gvisor.dev/gvisor@v0.0.0-20240520182842-f9d4d51c7e0f/test/packetdrill/tcp_defer_accept.pkt (about)

     1  // Test that a bare ACK does not complete a connection when TCP_DEFER_ACCEPT
     2  // timeout is not hit but an ACK w/ data does complete and deliver the
     3  // connection to the accept queue.
     4  
     5  0  socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
     6  +0 setsockopt(3, SOL_TCP, TCP_DEFER_ACCEPT, [5], 4) = 0
     7  +0.000 fcntl(3, F_SETFL, O_RDWR|O_NONBLOCK) = 0
     8  +0 bind(3, ..., ...) = 0
     9  
    10  // Set backlog to 1 so that we can easily test.
    11  +0 listen(3, 1) = 0
    12  
    13  // Establish a connection without timestamps.
    14  +0.0 < S 0:0(0) win 32792 <mss 1460,sackOK,nop,nop,nop,wscale 7>
    15  +0.0 > S. 0:0(0) ack 1    <...>
    16  
    17  // Send a bare ACK this should not complete the connection as we
    18  // set the TCP_DEFER_ACCEPT above.
    19  +0.0 < . 1:1(0) ack 1 win 257
    20  
    21  // The bare ACK should be dropped and no connection should be delivered
    22  // to the accept queue.
    23  +0.100 accept(3, ..., ...) = -1 EWOULDBLOCK (operation would block)
    24  
    25  // Send another bare ACK and it should still fail we set TCP_DEFER_ACCEPT
    26  // to 5 seconds above.
    27  +2.5 < . 1:1(0) ack 1 win 257
    28  +0.100 accept(3, ..., ...) = -1 EWOULDBLOCK (operation would block)
    29  
    30  // set accept socket back to blocking.
    31  +0.000 fcntl(3, F_SETFL, O_RDWR) = 0
    32  
    33  // Now send an ACK w/ data. This should complete the connection
    34  // and deliver the socket to the accept queue.
    35  +0.1 < . 1:5(4) ack 1 win 257
    36  +0.0 > . 1:1(0) ack 5 <...>
    37  
    38  // This should cause connection to transition to connected state.
    39  +0.000 accept(3, ..., ...) = 4
    40  +0.000 fcntl(4, F_SETFL, O_RDWR|O_NONBLOCK) = 0
    41  
    42  // Now read the data and we should get 4 bytes.
    43  +0.000 read(4,..., 4) = 4
    44  +0.000 close(4) = 0
    45  
    46  +0.0 > F. 1:1(0) ack 5 <...>
    47  +0.0 < F. 5:5(0) ack 2 win 257
    48  +0.01 > . 2:2(0) ack 6 <...>