/*
 * $Id: lifetime.c,v 1.3 2001/06/25 20:13:45 rufustfirefly Exp $
 *
 * Ticket lifetime.  This defines the table used to lookup lifetime
 * for the fixed part of rande of the one byte lifetime field.  Values
 * less than 0x80 are intrpreted as the number of 5 minute intervals.
 * Values from 0x80 to 0xBF should be looked up in this table.  The
 * value of 0x80 is the same using both methods: 10 and two-thirds
 * hours .  The lifetime of 0xBF is 30 days.  The intervening values
 * of have a fixed ratio of roughly 1.06914.  The value 0xFF is
 * defined to mean a ticket has no expiration time.  This should be
 * used advisedly since individual servers may impose defacto
 * upperbounds on ticket lifetimes.
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif /* HAVE_CONFIG_H */

#include <sys/types.h>
#include <netatalk/endian.h>

#define TKTLIFENUMFIXED 64
#define TKTLIFEMINFIXED 0x80
#define TKTLIFEMAXFIXED 0xBF
#define TKTLIFENOEXPIRE 0xFF
#define MAXTKTLIFETIME	(30*24*3600)	/* 30 days */
#ifndef NEVERDATE
#define NEVERDATE ((u_int32_t)-1L)
#endif /* NEVERDATE */

static int tkt_lifetimes[TKTLIFENUMFIXED] = {
    38400,				/* 10.67 hours, 0.44 days */ 
    41055,				/* 11.40 hours, 0.48 days */ 
    43894,				/* 12.19 hours, 0.51 days */ 
    46929,				/* 13.04 hours, 0.54 days */ 
    50174,				/* 13.94 hours, 0.58 days */ 
    53643,				/* 14.90 hours, 0.62 days */ 
    57352,				/* 15.93 hours, 0.66 days */ 
    61318,				/* 17.03 hours, 0.71 days */ 
    65558,				/* 18.21 hours, 0.76 days */ 
    70091,				/* 19.47 hours, 0.81 days */ 
    74937,				/* 20.82 hours, 0.87 days */ 
    80119,				/* 22.26 hours, 0.93 days */ 
    85658,				/* 23.79 hours, 0.99 days */ 
    91581,				/* 25.44 hours, 1.06 days */ 
    97914,				/* 27.20 hours, 1.13 days */ 
    104684,				/* 29.08 hours, 1.21 days */ 
    111922,				/* 31.09 hours, 1.30 days */ 
    119661,				/* 33.24 hours, 1.38 days */ 
    127935,				/* 35.54 hours, 1.48 days */ 
    136781,				/* 37.99 hours, 1.58 days */ 
    146239,				/* 40.62 hours, 1.69 days */ 
    156350,				/* 43.43 hours, 1.81 days */ 
    167161,				/* 46.43 hours, 1.93 days */ 
    178720,				/* 49.64 hours, 2.07 days */ 
    191077,				/* 53.08 hours, 2.21 days */ 
    204289,				/* 56.75 hours, 2.36 days */ 
    218415,				/* 60.67 hours, 2.53 days */ 
    233517,				/* 64.87 hours, 2.70 days */ 
    249664,				/* 69.35 hours, 2.89 days */ 
    266926,				/* 74.15 hours, 3.09 days */ 
    285383,				/* 79.27 hours, 3.30 days */ 
    305116,				/* 84.75 hours, 3.53 days */ 
    326213,				/* 90.61 hours, 3.78 days */ 
    348769,				/* 96.88 hours, 4.04 days */ 
    372885,				/* 103.58 hours, 4.32 days */ 
    398668,				/* 110.74 hours, 4.61 days */ 
    426234,				/* 118.40 hours, 4.93 days */ 
    455705,				/* 126.58 hours, 5.27 days */ 
    487215,				/* 135.34 hours, 5.64 days */ 
    520904,				/* 144.70 hours, 6.03 days */ 
    556921,				/* 154.70 hours, 6.45 days */ 
    595430,				/* 165.40 hours, 6.89 days */ 
    636601,				/* 176.83 hours, 7.37 days */ 
    680618,				/* 189.06 hours, 7.88 days */ 
    727680,				/* 202.13 hours, 8.42 days */ 
    777995,				/* 216.11 hours, 9.00 days */ 
    831789,				/* 231.05 hours, 9.63 days */ 
    889303,				/* 247.03 hours, 10.29 days */ 
    950794,				/* 264.11 hours, 11.00 days */ 
    1016537,				/* 282.37 hours, 11.77 days */ 
    1086825,				/* 301.90 hours, 12.58 days */ 
    1161973,				/* 322.77 hours, 13.45 days */ 
    1242318,				/* 345.09 hours, 14.38 days */ 
    1328218,				/* 368.95 hours, 15.37 days */ 
    1420057,				/* 394.46 hours, 16.44 days */ 
    1518247,				/* 421.74 hours, 17.57 days */ 
    1623226,				/* 450.90 hours, 18.79 days */ 
    1735464,				/* 482.07 hours, 20.09 days */ 
    1855462,				/* 515.41 hours, 21.48 days */ 
    1983758,				/* 551.04 hours, 22.96 days */ 
    2120925,				/* 589.15 hours, 24.55 days */ 
    2267576,				/* 629.88 hours, 26.25 days */ 
    2424367,				/* 673.44 hours, 28.06 days */ 
    2592000};				/* 720.00 hours, 30.00 days */ 

/*
 * krb_life_to_time - takes a start time and a Kerberos standard
 * lifetime char and returns the corresponding end time.  There are
 * four simple cases to be handled.  The first is a life of 0xff,
 * meaning no expiration, and results in an end time of 0xffffffff.
 * The second is when life is less than the values covered by the
 * table.  In this case, the end time is the start time plus the
 * number of 5 minute intervals specified by life.  The third case
 * returns start plus the MAXTKTLIFETIME if life is greater than
 * TKTLIFEMAXFIXED.  The last case, uses the life value (minus
 * TKTLIFEMINFIXED) as an index into the table to extract the lifetime
 * in seconds, which is added to start to produce the end time.
 */
u_int32_t krb_life_to_time(start, life)
u_int32_t start;
int life;
{
    life = (unsigned char) life;
    if (life == TKTLIFENOEXPIRE) return NEVERDATE;
    if (life < TKTLIFEMINFIXED) return start + life*5*60;
    if (life > TKTLIFEMAXFIXED) return start + MAXTKTLIFETIME;
    return start + tkt_lifetimes[life - TKTLIFEMINFIXED];
}

/*
 * krb_time_to_life - takes start and end times for the ticket and
 * returns a Kerberos standard lifetime char, possibily using the
 * tkt_lifetimes table for lifetimes above 127*5 minutes.  First, the
 * special case of (end == NEVERDATE) is handled to mean no
 * expiration.  Then negative lifetimes and those greater than the
 * maximum ticket lifetime are rejected.  Then lifetimes less than the
 * first table entry are handled by rounding the requested lifetime
 * *up* to the next 5 minute interval.  The final step is to search
 * the table for the smallest entry *greater than or equal* to the
 * requested entry.
 */
int krb_time_to_life(start, end)
u_int32_t start;
u_int32_t end;
{
    int32_t lifetime;
    int i;

    if (end == NEVERDATE) return TKTLIFENOEXPIRE;
    lifetime = end - start;
    if (lifetime > MAXTKTLIFETIME || lifetime <= 0) return 0;
    if (lifetime < tkt_lifetimes[0]) return (lifetime + 5*60 - 1)/(5*60);
    for (i=0; i<TKTLIFENUMFIXED; i++) {
	if (lifetime <= tkt_lifetimes[i]) {
	    return i+TKTLIFEMINFIXED;
	}
    }
    return 0;
}
