Description

• Type: Non-conformance Bug
• Priority: Minor

Non-conformance Bug

Version: development branch

Expected behavior
The DTLS RFC specifies the following regarding the record sequence number:

For each received record, the receiver MUST verify that the record contains a sequence number that does not duplicate the sequence number of any other record received during the life of this session. Duplicates are rejected through the use of a sliding receive window. The "right" edge of the window represents the highest validated sequence number value received on this session. Records that contain sequence numbers lower than the "left" edge of the window are rejected.

Actual behavior
One can complete a handshake with the following values for the record sequence number:

CH0.sequence_number = 0
CH2.sequence_number = 68
CKE.sequence_number = 0
CCC.sequence_number = 0

The problem also exists when the server sends records with non-unique record sequence numbers.

I have attached the completed handshake trace for the mentioned non-conformance.

invalid-RSN.zip