616 lines
11 KiB
C
616 lines
11 KiB
C
/* $OpenBSD: bs_cbs.c,v 1.24 2021/12/15 17:36:49 jsing Exp $ */
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/*
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* Copyright (c) 2014, Google Inc.
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*
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* Permission to use, copy, modify, and/or distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
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* SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
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* OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
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* CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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#include <stdlib.h>
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#include <string.h>
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#include "bytestring.h"
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void
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CBS_init(CBS *cbs, const uint8_t *data, size_t len)
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{
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cbs->data = data;
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cbs->initial_len = len;
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cbs->len = len;
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}
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void
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CBS_dup(const CBS *cbs, CBS *out)
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{
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CBS_init(out, CBS_data(cbs), CBS_len(cbs));
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out->initial_len = cbs->initial_len;
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}
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static int
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cbs_get(CBS *cbs, const uint8_t **p, size_t n)
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{
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if (cbs->len < n)
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return 0;
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*p = cbs->data;
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cbs->data += n;
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cbs->len -= n;
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return 1;
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}
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static int
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cbs_peek(CBS *cbs, const uint8_t **p, size_t n)
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{
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if (cbs->len < n)
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return 0;
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*p = cbs->data;
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return 1;
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}
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size_t
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CBS_offset(const CBS *cbs)
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{
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return cbs->initial_len - cbs->len;
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}
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int
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CBS_skip(CBS *cbs, size_t len)
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{
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const uint8_t *dummy;
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return cbs_get(cbs, &dummy, len);
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}
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const uint8_t *
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CBS_data(const CBS *cbs)
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{
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return cbs->data;
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}
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size_t
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CBS_len(const CBS *cbs)
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{
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return cbs->len;
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}
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int
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CBS_stow(const CBS *cbs, uint8_t **out_ptr, size_t *out_len)
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{
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free(*out_ptr);
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*out_ptr = NULL;
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*out_len = 0;
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if (cbs->len == 0)
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return 1;
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if ((*out_ptr = malloc(cbs->len)) == NULL)
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return 0;
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memcpy(*out_ptr, cbs->data, cbs->len);
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*out_len = cbs->len;
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return 1;
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}
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int
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CBS_strdup(const CBS *cbs, char **out_ptr)
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{
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free(*out_ptr);
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*out_ptr = NULL;
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if (CBS_contains_zero_byte(cbs))
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return 0;
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*out_ptr = strndup((const char *)cbs->data, cbs->len);
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return (*out_ptr != NULL);
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}
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int
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CBS_write_bytes(const CBS *cbs, uint8_t *dst, size_t dst_len, size_t *copied)
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{
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if (dst_len < cbs->len)
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return 0;
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memmove(dst, cbs->data, cbs->len);
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if (copied != NULL)
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*copied = cbs->len;
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return 1;
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}
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int
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CBS_contains_zero_byte(const CBS *cbs)
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{
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return memchr(cbs->data, 0, cbs->len) != NULL;
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}
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int
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CBS_mem_equal(const CBS *cbs, const uint8_t *data, size_t len)
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{
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if (len != cbs->len)
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return 0;
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return timingsafe_memcmp(cbs->data, data, len) == 0;
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}
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static int
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cbs_get_u(CBS *cbs, uint32_t *out, size_t len)
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{
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uint32_t result = 0;
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size_t i;
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const uint8_t *data;
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if (len < 1 || len > 4)
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return 0;
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if (!cbs_get(cbs, &data, len))
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return 0;
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for (i = 0; i < len; i++) {
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result <<= 8;
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result |= data[i];
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}
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*out = result;
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return 1;
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}
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int
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CBS_get_u8(CBS *cbs, uint8_t *out)
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{
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const uint8_t *v;
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if (!cbs_get(cbs, &v, 1))
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return 0;
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*out = *v;
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return 1;
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}
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int
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CBS_get_u16(CBS *cbs, uint16_t *out)
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{
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uint32_t v;
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if (!cbs_get_u(cbs, &v, 2))
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return 0;
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*out = v;
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return 1;
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}
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int
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CBS_get_u24(CBS *cbs, uint32_t *out)
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{
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return cbs_get_u(cbs, out, 3);
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}
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int
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CBS_get_u32(CBS *cbs, uint32_t *out)
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{
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return cbs_get_u(cbs, out, 4);
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}
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int
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CBS_get_u64(CBS *cbs, uint64_t *out)
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{
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uint32_t a, b;
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if (cbs->len < 8)
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return 0;
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if (!CBS_get_u32(cbs, &a))
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return 0;
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if (!CBS_get_u32(cbs, &b))
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return 0;
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*out = (uint64_t)a << 32 | b;
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return 1;
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}
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int
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CBS_get_last_u8(CBS *cbs, uint8_t *out)
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{
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if (cbs->len == 0)
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return 0;
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*out = cbs->data[cbs->len - 1];
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cbs->len--;
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return 1;
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}
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int
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CBS_get_bytes(CBS *cbs, CBS *out, size_t len)
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{
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const uint8_t *v;
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if (!cbs_get(cbs, &v, len))
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return 0;
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CBS_init(out, v, len);
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return 1;
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}
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static int
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cbs_get_length_prefixed(CBS *cbs, CBS *out, size_t len_len)
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{
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uint32_t len;
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if (!cbs_get_u(cbs, &len, len_len))
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return 0;
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return CBS_get_bytes(cbs, out, len);
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}
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int
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CBS_get_u8_length_prefixed(CBS *cbs, CBS *out)
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{
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return cbs_get_length_prefixed(cbs, out, 1);
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}
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int
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CBS_get_u16_length_prefixed(CBS *cbs, CBS *out)
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{
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return cbs_get_length_prefixed(cbs, out, 2);
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}
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int
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CBS_get_u24_length_prefixed(CBS *cbs, CBS *out)
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{
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return cbs_get_length_prefixed(cbs, out, 3);
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}
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static int
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cbs_peek_u(CBS *cbs, uint32_t *out, size_t len)
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{
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uint32_t result = 0;
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size_t i;
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const uint8_t *data;
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if (len < 1 || len > 4)
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return 0;
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if (!cbs_peek(cbs, &data, len))
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return 0;
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for (i = 0; i < len; i++) {
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result <<= 8;
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result |= data[i];
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}
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*out = result;
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return 1;
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}
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int
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CBS_peek_u8(CBS *cbs, uint8_t *out)
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{
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const uint8_t *v;
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if (!cbs_peek(cbs, &v, 1))
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return 0;
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*out = *v;
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return 1;
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}
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int
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CBS_peek_u16(CBS *cbs, uint16_t *out)
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{
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uint32_t v;
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if (!cbs_peek_u(cbs, &v, 2))
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return 0;
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*out = v;
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return 1;
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}
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int
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CBS_peek_u24(CBS *cbs, uint32_t *out)
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{
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return cbs_peek_u(cbs, out, 3);
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}
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int
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CBS_peek_u32(CBS *cbs, uint32_t *out)
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{
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return cbs_peek_u(cbs, out, 4);
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}
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int
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CBS_peek_last_u8(CBS *cbs, uint8_t *out)
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{
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if (cbs->len == 0)
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return 0;
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*out = cbs->data[cbs->len - 1];
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return 1;
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}
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int
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CBS_get_any_asn1_element(CBS *cbs, CBS *out, unsigned int *out_tag,
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size_t *out_header_len)
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{
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return cbs_get_any_asn1_element_internal(cbs, out, out_tag,
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out_header_len, 1);
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}
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/*
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* Review X.690 for details on ASN.1 DER encoding.
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*
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* If non-strict mode is enabled, then DER rules are relaxed
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* for indefinite constructs (violates DER but a little closer to BER).
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* Non-strict mode should only be used by bs_ber.c
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*
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* Sections 8, 10 and 11 for DER encoding
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*/
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int
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cbs_get_any_asn1_element_internal(CBS *cbs, CBS *out, unsigned int *out_tag,
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size_t *out_header_len, int strict)
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{
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uint8_t tag, length_byte;
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CBS header = *cbs;
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CBS throwaway;
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size_t len;
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if (out == NULL)
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out = &throwaway;
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/*
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* Get identifier octet and length octet. Only 1 octet for each
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* is a CBS limitation.
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*/
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if (!CBS_get_u8(&header, &tag) || !CBS_get_u8(&header, &length_byte))
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return 0;
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/* CBS limitation: long form tags are not supported. */
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if ((tag & 0x1f) == 0x1f)
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return 0;
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if (out_tag != NULL)
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*out_tag = tag;
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if ((length_byte & 0x80) == 0) {
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/* Short form length. */
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len = ((size_t) length_byte) + 2;
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if (out_header_len != NULL)
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*out_header_len = 2;
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} else {
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/* Long form length. */
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const size_t num_bytes = length_byte & 0x7f;
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uint32_t len32;
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/* ASN.1 reserved value for future extensions */
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if (num_bytes == 0x7f)
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return 0;
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/* Handle indefinite form length */
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if (num_bytes == 0) {
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/* DER encoding doesn't allow for indefinite form. */
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if (strict)
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return 0;
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/* Primitive cannot use indefinite in BER or DER. */
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if ((tag & CBS_ASN1_CONSTRUCTED) == 0)
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return 0;
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/* Constructed, indefinite length allowed in BER. */
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if (out_header_len != NULL)
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*out_header_len = 2;
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return CBS_get_bytes(cbs, out, 2);
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}
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/* CBS limitation. */
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if (num_bytes > 4)
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return 0;
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if (!cbs_get_u(&header, &len32, num_bytes))
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return 0;
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/* DER has a minimum length octet requirement. */
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if (len32 < 128)
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/* Should have used short form instead */
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return 0;
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if ((len32 >> ((num_bytes - 1) * 8)) == 0)
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/* Length should have been at least one byte shorter. */
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return 0;
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len = len32;
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if (len + 2 + num_bytes < len)
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/* Overflow. */
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return 0;
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len += 2 + num_bytes;
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if (out_header_len != NULL)
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*out_header_len = 2 + num_bytes;
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}
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return CBS_get_bytes(cbs, out, len);
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}
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static int
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cbs_get_asn1(CBS *cbs, CBS *out, unsigned int tag_value, int skip_header)
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{
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size_t header_len;
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unsigned int tag;
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CBS throwaway;
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if (out == NULL)
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out = &throwaway;
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if (!CBS_get_any_asn1_element(cbs, out, &tag, &header_len) ||
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tag != tag_value)
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return 0;
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if (skip_header && !CBS_skip(out, header_len))
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return 0;
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return 1;
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}
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int
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CBS_get_asn1(CBS *cbs, CBS *out, unsigned int tag_value)
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{
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return cbs_get_asn1(cbs, out, tag_value, 1 /* skip header */);
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}
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int
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CBS_get_asn1_element(CBS *cbs, CBS *out, unsigned int tag_value)
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{
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return cbs_get_asn1(cbs, out, tag_value, 0 /* include header */);
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}
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int
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CBS_peek_asn1_tag(const CBS *cbs, unsigned int tag_value)
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{
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if (CBS_len(cbs) < 1)
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return 0;
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/*
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* Tag number 31 indicates the start of a long form number.
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* This is valid in ASN.1, but CBS only supports short form.
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*/
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if ((tag_value & 0x1f) == 0x1f)
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return 0;
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return CBS_data(cbs)[0] == tag_value;
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}
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/* Encoding details are in ASN.1: X.690 section 8.3 */
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int
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CBS_get_asn1_uint64(CBS *cbs, uint64_t *out)
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{
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CBS bytes;
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const uint8_t *data;
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size_t i, len;
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if (!CBS_get_asn1(cbs, &bytes, CBS_ASN1_INTEGER))
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return 0;
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*out = 0;
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data = CBS_data(&bytes);
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len = CBS_len(&bytes);
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if (len == 0)
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/* An INTEGER is encoded with at least one content octet. */
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return 0;
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if ((data[0] & 0x80) != 0)
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/* Negative number. */
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return 0;
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if (data[0] == 0 && len > 1 && (data[1] & 0x80) == 0)
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/* Violates smallest encoding rule: excessive leading zeros. */
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return 0;
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for (i = 0; i < len; i++) {
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if ((*out >> 56) != 0)
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/* Too large to represent as a uint64_t. */
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return 0;
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*out <<= 8;
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*out |= data[i];
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}
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return 1;
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}
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int
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CBS_get_optional_asn1(CBS *cbs, CBS *out, int *out_present, unsigned int tag)
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{
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if (CBS_peek_asn1_tag(cbs, tag)) {
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if (!CBS_get_asn1(cbs, out, tag))
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return 0;
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*out_present = 1;
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} else {
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*out_present = 0;
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}
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return 1;
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}
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int
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CBS_get_optional_asn1_octet_string(CBS *cbs, CBS *out, int *out_present,
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unsigned int tag)
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{
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CBS child;
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int present;
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if (!CBS_get_optional_asn1(cbs, &child, &present, tag))
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return 0;
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if (present) {
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if (!CBS_get_asn1(&child, out, CBS_ASN1_OCTETSTRING) ||
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CBS_len(&child) != 0)
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return 0;
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} else {
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CBS_init(out, NULL, 0);
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}
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if (out_present)
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*out_present = present;
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return 1;
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}
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int
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CBS_get_optional_asn1_uint64(CBS *cbs, uint64_t *out, unsigned int tag,
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uint64_t default_value)
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{
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CBS child;
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int present;
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if (!CBS_get_optional_asn1(cbs, &child, &present, tag))
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return 0;
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if (present) {
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if (!CBS_get_asn1_uint64(&child, out) ||
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CBS_len(&child) != 0)
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return 0;
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} else {
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*out = default_value;
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}
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return 1;
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}
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int
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CBS_get_optional_asn1_bool(CBS *cbs, int *out, unsigned int tag,
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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;
|
|
}
|