Modifying entry in ApacheDS failes silently

When I request modify message on my local ApacheDS, the target entry is not edited and
my script has ended immediately at await conn.modify('cn=test,dc=example,dc=com', mods).

here is my environment:
OS: ubuntu 18.10
Dart: 2.1.1
ApacheDS: 2.0.0.AM25

script:

import 'package:dartdap/dartdap.dart';
import 'package:logging/logging.dart';

Future<LdapConnection> getLdapConnection() async {
  var ldapHost = "localhost";
  var ssl = false; // true = use LDAPS (i.e. LDAP over SSL/TLS)
  var ldapPort = 10389; // null = use standard LDAP/LDAPS port
  var bindDN = "uid=admin,ou=system"; // null=unauthenticated
  var password = "secret";

  var connection = LdapConnection(host: ldapHost);
  connection.setProtocol(ssl, ldapPort);
  await connection.setAuthentication(bindDN, password);

  return connection;
}

main(List<String> arguments) async {

  // configure logger
  Logger.root.onRecord.listen((LogRecord rec) {
    print('${rec.time}: ${rec.loggerName}: ${rec.level.name}: ${rec.message}');
  });

  new Logger("ldap.session").level = Level.ALL;
  new Logger("ldap.send.ldap").level = Level.ALL;
  new Logger("ldap.send.bytes").level = Level.ALL;
  new Logger("ldap.recv.ldap").level = Level.ALL;
  new Logger("ldap.recv.asn1").level = Level.ALL;
  new Logger("ldap.recv.bytes").level = Level.ALL;

  final conn = await getLdapConnection();

  final mods = [Modification.add('description', ['test'])];
  final result = await conn.modify('cn=test,dc=example,dc=com', mods);

  print(result);

  await conn.close(true);
}

ouput :

2019-02-20 10:51:32.829453: ldap.send.ldap: FINE: [2] Sending LDAP message: Msg(id=2, op=BND_REQ,controls=null)
2019-02-20 10:51:32.833675: ldap.send.bytes: FINEST: [2] Bytes sending (s): 0%���` �����uid=admin,ou=system��secret
2019-02-20 10:51:32.834307: ldap.send.bytes: FINEST: [2] Bytes sending: [48, 37, 2, 1, 2, 96, 32, 2, 1, 3, 4, 19, 117, 105, 100, 61, 97, 100, 109, 105, 110, 44, 111, 117, 61, 115, 121, 115, 116, 101, 109, 128, 6, 115, 101, 99, 114, 101, 116]
2019-02-20 10:51:32.837829: ldap.send.bytes: FINER: [2] Sent 39 bytes
2019-02-20 10:51:32.839215: ldap.recv.bytes: FINE: received: 14
2019-02-20 10:51:32.839664: ldap.recv.bytes: FINEST: received: [48, 12, 2, 1, 2, 97, 7, 10, 1, 0, 4, 0, 4, 0]
2019-02-20 10:51:32.839824: ldap.recv.bytes: FINER: parsed ASN.1 object: 14 bytes
2019-02-20 10:51:32.839913: ldap.recv.asn1: FINE: ASN.1 object received: tag=48, length=12
2019-02-20 10:51:32.840055: ldap.recv.asn1: FINEST: ASN.1 value: [2, 1, 2, 97, 7, 10, 1, 0, 4, 0, 4, 0]
2019-02-20 10:51:32.841655: ldap.recv.ldap: FINE: LDAP message received: Id=2 protocolOp=Seq[ASNInteger(0) OctetString() OctetString() ]
2019-02-20 10:51:32.842142: ldap.recv.ldap: FINER: LDAP response received: BND_RESP
2019-02-20 10:51:32.842292: ldap.recv.ldap: FINER: Response op=Msg(id=2, op=BND_RESP,controls=null)
2019-02-20 10:51:32.842424: ldap.recv.ldap: FINER: Parse LDAP result: Seq[ASNInteger(0) OctetString() OctetString() ]
2019-02-20 10:51:32.842735: ldap.send.ldap: FINE: LDAP request serviced: Msg(id=2, op=BND_REQ,controls=null) (14 ms)
2019-02-20 10:51:32.842907: ldap.recv.bytes: FINER: processed: all
2019-02-20 10:51:32.843512: ldap.send.ldap: FINE: [3] Sending LDAP message: Msg(id=3, op=MODIFY_REQUEST,controls=null)
2019-02-20 10:51:32.843604: ldap.send.bytes: FINEST: [3] Bytes sending (s): 0>���f9��cn=test,dc=example,dc=com0�0��� 0���description0���test
2019-02-20 10:51:32.843818: ldap.send.bytes: FINEST: [3] Bytes sending: [48, 62, 2, 1, 3, 102, 57, 4, 25, 99, 110, 61, 116, 101, 115, 116, 44, 100, 99, 61, 101, 120, 97, 109, 112, 108, 101, 44, 100, 99, 61, 99, 111, 109, 48, 28, 48, 26, 2, 1, 0, 48, 21, 4, 11, 100, 101, 115, 99, 114, 105, 112, 116, 105, 111, 110, 48, 6, 4, 4, 116, 101, 115, 116]
2019-02-20 10:51:32.843918: ldap.send.bytes: FINER: [3] Sent 64 bytes
2019-02-20 10:51:32.865674: ldap.recv.bytes: FINEST: LDAP stream transformer: byte stream done

On closer inspection of the encoded ModifyRequest, we're encoding the PartialAttribute values in an ASN.1 SEQUENCE OF, not a SET OF. This is invalid LDAP. The LDAP server is probably rejecting this bad protocol and closing the connection on us in retaliation.

See byte offset 0x0038:

0000   62: SEQUENCE {
0002    1:   INTEGER = 3
0005   57:   [APPLICATION 6] { -- ModifyRequest
0007   25:     STRING = 'cn=test,dc=example,dc=com' -- object
0022   28:     SEQUENCE { -- changes
0024   26:       SEQUENCE { -- change
0026    1:         INTEGER = 0 -- add
0029   21:         SEQUENCE { -- modication (PartialAttribute)
002B   11:           STRING = 'description' -- type
0038    6:           SEQUENCE { -- SHOULD BE SET
003A    4:             STRING = 'test'
0040     :           }
0040     :         }
0040     :       }
0040     :     }
0040     :   }
0040     : }

Try changing

dartdap/lib/src/dartdap/protocol/modify_request.dart

Line 54 in 2301352

var ss = new ASN1Sequence();

to use an ASN1Set() instead.

We're miscoding the change type (0 -> add) as an INTEGER instead of an ENUM too.

dartdap/lib/src/dartdap/protocol/modify_request.dart

Line 34 in 2301352

s.add(ASN1Integer.fromInt(m.operation));

Probably should be ASN1Enumerated

@chrisridd Nice catch!

@miyazakijunichi I pushed version 0.3.4 to pub. It has the changes suggested by Chris.

I have had zero time to test this (getting ready to head out on vacation) - so let me know if this fixes your issue.

@wstrange I tested in my environment, it's completely working!
Thank you for your fast reply and fixes!