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/*
* Copyright (C) 2014 Martine Lenders <mlenders@inf.fu-berlin.de>
* 2015 Freie Universitรคt Berlin
*
* This file is subject to the terms and conditions of the GNU Lesser
* General Public License v2.1. See the file LICENSE in the top level
* directory for more details.
*/
/**
* @defgroup net_gnrc_pktbuf Packet buffer
* @ingroup net_gnrc
* @brief A global network packet buffer.
*
* @note **WARNING!!** Do not store data structures that are not packed
* (defined with `__attribute__((packed))`) or enforce alignment in
* in any way in here if @ref GNRC_PKTBUF_SIZE > 0. On some RISC architectures
* this *will* lead to alignment problems and can potentially result
* in segmentation/hard faults and other unexpected behaviour.
*
* @{
*
* @file
* @brief Interface definition for the global network buffer. Network devices
* and layers can allocate space for packets here.
*
* @author Martine Lenders <mlenders@inf.fu-berlin.de>
* @author Hauke Petersen <hauke.petersen@fu-berlin.de>
*/
#ifndef GNRC_PKTBUF_H_
#define GNRC_PKTBUF_H_
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>
#include "atomic.h"
#include "cpu_conf.h"
#include "net/gnrc/pkt.h"
#include "net/gnrc/neterr.h"
#include "net/gnrc/nettype.h"
#include "utlist.h"
#ifdef __cplusplus
extern "C" {
#endif
/**
* @def GNRC_PKTBUF_SIZE
* @brief Maximum size of the static packet buffer.
*
* @details The rational here is to have at least space for 4 full-MTU IPv6
* packages (2 incoming, 2 outgoing; 2 * 2 * 1280 B = 5 KiB) +
* Meta-Data (roughly estimated to 1 KiB; might be smaller). If
* @ref GNRC_PKTBUF_SIZE is 0 the packet buffer will use dynamic memory
* management to allocate packets.
*/
#ifndef GNRC_PKTBUF_SIZE
#define GNRC_PKTBUF_SIZE (6144)
#endif /* GNRC_PKTBUF_SIZE */
/**
* @brief Initializes packet buffer module.
*/
void gnrc_pktbuf_init(void);
/**
* @brief Adds a new gnrc_pktsnip_t and its packet to the packet buffer.
*
* @warning **Do not** change the fields of the gnrc_pktsnip_t created by this
* function externally. This will most likely create memory leaks or
* not allowed memory access.
*
* @pre size < GNRC_PKTBUF_SIZE
*
* @param[in] next Next gnrc_pktsnip_t in the packet. Leave NULL if you
* want to create a new packet.
* @param[in] data Data of the new gnrc_pktsnip_t. If @p data is NULL no data
* will be inserted into `result`.
* @param[in] size Length of @p data. If this value is 0 the
* gnrc_pktsnip::data field of the newly created snip will
* be NULL.
* @param[in] type Protocol type of the gnrc_pktsnip_t.
*
* @return Pointer to the packet part that represents the new gnrc_pktsnip_t.
* @return NULL, if no space is left in the packet buffer.
*/
gnrc_pktsnip_t *gnrc_pktbuf_add(gnrc_pktsnip_t *next, void *data, size_t size,
gnrc_nettype_t type);
/**
* @brief Marks the first @p size bytes in a received packet with a new
* packet snip that is appended to the packet.
*
* Graphically this can be represented as follows:
*
* ~~~~~~~~~~~~~~~~~~~
* Before After
* ====== =====
* (next)
* pkt->data result->data <== pkt->data
* v v v
* +--------------------------------+ +----------------+---------------+
* +--------------------------------+ +----------------+---------------+
* \__________pkt->size___________/ \_result->size_/ \__pkt->size__/
* ~~~~~~~~~~~~~~~~~~~
*
* If `size == pkt->size` then the resulting snip will point to NULL in its
* gnrc_pktsnip_t::data field and its gnrc_pktsnip_t::size field will be 0.
*
* @pre @p pkt != NULL && @p size != 0
*
* @param[in] pkt A received packet.
* @param[in] size The size of the new packet snip.
* @param[in] type The type of the new packet snip.
*
* @return The new packet snip in @p pkt on success.
* @return NULL, if pkt == NULL or size == 0 or size > pkt->size or pkt->data == NULL.
* @return NULL, if no space is left in the packet buffer.
*/
gnrc_pktsnip_t *gnrc_pktbuf_mark(gnrc_pktsnip_t *pkt, size_t size, gnrc_nettype_t type);
/**
* @brief Reallocates gnrc_pktsnip_t::data of @p pkt in the packet buffer, without
* changing the content.
*
* @pre `pkt != NULL`
* @pre `(pkt->size > 0) <=> (pkt->data != NULL)`
* @pre gnrc_pktsnip_t::data of @p pkt is in the packet buffer if it is not NULL.
*
* @details If enough memory is available behind it or @p size is smaller than
* the original size of the packet then gnrc_pktsnip_t::data of @p pkt will
* not be moved. Otherwise, it will be moved. If no space is available
* nothing happens.
*
* @param[in] pkt A packet part.
* @param[in] size The size for @p pkt.
*
* @return 0, on success
* @return ENOMEM, if no space is left in the packet buffer.
*/
int gnrc_pktbuf_realloc_data(gnrc_pktsnip_t *pkt, size_t size);
/**
* @brief Increases gnrc_pktsnip_t::users of @p pkt atomically.
*
* @param[in] pkt A packet.
* @param[in] num Number you want to increment gnrc_pktsnip_t::users of @p pkt by.
*/
void gnrc_pktbuf_hold(gnrc_pktsnip_t *pkt, unsigned int num);
/**
* @brief Decreases gnrc_pktsnip_t::users of @p pkt atomically and removes it if it
* reaches 0 and reports a possible error through an error code, if
* @ref net_gnrc_neterr is included.
*
* @pre All snips of @p pkt must be in the packet buffer.
*
* @param[in] pkt A packet.
* @param[in] err An error code.
*/
void gnrc_pktbuf_release_error(gnrc_pktsnip_t *pkt, uint32_t err);
/**
* @brief Decreases gnrc_pktsnip_t::users of @p pkt atomically and removes it if it
* reaches 0 and reports @ref GNRC_NETERR_SUCCESS.
*
* @param[in] pkt A packet.
*/
static inline void gnrc_pktbuf_release(gnrc_pktsnip_t *pkt)
{
gnrc_pktbuf_release_error(pkt, GNRC_NETERR_SUCCESS);
}
/**
* @brief Must be called once before there is a write operation in a thread.
*
* @details This function duplicates a packet in the packet buffer if
* gnrc_pktsnip_t::users of @p pkt > 1.
*
* @note Do *not* call this function in a thread twice on the same packet.
*
* @param[in] pkt The packet you want to write into.
*
* @return The (new) pointer to the pkt.
* @return NULL, if gnrc_pktsnip_t::users of @p pkt > 1 and if there is not
* enough space in the packet buffer.
*/
gnrc_pktsnip_t *gnrc_pktbuf_start_write(gnrc_pktsnip_t *pkt);
/**
* @brief Create a IOVEC representation of the packet pointed to by *pkt*
*
* @pre `(len != NULL)`
*
* @details This function will create a new packet snip in the packet buffer,
* which points to the given *pkt* and contains a IOVEC representation
* of the referenced packet in its data section.
*
* @param[in] pkt Packet to export as IOVEC
* @param[out] len Number of elements in the IOVEC
*
* @return Pointer to the 'IOVEC packet snip'
* @return NULL, if packet is empty of the packet buffer is full
*/
gnrc_pktsnip_t *gnrc_pktbuf_get_iovec(gnrc_pktsnip_t *pkt, size_t *len);
/**
* @brief Deletes a snip from a packet and the packet buffer.
*
* @param[in] pkt A packet.
* @param[in] snip A snip in the packet.
*
* @return The new reference to @p pkt.
*/
gnrc_pktsnip_t *gnrc_pktbuf_remove_snip(gnrc_pktsnip_t *pkt, gnrc_pktsnip_t *snip);
/**
* @brief Replace a snip from a packet and the packet buffer by another snip.
*
* @param[in] pkt A packet
* @param[in] old snip currently in the packet
* @param[in] add snip which will replace old
*
* @return The new reference to @p pkt
*/
gnrc_pktsnip_t *gnrc_pktbuf_replace_snip(gnrc_pktsnip_t *pkt, gnrc_pktsnip_t *old, gnrc_pktsnip_t *add);
/**
* @brief Duplicates pktsnip chain upto (including) a snip with the given type
* as a continuous snip.
*
* Example:
* Input:
* buffer
* +---------------------------+ +------+
* | size = 8 | data +-------->| |
* | type = NETTYPE_IPV6_EXT |------------+ +------+
* +---------------------------+ . .
* | next . .
* v . .
* +---------------------------+ +------+
* | size = 40 | data +----------->| |
* | type = NETTYPE_IPV6 |---------+ +------+
* +---------------------------+ . .
* | next . .
* v
* +---------------------------+ +------+
* | size = 14 | data +-------------->| |
* | type = NETTYPE_NETIF |------+ +------+
* +---------------------------+ . .
*
*
* Output:
* buffer
* +---------------------------+ +------+
* | size = 48 | data +-------->| |
* | type = NETTYPE_IPV6 |------------+ | |
* +---------------------------+ | |
* | +------+
* | . .
* | next . .
* v
* +---------------------------+ +------+
* | size = 14 | data +-------------->| |
* | type = NETTYPE_NETIF |------+ +------+
* +---------------------------+ . .
*
* The original snip is keeped as is except `users` decremented.
*
* @param[in,out] pkt The snip to duplicate.
* @param[in] type The type of snip to stop duplication.
*
* @return The duplicated snip, if succeeded.
* @return NULL, if no space is left in the packet buffer.
*/
gnrc_pktsnip_t *gnrc_pktbuf_duplicate_upto(gnrc_pktsnip_t *pkt, gnrc_nettype_t type);
#ifdef DEVELHELP
/**
* @brief Prints some statistics about the packet buffer to stdout.
*
* @note Only available with DEVELHELP defined.
*
* @details Statistics include maximum number of reserved bytes.
*/
void gnrc_pktbuf_stats(void);
#endif
/* for testing */
#ifdef TEST_SUITES
/**
* @brief Checks if packet buffer is empty
*
* @return true, if packet buffer is empty
* @return false, if packet buffer is not empty
*/
bool gnrc_pktbuf_is_empty(void);
/**
* @brief Checks if the implementation's internal invariants still uphold
*
* @return true, the packet buffer is sane.
* @return false, the packet buffer is insane.
*/
bool gnrc_pktbuf_is_sane(void);
#endif
#ifdef __cplusplus
}
#endif
#endif /* GNRC_PKTBUF_H_ */
/** @} */
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