der.c

 
#include <freerdp/config.h>
 
#include <winpr/crt.h>
 
#include <freerdp/crypto/der.h>
 
int _der_skip_length(int length)
{
  if (length > 0x7F && length <= 0xFF)
    return 2;
  else if (length > 0xFF)
    return 3;
  else
    return 1;
}
 
int der_write_length(wStream* s, int length)
{
  if (length > 0x7F && length <= 0xFF)
  {
    Stream_Write_UINT8(s, 0x81);
    Stream_Write_UINT8(s, length);
    return 2;
  }
  else if (length > 0xFF)
  {
    Stream_Write_UINT8(s, 0x82);
    Stream_Write_UINT16_BE(s, length);
    return 3;
  }
  else
  {
    Stream_Write_UINT8(s, length);
    return 1;
  }
}
 
int der_get_content_length(int length)
{
  if (length > 0x81 && length <= 0x102)
    return length - 3;
  else if (length > 0x102)
    return length - 4;
  else
    return length - 2;
}
 
int der_skip_contextual_tag(int length)
{
  return _der_skip_length(length) + 1;
}
 
int der_write_contextual_tag(wStream* s, BYTE tag, int length, BOOL pc)
{
  Stream_Write_UINT8(s, (ER_CLASS_CTXT | ER_PC(pc)) | (ER_TAG_MASK & tag));
  return der_write_length(s, length) + 1;
}
 
static void der_write_universal_tag(wStream* s, BYTE tag, BOOL pc)
{
  Stream_Write_UINT8(s, (ER_CLASS_UNIV | ER_PC(pc)) | (ER_TAG_MASK & tag));
}
 
int der_skip_octet_string(int length)
{
  return 1 + _der_skip_length(length) + length;
}
 
void der_write_octet_string(wStream* s, BYTE* oct_str, int length)
{
  der_write_universal_tag(s, ER_TAG_OCTET_STRING, FALSE);
  der_write_length(s, length);
  Stream_Write(s, oct_str, length);
}
 
int der_skip_sequence_tag(int length)
{
  return 1 + _der_skip_length(length);
}
 
int der_write_sequence_tag(wStream* s, int length)
{
  Stream_Write_UINT8(s, (ER_CLASS_UNIV | ER_CONSTRUCT) | (ER_TAG_MASK & ER_TAG_SEQUENCE));
  return der_write_length(s, length) + 1;
}