sctp_set_opt
extern int sctp_set_opt(struct sctp_s *conn, int level, int opt,
error = sctp_set_opt((struct sctp_s *)conn, level, option_name,
error = sctp_set_opt((struct sctp_s *)so->so_proto_handle,
rc = sctp_set_opt((struct sctp_s *)ssa->ssa_conn, level,
error = sctp_set_opt((struct sctp_s *)conn, IPPROTO_SCTP,
error = sctp_set_opt((struct sctp_s *)ssa->ssa_conn,
error = sctp_set_opt(ssa->ssa_conn, IPPROTO_SCTP, SCTP_INITMSG,