libpurple/protocols/zephyr/ZMkAuth.c

   1 /* This file is part of the Project Athena Zephyr Notification System.
   2  * It contains source for the ZMakeAuthentication function.
   3  *
   4  *      Created by:     Robert French
   5  *
   6  *      Copyright (c) 1987 by the Massachusetts Institute of Technology.
   7  *      For copying and distribution information, see the file
   8  *      "mit-copyright.h".
   9  */
  10
  11 #include "internal.h"
  12
  13 #ifndef ERROR_TABLE_BASE_krb
  14 #define ERROR_TABLE_BASE_krb (39525376L)
  15 #endif
  16
  17 #ifdef ZEPHYR_USES_KERBEROS
  18 #ifdef WIN32
  19
  20 #else
  21 #include <krb_err.h>
  22 #endif
  23 static long last_authent_time = 0L;
  24 static KTEXT_ST last_authent;
  25 #endif
  26
  27 Code_t ZMakeAuthentication(notice, buffer, buffer_len, len)
  28     register ZNotice_t *notice;
  29     char *buffer;
  30     int buffer_len;
  31     int *len;
  32 {
  33 #ifdef ZEPHYR_USES_KERBEROS
  34     int result;
  35     time_t now;
  36     KTEXT_ST authent;
  37     char *cstart, *cend;
  38     ZChecksum_t checksum;
  39     CREDENTIALS cred;
  40     extern unsigned long des_quad_cksum();
  41
  42     now = time(0);
  43     if (last_authent_time == 0 || (now - last_authent_time > 120)) {
  44         result = krb_mk_req(&authent, SERVER_SERVICE,
  45                             SERVER_INSTANCE, __Zephyr_realm, 0);
  46         if (result != MK_AP_OK) {
  47             last_authent_time = 0;
  48             return (result+ERROR_TABLE_BASE_krb);
  49         }
  50         last_authent_time = now;
  51         last_authent = authent;
  52     }
  53     else {
  54         authent = last_authent;
  55     }
  56     notice->z_auth = 1;
  57     notice->z_authent_len = authent.length;
  58     notice->z_ascii_authent = (char *)malloc((unsigned)authent.length*3);
  59     /* zero length authent is an error, so malloc(0) is not a problem */
  60     if (!notice->z_ascii_authent)
  61         return (ENOMEM);
  62     if ((result = ZMakeAscii(notice->z_ascii_authent,
  63                              authent.length*3,
  64                              authent.dat,
  65                              authent.length)) != ZERR_NONE) {
  66         free(notice->z_ascii_authent);
  67         return (result);
  68     }
  69     result = Z_FormatRawHeader(notice, buffer, buffer_len, len, &cstart,
  70                                &cend);
  71     free(notice->z_ascii_authent);
  72     notice->z_authent_len = 0;
  73     if (result)
  74         return(result);
  75
  76     /* Compute a checksum over the header and message. */
  77     if ((result = krb_get_cred(SERVER_SERVICE, SERVER_INSTANCE,
  78                               __Zephyr_realm, &cred)) != 0)
  79         return result;
  80     checksum = des_quad_cksum(buffer, NULL, cstart - buffer, 0, (C_Block *)cred.session);
  81     checksum ^= des_quad_cksum(cend, NULL, buffer + *len - cend, 0,
  82                                (C_Block *)cred.session);
  83     checksum ^= des_quad_cksum(notice->z_message, NULL, notice->z_message_len,
  84                                0, (C_Block *)cred.session);
  85     notice->z_checksum = checksum;
  86     ZMakeAscii32(cstart, buffer + buffer_len - cstart, checksum);
  87
  88     return (ZERR_NONE);
  89 #else
  90     notice->z_checksum = 0;
  91     notice->z_auth = 1;
  92     notice->z_authent_len = 0;
  93     notice->z_ascii_authent = "";
  94     return (Z_FormatRawHeader(notice, buffer, buffer_len, len, NULL, NULL));
  95 #endif
  96 }