* Open the file of upap secrets and scan for a suitable secret.
* Open the file of pap secrets and scan for a suitable secret.
null_login(unit)    int unit;{    char *filename;    FILE *f;    int i, ret;    struct wordlist *addrs;    char secret[MAXWORDLEN];    /*     * Open the file of upap secrets and scan for a suitable secret.     * We don't accept a wildcard client.     */    filename = _PATH_UPAPFILE;    addrs = NULL;    f = fopen(filename, "r");    if (f == NULL)	return 0;    check_access(f, filename);    i = scan_authfile(f, "", our_name, (u_int32_t)0, secret, &addrs, filename);    ret = i >= 0 && (i & NONWILD_CLIENT) != 0 && secret[0] == 0;    BZERO(secret, sizeof(secret));    if (ret) {	if (addresses[unit] != NULL)	    free_wordlist(addresses[unit]);	addresses[unit] = addrs;    }    fclose(f);    return ret;}