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ZMkAuth.c

/* This file is part of the Project Athena Zephyr Notification System.
 * It contains source for the ZMakeAuthentication function.
 *
 *    Created by: Robert French
 *
 *    $Id: ZMkAuth.c,v 1.19 1999/01/22 23:19:16 ghudson Exp $
 *
 *    Copyright (c) 1987 by the Massachusetts Institute of Technology.
 *    For copying and distribution information, see the file
 *    "mit-copyright.h". 
 */

#include <internal.h>

#ifndef lint
static const char rcsid_ZMakeAuthentication_c[] = "$Id: ZMkAuth.c,v 1.19 1999/01/22 23:19:16 ghudson Exp $";
#endif

#ifdef HAVE_KRB4
#include <krb_err.h>
static long last_authent_time = 0L;
static KTEXT_ST last_authent;
#endif

Code_t ZResetAuthentication () {
#ifdef HAVE_KRB4
    last_authent_time = 0L;
#endif
    return ZERR_NONE;
}

Code_t ZMakeAuthentication(notice, buffer, buffer_len, len)
    register ZNotice_t *notice;
    char *buffer;
    int buffer_len;
    int *len;
{
#ifdef HAVE_KRB4
    int result;
    time_t now;
    KTEXT_ST authent;
    char *cstart, *cend;
    ZChecksum_t checksum;
    CREDENTIALS cred;
    extern unsigned long des_quad_cksum();

    now = time(0);
    if (last_authent_time == 0 || (now - last_authent_time > 120)) {
      result = krb_mk_req(&authent, SERVER_SERVICE, 
                      SERVER_INSTANCE, __Zephyr_realm, 0);
      if (result != MK_AP_OK) {
          last_authent_time = 0;
          return (result+krb_err_base);
        }
      last_authent_time = now;
      last_authent = authent;
    }
    else {
      authent = last_authent;
    }
    notice->z_auth = 1;
    notice->z_authent_len = authent.length;
    notice->z_ascii_authent = (char *)malloc((unsigned)authent.length*3);
    /* zero length authent is an error, so malloc(0) is not a problem */
    if (!notice->z_ascii_authent)
      return (ENOMEM);
    if ((result = ZMakeAscii(notice->z_ascii_authent, 
                       authent.length*3, 
                       authent.dat, 
                       authent.length)) != ZERR_NONE) {
      free(notice->z_ascii_authent);
      return (result);
    }
    result = Z_FormatRawHeader(notice, buffer, buffer_len, len, &cstart,
                         &cend);
    free(notice->z_ascii_authent);
    notice->z_authent_len = 0;
    if (result)
      return(result);

    /* Compute a checksum over the header and message. */
    if ((result = krb_get_cred(SERVER_SERVICE, SERVER_INSTANCE, 
                        __Zephyr_realm, &cred)) != 0)
      return result;
    checksum = des_quad_cksum(buffer, NULL, cstart - buffer, 0, cred.session);
    checksum ^= des_quad_cksum(cend, NULL, buffer + *len - cend, 0,
                         cred.session);
    checksum ^= des_quad_cksum(notice->z_message, NULL, notice->z_message_len,
                         0, cred.session);
    notice->z_checksum = checksum;
    ZMakeAscii32(cstart, buffer + buffer_len - cstart, checksum);

    return (ZERR_NONE);
#else
    notice->z_checksum = 0;
    notice->z_auth = 1;
    notice->z_authent_len = 0;
    notice->z_ascii_authent = "";
    return (Z_FormatRawHeader(notice, buffer, buffer_len, len, NULL, NULL));
#endif
}

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