/* This file is part of the Project Athena Zephyr Notification System.
 * It contains source for the ZCheckAuthentication function.
 *
 *	Created by:	Robert French
 *
 *	$Source: /afs/sipb.mit.edu/project/sipb-athena/repository/src/zephyr/lib/ZCkAuth.c,v $
 *	$Author: ghudson $
 *
 *	Copyright (c) 1987,1991 by the Massachusetts Institute of Technology.
 *	For copying and distribution information, see the file
 *	"mit-copyright.h". 
 */
/* $Header: /afs/sipb.mit.edu/project/sipb-athena/repository/src/zephyr/lib/ZCkAuth.c,v 1.20 1996/06/02 08:05:41 ghudson Exp $ */

#ifndef lint
static char rcsid_ZCheckAuthentication_c[] =
    "$Zephyr: /mit/zephyr/src/lib/RCS/ZCheckAuthentication.c,v 1.14 89/03/24 14:17:38 jtkohl Exp Locker: raeburn $";
#endif

#include <zephyr/mit-copyright.h>
#include <sys/param.h>
#include <zephyr/zephyr_internal.h>

/* Check authentication of the notice.
   If it looks authentic but fails the Kerberos check, return -1.
   If it looks authentic and passes the Kerberos check, return 1.
   If it doesn't look authentic, return 0

   When not using Kerberos, return (looks-authentic-p)
   Only used by clients; the server uses its own routine.
 */
int ZCheckAuthentication(notice, from)
    ZNotice_t *notice;
    struct sockaddr_in *from;
{	
#ifdef Z_HaveKerberos
    int result;
    char srcprincipal[ANAME_SZ+INST_SZ+REALM_SZ+4];
    KTEXT_ST authent;
    AUTH_DAT dat;
    ZChecksum_t our_checksum;
    CREDENTIALS cred;

    /* If the value is already known, return it. */
    if (notice->z_checked_auth != ZAUTH_UNSET)
	return (notice->z_checked_auth);

    if (!notice->z_auth)
	return (ZAUTH_NO);
	
    if (result = krb_get_cred(SERVER_SERVICE, SERVER_INSTANCE, 
			      __Zephyr_realm, &cred))
	return (ZAUTH_NO);

#ifdef NOENCRYPTION
    our_checksum = 0;
#else
    our_checksum = (ZChecksum_t)des_quad_cksum(notice->z_packet, NULL, 
					   notice->z_default_format+
					   strlen(notice->z_default_format)+1-
					   notice->z_packet, 0, cred.session);
#endif
    /* if mismatched checksum, then the packet was corrupted */
    return ((our_checksum == notice->z_checksum) ? ZAUTH_YES : ZAUTH_FAILED);

#else
    return (notice->z_auth ? ZAUTH_YES : ZAUTH_NO);
#endif
}