@code{ECONNRESET}, @code{ENOBUFS}, @code{EISCONN}, @code{ENOTCONN},
@code{ETIMEDOUT}, @code{ECONNREFUSED}, @code{EHOSTUNREACH}, @code{EALREADY},
@code{EINPROGRESS} are not defined on some platforms:
@code{ECONNRESET}, @code{ENOBUFS}, @code{EISCONN}, @code{ENOTCONN},
@code{ETIMEDOUT}, @code{ECONNREFUSED}, @code{EHOSTUNREACH}, @code{EALREADY},
@code{EINPROGRESS} are not defined on some platforms: