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https://github.com/RIOT-OS/RIOT.git
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4b8881abb4
Reordered struct members to not waste memory due to padding.
Before:
``` C
typedef struct {
uint8_t src_l2addr_len;
uint8_t dst_l2addr_len;
kernel_pid_t if_pid; // <-- 16 bit, is aligned to 16 bit
uint8_t flags;
uint8_t __padding_byte; // <-- Inserted to fulfill padding requirements
int16_t rssi; // <-- 16 bit, is NOT aligned to 16 bit
uint8_t lqi;
uint8_t __padding_byte2;// <-- Inserted to fulfill padding requirements
} gnrc_netif_hdr_t;
```
Now:
``` C
typedef struct {
uint8_t src_l2addr_len;
uint8_t dst_l2addr_len;
kernel_pid_t if_pid; // <-- 16 bit, is aligned to 16 bit
uint8_t flags;
uint8_t lqi;
int16_t rssi; // <-- 16 bit, is aligned to 16 bit
} gnrc_netif_hdr_t;
```
When build for the `bluepill` board, the new layout reduces the size by 2 bytes.
247 lines
7.5 KiB
C
247 lines
7.5 KiB
C
/*
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* Copyright (C) 2015 Freie Universität Berlin
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*
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* This file is subject to the terms and conditions of the GNU Lesser
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* General Public License v2.1. See the file LICENSE in the top level
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* directory for more details.
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*/
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/**
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* @defgroup net_gnrc_netif_hdr Generic network interface header
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* @ingroup net_gnrc_netif
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* @{
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*
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* @file
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* @brief Generic network interface header
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*
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* @author Hauke Petersen <hauke.petersen@fu-berlin.de>
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* @author Martine Lenders <mlenders@inf.fu-berlin.de>
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*/
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#ifndef NET_GNRC_NETIF_HDR_H
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#define NET_GNRC_NETIF_HDR_H
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#include <string.h>
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#include <stdint.h>
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#include "net/gnrc/pkt.h"
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#include "net/gnrc/pktbuf.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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/**
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* @brief Maximum length of the l2 addresses of the generic interface header
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* in bytes.
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*/
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#define GNRC_NETIF_HDR_L2ADDR_MAX_LEN (8)
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/**
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* @brief Maximum length of the string representatiom of l2 addresses of the
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* generic interface header in bytes.
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*/
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#define GNRC_NETIF_HDR_L2ADDR_PRINT_LEN (GNRC_NETIF_HDR_L2ADDR_MAX_LEN * 3)
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/**
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* @{
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* @name Flags for the gnrc_netif_hdr_t
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*/
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/**
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* @brief Send packet broadcast.
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*
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* @details Packets with this flag set must be send broadcast.
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* gnrc_netif_hdr_t::dst_l2addr_len and any appended destination
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* address must be ignored.
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* If the link layer does not support broadcast the packet must be
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* dropped silently.
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*/
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#define GNRC_NETIF_HDR_FLAGS_BROADCAST (0x80)
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/**
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* @brief Send packet multicast.
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*
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* @details Packets with this flag set must be send multicast.
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* gnrc_netif_hdr_t::dst_l2addr_len and any appended destination
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* address must be ignored.
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* The context for the multicast address must be derived from the
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* network layer destination address.
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* If the link layer does not support multicast it should interpret
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* this flag the same way it does @ref GNRC_NETIF_HDR_FLAGS_BROADCAST.
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*/
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#define GNRC_NETIF_HDR_FLAGS_MULTICAST (0x40)
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/**
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* @}
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*/
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/**
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* @brief Generic network interface header
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*
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* The link layer addresses included in this header are put in memory directly
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* following this struct.
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*/
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typedef struct {
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uint8_t src_l2addr_len; /**< length of l2 source address in byte */
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uint8_t dst_l2addr_len; /**< length of l2 destination address in byte */
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kernel_pid_t if_pid; /**< PID of network interface */
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uint8_t flags; /**< flags as defined above */
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uint8_t lqi; /**< lqi of received packet (optional) */
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int16_t rssi; /**< rssi of received packet in dBm (optional) */
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} gnrc_netif_hdr_t;
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/**
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* @brief Initialize the given generic network interface header
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*
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* @param[in] hdr header to initialize
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* @param[in] src_l2addr_len link layer source address length
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* @param[in] dst_l2addr_len link layer destination address length
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*/
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static inline void gnrc_netif_hdr_init(gnrc_netif_hdr_t *hdr, uint8_t src_l2addr_len,
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uint8_t dst_l2addr_len)
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{
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hdr->src_l2addr_len = src_l2addr_len;
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hdr->dst_l2addr_len = dst_l2addr_len;
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hdr->if_pid = KERNEL_PID_UNDEF;
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hdr->rssi = 0;
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hdr->lqi = 0;
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hdr->flags = 0;
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}
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/**
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* @brief Get the size of the given generic network interface header
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*
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* @param[in] hdr header to get the size of
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*
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* @return the size of the given header, including link layer
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* addresses
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*/
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static inline size_t gnrc_netif_hdr_sizeof(gnrc_netif_hdr_t *hdr)
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{
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return sizeof(gnrc_netif_hdr_t) + hdr->src_l2addr_len + hdr->dst_l2addr_len;
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}
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/**
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* @brief Get the source address from the given header
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*
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* @param[in] hdr header to read from
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*
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* @return pointer to source address on success
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* @return NULL on error
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*/
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static inline uint8_t *gnrc_netif_hdr_get_src_addr(gnrc_netif_hdr_t *hdr)
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{
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return ((uint8_t *)(hdr + 1));
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}
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/**
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* @brief Set the source address in the given header
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*
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* @param[in] hdr header to write to
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* @param[in] addr new source address
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* @param[in] addr_len *addr* length
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*/
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static inline void gnrc_netif_hdr_set_src_addr(gnrc_netif_hdr_t *hdr, uint8_t *addr,
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uint8_t addr_len)
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{
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if (addr_len != hdr->src_l2addr_len) {
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return;
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}
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memcpy(((uint8_t *)(hdr + 1)), addr, addr_len);
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}
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/**
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* @brief Get the destination address from the given header
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*
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* @param[in] hdr header to read from
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*
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* @return pointer to destination address on success
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* @return NULL on error
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*/
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static inline uint8_t *gnrc_netif_hdr_get_dst_addr(gnrc_netif_hdr_t *hdr)
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{
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return (((uint8_t *)(hdr + 1)) + hdr->src_l2addr_len);
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}
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/**
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* @brief Set the destination address in the given header
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*
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* @param[in] hdr header to write to
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* @param[in] addr new destination address
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* @param[in] addr_len *addr* length
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*/
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static inline void gnrc_netif_hdr_set_dst_addr(gnrc_netif_hdr_t *hdr, uint8_t *addr,
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uint8_t addr_len)
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{
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if (addr_len != hdr->dst_l2addr_len) {
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return;
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}
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memcpy(((uint8_t *)(hdr + 1)) + hdr->src_l2addr_len, addr, addr_len);
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}
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/**
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* @brief Builds a generic network interface header for sending and
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* adds it to the packet buffer.
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*
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* @param[in] src Source address for the header. Can be NULL if not
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* known or required.
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* @param[in] src_len Length of @p src. Can be 0 if not known or required.
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* @param[in] dst Destination address for the header. Can be NULL if not
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* known or required.
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* @param[in] dst_len Length of @p dst. Can be 0 if not known or required.
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*
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* @return The generic network layer header on success.
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* @return NULL on error.
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*/
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gnrc_pktsnip_t *gnrc_netif_hdr_build(uint8_t *src, uint8_t src_len, uint8_t *dst, uint8_t dst_len);
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/**
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* @brief Outputs a generic interface header to stdout.
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*
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* @param[in] hdr A generic interface header.
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*/
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void gnrc_netif_hdr_print(gnrc_netif_hdr_t *hdr);
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/**
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* @brief Fetch the netif header flags of a gnrc packet
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*
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* @param[in] pkt gnrc packet from whom to fetch
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*
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* @return netif header flags of @p pkt
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* @return 0, if no header is present
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*/
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uint8_t gnrc_netif_hdr_get_flag(gnrc_pktsnip_t* pkt);
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/**
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* @brief Extract the destination address out of a gnrc packet
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*
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* @param[in] pkt gnrc packet from whom to extract
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* @param[out] pointer_to_addr pointer to address will be stored here
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*
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* @return length of destination address
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* @return -ENOENT, if no netif header is presented in @p pkt or if no
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* destination address field presented in netif header.
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*/
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int gnrc_netif_hdr_get_dstaddr(gnrc_pktsnip_t* pkt, uint8_t** pointer_to_addr);
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/**
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* @brief Extract the source address out of a gnrc packet
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*
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* @param[in] pkt gnrc packet from whom to extract
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* @param[out] pointer_to_addr pointer to address will be stored here
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*
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* @return length of source address
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* @return -ENOENT, if no netif header is presented in @p pkt or if no
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* source address field presented in netif header.
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*/
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int gnrc_netif_hdr_get_srcaddr(gnrc_pktsnip_t* pkt, uint8_t** pointer_to_addr);
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#ifdef __cplusplus
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}
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#endif
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#endif /* NET_GNRC_NETIF_HDR_H */
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/** @} */
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