enum option_type

enum option_type {
    OPT_INT           = 1,
    OPT_LINGER        = 2,
    OPT_TIMEVAL       = 3,
    OPT_MREQN         = 4,
    OPT_MREQ          = 5,
    OPT_MREQ6         = 6,
    OPT_IPADDR        = 7,
    OPT_IPADDR6       = 8,
    OPT_TCP_INFO      = 9,
    OPT_HANDLE        = 10,
    OPT_GROUP_REQ     = 11,
    OPT_IP_PKTOPTIONS = 12,
    OPT_MREQ_SOURCE   = 13,
};