// Test delay ack and quick ack

// Establish a connection.
0   socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
+0  setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0

+0  bind(3, ..., ...) = 0
+0  listen(3, 1) = 0

+0  < S 0:0(0) win 32792 <mss 1000,sackOK,nop,nop,nop,wscale 7>
+0  > S. 0:0(0) ack 1 <...>

+.1 < . 1:1(0) ack 1 win 32792
+0  accept(3, ..., ...) = 4

//receive 1 pkt and ack immediately (quickack)
+0 < . 1:1001(1000) ack 1 win 32792
+0 > . 1:1(0) ack 1001

//receive 1 pkt and delayack
+0 < . 1001:2001(1000) ack 1 win 32792
+0.1 ~ +0.2 > . 1:1(0) ack 2001

//receive 1 pkt and ack immediately (quickack)
+0 < . 2001:3001(1000) ack 1 win 32792
+0 > . 1:1(0) ack 3001