blob: d6e94427270e58c879becaa09ff1d98bc19af798 [file] [log] [blame]
/* Copyright (c) 2014, Google Inc.
*
* Permission to use, copy, modify, and/or 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.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
* SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
* OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
* CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
#include <openssl/buf.h>
#include <openssl/mem.h>
#include <openssl/bytestring.h>
#include <assert.h>
#include <string.h>
#include "internal.h"
void CBS_init(CBS *cbs, const uint8_t *data, size_t len) {
cbs->data = data;
cbs->len = len;
}
static int cbs_get(CBS *cbs, const uint8_t **p, size_t n) {
if (cbs->len < n) {
return 0;
}
*p = cbs->data;
cbs->data += n;
cbs->len -= n;
return 1;
}
int CBS_skip(CBS *cbs, size_t len) {
const uint8_t *dummy;
return cbs_get(cbs, &dummy, len);
}
const uint8_t *CBS_data(const CBS *cbs) {
return cbs->data;
}
size_t CBS_len(const CBS *cbs) {
return cbs->len;
}
int CBS_stow(const CBS *cbs, uint8_t **out_ptr, size_t *out_len) {
if (*out_ptr != NULL) {
OPENSSL_free(*out_ptr);
*out_ptr = NULL;
}
*out_len = 0;
if (cbs->len == 0) {
return 1;
}
*out_ptr = BUF_memdup(cbs->data, cbs->len);
if (*out_ptr == NULL) {
return 0;
}
*out_len = cbs->len;
return 1;
}
int CBS_strdup(const CBS *cbs, char **out_ptr) {
if (*out_ptr != NULL) {
OPENSSL_free(*out_ptr);
}
*out_ptr = BUF_strndup((const char*)cbs->data, cbs->len);
return (*out_ptr != NULL);
}
int CBS_contains_zero_byte(const CBS *cbs) {
return memchr(cbs->data, 0, cbs->len) != NULL;
}
int CBS_mem_equal(const CBS *cbs, const uint8_t *data, size_t len) {
if (len != cbs->len)
return 0;
return CRYPTO_memcmp(cbs->data, data, len) == 0;
}
static int cbs_get_u(CBS *cbs, uint32_t *out, size_t len) {
uint32_t result = 0;
size_t i;
const uint8_t *data;
if (!cbs_get(cbs, &data, len)) {
return 0;
}
for (i = 0; i < len; i++) {
result <<= 8;
result |= data[i];
}
*out = result;
return 1;
}
int CBS_get_u8(CBS *cbs, uint8_t *out) {
const uint8_t *v;
if (!cbs_get(cbs, &v, 1)) {
return 0;
}
*out = *v;
return 1;
}
int CBS_get_u16(CBS *cbs, uint16_t *out) {
uint32_t v;
if (!cbs_get_u(cbs, &v, 2)) {
return 0;
}
*out = v;
return 1;
}
int CBS_get_u24(CBS *cbs, uint32_t *out) {
return cbs_get_u(cbs, out, 3);
}
int CBS_get_u32(CBS *cbs, uint32_t *out) {
return cbs_get_u(cbs, out, 4);
}
int CBS_get_bytes(CBS *cbs, CBS *out, size_t len) {
const uint8_t *v;
if (!cbs_get(cbs, &v, len)) {
return 0;
}
CBS_init(out, v, len);
return 1;
}
static int cbs_get_length_prefixed(CBS *cbs, CBS *out, size_t len_len) {
uint32_t len;
if (!cbs_get_u(cbs, &len, len_len)) {
return 0;
}
return CBS_get_bytes(cbs, out, len);
}
int CBS_get_u8_length_prefixed(CBS *cbs, CBS *out) {
return cbs_get_length_prefixed(cbs, out, 1);
}
int CBS_get_u16_length_prefixed(CBS *cbs, CBS *out) {
return cbs_get_length_prefixed(cbs, out, 2);
}
int CBS_get_u24_length_prefixed(CBS *cbs, CBS *out) {
return cbs_get_length_prefixed(cbs, out, 3);
}
int CBS_get_any_asn1_element(CBS *cbs, CBS *out, unsigned *out_tag,
size_t *out_header_len) {
uint8_t tag, length_byte;
CBS header = *cbs;
if (!CBS_get_u8(&header, &tag) ||
!CBS_get_u8(&header, &length_byte)) {
return 0;
}
if ((tag & 0x1f) == 0x1f) {
/* Long form tags are not supported. */
return 0;
}
*out_tag = tag;
size_t len;
if ((length_byte & 0x80) == 0) {
/* Short form length. */
len = ((size_t) length_byte) + 2;
*out_header_len = 2;
} else {
/* Long form length. */
const size_t num_bytes = length_byte & 0x7f;
uint32_t len32;
if ((tag & CBS_ASN1_CONSTRUCTED) != 0 && num_bytes == 0) {
/* indefinite length */
*out_header_len = 2;
return CBS_get_bytes(cbs, out, 2);
}
if (num_bytes == 0 || num_bytes > 4) {
return 0;
}
if (!cbs_get_u(&header, &len32, num_bytes)) {
return 0;
}
if (len32 < 128) {
/* Length should have used short-form encoding. */
return 0;
}
if ((len32 >> ((num_bytes-1)*8)) == 0) {
/* Length should have been at least one byte shorter. */
return 0;
}
len = len32;
if (len + 2 + num_bytes < len) {
/* Overflow. */
return 0;
}
len += 2 + num_bytes;
*out_header_len = 2 + num_bytes;
}
return CBS_get_bytes(cbs, out, len);
}
static int cbs_get_asn1(CBS *cbs, CBS *out, unsigned tag_value,
int skip_header) {
size_t header_len;
unsigned tag;
CBS throwaway;
if (out == NULL) {
out = &throwaway;
}
if (!CBS_get_any_asn1_element(cbs, out, &tag, &header_len) ||
tag != tag_value ||
(header_len > 0 &&
/* This ensures that the tag is either zero length or
* indefinite-length. */
CBS_len(out) == header_len &&
CBS_data(out)[header_len - 1] == 0x80)) {
return 0;
}
if (skip_header && !CBS_skip(out, header_len)) {
assert(0);
return 0;
}
return 1;
}
int CBS_get_asn1(CBS *cbs, CBS *out, unsigned tag_value) {
return cbs_get_asn1(cbs, out, tag_value, 1 /* skip header */);
}
int CBS_get_asn1_element(CBS *cbs, CBS *out, unsigned tag_value) {
return cbs_get_asn1(cbs, out, tag_value, 0 /* include header */);
}
int CBS_get_asn1_uint64(CBS *cbs, uint64_t *out) {
CBS bytes;
const uint8_t *data;
size_t i, len;
if (!CBS_get_asn1(cbs, &bytes, CBS_ASN1_INTEGER)) {
return 0;
}
*out = 0;
data = CBS_data(&bytes);
len = CBS_len(&bytes);
if (len > 0 && (data[0] & 0x80) != 0) {
/* negative number */
return 0;
}
for (i = 0; i < len; i++) {
if ((*out >> 56) != 0) {
/* Too large to represent as a uint64_t. */
return 0;
}
*out <<= 8;
*out |= data[i];
}
return 1;
}