TCP receive window management

[Madhusudhan Ravi]

I have a question regarding the freeBSD receive window advertisement and updating sender side flow control state based on this.

Is it expected that a retransmitted packet not carry an updated receive window?
The following are the state variables used for maintaining a peer's rcv window state on the sender side. snd_wnd, snd_wl1, snd_wl2. In tcp_input at the label step6: where these states are updated there are checks which make sure rcv window is not updated by old segments.

 if ((thflags & TH_ACK) &&
 (SEQ_LT(tp->snd_wl1, th->th_seq) ||
 (tp->snd_wl1 == th->th_seq && (SEQ_LT(tp->snd_wl2, th->th_ack) ||
 (tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd))))) {

Based on the above checks for the case of a fast retransmitted packet that does ack additional data ((SEQ_LT(tp->snd_wl2, th->th_ack) is TRUE)  and has the latest rcv window. th_seq could be < snd_wl1 and in this case rcv window is not updated to the latest one. Is this intentional or is there something that I am missing.

Thanks
Madhu