329 lines
11 KiB
C
329 lines
11 KiB
C
/*
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* Copyright 1985, 1986, 1987, 1988 by the Massachusetts Institute
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* of Technology.
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* For copying and distribution information, please see the file
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* <Copyright.MIT>.
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*
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* from: der: rd_req.c,v 4.16 89/03/22 14:52:06 jtkohl Exp $
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* $Id: rd_req.c,v 1.2 1994/07/19 19:26:13 g89r4222 Exp $
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*/
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#ifndef lint
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static char *rcsid =
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"$Id: rd_req.c,v 1.2 1994/07/19 19:26:13 g89r4222 Exp $";
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#endif /* lint */
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#include <des.h>
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#include <krb.h>
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#include <prot.h>
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#include <sys/time.h>
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#include <strings.h>
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extern int krb_ap_req_debug;
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static struct timeval t_local = { 0, 0 };
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/*
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* Keep the following information around for subsequent calls
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* to this routine by the same server using the same key.
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*/
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static Key_schedule serv_key; /* Key sched to decrypt ticket */
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static C_Block ky; /* Initialization vector */
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static int st_kvno; /* version number for this key */
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static char st_rlm[REALM_SZ]; /* server's realm */
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static char st_nam[ANAME_SZ]; /* service name */
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static char st_inst[INST_SZ]; /* server's instance */
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/*
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* This file contains two functions. krb_set_key() takes a DES
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* key or password string and returns a DES key (either the original
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* key, or the password converted into a DES key) and a key schedule
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* for it.
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*
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* krb_rd_req() reads an authentication request and returns information
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* about the identity of the requestor, or an indication that the
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* identity information was not authentic.
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*/
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/*
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* krb_set_key() takes as its first argument either a DES key or a
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* password string. The "cvt" argument indicates how the first
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* argument "key" is to be interpreted: if "cvt" is null, "key" is
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* taken to be a DES key; if "cvt" is non-null, "key" is taken to
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* be a password string, and is converted into a DES key using
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* string_to_key(). In either case, the resulting key is returned
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* in the external static variable "ky". A key schedule is
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* generated for "ky" and returned in the external static variable
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* "serv_key".
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*
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* This routine returns the return value of des_key_sched.
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*
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* krb_set_key() needs to be in the same .o file as krb_rd_req() so that
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* the key set by krb_set_key() is available in private storage for
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* krb_rd_req().
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*/
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int
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krb_set_key(key,cvt)
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char *key;
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int cvt;
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{
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#ifdef NOENCRYPTION
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bzero(ky, sizeof(ky));
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return KSUCCESS;
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#else
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if (cvt)
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string_to_key(key,ky);
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else
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bcopy(key,(char *)ky,8);
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return(des_key_sched(ky,serv_key));
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#endif
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}
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/*
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* krb_rd_req() takes an AUTH_MSG_APPL_REQUEST or
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* AUTH_MSG_APPL_REQUEST_MUTUAL message created by krb_mk_req(),
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* checks its integrity and returns a judgement as to the requestor's
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* identity.
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*
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* The "authent" argument is a pointer to the received message.
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* The "service" and "instance" arguments name the receiving server,
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* and are used to get the service's ticket to decrypt the ticket
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* in the message, and to compare against the server name inside the
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* ticket. "from_addr" is the network address of the host from which
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* the message was received; this is checked against the network
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* address in the ticket. If "from_addr" is zero, the check is not
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* performed. "ad" is an AUTH_DAT structure which is
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* filled in with information about the sender's identity according
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* to the authenticator and ticket sent in the message. Finally,
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* "fn" contains the name of the file containing the server's key.
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* (If "fn" is NULL, the server's key is assumed to have been set
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* by krb_set_key(). If "fn" is the null string ("") the default
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* file KEYFILE, defined in "krb.h", is used.)
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*
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* krb_rd_req() returns RD_AP_OK if the authentication information
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* was genuine, or one of the following error codes (defined in
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* "krb.h"):
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*
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* RD_AP_VERSION - wrong protocol version number
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* RD_AP_MSG_TYPE - wrong message type
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* RD_AP_UNDEC - couldn't decipher the message
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* RD_AP_INCON - inconsistencies found
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* RD_AP_BADD - wrong network address
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* RD_AP_TIME - client time (in authenticator)
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* too far off server time
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* RD_AP_NYV - Kerberos time (in ticket) too
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* far off server time
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* RD_AP_EXP - ticket expired
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*
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* For the message format, see krb_mk_req().
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*
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* Mutual authentication is not implemented.
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*/
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krb_rd_req(authent,service,instance,from_addr,ad,fn)
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register KTEXT authent; /* The received message */
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char *service; /* Service name */
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char *instance; /* Service instance */
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long from_addr; /* Net address of originating host */
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AUTH_DAT *ad; /* Structure to be filled in */
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char *fn; /* Filename to get keys from */
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{
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static KTEXT_ST ticket; /* Temp storage for ticket */
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static KTEXT tkt = &ticket;
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static KTEXT_ST req_id_st; /* Temp storage for authenticator */
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register KTEXT req_id = &req_id_st;
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char realm[REALM_SZ]; /* Realm of issuing kerberos */
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static Key_schedule seskey_sched; /* Key sched for session key */
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unsigned char skey[KKEY_SZ]; /* Session key from ticket */
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char sname[SNAME_SZ]; /* Service name from ticket */
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char iname[INST_SZ]; /* Instance name from ticket */
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char r_aname[ANAME_SZ]; /* Client name from authenticator */
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char r_inst[INST_SZ]; /* Client instance from authenticator */
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char r_realm[REALM_SZ]; /* Client realm from authenticator */
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unsigned int r_time_ms; /* Fine time from authenticator */
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unsigned long r_time_sec; /* Coarse time from authenticator */
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register char *ptr; /* For stepping through */
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unsigned long delta_t; /* Time in authenticator - local time */
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long tkt_age; /* Age of ticket */
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static int swap_bytes; /* Need to swap bytes? */
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static int mutual; /* Mutual authentication requested? */
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static unsigned char s_kvno;/* Version number of the server's key
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* Kerberos used to encrypt ticket */
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int status;
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if (authent->length <= 0)
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return(RD_AP_MODIFIED);
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ptr = (char *) authent->dat;
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/* get msg version, type and byte order, and server key version */
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/* check version */
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if (KRB_PROT_VERSION != (unsigned int) *ptr++)
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return(RD_AP_VERSION);
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/* byte order */
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swap_bytes = 0;
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if ((*ptr & 1) != HOST_BYTE_ORDER)
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swap_bytes++;
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/* check msg type */
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mutual = 0;
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switch (*ptr++ & ~1) {
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case AUTH_MSG_APPL_REQUEST:
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break;
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case AUTH_MSG_APPL_REQUEST_MUTUAL:
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mutual++;
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break;
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default:
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return(RD_AP_MSG_TYPE);
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}
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#ifdef lint
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/* XXX mutual is set but not used; why??? */
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/* this is a crock to get lint to shut up */
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if (mutual)
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mutual = 0;
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#endif /* lint */
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s_kvno = *ptr++; /* get server key version */
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(void) strcpy(realm,ptr); /* And the realm of the issuing KDC */
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ptr += strlen(ptr) + 1; /* skip the realm "hint" */
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/*
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* If "fn" is NULL, key info should already be set; don't
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* bother with ticket file. Otherwise, check to see if we
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* already have key info for the given server and key version
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* (saved in the static st_* variables). If not, go get it
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* from the ticket file. If "fn" is the null string, use the
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* default ticket file.
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*/
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if (fn && (strcmp(st_nam,service) || strcmp(st_inst,instance) ||
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strcmp(st_rlm,realm) || (st_kvno != s_kvno))) {
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if (*fn == 0) fn = KEYFILE;
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st_kvno = s_kvno;
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#ifndef NOENCRYPTION
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if (read_service_key(service,instance,realm,s_kvno,fn,(char *)skey))
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return(RD_AP_UNDEC);
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if (status=krb_set_key((char *)skey,0)) return(status);
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#endif
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(void) strcpy(st_rlm,realm);
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(void) strcpy(st_nam,service);
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(void) strcpy(st_inst,instance);
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}
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/* Get ticket from authenticator */
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tkt->length = (int) *ptr++;
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if ((tkt->length + (ptr+1 - (char *) authent->dat)) > authent->length)
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return(RD_AP_MODIFIED);
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bcopy(ptr+1,(char *)(tkt->dat),tkt->length);
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if (krb_ap_req_debug)
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log("ticket->length: %d",tkt->length);
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#ifndef NOENCRYPTION
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/* Decrypt and take apart ticket */
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#endif
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if (decomp_ticket(tkt,&ad->k_flags,ad->pname,ad->pinst,ad->prealm,
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&(ad->address),ad->session, &(ad->life),
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&(ad->time_sec),sname,iname,ky,serv_key))
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return(RD_AP_UNDEC);
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if (krb_ap_req_debug) {
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log("Ticket Contents.");
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log(" Aname: %s.%s",ad->pname,
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((int)*(ad->prealm) ? ad->prealm : "Athena"));
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log(" Service: %s%s%s",sname,((int)*iname ? "." : ""),iname);
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}
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/* Extract the authenticator */
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req_id->length = (int) *(ptr++);
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if ((req_id->length + (ptr + tkt->length - (char *) authent->dat)) >
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authent->length)
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return(RD_AP_MODIFIED);
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bcopy(ptr + tkt->length, (char *)(req_id->dat),req_id->length);
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#ifndef NOENCRYPTION
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key_sched(ad->session,seskey_sched);
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pcbc_encrypt((C_Block *)req_id->dat,(C_Block *)req_id->dat,
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(long)req_id->length,seskey_sched,ad->session,DES_DECRYPT);
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#endif /* NOENCRYPTION */
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#define check_ptr() if ((ptr - (char *) req_id->dat) > req_id->length) return(RD_AP_MODIFIED);
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ptr = (char *) req_id->dat;
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(void) strcpy(r_aname,ptr); /* Authentication name */
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ptr += strlen(r_aname)+1;
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check_ptr();
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(void) strcpy(r_inst,ptr); /* Authentication instance */
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ptr += strlen(r_inst)+1;
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check_ptr();
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(void) strcpy(r_realm,ptr); /* Authentication name */
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ptr += strlen(r_realm)+1;
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check_ptr();
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bcopy(ptr,(char *)&ad->checksum,4); /* Checksum */
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ptr += 4;
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check_ptr();
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if (swap_bytes) swap_u_long(ad->checksum);
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r_time_ms = *(ptr++); /* Time (fine) */
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#ifdef lint
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/* XXX r_time_ms is set but not used. why??? */
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/* this is a crock to get lint to shut up */
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if (r_time_ms)
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r_time_ms = 0;
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#endif /* lint */
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check_ptr();
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/* assume sizeof(r_time_sec) == 4 ?? */
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bcopy(ptr,(char *)&r_time_sec,4); /* Time (coarse) */
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if (swap_bytes) swap_u_long(r_time_sec);
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/* Check for authenticity of the request */
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if (krb_ap_req_debug)
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log("Pname: %s %s",ad->pname,r_aname);
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if (strcmp(ad->pname,r_aname) != 0)
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return(RD_AP_INCON);
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if (strcmp(ad->pinst,r_inst) != 0)
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return(RD_AP_INCON);
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if (krb_ap_req_debug)
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log("Realm: %s %s",ad->prealm,r_realm);
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if ((strcmp(ad->prealm,r_realm) != 0))
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return(RD_AP_INCON);
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if (krb_ap_req_debug)
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log("Address: %d %d",ad->address,from_addr);
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if (from_addr && (ad->address != from_addr))
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return(RD_AP_BADD);
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(void) gettimeofday(&t_local,(struct timezone *) 0);
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delta_t = abs((int)(t_local.tv_sec - r_time_sec));
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if (delta_t > CLOCK_SKEW) {
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if (krb_ap_req_debug)
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log("Time out of range: %d - %d = %d",
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t_local.tv_sec,r_time_sec,delta_t);
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return(RD_AP_TIME);
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}
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/* Now check for expiration of ticket */
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tkt_age = t_local.tv_sec - ad->time_sec;
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if (krb_ap_req_debug)
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log("Time: %d Issue Date: %d Diff: %d Life %x",
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t_local.tv_sec,ad->time_sec,tkt_age,ad->life);
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if (t_local.tv_sec < ad->time_sec) {
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if ((ad->time_sec - t_local.tv_sec) > CLOCK_SKEW)
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return(RD_AP_NYV);
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}
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else if ((t_local.tv_sec - ad->time_sec) > 5 * 60 * ad->life)
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return(RD_AP_EXP);
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/* All seems OK */
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ad->reply.length = 0;
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return(RD_AP_OK);
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}
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