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/*
* Copyright (C) 2019 Red Hat, Inc.
*
* Author: Daiki Ueno
*
* This file is part of GnuTLS.
*
* The GnuTLS is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License
* as published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>
*
*/
#include "gnutls_int.h"
#include "iov.h"
/**
* _gnutls_iov_iter_init:
* @iter: the iterator
* @iov: the data buffers
* @iov_count: the number of data buffers
* @block_size: block size to iterate
*
* Initialize the iterator.
*
* Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise
* an error code is returned
*/
int
_gnutls_iov_iter_init(struct iov_iter_st *iter,
const giovec_t *iov, size_t iov_count,
size_t block_size)
{
if (unlikely(block_size > MAX_CIPHER_BLOCK_SIZE))
return gnutls_assert_val(GNUTLS_E_INVALID_REQUEST);
iter->iov = iov;
iter->iov_count = iov_count;
iter->iov_index = 0;
iter->iov_offset = 0;
iter->block_size = block_size;
iter->block_offset = 0;
return 0;
}
/**
* _gnutls_iov_iter_next:
* @iter: the iterator
* @data: the return location of extracted data
*
* Retrieve block(s) pointed by @iter and advance it to the next
* position. It returns the number of bytes in @data. At the end of
* iteration, 0 is returned.
*
* If the data stored in @iter is not multiple of the block size, the
* remaining data is stored in the "block" field of @iter with the
* size stored in the "block_offset" field.
*
* Returns: On success, a value greater than or equal to zero is
* returned, otherwise a negative error code is returned
*/
ssize_t
_gnutls_iov_iter_next(struct iov_iter_st *iter, uint8_t **data)
{
while (iter->iov_index < iter->iov_count) {
const giovec_t *iov = &iter->iov[iter->iov_index];
uint8_t *p = iov->iov_base;
size_t len = iov->iov_len;
size_t block_left;
if (!p) {
// skip NULL iov entries, else we run into issues below
iter->iov_index++;
continue;
}
if (unlikely(len < iter->iov_offset))
return gnutls_assert_val(GNUTLS_E_UNEXPECTED_PACKET_LENGTH);
len -= iter->iov_offset;
p += iter->iov_offset;
/* We have at least one full block, return a whole set
* of full blocks immediately. */
if (iter->block_offset == 0 && len >= iter->block_size) {
if ((len % iter->block_size) == 0) {
iter->iov_index++;
iter->iov_offset = 0;
} else {
len -= (len % iter->block_size);
iter->iov_offset += len;
}
/* Return the blocks. */
*data = p;
return len;
}
/* We can complete one full block to return. */
block_left = iter->block_size - iter->block_offset;
if (len >= block_left) {
memcpy(iter->block + iter->block_offset, p, block_left);
if (len == block_left) {
iter->iov_index++;
iter->iov_offset = 0;
} else
iter->iov_offset += block_left;
iter->block_offset = 0;
/* Return the filled block. */
*data = iter->block;
return iter->block_size;
}
/* Not enough data for a full block, store in temp
* memory and continue. */
memcpy(iter->block + iter->block_offset, p, len);
iter->block_offset += len;
iter->iov_index++;
iter->iov_offset = 0;
}
if (iter->block_offset > 0) {
size_t len = iter->block_offset;
/* Return the incomplete block. */
*data = iter->block;
iter->block_offset = 0;
return len;
}
return 0;
}
/**
* _gnutls_iov_iter_sync:
* @iter: the iterator
* @data: data returned by _gnutls_iov_iter_next
* @data_size: size of @data
*
* Flush the content of temp buffer (if any) to the data buffer.
*/
int
_gnutls_iov_iter_sync(struct iov_iter_st *iter, const uint8_t *data,
size_t data_size)
{
size_t iov_index;
size_t iov_offset;
/* We didn't return the cached block. */
if (data != iter->block)
return 0;
iov_index = iter->iov_index;
iov_offset = iter->iov_offset;
/* When syncing a cache block we walk backwards because we only have a
* pointer to were the block ends in the iovec, walking backwards is
* fine as we are always writing a full block, so the whole content
* is written in the right places:
* iovec: |--0--|---1---|--2--|-3-|
* block: |-----------------------|
* 1st write |---|
* 2nd write |-----
* 3rd write |-------
* last write |-----
*/
while (data_size > 0) {
const giovec_t *iov;
uint8_t *p;
size_t to_write;
while (iov_offset == 0) {
if (unlikely(iov_index == 0))
return gnutls_assert_val(GNUTLS_E_INTERNAL_ERROR);
iov_index--;
iov_offset = iter->iov[iov_index].iov_len;
}
iov = &iter->iov[iov_index];
p = iov->iov_base;
to_write = MIN(data_size, iov_offset);
iov_offset -= to_write;
data_size -= to_write;
memcpy(p + iov_offset, &iter->block[data_size], to_write);
}
return 0;
}
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