// Test TCP_MAXSEG works on passive/server TCP connections. // Set up a listening socket. 0.000 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3 0.000 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0 0.000 bind(3, ..., ...) = 0 0.000 listen(3, 1) = 0 // Set MSS to 1100. 0.010 setsockopt(3, SOL_TCP, TCP_MAXSEG, [1100], 4) = 0 // TODO(ncardwell): the following is silly; should we fix it? 0.020 getsockopt(3, SOL_TCP, TCP_MAXSEG, [536], [4]) = 0 // Establish a connection with an outgoing advertised MSS of 1100. 0.100 < S 0:0(0) win 32792 0.100 > S. 0:0(0) ack 1 0.200 < . 1:1(0) ack 1 win 257 0.300 accept(3, ..., ...) = 4 0.400 getsockopt(4, SOL_TCP, TCP_MAXSEG, [1100], [4]) = 0 0.500 %{ assert tcpi_advmss == 1100; assert tcpi_snd_mss == 1100 }% // IW10 MSS should yield outgoing TSO packet with 10*1100 == 11000 bytes: 0.600 write(4, ..., 12000) = 12000 0.600 > . 1:11001(11000) ack 1