3.1.1.1.2 RDP-UDP2 Packet Header

The header (section 2.2.1.1) is a 16-bit structure that is mandatory for all RDP-UDP2 packets. The header has a Flags field that is a bit mask that indicates the presence of the optional payloads. The LogWindowSize field in the header contains the log2 of the receiving window size announced by the sender.

The ACK flag and the ACKVEC flag are mutually exclusive and both MUST NOT be set to 1 in the Flags field of an RDP-UDP2 packet header.

The user generated data from higher layers of the RDP stack is encapsulated in the DATA payload which is composed of a DataHeader payload and a DataBody payload. Both payloads MUST be present if the Flags field in the RDP-UDP2 header has the DATA bit set to 1.