Support for Active Directory multidomain forest

In AD forest samAccountName (or uid) may not be unique in the
entire forest and userPrincipalName contains "@" symbol
disallowed in Matrix User Identifiers.

This commit reflects changes in ldap_auth_provider that adds
mxid generation logic for Active Directory.

Signed-off-by: Yuri Konotopov <ykonotopov@gnome.org>

src/main/java/io/kamax/mxisd/config/ldap/LdapConfig.java

@@ -291,6 +291,9 @@ public abstract class LdapConfig {
     private boolean enabled;
     private String filter;
 
+    private boolean activeDirectory;
+    private String defaultDomain;
+
     private Connection connection = new Connection();
     private Attribute attribute = new Attribute();
     private Auth auth = new Auth();
@@ -316,6 +319,22 @@ public abstract class LdapConfig {
         this.filter = filter;
     }
 
+    public boolean isActiveDirectory() {
+        return activeDirectory;
+    }
+
+    public void setActiveDirectory(boolean activeDirectory) {
+        this.activeDirectory = activeDirectory;
+    }
+
+    public String getDefaultDomain() {
+        return defaultDomain;
+    }
+
+    public void setDefaultDomain(String defaultDomain) {
+        this.defaultDomain = defaultDomain;
+    }
+
     public Connection getConnection() {
         return connection;
     }
@@ -407,6 +426,15 @@ public abstract class LdapConfig {
             throw new ConfigurationException("ldap.identity.token");
         }
 
+        if(isActiveDirectory()) {
+            if(!StringUtils.equals(LdapBackend.UID, uidType)) {
+                throw new IllegalArgumentException(String.format(
+                    "Attribute UID type should be set to %s in Active Directory mode",
+                    LdapBackend.UID
+                ));
+            }
+        }
+
         // Build queries
         attribute.getThreepid().forEach((k, v) -> {
             if (StringUtils.isBlank(identity.getMedium().get(k))) {