelmersen,dc=online"; // service account
+    */
+
+    private static final String LDAP_URL = "ldap://juri:389";
+    private static final String BASE_DN = "dc=fet,dc=htu,dc=tuwien,dc=ac,dc=at";
+    private static final String ADMIN_DN = "cn=admin,dc=fet,dc=htu,dc=tuwien,dc=ac,dc=at"; // service account
+    public static User authenticate(String username, String password) {
+
+        try {
+            // 1. Bind as admin/service account
+            Hashtable<String, String> env = new Hashtable<>();
+            env.put(Context.INITIAL_CONTEXT_FACTORY, "com.sun.jndi.ldap.LdapCtxFactory");
+            env.put(Context.PROVIDER_URL, LDAP_URL);
+            env.put(Context.SECURITY_AUTHENTICATION, "simple");
+            env.put(Context.SECURITY_PRINCIPAL, ADMIN_DN);
+            env.put(Context.SECURITY_CREDENTIALS, ADMIN_PASSWORD);
+
+            DirContext ctx = new InitialDirContext(env);
+
+            // 2. Search for user DN
+            String filter = "(uid=" + escapeLDAPSearchFilter(username) + ")";
+            SearchControls controls = new SearchControls();
+            controls.setSearchScope(SearchControls.SUBTREE_SCOPE);
+            NamingEnumeration<SearchResult> results = ctx.search(BASE_DN, filter, controls);
+
+            if (!results.hasMore()) {
+                ctx.close();
+                return null; // user not found
+            }
+
+            /*
+            {
+                givenname=givenName: Sebastian,
+                sn=sn: Helmersen,
+                userpassword=userPassword: [B@2b6cb5b5,
+                loginshell=loginShell: /bin/bash,
+                gidnumber=gidNumber: 2000,
+                uidnumber=uidNumber: 1196,
+                mail=mail: helmi@fet.at,
+                objectclass=objectClass: posixAccount,
+                inetOrgPerson,
+                organizationalPerson,
+                person,
+                uid=uid: helmi,
+                cn=cn: Sebastian Helmersen,
+                homedirectory=homeDirectory: /home/helmi
+            }
+             */
+            // System.out.println("Results: " + results.toString());
+
+
+            SearchResult result = results.next();
+            String userDN = result.getNameInNamespace();
+            ctx.close();
+
+            // 3. Try binding with userDN + password
+            Hashtable<String, String> authEnv = new Hashtable<>();
+            authEnv.put(Context.INITIAL_CONTEXT_FACTORY, "com.sun.jndi.ldap.LdapCtxFactory");
+            authEnv.put(Context.PROVIDER_URL, LDAP_URL);
+            authEnv.put(Context.SECURITY_AUTHENTICATION, "simple");
+            authEnv.put(Context.SECURITY_PRINCIPAL, userDN);
+            authEnv.put(Context.SECURITY_CREDENTIALS, password);
+
+            new InitialDirContext(authEnv).close(); // bind attempt
+
+            return new user(result.getAttributes()); // success
+
+        } catch (Exception e) {
+            e.printStackTrace();
+            return null; // failed (invalid credentials or LDAP error)
+        }
+    }
+
+    public static String escapeLDAPSearchFilter(String input) {
+        StringBuilder sb = new StringBuilder();
+        for (int i = 0; i < input.length(); i++) {
+            char c = input.charAt(i);
+            switch (c) {
+                case '\\': sb.append("\\5c"); break;
+                case '*': sb.append("\\2a"); break;
+                case '(': sb.append("\\28"); break;
+                case ')': sb.append("\\29"); break;
+                case '\u0000': sb.append("\\00"); break;
+                default: sb.append(c);
+            }
+        }
+        return sb.toString();
+    }
+}