325 lines
11 KiB
C
325 lines
11 KiB
C
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/*
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* Copyright (c) 1995, 1996, 1997 Kungliga Tekniska H<EFBFBD>gskolan
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* (Royal Institute of Technology, Stockholm, Sweden).
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the Kungliga Tekniska
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* H<EFBFBD>gskolan and its contributors.
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*
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* 4. Neither the name of the Institute nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include "krb_locl.h"
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RCSID("$Id: rd_req.c,v 1.24 1997/05/11 11:05:28 assar Exp $");
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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 des_key_schedule serv_key; /* Key sched to decrypt ticket */
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static des_cblock 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(void *key, int cvt)
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{
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#ifdef NOENCRYPTION
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memset(ky, 0, sizeof(ky));
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return KSUCCESS;
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#else /* Encrypt */
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if (cvt)
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des_string_to_key((char*)key, &ky);
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else
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memcpy((char*)ky, key, 8);
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return(des_key_sched(&ky, serv_key));
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#endif /* NOENCRYPTION */
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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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int
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krb_rd_req(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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int32_t 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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KTEXT req_id = &req_id_st;
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char realm[REALM_SZ]; /* Realm of issuing kerberos */
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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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u_int32_t r_time_sec; /* Coarse time from authenticator */
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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 unsigned char s_kvno;/* Version number of the server's key
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* Kerberos used to encrypt ticket */
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struct timeval tv;
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int status;
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int pvno;
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int type;
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int little_endian;
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unsigned char *p;
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if (authent->length <= 0)
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return(RD_AP_MODIFIED);
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p = authent->dat;
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/* get msg version, type and byte order, and server key version */
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pvno = *p++;
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if(pvno != KRB_PROT_VERSION)
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return RD_AP_VERSION;
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type = *p++;
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little_endian = type & 1;
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type &= ~1;
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if(type != AUTH_MSG_APPL_REQUEST && type != AUTH_MSG_APPL_REQUEST_MUTUAL)
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return RD_AP_MSG_TYPE;
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s_kvno = *p++;
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p += krb_get_string(p, realm);
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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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if (read_service_key(service, instance, realm, s_kvno,
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fn, (char *)skey))
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return(RD_AP_UNDEC);
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if ((status = krb_set_key((char*)skey, 0)))
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return(status);
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strcpy(st_rlm, realm);
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strcpy(st_nam, service);
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strcpy(st_inst, instance);
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}
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tkt->length = *p++;
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req_id->length = *p++;
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if(tkt->length + (p - authent->dat) > authent->length)
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return RD_AP_MODIFIED;
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memcpy(tkt->dat, p, tkt->length);
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p += tkt->length;
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if (krb_ap_req_debug)
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krb_log("ticket->length: %d",tkt->length);
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/* Decrypt and take apart ticket */
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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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krb_log("Ticket Contents.");
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krb_log(" Aname: %s.%s",ad->pname, ad->prealm);
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krb_log(" Service: %s", krb_unparse_name_long(sname, iname, NULL));
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}
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/* Extract the authenticator */
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if(req_id->length + (p - authent->dat) > authent->length)
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return RD_AP_MODIFIED;
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memcpy(req_id->dat, p, req_id->length);
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p = req_id->dat;
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#ifndef NOENCRYPTION
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/* And decrypt it with the session key from the ticket */
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if (krb_ap_req_debug) krb_log("About to decrypt authenticator");
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encrypt_ktext(req_id, &ad->session, DES_DECRYPT);
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if (krb_ap_req_debug) krb_log("Done.");
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#endif /* NOENCRYPTION */
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/* cast req_id->length to int? */
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#define check_ptr() if ((ptr - (char *) req_id->dat) > req_id->length) return(RD_AP_MODIFIED);
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p += krb_get_nir(p, r_aname, r_inst, r_realm); /* XXX no rangecheck */
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p += krb_get_int(p, &ad->checksum, 4, little_endian);
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p++; /* time_5ms is not used */
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p += krb_get_int(p, &r_time_sec, 4, little_endian);
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/* Check for authenticity of the request */
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if (krb_ap_req_debug)
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krb_log("Principal: %s.%s@%s / %s.%s@%s",ad->pname,ad->pinst, ad->prealm,
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r_aname, r_inst, r_realm);
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if (strcmp(ad->pname, r_aname) != 0 ||
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strcmp(ad->pinst, r_inst) != 0 ||
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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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krb_log("Address: %x %x", ad->address, from_addr);
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if (from_addr && (!krb_equiv(ad->address, from_addr)))
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return RD_AP_BADD;
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gettimeofday(&tv, NULL);
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delta_t = abs((int)(tv.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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krb_log("Time out of range: %lu - %lu = %lu",
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(unsigned long)t_local.tv_sec,
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(unsigned long)r_time_sec,
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(unsigned long)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 = tv.tv_sec - ad->time_sec;
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if (krb_ap_req_debug)
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krb_log("Time: %ld Issue Date: %lu Diff: %ld Life %x",
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(long)tv.tv_sec,
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(unsigned long)ad->time_sec,
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tkt_age,
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ad->life);
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if ((tkt_age < 0) && (-tkt_age > CLOCK_SKEW))
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return RD_AP_NYV;
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if (tv.tv_sec > krb_life_to_time(ad->time_sec, 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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