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- /* 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"
- #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);
- }
-
- static int cbs_get_any_asn1_element(CBS *cbs, CBS *out, unsigned *out_tag,
- size_t *out_header_len, int ber_ok) {
- uint8_t tag, length_byte;
- CBS header = *cbs;
- CBS throwaway;
-
- if (out == NULL) {
- out = &throwaway;
- }
-
- if (!CBS_get_u8(&header, &tag) ||
- !CBS_get_u8(&header, &length_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).
- if ((tag & 0x1f) == 0x1f) {
- return 0;
- }
-
- if (out_tag != NULL) {
- *out_tag = tag;
- }
-
- 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) + 2;
- if (out_header_len != NULL) {
- *out_header_len = 2;
- }
- } 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 = 2;
- }
- return CBS_get_bytes(cbs, out, 2);
- }
-
- // 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 + 2 + num_bytes < len) {
- // Overflow.
- return 0;
- }
- len += 2 + num_bytes;
- if (out_header_len != NULL) {
- *out_header_len = 2 + 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;
- }
- return CBS_data(cbs)[0] == tag_value;
- }
-
- 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_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;
- }
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