EBADF              The socket descriptor is invalid.
    ECONNRESET         A connection was forcibly closed by a peer.
    EDESTADDRREQ       The socket is not connection-oriented, and no
                       peer address is set.
    EFAULT             The message argument is not in a readable or
                       writable part of the user address space.
    EINTR              A signal interrupted the send() before any
                       data was transmitted.
    EMSGSIZE           The message is too large to be sent all at
                       once, as the socket requires.
    ENETDOWN           The local network connection is not
                       operational.
    ENETUNREACH        The destination network is unreachable.
    ENOBUFS            The system has insufficient resources to
                       complete the call.
    ENOTCONN           The socket is not connected or has not had the
                       peer prespecified.
    ENOTSOCK           The socket descriptor is invalid.
    EOPNOTSUPP         The socket argument is associated with a
                       socket that does not support one or more of
                       the values set in flags.
    EWOULDBLOCK        The socket is marked nonblocking, and no space
                       is available for the send() function.