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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "secder.h"
#include "secerr.h"
static PRUint32
der_indefinite_length(unsigned char *buf, unsigned char *end)
{
PRUint32 len, ret, dataLen;
unsigned char tag, lenCode;
int dataLenLen;
len = 0;
while (1) {
if ((buf + 2) > end) {
return (0);
}
tag = *buf++;
lenCode = *buf++;
len += 2;
if ((tag == 0) && (lenCode == 0)) {
return (len);
}
if (lenCode == 0x80) { /* indefinite length */
ret = der_indefinite_length(buf, end); /* recurse to find length */
if (ret == 0)
return 0;
len += ret;
buf += ret;
} else { /* definite length */
if (lenCode & 0x80) {
/* Length of data is in multibyte format */
dataLenLen = lenCode & 0x7f;
switch (dataLenLen) {
case 1:
dataLen = buf[0];
break;
case 2:
dataLen = (buf[0] << 8) | buf[1];
break;
case 3:
dataLen = ((unsigned long)buf[0] << 16) | (buf[1] << 8) | buf[2];
break;
case 4:
dataLen = ((unsigned long)buf[0] << 24) |
((unsigned long)buf[1] << 16) | (buf[2] << 8) | buf[3];
break;
default:
PORT_SetError(SEC_ERROR_BAD_DER);
return SECFailure;
}
} else {
/* Length of data is in single byte */
dataLen = lenCode;
dataLenLen = 0;
}
/* skip this item */
buf = buf + dataLenLen + dataLen;
len = len + dataLenLen + dataLen;
}
}
}
/*
** Capture the next thing in the buffer.
** Returns the length of the header and the length of the contents.
*/
static SECStatus
der_capture(unsigned char *buf, unsigned char *end,
int *header_len_p, PRUint32 *contents_len_p)
{
unsigned char *bp;
unsigned char whole_tag;
PRUint32 contents_len;
int tag_number;
if ((buf + 2) > end) {
*header_len_p = 0;
*contents_len_p = 0;
if (buf == end)
return SECSuccess;
return SECFailure;
}
bp = buf;
/* Get tag and verify that it is ok. */
whole_tag = *bp++;
tag_number = whole_tag & DER_TAGNUM_MASK;
/*
* XXX This code does not (yet) handle the high-tag-number form!
*/
if (tag_number == DER_HIGH_TAG_NUMBER) {
PORT_SetError(SEC_ERROR_BAD_DER);
return SECFailure;
}
if ((whole_tag & DER_CLASS_MASK) == DER_UNIVERSAL) {
/* Check that the universal tag number is one we implement. */
switch (tag_number) {
case DER_BOOLEAN:
case DER_INTEGER:
case DER_BIT_STRING:
case DER_OCTET_STRING:
case DER_NULL:
case DER_OBJECT_ID:
case DER_SEQUENCE:
case DER_SET:
case DER_PRINTABLE_STRING:
case DER_T61_STRING:
case DER_IA5_STRING:
case DER_VISIBLE_STRING:
case DER_UTC_TIME:
case 0: /* end-of-contents tag */
break;
default:
PORT_SetError(SEC_ERROR_BAD_DER);
return SECFailure;
}
}
/*
* Get first byte of length code (might contain entire length, might not).
*/
contents_len = *bp++;
/*
* If the high bit is set, then the length is in multibyte format,
* or the thing has an indefinite-length.
*/
if (contents_len & 0x80) {
int bytes_of_encoded_len;
bytes_of_encoded_len = contents_len & 0x7f;
contents_len = 0;
switch (bytes_of_encoded_len) {
case 4:
contents_len |= *bp++;
contents_len <<= 8;
/* fallthru */
case 3:
contents_len |= *bp++;
contents_len <<= 8;
/* fallthru */
case 2:
contents_len |= *bp++;
contents_len <<= 8;
/* fallthru */
case 1:
contents_len |= *bp++;
break;
case 0:
contents_len = der_indefinite_length(bp, end);
if (contents_len)
break;
/* fallthru */
default:
PORT_SetError(SEC_ERROR_BAD_DER);
return SECFailure;
}
}
if ((bp + contents_len) > end) {
/* Ran past end of buffer */
PORT_SetError(SEC_ERROR_BAD_DER);
return SECFailure;
}
*header_len_p = (int)(bp - buf);
*contents_len_p = contents_len;
return SECSuccess;
}
SECStatus
DER_Lengths(SECItem *item, int *header_len_p, PRUint32 *contents_len_p)
{
return (der_capture(item->data, &item->data[item->len], header_len_p,
contents_len_p));
}
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