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/*
* decomp_tkt.c
*
* Copyright 1985, 1986, 1987, 1988 by the Massachusetts Institute
* of Technology.
*
* For copying and distribution information, please see the file
* <mit-copyright.h>.
*/
#include "mit-copyright.h"
#include "des.h"
#include "krb.h"
#include "prot.h"
#include <string.h>
#ifdef KRB_CRYPT_DEBUG
extern int krb_debug;
#endif
/*
* This routine takes a ticket and pointers to the variables that
* should be filled in based on the information in the ticket. It
#ifndef NOENCRYPTION
* decrypts the ticket using the given key, and
#endif
* fills in values for its arguments.
*
* Note: if the client realm field in the ticket is the null string,
* then the "prealm" variable is filled in with the local realm (as
* defined by KRB_REALM).
*
* If the ticket byte order is different than the host's byte order
* (as indicated by the byte order bit of the "flags" field), then
* the KDC timestamp "time_sec" is byte-swapped. The other fields
* potentially affected by byte order, "paddress" and "session" are
* not byte-swapped.
*
* The routine returns KFAILURE if any of the "pname", "pinstance",
* or "prealm" fields is too big, otherwise it returns KSUCCESS.
*
* The corresponding routine to generate tickets is create_ticket.
* When changes are made to this routine, the corresponding changes
* should also be made to that file.
*
* See create_ticket.c for the format of the ticket packet.
*/
int
decomp_ticket(tkt, flags, pname, pinstance, prealm, paddress, session,
life, time_sec, sname, sinstance, key, key_s)
KTEXT tkt; /* The ticket to be decoded */
unsigned char *flags; /* Kerberos ticket flags */
char *pname; /* Authentication name */
char *pinstance; /* Principal's instance */
char *prealm; /* Principal's authentication domain */
unsigned KRB4_32 *paddress; /* Net address of entity
* requesting ticket */
C_Block session; /* Session key inserted in ticket */
int *life; /* Lifetime of the ticket */
unsigned KRB4_32 *time_sec; /* Issue time and date */
char *sname; /* Service name */
char *sinstance; /* Service instance */
C_Block key; /* Service's secret key
* (to decrypt the ticket) */
Key_schedule key_s; /* The precomputed key schedule */
{
static int tkt_swap_bytes;
unsigned char *uptr;
char *ptr = (char *)tkt->dat;
#ifndef NOENCRYPTION
/* Do the decryption */
#ifdef KRB_CRYPT_DEBUG
if (krb_debug) {
FILE *fp;
char *keybuf[BUFSIZ]; /* Avoid secret stuff in stdio buffers */
fp = fopen("/kerberos/tkt.des", "wb");
setbuf(fp, keybuf);
fwrite(tkt->dat, 1, tkt->length, fp);
fclose(fp);
memset(keybuf, 0, sizeof(keybuf)); /* Clear the buffer */
}
#endif
pcbc_encrypt((C_Block *)tkt->dat,(C_Block *)tkt->dat,
(long) tkt->length,key_s,(C_Block *) key,0);
#endif /* ! NOENCRYPTION */
#ifdef KRB_CRYPT_DEBUG
if (krb_debug) {
FILE *fp;
char *keybuf[BUFSIZ]; /* Avoid secret stuff in stdio buffers */
fp = fopen("/kerberos/tkt.clear", "wb");
setbuf(fp, keybuf);
fwrite(tkt->dat, 1, tkt->length, fp);
fclose(fp);
memset(keybuf, 0, sizeof(keybuf)); /* Clear the buffer */
}
#endif
*flags = *ptr; /* get flags byte */
ptr += sizeof(*flags);
tkt_swap_bytes = 0;
if (HOST_BYTE_ORDER != ((*flags >> K_FLAG_ORDER)& 1))
tkt_swap_bytes++;
if (strlen(ptr) > ANAME_SZ)
return(KFAILURE);
(void) strcpy(pname,ptr); /* pname */
ptr += strlen(pname) + 1;
if (strlen(ptr) > INST_SZ)
return(KFAILURE);
(void) strcpy(pinstance,ptr); /* instance */
ptr += strlen(pinstance) + 1;
if (strlen(ptr) > REALM_SZ)
return(KFAILURE);
(void) strcpy(prealm,ptr); /* realm */
ptr += strlen(prealm) + 1;
/* temporary hack until realms are dealt with properly */
if (*prealm == 0)
(void) strcpy(prealm,KRB_REALM);
memcpy((char *)paddress, ptr, 4); /* net address */
ptr += 4;
memcpy((char *)session, ptr, 8); /* session key */
ptr+= 8;
#ifdef notdef /* DONT SWAP SESSION KEY spm 10/22/86 */
if (tkt_swap_bytes)
swap_C_Block(session);
#endif
/* get lifetime, being certain we don't get negative lifetimes */
uptr = (unsigned char *) ptr++;
*life = (int) *uptr;
memcpy((char *) time_sec, ptr, 4); /* issue time */
ptr += 4;
if (tkt_swap_bytes)
swap_u_long(*time_sec);
(void) strcpy(sname,ptr); /* service name */
ptr += 1 + strlen(sname);
(void) strcpy(sinstance,ptr); /* instance */
ptr += 1 + strlen(sinstance);
#ifdef KRB_CRYPT_DEBUG
if (krb_debug) {
krb_log("service=%s.%s len(sname)=%d, len(sinstance)=%d",
sname, sinstance, strlen(sname), strlen(sinstance));
krb_log("ptr - tkt->dat=%d",(char *)ptr - (char *)tkt->dat);
}
#endif
return(KSUCCESS);
}
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