Closed vvidic closed 6 years ago
It seems the packets are not the same in the end. Client sents OWAMP-Test (size 14) and the server replies with TWAMP-Test (size 41). However the RFC5357 says the smaller packets may be padded in order to get the same size in both directions:
Note that the Reflector test packet formats are larger than the
Sender's formats. The Session-Sender MAY append sufficient Packet
Padding to allow the same IP packet payload lengths to be used in
each direction of transmission (this is usually desirable). To
compensate for the Reflector's larger test packet format, the Sender
appends at least 27 octets of padding in unauthenticated mode, and at
least 56 octets in authenticated and encrypted modes.
The code for padding was already there but did not work correctly because auth mode was not set correctly.
This needs to be properly tested with OWAMP deployments too.
From my testing the packet size for owping does not change from 14 by this patch:
12:13:11.753677 IP 161.53.160.238.9747 > 193.198.241.30.9006: UDP, length 14
12:13:11.758480 IP 161.53.160.238.9747 > 193.198.241.30.9006: UDP, length 14
12:13:11.763926 IP 161.53.160.238.9747 > 193.198.241.30.9006: UDP, length 14
12:13:11.849438 IP 161.53.160.238.9747 > 193.198.241.30.9006: UDP, length 14
Ok, thanks for the tests, that is already a good sign. What we also need to check is that the different authentication modes are still working fine. IIRC @erik-geant had added unit tests about that, but we also need to test it between 2 real (O|T)WAMP instances.
Can this be closed? It appears to have been merged and we have seen no issues with TWAMP.
yes, the unit test are still passing ... closing
Packet size should be the same in both directions (41 bytes if no padding), but we are sending much less in request packets:
This is causing the wireshark dissector to report these as malformed packets.