SCTP_IFNAMSIZ
SCTP_SNPRINTF(sctp_ifnp->ifn_name, SCTP_IFNAMSIZ, "%s", if_name);
SCTP_SNPRINTF(sctp_ifnp->ifn_name, SCTP_IFNAMSIZ, "%s", "unknown");
char ifn_name[SCTP_IFNAMSIZ];