ossp-pkg/xds/xml-decode-octetstream.c
1.3
/*
XDS - OSSP Extensible Data Serialization Library
Copyright (c) 2001 The OSSP Project (http://www.ossp.org/)
Copyright (c) 2001 Cable & Wireless Deutschland (http://www.cw.com/de/)
This file is part of OSSP XDS, an extensible data serialization
library which can be found at http://www.ossp.com/pkg/xds/.
Permission to use, copy, modify, and distribute this software for
any purpose with or without fee is hereby granted, provided that
the above copyright notice and this permission notice appear in all
copies.
THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
IN NO EVENT SHALL THE AUTHORS AND COPYRIGHT HOLDERS AND THEIR
CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
SUCH DAMAGE.
*/
#include <string.h>
#include <ctype.h>
#include "xds.h"
static int base64_decode(unsigned char *dst, size_t dstlen, char const *src, size_t srclen)
{
int dstidx, state, ch = 0;
unsigned char res;
char *pos;
if (srclen == 0)
return 0;
state = 0;
dstidx = 0;
res = 0;
while (srclen-- > 0)
{
ch = *src++;
if (isascii(ch) && isspace(ch)) /* Skip whitespace anywhere */
continue;
if (ch == xds_pad64)
break;
pos = strchr(xds_base64, ch);
if (pos == 0) /* A non-base64 character */
return -1;
switch (state)
{
case 0:
if (dst != NULL)
{
if ((size_t)dstidx >= dstlen)
return -1;
dst[dstidx] = ((pos - xds_base64) << 2);
}
state = 1;
break;
case 1:
if (dst != NULL)
{
if ((size_t)dstidx >= dstlen)
return -1;
dst[dstidx] |= ((pos - xds_base64) >> 4);
res = (((pos - xds_base64) & 0x0f) << 4);
}
dstidx++;
state = 2;
break;
case 2:
if (dst != NULL)
{
if ((size_t)dstidx >= dstlen)
return -1;
dst[dstidx] = res | ((pos - xds_base64) >> 2);
res = ((pos - xds_base64) & 0x03) << 6;
}
dstidx++;
state = 3;
break;
case 3:
if (dst != NULL)
{
if ((size_t)dstidx >= dstlen)
return -1;
dst[dstidx] = res | (pos - xds_base64);
}
dstidx++;
state = 0;
break;
default:
break;
}
}
/*
* We are done decoding Base-64 chars. Let's see if we ended
* on a byte boundary, and/or with erroneous trailing characters.
*/
if (ch == xds_pad64)
{ /* We got a pad char. */
switch (state)
{
case 0: /* Invalid = in first position */
case 1: /* Invalid = in second position */
return -1;
case 2: /* Valid, means one byte of info */
/* Skip any number of spaces. */
while(srclen > 0)
{
ch = *src++;
--srclen;
if (!(isascii(ch) && isspace(ch)))
break;
}
/* Make sure there is another trailing = sign. */
if (ch != xds_pad64)
return -1;
/* FALLTHROUGH */
case 3: /* Valid, means two bytes of info */
/*
* We know this char is an =. Is there anything but
* whitespace after it?
*/
while(srclen > 0)
{
ch = *src++;
--srclen;
if (!(isascii(ch) && isspace(ch)))
return -1;
}
/*
* Now make sure for cases 2 and 3 that the "extra"
* bits that slopped past the last full byte were
* zeros. If we don't check them, they become a
* subliminal channel.
*/
if (dst != NULL && res != 0)
return -1;
default:
break;
}
}
else
{
/*
* We ended by seeing the end of the string. Make sure we
* have no partial bytes lying around.
*/
if (state != 0)
return -1;
}
return dstidx;
}
int xml_decode_octetstream(xds_t* xds, void* engine_context,
void* buffer, size_t buffer_size, size_t* used_buffer_size,
va_list* args)
{
char* p;
size_t p_len;
xds_uint8_t** data;
size_t* data_len;
/* We need at least 27 byte for the starting and ending tag. */
xds_init_encoding_engine(13 + 14);
/* Get parameters from stack. */
data = va_arg(*args, xds_uint8_t**);
xds_check_parameter(data != NULL);
data_len = va_arg(*args, size_t*);
/* Check for the opening tag. */
if (memcmp("<octetstream>", buffer, 13) != 0)
return XDS_ERR_TYPE_MISMATCH;
/* Find the end of the data and calculate the length of the
base64-encoded stuff. */
p = (char*)buffer + 13;
while(p < ((char*)buffer+buffer_size) && *p != '<')
++p;
if (p == ((char*)buffer+buffer_size))
return XDS_ERR_TYPE_MISMATCH;
else
{
p_len = p - ((char*)buffer + 13);
p = (char*)buffer + 13;
}
/* Now find out how long the decoded data is going to be, allocate
a buffer for it, and decode away. */
*data_len = base64_decode(NULL, 0, p, p_len);
if (*data_len == (size_t)-1)
return XDS_ERR_UNKNOWN;
*data = malloc(*data_len);
if (*data == NULL)
return XDS_ERR_NO_MEM;
base64_decode(*data, *data_len, p, p_len);
/* Check that we have a closing tag. */
if (memcmp(p + p_len, "</octetstream>", 14) != 0)
{
free(*data);
return XDS_ERR_TYPE_MISMATCH;
}
/* Done. */
*used_buffer_size = 13 + p_len + 14;
return XDS_OK;
}
