ldap: automatically detect if server supports pagination

src/externalldap.js

@@ -170,33 +170,60 @@ async function clientSearch(client, dn, searchOptions) {
     });
 }
 
+async function supportsPagination(client) {
+    assert.strictEqual(typeof client, 'object');
+
+    const searchOptions = {
+        scope: 'base',
+        filter: '(objectClass=*)',
+        attributes: ['supportedControl', 'supportedExtension', 'supportedFeature']
+    };
+
+    const result = await clientSearch(client, '', searchOptions);
+    client.unbind();
+    const controls = result.supportedControl;
+    if (!controls || !Array.isArray(controls)) {
+        debug('supportsPagination: no supportedControl attribute returned');
+        return false;
+    }
+
+    if (!controls.includes(ldap.PagedResultsControl.OID)) {
+        debug('supportsPagination: server does not support pagination. Available controls:', controls);
+        return false;
+    }
+
+    debug('supportsPagination: server supports pagination');
+    return true;
+}
+
 async function ldapGetByDN(config, dn) {
     assert.strictEqual(typeof config, 'object');
     assert.strictEqual(typeof dn, 'string');
 
-    const searchOptions = {
-        paged: true,
-        scope: 'sub'    // We may have to make this configurable
-    };
-
     debug(`ldapGetByDN: Get object at ${dn}`);
 
     const client = await getClient(config, { bind: true });
+    const paged = await supportsPagination(client);
+    const searchOptions = {
+        paged,
+        scope: 'sub'
+    };
     const result = await clientSearch(client, dn, searchOptions);
     client.unbind();
     if (result.length === 0) throw new BoxError(BoxError.NOT_FOUND, `dn ${dn} not found`);
     return result[0];
 }
 
-// TODO support search by email
 async function ldapUserSearch(config, options) {
     assert.strictEqual(typeof config, 'object');
     assert.strictEqual(typeof options, 'object');
 
+    const client = await getClient(config, { bind: true });
+    const paged = await supportsPagination(client);
     const searchOptions = {
-        paged: true,
+        paged,
         filter: ldap.parseFilter(config.filter),
-        scope: 'sub'    // We may have to make this configurable
+        scope: 'sub'
     };
 
     if (options.filter) { // https://github.com/ldapjs/node-ldapjs/blob/master/docs/filters.md
@@ -204,7 +231,6 @@ async function ldapUserSearch(config, options) {
         searchOptions.filter = new ldap.AndFilter({ filters: [ extraFilter, searchOptions.filter ] });
     }
 
-    const client = await getClient(config, { bind: true });
     const result = await clientSearch(client, config.baseDn, searchOptions);
     client.unbind();
     return result;