_ Git - BearSSL/blob - src/x509/asn1enc.c

   1 /*
   2  * Copyright (c) 2018 Thomas Pornin <pornin@bolet.org>
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining
   5  * a copy of this software and associated documentation files (the
   6  * "Software"), to deal in the Software without restriction, including
   7  * without limitation the rights to use, copy, modify, merge, publish,
   8  * distribute, sublicense, and/or sell copies of the Software, and to
   9  * permit persons to whom the Software is furnished to do so, subject to
  10  * the following conditions:
  11  *
  12  * The above copyright notice and this permission notice shall be
  13  * included in all copies or substantial portions of the Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  16  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  17  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  18  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
  19  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
  20  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  21  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  22  * SOFTWARE.
  23  */
  24
  25 #include "inner.h"
  26
  27 /* see inner.h */
  28 br_asn1_uint
  29 br_asn1_uint_prepare(const void *xdata, size_t xlen)
  30 {
  31         const unsigned char *x;
  32         br_asn1_uint t;
  33
  34         x = xdata;
  35         while (xlen > 0 && *x == 0) {
  36                 x ++;
  37                 xlen --;
  38         }
  39         t.data = x;
  40         t.len = xlen;
  41         t.asn1len = xlen;
  42         if (xlen == 0 || x[0] >= 0x80) {
  43                 t.asn1len ++;
  44         }
  45         return t;
  46 }
  47
  48 /* see inner.h */
  49 size_t
  50 br_asn1_encode_length(void *dest, size_t len)
  51 {
  52         unsigned char *buf;
  53         size_t z;
  54         int i, j;
  55
  56         buf = dest;
  57         if (len < 0x80) {
  58                 if (buf != NULL) {
  59                         *buf = len;
  60                 }
  61                 return 1;
  62         }
  63         i = 0;
  64         for (z = len; z != 0; z >>= 8) {
  65                 i ++;
  66         }
  67         if (buf != NULL) {
  68                 *buf ++ = 0x80 + i;
  69                 for (j = i - 1; j >= 0; j --) {
  70                         *buf ++ = len >> (j << 3);
  71                 }
  72         }
  73         return i + 1;
  74 }
  75
  76 /* see inner.h */
  77 size_t
  78 br_asn1_encode_uint(void *dest, br_asn1_uint pp)
  79 {
  80         unsigned char *buf;
  81         size_t lenlen;
  82
  83         if (dest == NULL) {
  84                 return 1 + br_asn1_encode_length(NULL, pp.asn1len) + pp.asn1len;
  85         }
  86         buf = dest;
  87         *buf ++ = 0x02;
  88         lenlen = br_asn1_encode_length(buf, pp.asn1len);
  89         buf += lenlen;
  90         *buf = 0x00;
  91         memcpy(buf + pp.asn1len - pp.len, pp.data, pp.len);
  92         return 1 + lenlen + pp.asn1len;
  93 }