gre_in_cksum      298 net/if_gre.c   			mob_h.hcrc = gre_in_cksum((u_int16_t *) &mob_h, msiz);
gre_in_cksum      303 netinet/ip_gre.c 	if (gre_in_cksum((u_short *) &mip->mh, msiz) != 0) {