blob: 2d65be87638bc12f17f7396d8ec64ff7ac4c971f [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/bytestring.h>
#include <assert.h>
#include <string.h>
#include <openssl/mem.h>
void CBB_zero(CBB *cbb) {
memset(cbb, 0, sizeof(CBB));
}
static int cbb_init(CBB *cbb, uint8_t *buf, size_t cap) {
/* This assumes that |cbb| has already been zeroed. */
struct cbb_buffer_st *base;
base = OPENSSL_malloc(sizeof(struct cbb_buffer_st));
if (base == NULL) {
return 0;
}
base->buf = buf;
base->len = 0;
base->cap = cap;
base->can_resize = 1;
base->error = 0;
cbb->base = base;
cbb->is_top_level = 1;
return 1;
}
int CBB_init(CBB *cbb, size_t initial_capacity) {
CBB_zero(cbb);
uint8_t *buf = OPENSSL_malloc(initial_capacity);
if (initial_capacity > 0 && buf == NULL) {
return 0;
}
if (!cbb_init(cbb, buf, initial_capacity)) {
OPENSSL_free(buf);
return 0;
}
return 1;
}
int CBB_init_fixed(CBB *cbb, uint8_t *buf, size_t len) {
CBB_zero(cbb);
if (!cbb_init(cbb, buf, len)) {
return 0;
}
cbb->base->can_resize = 0;
return 1;
}
void CBB_cleanup(CBB *cbb) {
if (cbb->base) {
/* Only top-level |CBB|s are cleaned up. Child |CBB|s are non-owning. They
* are implicitly discarded when the parent is flushed or cleaned up. */
assert(cbb->is_top_level);
if (cbb->base->can_resize) {
OPENSSL_free(cbb->base->buf);
}
OPENSSL_free(cbb->base);
}
cbb->base = NULL;
}
static int cbb_buffer_reserve(struct cbb_buffer_st *base, uint8_t **out,
size_t len) {
size_t newlen;
if (base == NULL) {
return 0;
}
newlen = base->len + len;
if (newlen < base->len) {
/* Overflow */
goto err;
}
if (newlen > base->cap) {
size_t newcap = base->cap * 2;
uint8_t *newbuf;
if (!base->can_resize) {
goto err;
}
if (newcap < base->cap || newcap < newlen) {
newcap = newlen;
}
newbuf = OPENSSL_realloc(base->buf, newcap);
if (newbuf == NULL) {
goto err;
}
base->buf = newbuf;
base->cap = newcap;
}
if (out) {
*out = base->buf + base->len;
}
return 1;
err:
base->error = 1;
return 0;
}
static int cbb_buffer_add(struct cbb_buffer_st *base, uint8_t **out,
size_t len) {
if (!cbb_buffer_reserve(base, out, len)) {
return 0;
}
/* This will not overflow or |cbb_buffer_reserve| would have failed. */
base->len += len;
return 1;
}
static int cbb_buffer_add_u(struct cbb_buffer_st *base, uint32_t v,
size_t len_len) {
if (len_len == 0) {
return 1;
}
uint8_t *buf;
if (!cbb_buffer_add(base, &buf, len_len)) {
return 0;
}
for (size_t i = len_len - 1; i < len_len; i--) {
buf[i] = v;
v >>= 8;
}
if (v != 0) {
base->error = 1;
return 0;
}
return 1;
}
int CBB_finish(CBB *cbb, uint8_t **out_data, size_t *out_len) {
if (!cbb->is_top_level) {
return 0;
}
if (!CBB_flush(cbb)) {
return 0;
}
if (cbb->base->can_resize && (out_data == NULL || out_len == NULL)) {
/* |out_data| and |out_len| can only be NULL if the CBB is fixed. */
return 0;
}
if (out_data != NULL) {
*out_data = cbb->base->buf;
}
if (out_len != NULL) {
*out_len = cbb->base->len;
}
cbb->base->buf = NULL;
CBB_cleanup(cbb);
return 1;
}
/* CBB_flush recurses and then writes out any pending length prefix. The
* current length of the underlying base is taken to be the length of the
* length-prefixed data. */
int CBB_flush(CBB *cbb) {
size_t child_start, i, len;
/* If |cbb->base| has hit an error, the buffer is in an undefined state, so
* fail all following calls. In particular, |cbb->child| may point to invalid
* memory. */
if (cbb->base == NULL || cbb->base->error) {
return 0;
}
if (cbb->child == NULL || cbb->child->pending_len_len == 0) {
return 1;
}
child_start = cbb->child->offset + cbb->child->pending_len_len;
if (!CBB_flush(cbb->child) ||
child_start < cbb->child->offset ||
cbb->base->len < child_start) {
goto err;
}
len = cbb->base->len - child_start;
if (cbb->child->pending_is_asn1) {
/* For ASN.1 we assume that we'll only need a single byte for the length.
* If that turned out to be incorrect, we have to move the contents along
* in order to make space. */
uint8_t len_len;
uint8_t initial_length_byte;
assert (cbb->child->pending_len_len == 1);
if (len > 0xfffffffe) {
/* Too large. */
goto err;
} else if (len > 0xffffff) {
len_len = 5;
initial_length_byte = 0x80 | 4;
} else if (len > 0xffff) {
len_len = 4;
initial_length_byte = 0x80 | 3;
} else if (len > 0xff) {
len_len = 3;
initial_length_byte = 0x80 | 2;
} else if (len > 0x7f) {
len_len = 2;
initial_length_byte = 0x80 | 1;
} else {
len_len = 1;
initial_length_byte = (uint8_t)len;
len = 0;
}
if (len_len != 1) {
/* We need to move the contents along in order to make space. */
size_t extra_bytes = len_len - 1;
if (!cbb_buffer_add(cbb->base, NULL, extra_bytes)) {
goto err;
}
memmove(cbb->base->buf + child_start + extra_bytes,
cbb->base->buf + child_start, len);
}
cbb->base->buf[cbb->child->offset++] = initial_length_byte;
cbb->child->pending_len_len = len_len - 1;
}
for (i = cbb->child->pending_len_len - 1; i < cbb->child->pending_len_len;
i--) {
cbb->base->buf[cbb->child->offset + i] = (uint8_t)len;
len >>= 8;
}
if (len != 0) {
goto err;
}
cbb->child->base = NULL;
cbb->child = NULL;
return 1;
err:
cbb->base->error = 1;
return 0;
}
const uint8_t *CBB_data(const CBB *cbb) {
assert(cbb->child == NULL);
return cbb->base->buf + cbb->offset + cbb->pending_len_len;
}
size_t CBB_len(const CBB *cbb) {
assert(cbb->child == NULL);
assert(cbb->offset + cbb->pending_len_len <= cbb->base->len);
return cbb->base->len - cbb->offset - cbb->pending_len_len;
}
static int cbb_add_length_prefixed(CBB *cbb, CBB *out_contents,
uint8_t len_len) {
uint8_t *prefix_bytes;
if (!CBB_flush(cbb)) {
return 0;
}
size_t offset = cbb->base->len;
if (!cbb_buffer_add(cbb->base, &prefix_bytes, len_len)) {
return 0;
}
memset(prefix_bytes, 0, len_len);
memset(out_contents, 0, sizeof(CBB));
out_contents->base = cbb->base;
cbb->child = out_contents;
cbb->child->offset = offset;
cbb->child->pending_len_len = len_len;
cbb->child->pending_is_asn1 = 0;
return 1;
}
int CBB_add_u8_length_prefixed(CBB *cbb, CBB *out_contents) {
return cbb_add_length_prefixed(cbb, out_contents, 1);
}
int CBB_add_u16_length_prefixed(CBB *cbb, CBB *out_contents) {
return cbb_add_length_prefixed(cbb, out_contents, 2);
}
int CBB_add_u24_length_prefixed(CBB *cbb, CBB *out_contents) {
return cbb_add_length_prefixed(cbb, out_contents, 3);
}
int CBB_add_asn1(CBB *cbb, CBB *out_contents, unsigned tag) {
if (tag > 0xff ||
(tag & 0x1f) == 0x1f) {
/* Long form identifier octets are not supported. Further, all current valid
* tag serializations are 8 bits. */
cbb->base->error = 1;
return 0;
}
if (!CBB_flush(cbb) ||
/* |tag|'s representation matches the DER encoding. */
!CBB_add_u8(cbb, (uint8_t)tag)) {
return 0;
}
size_t offset = cbb->base->len;
if (!CBB_add_u8(cbb, 0)) {
return 0;
}
memset(out_contents, 0, sizeof(CBB));
out_contents->base = cbb->base;
cbb->child = out_contents;
cbb->child->offset = offset;
cbb->child->pending_len_len = 1;
cbb->child->pending_is_asn1 = 1;
return 1;
}
int CBB_add_bytes(CBB *cbb, const uint8_t *data, size_t len) {
uint8_t *dest;
if (!CBB_flush(cbb) ||
!cbb_buffer_add(cbb->base, &dest, len)) {
return 0;
}
memcpy(dest, data, len);
return 1;
}
int CBB_add_space(CBB *cbb, uint8_t **out_data, size_t len) {
if (!CBB_flush(cbb) ||
!cbb_buffer_add(cbb->base, out_data, len)) {
return 0;
}
return 1;
}
int CBB_reserve(CBB *cbb, uint8_t **out_data, size_t len) {
if (!CBB_flush(cbb) ||
!cbb_buffer_reserve(cbb->base, out_data, len)) {
return 0;
}
return 1;
}
int CBB_did_write(CBB *cbb, size_t len) {
size_t newlen = cbb->base->len + len;
if (cbb->child != NULL ||
newlen < cbb->base->len ||
newlen > cbb->base->cap) {
return 0;
}
cbb->base->len = newlen;
return 1;
}
int CBB_add_u8(CBB *cbb, uint8_t value) {
if (!CBB_flush(cbb)) {
return 0;
}
return cbb_buffer_add_u(cbb->base, value, 1);
}
int CBB_add_u16(CBB *cbb, uint16_t value) {
if (!CBB_flush(cbb)) {
return 0;
}
return cbb_buffer_add_u(cbb->base, value, 2);
}
int CBB_add_u24(CBB *cbb, uint32_t value) {
if (!CBB_flush(cbb)) {
return 0;
}
return cbb_buffer_add_u(cbb->base, value, 3);
}
int CBB_add_u32(CBB *cbb, uint32_t value) {
if (!CBB_flush(cbb)) {
return 0;
}
return cbb_buffer_add_u(cbb->base, value, 4);
}
void CBB_discard_child(CBB *cbb) {
if (cbb->child == NULL) {
return;
}
cbb->base->len = cbb->child->offset;
cbb->child->base = NULL;
cbb->child = NULL;
}
int CBB_add_asn1_uint64(CBB *cbb, uint64_t value) {
CBB child;
int started = 0;
if (!CBB_add_asn1(cbb, &child, CBS_ASN1_INTEGER)) {
return 0;
}
for (size_t i = 0; i < 8; i++) {
uint8_t byte = (value >> 8*(7-i)) & 0xff;
if (!started) {
if (byte == 0) {
/* Don't encode leading zeros. */
continue;
}
/* If the high bit is set, add a padding byte to make it
* unsigned. */
if ((byte & 0x80) && !CBB_add_u8(&child, 0)) {
return 0;
}
started = 1;
}
if (!CBB_add_u8(&child, byte)) {
return 0;
}
}
/* 0 is encoded as a single 0, not the empty string. */
if (!started && !CBB_add_u8(&child, 0)) {
return 0;
}
return CBB_flush(cbb);
}