/src/gnutls/lib/mbuffers.h

Source
/*
 * Copyright (C) 2009-2012 Free Software Foundation, Inc.
 *
 * Author: Jonathan Bastien-Filiatrault
 *
 * This file is part of GNUTLS.
 *
 * The GNUTLS library 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/>
 *
 */

#ifndef GNUTLS_LIB_MBUFFERS_H
#define GNUTLS_LIB_MBUFFERS_H

#include "gnutls_int.h"
#include "errors.h"
#include <assert.h>

void _mbuffer_head_init(mbuffer_head_st *buf);
void _mbuffer_head_clear(mbuffer_head_st *buf);
void _mbuffer_enqueue(mbuffer_head_st *buf, mbuffer_st *bufel);
mbuffer_st *_mbuffer_dequeue(mbuffer_head_st *buf, mbuffer_st *bufel);
int _mbuffer_head_remove_bytes(mbuffer_head_st *buf, size_t bytes);
mbuffer_st *_mbuffer_alloc(size_t maximum_size);
int _mbuffer_linearize(mbuffer_head_st *buf);

mbuffer_st *_mbuffer_head_get_first(mbuffer_head_st *buf, gnutls_datum_t *msg);
mbuffer_st *_mbuffer_head_get_next(mbuffer_st *cur, gnutls_datum_t *msg);

void _mbuffer_head_push_first(mbuffer_head_st *buf, mbuffer_st *bufel);

mbuffer_st *_mbuffer_head_pop_first(mbuffer_head_st *buf);

/* This is dangerous since it will replace bufel with a new
 * one.
 */
int _mbuffer_append_data(mbuffer_st *bufel, void *newdata, size_t newdata_size);

/* For "user" use. One can have buffer data and header.
 */

inline static void *_mbuffer_get_uhead_ptr(mbuffer_st *bufel)
{
  return bufel->msg.data + bufel->mark;
}

inline static void *_mbuffer_get_udata_ptr(mbuffer_st *bufel)
{
  return bufel->msg.data + bufel->uhead_mark + bufel->mark;
}

inline static void _mbuffer_set_udata_size(mbuffer_st *bufel, size_t size)
{
  bufel->msg.size = size + bufel->uhead_mark + bufel->mark;
}

inline static void _mbuffer_set_udata(mbuffer_st *bufel, void *data,
              size_t data_size)
{
  memcpy(_mbuffer_get_udata_ptr(bufel), data, data_size);
  _mbuffer_set_udata_size(bufel, data_size);
}

inline static size_t _mbuffer_get_udata_size(mbuffer_st *bufel)
{
  return bufel->msg.size - bufel->uhead_mark - bufel->mark;
}

/* discards size bytes from the begging of the buffer */
inline static void _mbuffer_consume(mbuffer_head_st *buf, mbuffer_st *bufel,
            size_t size)
{
  bufel->uhead_mark = 0;
  if (bufel->mark + size < bufel->msg.size)
    bufel->mark += size;
  else
    bufel->mark = bufel->msg.size;

  buf->byte_length -= size;
}

inline static size_t _mbuffer_get_uhead_size(mbuffer_st *bufel)
{
  return bufel->uhead_mark;
}

inline static void _mbuffer_set_uhead_size(mbuffer_st *bufel, size_t size)
{
  bufel->uhead_mark = size;
}

inline static void _mbuffer_init(mbuffer_st *bufel, size_t max)
{
  memset(bufel, 0, sizeof(*bufel));
  bufel->maximum_size = max;

  /* payload points after the mbuffer_st structure */
  bufel->msg.data = (uint8_t *)bufel + sizeof(mbuffer_st);
}

/* Helper functions to utilize a gnutls_buffer_st in order
 * to generate a gnutls_mbuffer_st, without multiple allocations.
 */
inline static int _gnutls_buffer_init_mbuffer(gnutls_buffer_st *buf,
                size_t header_size)
{
  int ret;
  mbuffer_st *bufel;

  _gnutls_buffer_init(buf);

  ret = _gnutls_buffer_resize(buf, sizeof(mbuffer_st) + header_size);
  if (ret < 0)
    return gnutls_assert_val(ret);

  /* we store the uhead size on the uninitialized bufel, only to read
   * it back on _gnutls_buffer_to_mbuffer(). */
  bufel = (void *)buf->data;
  _mbuffer_set_uhead_size(bufel, header_size);

  buf->length = sizeof(mbuffer_st) + header_size;

  return 0;
}

#define _gnutls_buffer_init_handshake_mbuffer(b) \
  _gnutls_buffer_init_mbuffer(b, HANDSHAKE_HEADER_SIZE(session))

/* Cannot fail */
inline static mbuffer_st *_gnutls_buffer_to_mbuffer(gnutls_buffer_st *buf)
{
  mbuffer_st *bufel;
  unsigned header_size;

  bufel = (void *)buf->data;

  header_size = _mbuffer_get_uhead_size(bufel);
  assert(buf->length >= sizeof(mbuffer_st) + header_size);

  _mbuffer_init(bufel, buf->length - sizeof(mbuffer_st));

  _mbuffer_set_udata_size(bufel, buf->length - sizeof(mbuffer_st));
  _mbuffer_set_uhead_size(bufel, header_size);

  _gnutls_buffer_init(buf); /* avoid double frees */

  return bufel;
}

inline static mbuffer_st *_gnutls_handshake_alloc(gnutls_session_t session,
              size_t maximum)
{
  mbuffer_st *bufel =
    _mbuffer_alloc(HANDSHAKE_HEADER_SIZE(session) + maximum);

  if (!bufel)
    return NULL;

  _mbuffer_set_uhead_size(bufel, HANDSHAKE_HEADER_SIZE(session));
  _mbuffer_set_udata_size(bufel, maximum);

  return bufel;
}

/* Free a segment, if the pointer is not NULL
 *
 * We take a ** to detect and fix double free bugs (the dangling
 * pointer case). It also makes sure the pointer has a known value
 * after freeing.
 */
inline static void _mbuffer_xfree(mbuffer_st **bufel)
{
  if (*bufel)
    gnutls_free(*bufel);

  *bufel = NULL;
}

#ifdef ENABLE_ALIGN16
mbuffer_st *_mbuffer_alloc_align16(size_t maximum_size, unsigned align_pos);
int _mbuffer_linearize_align16(mbuffer_head_st *buf, unsigned align_pos);
#else
#define _mbuffer_alloc_align16(x, y) _mbuffer_alloc(x)
#define _mbuffer_linearize_align16(x, y) _mbuffer_linearize(x)
#endif

#endif /* GNUTLS_LIB_MBUFFERS_H */

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Created: 2026-05-16 06:52