LDAP importer crash when group map is too big

Description:

When running a sync with a real big group map (more than 500 lines), the LDAP sync fails.

With a smaller map, all is working as expected.

Steps to reproduce:

Not sure if it's an error with Samba4 closing the connection because of the flood. The strange part is the encryption error message (see logs below).

BTW, the group mapping code looks not optimal. It should get groups content on start and then compare this for every available user.

Actually, looks like it is doing an LDAP request per user and per group.

But I may be wrong as I guess this based on the logs (and based on LDAP groups filter).

Server Setup Information:

Version of Rocket.Chat Server: 3.7.1
Operating System: Debian 10
Deployment Method: tar
Number of Running Instances: 1
DB Replicaset Oplog: ??
NodeJS Version: 12.18.1-1nodesource1
MongoDB Version: 4.2.8

LDAP:

Groups filter: (&(cn=#{groupName})(member=CN=#{username},OU=*))

Relevant logs:

Oct 31 17:11:15 srv-rocket rocketchat[106]: server.js:204 LDAPSync ➔ error LDAPError [StrongAuthRequiredError]: BindSimple: Transport encryption required.
Oct 31 17:11:15 srv-rocket rocketchat[106]:     at messageCallback (/opt/Rocket.Chat/programs/server/npm/node_modules/ldapjs/lib/client/client.js:1419:45)
Oct 31 17:11:15 srv-rocket rocketchat[106]:     at Parser.onMessage (/opt/Rocket.Chat/programs/server/npm/node_modules/ldapjs/lib/client/client.js:1089:14)
Oct 31 17:11:15 srv-rocket rocketchat[106]:     at Parser.emit (events.js:210:5)
Oct 31 17:11:15 srv-rocket rocketchat[106]:     at Parser.EventEmitter.emit (domain.js:475:20)
Oct 31 17:11:15 srv-rocket rocketchat[106]:     at Parser.write (/opt/Rocket.Chat/programs/server/npm/node_modules/ldapjs/lib/messages/parser.js:111:8)
Oct 31 17:11:15 srv-rocket rocketchat[106]:     at Socket.onData (/opt/Rocket.Chat/programs/server/npm/node_modules/ldapjs/lib/client/client.js:1076:22)
Oct 31 17:11:15 srv-rocket rocketchat[106]:     at Socket.emit (events.js:210:5)
Oct 31 17:11:15 srv-rocket rocketchat[106]:     at Socket.EventEmitter.emit (domain.js:475:20)
Oct 31 17:11:15 srv-rocket rocketchat[106]:     at addChunk (_stream_readable.js:309:12)
Oct 31 17:11:15 srv-rocket rocketchat[106]:     at readableAddChunk (_stream_readable.js:290:11)
Oct 31 17:11:15 srv-rocket rocketchat[106]:     at Socket.Readable.push (_stream_readable.js:224:10)
Oct 31 17:11:15 srv-rocket rocketchat[106]:     at TCP.onStreamRead (internal/stream_base_commons.js:182:23) {
Oct 31 17:11:15 srv-rocket rocketchat[106]:   lde_message: 'BindSimple: Transport encryption required.',
Oct 31 17:11:15 srv-rocket rocketchat[106]:   lde_dn: null
Oct 31 17:11:15 srv-rocket rocketchat[106]: }

RocketChat / Rocket.Chat