+
+ /* If our window is 0 and the packet is in sequence, let it pass
+ * through for ack processing. It should be dropped later. */
+ if (tc0->rcv_wnd == 0
+ && tc0->rcv_nxt == vnet_buffer (b0)->tcp.seq_number)
+ goto check_reset;
+
+ /* If we entered recovery and peer did so as well, there's a chance that
+ * dup acks won't be acceptable on either end because seq_end may be less
+ * than rcv_las. This can happen if acks are lost in both directions. */
+ if (tcp_in_recovery (tc0)
+ && seq_geq (vnet_buffer (b0)->tcp.seq_number,
+ tc0->rcv_las - tc0->rcv_wnd)
+ && seq_leq (vnet_buffer (b0)->tcp.seq_end,
+ tc0->rcv_nxt + tc0->rcv_wnd))
+ goto check_reset;
+
+ *error0 = TCP_ERROR_RCV_WND;
+
+ /* If not RST, send dup ack */
+ if (!tcp_rst (th0))
+ {
+ tcp_program_dupack (wrk, tc0);
+ TCP_EVT_DBG (TCP_EVT_DUPACK_SENT, tc0, vnet_buffer (b0)->tcp);
+ }
+ goto error;
+
+ check_reset:
+ ;