pineapple/externals/libressl/crypto/bytestring/bs_cbb.c

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2022-04-24 22:29:35 +02:00
/* $OpenBSD: bs_cbb.c,v 1.3 2022/01/06 14:32:55 jsing Exp $ */
/*
* 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 <stdlib.h>
#include <string.h>
#include "bytestring.h"
#define CBB_INITIAL_SIZE 64
static int
cbb_init(CBB *cbb, uint8_t *buf, size_t cap)
{
struct cbb_buffer_st *base;
if ((base = calloc(1, sizeof(struct cbb_buffer_st))) == NULL)
return 0;
base->buf = buf;
base->len = 0;
base->cap = cap;
base->can_resize = 1;
cbb->base = base;
cbb->is_top_level = 1;
return 1;
}
int
CBB_init(CBB *cbb, size_t initial_capacity)
{
uint8_t *buf = NULL;
memset(cbb, 0, sizeof(*cbb));
if (initial_capacity == 0)
initial_capacity = CBB_INITIAL_SIZE;
if ((buf = calloc(1, initial_capacity)) == NULL)
return 0;
if (!cbb_init(cbb, buf, initial_capacity)) {
free(buf);
return 0;
}
return 1;
}
int
CBB_init_fixed(CBB *cbb, uint8_t *buf, size_t len)
{
memset(cbb, 0, sizeof(*cbb));
if (!cbb_init(cbb, buf, len))
return 0;
cbb->base->can_resize = 0;
return 1;
}
void
CBB_cleanup(CBB *cbb)
{
if (cbb->base) {
if (cbb->base->can_resize)
freezero(cbb->base->buf, cbb->base->cap);
free(cbb->base);
}
cbb->base = NULL;
cbb->child = NULL;
}
static int
cbb_buffer_add(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 */
return 0;
if (newlen > base->cap) {
size_t newcap = base->cap * 2;
uint8_t *newbuf;
if (!base->can_resize)
return 0;
if (newcap < base->cap || newcap < newlen)
newcap = newlen;
newbuf = recallocarray(base->buf, base->cap, newcap, 1);
if (newbuf == NULL)
return 0;
base->buf = newbuf;
base->cap = newcap;
}
if (out)
*out = base->buf + base->len;
base->len = newlen;
return 1;
}
static int
cbb_add_u(CBB *cbb, uint32_t v, size_t len_len)
{
uint8_t *buf;
size_t i;
if (len_len == 0)
return 1;
if (len_len > 4)
return 0;
if (!CBB_flush(cbb) || !cbb_buffer_add(cbb->base, &buf, len_len))
return 0;
for (i = len_len - 1; i < len_len; i--) {
buf[i] = v;
v >>= 8;
}
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 == NULL)
return 0;
if (cbb->child == NULL || cbb->pending_len_len == 0)
return 1;
child_start = cbb->offset + cbb->pending_len_len;
if (!CBB_flush(cbb->child) || child_start < cbb->offset ||
cbb->base->len < child_start)
return 0;
len = cbb->base->len - child_start;
if (cbb->pending_is_asn1) {
/*
* For ASN.1, we assumed that we were using short form which
* only requires a single byte for the length octet.
*
* If it turns out that we need long form, we have to move
* the contents along in order to make space for more length
* octets.
*/
size_t len_len = 1; /* total number of length octets */
uint8_t initial_length_byte;
/* We already wrote 1 byte for the length. */
if (cbb->pending_len_len != 1)
return 0;
/* Check for long form */
if (len > 0xfffffffe)
return 0; /* 0xffffffff is reserved */
else if (len > 0xffffff)
len_len = 5;
else if (len > 0xffff)
len_len = 4;
else if (len > 0xff)
len_len = 3;
else if (len > 0x7f)
len_len = 2;
if (len_len == 1) {
/* For short form, the initial byte is the length. */
initial_length_byte = len;
len = 0;
} else {
/*
* For long form, the initial byte is the number of
* subsequent length octets (plus bit 8 set).
*/
initial_length_byte = 0x80 | (len_len - 1);
/*
* We need to move the contents along in order to make
* space for the long form length octets.
*/
size_t extra_bytes = len_len - 1;
if (!cbb_buffer_add(cbb->base, NULL, extra_bytes))
return 0;
memmove(cbb->base->buf + child_start + extra_bytes,
cbb->base->buf + child_start, len);
}
cbb->base->buf[cbb->offset++] = initial_length_byte;
cbb->pending_len_len = len_len - 1;
}
for (i = cbb->pending_len_len - 1; i < cbb->pending_len_len; i--) {
cbb->base->buf[cbb->offset + i] = len;
len >>= 8;
}
if (len != 0)
return 0;
cbb->child->base = NULL;
cbb->child = NULL;
cbb->pending_len_len = 0;
cbb->pending_is_asn1 = 0;
cbb->offset = 0;
return 1;
}
void
CBB_discard_child(CBB *cbb)
{
if (cbb->child == NULL)
return;
cbb->base->len = cbb->offset;
cbb->child->base = NULL;
cbb->child = NULL;
cbb->pending_len_len = 0;
cbb->pending_is_asn1 = 0;
cbb->offset = 0;
}
static int
cbb_add_length_prefixed(CBB *cbb, CBB *out_contents, size_t len_len)
{
uint8_t *prefix_bytes;
if (!CBB_flush(cbb))
return 0;
cbb->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->pending_len_len = len_len;
cbb->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 int tag)
{
if (tag > UINT8_MAX)
return 0;
/* Long form identifier octets are not supported. */
if ((tag & 0x1f) == 0x1f)
return 0;
/* Short-form identifier octet only needs a single byte */
if (!CBB_flush(cbb) || !CBB_add_u8(cbb, tag))
return 0;
/*
* Add 1 byte to cover the short-form length octet case. If it turns
* out we need long-form, it will be extended later.
*/
cbb->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->pending_len_len = 1;
cbb->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;
memset(*out_data, 0, len);
return 1;
}
int
CBB_add_u8(CBB *cbb, size_t value)
{
if (value > UINT8_MAX)
return 0;
return cbb_add_u(cbb, (uint32_t)value, 1);
}
int
CBB_add_u16(CBB *cbb, size_t value)
{
if (value > UINT16_MAX)
return 0;
return cbb_add_u(cbb, (uint32_t)value, 2);
}
int
CBB_add_u24(CBB *cbb, size_t value)
{
if (value > 0xffffffUL)
return 0;
return cbb_add_u(cbb, (uint32_t)value, 3);
}
int
CBB_add_u32(CBB *cbb, size_t value)
{
if (value > 0xffffffffUL)
return 0;
return cbb_add_u(cbb, (uint32_t)value, 4);
}
int
CBB_add_u64(CBB *cbb, uint64_t value)
{
uint32_t a, b;
a = value >> 32;
b = value & 0xffffffff;
if (!CBB_add_u32(cbb, a))
return 0;
return CBB_add_u32(cbb, b);
}
int
CBB_add_asn1_uint64(CBB *cbb, uint64_t value)
{
CBB child;
size_t i;
int started = 0;
if (!CBB_add_asn1(cbb, &child, CBS_ASN1_INTEGER))
return 0;
for (i = 0; i < 8; i++) {
uint8_t byte = (value >> 8 * (7 - i)) & 0xff;
/*
* ASN.1 restriction: first 9 bits cannot be all zeroes or
* all ones. Since this function only encodes unsigned
* integers, the only concerns are not encoding leading
* zeros and adding a padding byte if necessary.
*
* In practice, this means:
* 1) Skip leading octets of all zero bits in the value
* 2) After skipping the leading zero octets, if the next 9
* bits are all ones, add an all zero prefix octet (and
* set the high bit of the prefix octet if negative).
*
* Additionally, for an unsigned value, add an all zero
* prefix if the high bit of the first octet would be one.
*/
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);
}