• Yuchung Cheng's avatar
    net-tcp: Fast Open client - sendmsg(MSG_FASTOPEN) · cf60af03
    Yuchung Cheng authored
    sendmsg() (or sendto()) with MSG_FASTOPEN is a combo of connect(2)
    and write(2). The application should replace connect() with it to
    send data in the opening SYN packet.
    For blocking socket, sendmsg() blocks until all the data are buffered
    locally and the handshake is completed like connect() call. It
    returns similar errno like connect() if the TCP handshake fails.
    For non-blocking socket, it returns the number of bytes queued (and
    transmitted in the SYN-data packet) if cookie is available. If cookie
    is not available, it transmits a data-less SYN packet with Fast Open
    cookie request option and returns -EINPROGRESS like connect().
    Using MSG_FASTOPEN on connecting or connected socket will result in
    simlar errno like repeating connect() calls. Therefore the application
    should only use this flag on new sockets.
    The buffer size of sendmsg() is independent of the MSS of the connection.
    Signed-off-by: default avatarYuchung Cheng <ycheng@google.com>
    Acked-by: default avatarEric Dumazet <edumazet@google.com>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
inet_common.h 1.65 KB