src/aklog/skipwrap.c

   1
   2 /*
   3  * Copyright (c) 2006
   4  * The Regents of the University of Michigan
   5  * ALL RIGHTS RESERVED
   6  *
   7  * Permission is granted to use, copy, create derivative works
   8  * and redistribute this software and such derivative works
   9  * for any purpose, so long as the name of the University of
  10  * Michigan is not used in any advertising or publicity
  11  * pertaining to the use or distribution of this software
  12  * without specific, written prior authorization.  If the
  13  * above copyright notice or any other identification of the
  14  * University of Michigan is included in any copy of any
  15  * portion of this software, then the disclaimer below must
  16  * also be included.
  17  *
  18  * This software is provided as is, without representation
  19  * from the University of Michigan as to its fitness for any
  20  * purpose, and without warranty by the University of
  21  * Michigan of any kind, either express or implied, including
  22  * without limitation the implied warranties of
  23  * merchantability and fitness for a particular purpose.  The
  24  * regents of the University of Michigan shall not be liable
  25  * for any damages, including special, indirect, incidental, or
  26  * consequential damages, with respect to any claim arising
  27  * out of or in connection with the use of the software, even
  28  * if it has been or is hereafter advised of the possibility of
  29  * such damages.
  30  */
  31
  32 #include <afsconfig.h>
  33 #include <afs/param.h>
  34
  35 #include <roken.h>
  36
  37 #define KERBEROS_APPLE_DEPRECATED(x)
  38 #include "aklog.h"
  39 #include <krb5.h>
  40 #include "skipwrap.h"
  41
  42 /* evil hack */
  43 #define SEQUENCE 16
  44 #define CONSTRUCTED 32
  45 #define APPLICATION 64
  46 #define CONTEXT_SPECIFIC 128
  47 static int skip_get_number(char **pp, size_t *lp, int *np)
  48 {
  49     unsigned l;
  50     int r, n, i;
  51     char *p;
  52
  53     l = *lp;
  54     if (l < 1) {
  55 #ifdef DEBUG
  56         fprintf(stderr, "skip_bad_number: missing number\n");
  57 #endif
  58         return -1;
  59     }
  60     p = *pp;
  61     r = (unsigned char)*p;
  62     ++p; --l;
  63     if (r & 0x80) {
  64         n = (r&0x7f);
  65         if (l < n) {
  66 #ifdef DEBUG
  67             fprintf(stderr, "skip_bad_number: truncated number\n");
  68 #endif
  69             return -1;
  70         }
  71         r = 0;
  72         for (i = n; --i >= 0; ) {
  73             r <<= 8;
  74             r += (unsigned char)*p;
  75             ++p; --l;
  76         }
  77     }
  78     *np = r;
  79     *pp = p;
  80     *lp = l;
  81     return 0;
  82 }
  83
  84 int
  85 afs_krb5_skip_ticket_wrapper(char *tix, size_t tixlen, char **enc, size_t *enclen)
  86 {
  87     char *p = tix;
  88     size_t l = tixlen;
  89     int code;
  90     int num;
  91
  92     if (l < 1) return -1;
  93     if (*p != (char) (CONSTRUCTED+APPLICATION+1)) return -1;
  94     ++p; --l;
  95     if ((code = skip_get_number(&p, &l, &num))) return code;
  96     if (l != num) return -1;
  97     if (l < 1) return -1;
  98     if (*p != (char)(CONSTRUCTED+SEQUENCE)) return -1;
  99     ++p; --l;
 100     if ((code = skip_get_number(&p, &l, &num))) return code;
 101     if (l != num) return -1;
 102     if (l < 1) return -1;
 103     if (*p != (char)(CONSTRUCTED+CONTEXT_SPECIFIC+0)) return -1;
 104     ++p; --l;
 105     if ((code = skip_get_number(&p, &l, &num))) return code;
 106     if (l < num) return -1;
 107     l -= num; p += num;
 108     if (l < 1) return -1;
 109     if (*p != (char)(CONSTRUCTED+CONTEXT_SPECIFIC+1)) return -1;
 110     ++p; --l;
 111     if ((code = skip_get_number(&p, &l, &num))) return code;
 112     if (l < num) return -1;
 113     l -= num; p += num;
 114     if (l < 1) return -1;
 115     if (*p != (char)(CONSTRUCTED+CONTEXT_SPECIFIC+2)) return -1;
 116     ++p; --l;
 117     if ((code = skip_get_number(&p, &l, &num))) return code;
 118     if (l < num) return -1;
 119     l -= num; p += num;
 120     if (l < 1) return -1;
 121     if (*p != (char)(CONSTRUCTED+CONTEXT_SPECIFIC+3)) return -1;
 122     ++p; --l;
 123     if ((code = skip_get_number(&p, &l, &num))) return code;
 124     if (l != num) return -1;
 125     *enc = p;
 126     *enclen = l;
 127     return 0;
 128 }