reactos/base/applications/mstsc/asn.c

   1 /* -*- c-basic-offset: 8 -*-
   2    rdesktop: A Remote Desktop Protocol client.
   3    ASN.1 utility functions
   4    Copyright 2012 Henrik Andersson <hean01@cendio.se> for Cendio AB
   5
   6    This program is free software: you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation, either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program.     If not, see <http://www.gnu.org/licenses/>.
  18 */
  19
  20 #include "precomp.h"
  21
  22
  23 /* Parse an ASN.1 BER header */
  24 RD_BOOL
  25 ber_parse_header(STREAM s, int tagval, int *length)
  26 {
  27         int tag, len;
  28
  29         if (tagval > 0xff)
  30         {
  31                 in_uint16_be(s, tag);
  32         }
  33         else
  34         {
  35                 in_uint8(s, tag);
  36         }
  37
  38         if (tag != tagval)
  39         {
  40                 error("expected tag %d, got %d\n", tagval, tag);
  41                 return False;
  42         }
  43
  44         in_uint8(s, len);
  45
  46         if (len & 0x80)
  47         {
  48                 len &= ~0x80;
  49                 *length = 0;
  50                 while (len--)
  51                         next_be(s, *length);
  52         }
  53         else
  54                 *length = len;
  55
  56         return s_check(s);
  57 }
  58
  59 /* Output an ASN.1 BER header */
  60 void
  61 ber_out_header(STREAM s, int tagval, int length)
  62 {
  63         if (tagval > 0xff)
  64         {
  65                 out_uint16_be(s, tagval);
  66         }
  67         else
  68         {
  69                 out_uint8(s, tagval);
  70         }
  71
  72         if (length >= 0x80)
  73         {
  74                 out_uint8(s, 0x82);
  75                 out_uint16_be(s, length);
  76         }
  77         else
  78                 out_uint8(s, length);
  79 }
  80
  81 /* Output an ASN.1 BER integer */
  82 void
  83 ber_out_integer(STREAM s, int value)
  84 {
  85         ber_out_header(s, BER_TAG_INTEGER, 2);
  86         out_uint16_be(s, value);
  87 }
  88
  89 RD_BOOL
  90 ber_in_header(STREAM s, int *tagval, int *decoded_len)
  91 {
  92         in_uint8(s, *tagval);
  93         in_uint8(s, *decoded_len);
  94
  95         if (*decoded_len < 0x80)
  96                 return True;
  97         else if (*decoded_len == 0x81)
  98         {
  99                 in_uint8(s, *decoded_len);
 100                 return True;
 101         }
 102         else if (*decoded_len == 0x82)
 103         {
 104                 in_uint16_be(s, *decoded_len);
 105                 return True;
 106         }
 107
 108         return False;
 109 }