Make all groups appear in LDAP, get posix GIDs

app/models/auth/Group.model.js

@@ -32,21 +32,31 @@ class GroupModel extends Model {
         return await User.find({ _id: { $in: this.user_ids.map(x => this.constructor.to_object_id(x)) } })
     }
 
+    async get_gid_number() {
+        if ( !this.posix_group_id ) {
+            const Setting = this.models.get('Setting')
+            let last_uid = await Setting.get('ldap.last_alloc_uid')
+            if ( last_uid < 1 ) {
+                last_uid = this.configs.get('ldap:server.schema.start_uid')
+            }
+
+            this.posix_group_id = last_uid + 1
+            await Setting.set('ldap.last_alloc_uid', this.posix_group_id)
+            await this.save()
+        }
+
+        return this.posix_group_id
+    }
+
     async to_ldap() {
         const users = await this.users()
-        const data = {
+        return {
             cn: this.name,
             dn: this.dn.format(this.configs.get('ldap:server.format')),
-            objectClass: ['groupOfNames'],
+            objectClass: ['groupOfNames', 'posixGroup'],
+            gidNumber: await this.get_gid_number(),
             member: users.map(x => x.dn.format(this.configs.get('ldap:server.format'))),
         }
-
-        if ( this.posix_group_id ) {
-            data.objectClass.push('posixGroup')
-            data.gidNumber = String(this.posix_group_id)
-        }
-
-        return data
     }
 
     static async ldap_directory() {