LDAP server - add handling for root DSE queries (needed for Radicale 3.5.2+)

app/unit/LDAPRoutingUnit.js

@@ -88,8 +88,15 @@ class LDAPRoutingUnit extends CanonicalUnit {
                         route_functions.push(route_handler)
                     }
 
-                    this.output.debug(`Registering route ${type} :: ${[route_prefix, suffix].join(',')} with ${route_functions.length} handlers.`)
-                    this.ldap_server.server[type]([route_prefix, suffix].join(','), ...route_functions)
+                    // Routers marked `absolute` opt out of the base DC suffix. The Root
+                    // DSE needs this: its DN is the zero-length string, which sits
+                    // outside every naming context by definition. (RFC 4512 §5.1)
+                    const route_dn = instance.absolute === true
+                        ? route_prefix
+                        : [route_prefix, suffix].join(',')
+
+                    this.output.debug(`Registering route ${type} :: ${route_dn} with ${route_functions.length} handlers.`)
+                    this.ldap_server.server[type](route_dn, ...route_functions)
                 }
             } else {
                 // Unbind has a default handler, so don't warn about that.