/* 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. */
#if !defined(__STDC_FORMAT_MACROS)
#define __STDC_FORMAT_MACROS
#endif
#include <openssl/buf.h>
#include <openssl/mem.h>
#include <openssl/bytestring.h>
#include <assert.h>
#include <inttypes.h>
#include <string.h>
#include "internal.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) {
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 OPENSSL_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;
const uint8_t *data;
if (!cbs_get(cbs, &data, len)) {
return 0;
}
for (size_t 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_last_u8(CBS *cbs, uint8_t *out) {
if (cbs->len == 0) {
return 0;
}
*out = cbs->data[cbs->len - 1];
cbs->len--;
return 1;
}
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;
}
int CBS_copy_bytes(CBS *cbs, uint8_t *out, size_t len) {
const uint8_t *v;
if (!cbs_get(cbs, &v, len)) {
return 0;
}
OPENSSL_memcpy(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);
}
// parse_base128_integer reads a big-endian base-128 integer from |cbs| and sets
// |*out| to the result. This is the encoding used in DER for both high tag
// number form and OID components.
static int parse_base128_integer(CBS *cbs, uint64_t *out) {
uint64_t v = 0;
uint8_t b;
do {
if (!CBS_get_u8(cbs, &b)) {
return 0;
}
if ((v >> (64 - 7)) != 0) {
// The value is too large.
return 0;
}
if (v == 0 && b == 0x80) {
// The value must be minimally encoded.
return 0;
}
v = (v << 7) | (b & 0x7f);
// Values end at an octet with the high bit cleared.
} while (b & 0x80);
*out = v;
return 1;
}
static int parse_asn1_tag(CBS *cbs, unsigned *out) {
uint8_t tag_byte;
if (!CBS_get_u8(cbs, &tag_byte)) {
return 0;
}
// ITU-T X.690 section 8.1.2.3 specifies the format for identifiers with a tag
// number no greater than 30.
//
// If the number portion is 31 (0x1f, the largest value that fits in the
// allotted bits), then the tag is more than one byte long and the
// continuation bytes contain the tag number. This parser only supports tag
// numbers less than 31 (and thus single-byte tags).
unsigned tag = ((unsigned)tag_byte & 0xe0) << CBS_ASN1_TAG_SHIFT;
unsigned tag_number = tag_byte & 0x1f;
if (tag_number == 0x1f) {
uint64_t v;
if (!parse_base128_integer(cbs, &v) ||
// Check the tag number is within our supported bounds.
v > CBS_ASN1_TAG_NUMBER_MASK ||
// Small tag numbers should have used low tag number form.
v < 0x1f) {
return 0;
}
tag_number = (unsigned)v;
}
tag |= tag_number;
*out = tag;
return 1;
}
static int cbs_get_any_asn1_element(CBS *cbs, CBS *out, unsigned *out_tag,
size_t *out_header_len, int ber_ok) {
CBS header = *cbs;
CBS throwaway;
if (out == NULL) {
out = &throwaway;
}
unsigned tag;
if (!parse_asn1_tag(&header, &tag)) {
return 0;
}
if (out_tag != NULL) {
*out_tag = tag;
}
uint8_t length_byte;
if (!CBS_get_u8(&header, &length_byte)) {
return 0;
}
size_t header_len = CBS_len(cbs) - CBS_len(&header);
size_t len;
// The format for the length encoding is specified in ITU-T X.690 section
// 8.1.3.
if ((length_byte & 0x80) == 0) {
// Short form length.
len = ((size_t) length_byte) + header_len;
if (out_header_len != NULL) {
*out_header_len = header_len;
}
} else {
// The high bit indicate that this is the long form, while the next 7 bits
// encode the number of subsequent octets used to encode the length (ITU-T
// X.690 clause 8.1.3.5.b).
const size_t num_bytes = length_byte & 0x7f;
uint32_t len32;
if (ber_ok && (tag & CBS_ASN1_CONSTRUCTED) != 0 && num_bytes == 0) {
// indefinite length
if (out_header_len != NULL) {
*out_header_len = header_len;
}
return CBS_get_bytes(cbs, out, header_len);
}
// ITU-T X.690 clause 8.1.3.5.c specifies that the value 0xff shall not be
// used as the first byte of the length. If this parser encounters that
// value, num_bytes will be parsed as 127, which will fail the check below.
if (num_bytes == 0 || num_bytes > 4) {
return 0;
}
if (!cbs_get_u(&header, &len32, num_bytes)) {
return 0;
}
// ITU-T X.690 section 10.1 (DER length forms) requires encoding the length
// with the minimum number of octets.
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 + header_len + num_bytes < len) {
// Overflow.
return 0;
}
len += header_len + num_bytes;
if (out_header_len != NULL) {
*out_header_len = header_len + num_bytes;
}
}
return CBS_get_bytes(cbs, out, len);
}
int CBS_get_any_asn1(CBS *cbs, CBS *out, unsigned *out_tag) {
size_t header_len;
if (!CBS_get_any_asn1_element(cbs, out, out_tag, &header_len)) {
return 0;
}
if (!CBS_skip(out, header_len)) {
assert(0);
return 0;
}
return 1;
}
int CBS_get_any_asn1_element(CBS *cbs, CBS *out, unsigned *out_tag,
size_t *out_header_len) {
return cbs_get_any_asn1_element(cbs, out, out_tag, out_header_len,
0 /* DER only */);
}
int CBS_get_any_ber_asn1_element(CBS *cbs, CBS *out, unsigned *out_tag,
size_t *out_header_len) {
return cbs_get_any_asn1_element(cbs, out, out_tag, out_header_len,
1 /* BER allowed */);
}
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) {
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_peek_asn1_tag(const CBS *cbs, unsigned tag_value) {
if (CBS_len(cbs) < 1) {
return 0;
}
CBS copy = *cbs;
unsigned actual_tag;
return parse_asn1_tag(©, &actual_tag) && tag_value == actual_tag;
}
int CBS_get_asn1_uint64(CBS *cbs, uint64_t *out) {
CBS bytes;
if (!CBS_get_asn1(cbs, &bytes, CBS_ASN1_INTEGER)) {
return 0;
}
*out = 0;
const uint8_t *data = CBS_data(&bytes);
size_t len = CBS_len(&bytes);
if (len == 0) {
// An INTEGER is encoded with at least one octet.
return 0;
}
if ((data[0] & 0x80) != 0) {
// Negative number.
return 0;
}
if (data[0] == 0 && len > 1 && (data[1] & 0x80) == 0) {
// Extra leading zeros.
return 0;
}
for (size_t 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;
}
int CBS_get_asn1_bool(CBS *cbs, int *out) {
CBS bytes;
if (!CBS_get_asn1(cbs, &bytes, CBS_ASN1_BOOLEAN) ||
CBS_len(&bytes) != 1) {
return 0;
}
const uint8_t value = *CBS_data(&bytes);
if (value != 0 && value != 0xff) {
return 0;
}
*out = !!value;
return 1;
}
int CBS_get_optional_asn1(CBS *cbs, CBS *out, int *out_present, unsigned tag) {
int present = 0;
if (CBS_peek_asn1_tag(cbs, tag)) {
if (!CBS_get_asn1(cbs, out, tag)) {
return 0;
}
present = 1;
}
if (out_present != NULL) {
*out_present = present;
}
return 1;
}
int CBS_get_optional_asn1_octet_string(CBS *cbs, CBS *out, int *out_present,
unsigned tag) {
CBS child;
int present;
if (!CBS_get_optional_asn1(cbs, &child, &present, tag)) {
return 0;
}
if (present) {
if (!CBS_get_asn1(&child, out, CBS_ASN1_OCTETSTRING) ||
CBS_len(&child) != 0) {
return 0;
}
} else {
CBS_init(out, NULL, 0);
}
if (out_present) {
*out_present = present;
}
return 1;
}
int CBS_get_optional_asn1_uint64(CBS *cbs, uint64_t *out, unsigned tag,
uint64_t default_value) {
CBS child;
int present;
if (!CBS_get_optional_asn1(cbs, &child, &present, tag)) {
return 0;
}
if (present) {
if (!CBS_get_asn1_uint64(&child, out) ||
CBS_len(&child) != 0) {
return 0;
}
} else {
*out = default_value;
}
return 1;
}
int CBS_get_optional_asn1_bool(CBS *cbs, int *out, unsigned tag,
int default_value) {
CBS child, child2;
int present;
if (!CBS_get_optional_asn1(cbs, &child, &present, tag)) {
return 0;
}
if (present) {
uint8_t boolean;
if (!CBS_get_asn1(&child, &child2, CBS_ASN1_BOOLEAN) ||
CBS_len(&child2) != 1 ||
CBS_len(&child) != 0) {
return 0;
}
boolean = CBS_data(&child2)[0];
if (boolean == 0) {
*out = 0;
} else if (boolean == 0xff) {
*out = 1;
} else {
return 0;
}
} else {
*out = default_value;
}
return 1;
}
int CBS_is_valid_asn1_bitstring(const CBS *cbs) {
CBS in = *cbs;
uint8_t num_unused_bits;
if (!CBS_get_u8(&in, &num_unused_bits) ||
num_unused_bits > 7) {
return 0;
}
if (num_unused_bits == 0) {
return 1;
}
// All num_unused_bits bits must exist and be zeros.
uint8_t last;
if (!CBS_get_last_u8(&in, &last) ||
(last & ((1 << num_unused_bits) - 1)) != 0) {
return 0;
}
return 1;
}
int CBS_asn1_bitstring_has_bit(const CBS *cbs, unsigned bit) {
if (!CBS_is_valid_asn1_bitstring(cbs)) {
return 0;
}
const unsigned byte_num = (bit >> 3) + 1;
const unsigned bit_num = 7 - (bit & 7);
// Unused bits are zero, and this function does not distinguish between
// missing and unset bits. Thus it is sufficient to do a byte-level length
// check.
return byte_num < CBS_len(cbs) &&
(CBS_data(cbs)[byte_num] & (1 << bit_num)) != 0;
}
static int add_decimal(CBB *out, uint64_t v) {
char buf[DECIMAL_SIZE(uint64_t) + 1];
BIO_snprintf(buf, sizeof(buf), "%" PRIu64, v);
return CBB_add_bytes(out, (const uint8_t *)buf, strlen(buf));
}
char *CBS_asn1_oid_to_text(const CBS *cbs) {
CBB cbb;
if (!CBB_init(&cbb, 32)) {
goto err;
}
CBS copy = *cbs;
// The first component is 40 * value1 + value2, where value1 is 0, 1, or 2.
uint64_t v;
if (!parse_base128_integer(©, &v)) {
goto err;
}
if (v >= 80) {
if (!CBB_add_bytes(&cbb, (const uint8_t *)"2.", 2) ||
!add_decimal(&cbb, v - 80)) {
goto err;
}
} else if (!add_decimal(&cbb, v / 40) ||
!CBB_add_u8(&cbb, '.') ||
!add_decimal(&cbb, v % 40)) {
goto err;
}
while (CBS_len(©) != 0) {
if (!parse_base128_integer(©, &v) ||
!CBB_add_u8(&cbb, '.') ||
!add_decimal(&cbb, v)) {
goto err;
}
}
uint8_t *txt;
size_t txt_len;
if (!CBB_add_u8(&cbb, '\0') ||
!CBB_finish(&cbb, &txt, &txt_len)) {
goto err;
}
return (char *)txt;
err:
CBB_cleanup(&cbb);
return NULL;
}