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/*
* Copyright 2000, 2001 by the Massachusetts Institute of Technology.
* All Rights Reserved.
*
* Export of this software from the United States of America may
* require a specific license from the United States Government.
* It is the responsibility of any person or organization contemplating
* export to obtain such a license before exporting.
*
* WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
* distribute this software and its documentation for any purpose and
* without fee is hereby granted, provided that the above copyright
* notice appear in all copies and that both that copyright notice and
* this permission notice appear in supporting documentation, and that
* the name of M.I.T. not be used in advertising or publicity pertaining
* to distribution of the software without specific, written prior
* permission. Furthermore if you modify this software you must label
* your software as modified software and not distribute it in such a
* fashion that it might be confused with the original M.I.T. software.
* M.I.T. makes no representations about the suitability of
* this software for any purpose. It is provided "as is" without express
* or implied warranty.
*
*/
#include "krb.h"
/*
* Only lifetime bytes values less than 128 are on a linear scale.
* The following table contains an exponential scale that covers the
* lifetime values 128 to 191 inclusive (a total of 64 values).
* Values greater than 191 get interpreted the same as 191, but they
* will never be generated by the functions in this file.
*
* The ratio is approximately 1.069144898 (actually exactly
* exp(log(67.5)/63), where 67.5 = 2592000/38400, and 259200 = 30
* days, and 38400 = 128*5 minutes. This allows a lifetime byte of
* 191 to correspond to a ticket life of exactly 30 days and a
* lifetime byte of 128 to correspond to exactly 128*5 minutes, with
* the other values spread on an exponential curve fit in between
* them. This table should correspond exactly to the set of extended
* ticket lifetime values used by AFS and CMU.
*
* The following awk script is sufficient to reproduce the table:
* BEGIN {
* r = exp(log(2592000/38400)/63);
* x = 38400;
* for (i=0;i<64;i++) {
* printf("%d\n",x+0.5);
* x *= r;
* }
* }
*/
#ifndef SHORT_LIFETIME
#define NLIFETIMES 64
static const KRB4_32 lifetimes[NLIFETIMES] = {
38400, 41055, /* 00:10:40:00, 00:11:24:15 */
43894, 46929, /* 00:12:11:34, 00:13:02:09 */
50174, 53643, /* 00:13:56:14, 00:14:54:03 */
57352, 61318, /* 00:15:55:52, 00:17:01:58 */
65558, 70091, /* 00:18:12:38, 00:19:28:11 */
74937, 80119, /* 00:20:48:57, 00:22:15:19 */
85658, 91581, /* 00:23:47:38, 01:01:26:21 */
97914, 104684, /* 01:03:11:54, 01:05:04:44 */
111922, 119661, /* 01:07:05:22, 01:09:14:21 */
127935, 136781, /* 01:11:32:15, 01:13:59:41 */
146239, 156350, /* 01:16:37:19, 01:19:25:50 */
167161, 178720, /* 01:22:26:01, 02:01:38:40 */
191077, 204289, /* 02:05:04:37, 02:08:44:49 */
218415, 233517, /* 02:12:40:15, 02:16:51:57 */
249664, 266926, /* 02:21:21:04, 03:02:08:46 */
285383, 305116, /* 03:07:16:23, 03:12:45:16 */
326213, 348769, /* 03:18:36:53, 04:00:52:49 */
372885, 398668, /* 04:07:34:45, 04:14:44:28 */
426234, 455705, /* 04:22:23:54, 05:06:35:05 */
487215, 520904, /* 05:15:20:15, 06:00:41:44 */
556921, 595430, /* 06:10:42:01, 06:21:23:50 */
636601, 680618, /* 07:08:50:01, 07:21:03:38 */
727680, 777995, /* 08:10:08:00, 09:00:06:35 */
831789, 889303, /* 09:15:03:09, 10:07:01:43 */
950794, 1016537, /* 11:00:06:34, 11:18:22:17 */
1086825, 1161973, /* 12:13:53:45, 13:10:46:13 */
1242318, 1328218, /* 14:09:05:18, 15:08:56:58 */
1420057, 1518247, /* 16:10:27:37, 17:13:44:07 */
1623226, 1735464, /* 18:18:53:46, 20:02:04:24 */
1855462, 1983758, /* 21:11:24:22, 22:23:02:38 */
2120925, 2267576, /* 24:13:08:45, 26:05:52:56 */
2424367, 2592000 /* 28:01:26:07, 30:00:00:00 */
};
#define MINFIXED 0x80
#define MAXFIXED (MINFIXED + NLIFETIMES - 1)
#endif /* !SHORT_LIFETIME */
/*
* krb_life_to_time
*
* Given a start date and a lifetime byte, compute the expiration
* date.
*/
KRB4_32 KRB5_CALLCONV
krb_life_to_time(KRB4_32 start, int life)
{
if (life < 0 || life > 255) /* possibly sign botch in caller */
return start;
#ifndef SHORT_LIFETIME
if (life < MINFIXED)
return start + life * 5 * 60;
if (life > MAXFIXED)
return start + lifetimes[NLIFETIMES - 1];
return start + lifetimes[life - MINFIXED];
#else /* SHORT_LIFETIME */
return start + life * 5 * 60;
#endif /* SHORT_LIFETIME */
}
/*
* krb_time_to_life
*
* Given the start date and the end date, compute the lifetime byte.
* Round up, since we can adjust the start date backwards if we are
* issuing the ticket to cause it to expire at the correct time.
*/
int KRB5_CALLCONV
krb_time_to_life(KRB4_32 start, KRB4_32 end)
{
KRB4_32 dt;
#ifndef SHORT_LIFETIME
int i;
#endif
dt = end - start;
if (dt <= 0)
return 0;
#ifndef SHORT_LIFETIME
if (dt < lifetimes[0])
return (dt + 5 * 60 - 1) / (5 * 60);
/* This depends on the array being ordered. */
for (i = 0; i < NLIFETIMES; i++) {
if (lifetimes[i] >= dt)
return i + MINFIXED;
}
return MAXFIXED;
#else /* SHORT_LIFETIME */
if (dt > 5 * 60 * 255)
return 255;
else
return (dt + 5 * 60 - 1) / (5 * 60);
#endif /* SHORT_LIFETIME */
}
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