A user on a networked machine can be identified by (a) the machine name, such as krypton; (b) the user's UID: see the geteuid man page; and (c) the group numbers to which the user belongs: see the getgroups man page. A structure with this information and its associated XDR routine could be coded as in Example A-7.
struct netuser { char *nu_machinename; int nu_uid; u_int nu_glen; int *nu_gids; }; #define NLEN 255 /* machine names < 256 chars */ #define NGRPS 20 /* user can't be in > 20 groups */ bool_t xdr_netuser(xdrs, nup) XDR *xdrs; struct netuser *nup; { return(xdr_string(xdrs, &nup->nu_machinename, NLEN) && xdr_int(xdrs, &nup->nu_uid) && xdr_array(xdrs, &nup->nu_gids, &nup->nu_glen, NGRPS, sizeof (int), xdr_int)); }