mirror of
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168 lines
5.2 KiB
C
168 lines
5.2 KiB
C
/*
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* Copyright (c) 2010, Swedish Institute of Computer Science.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the Institute nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* This file is part of the Contiki operating system.
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*
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*/
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/**
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* \file
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* Creates and parses the ContikiMAC header.
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* \author
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* Konrad Krentz <konrad.krentz@gmail.com>
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*/
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#include "net/mac/contikimac/contikimac-framer.h"
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#include "net/packetbuf.h"
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#include "net/netstack.h"
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#include <string.h>
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#define CONTIKIMAC_ID 0x00
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/* SHORTEST_PACKET_SIZE is the shortest packet that ContikiMAC
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allows. Packets have to be a certain size to be able to be detected
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by two consecutive CCA checks, and here is where we define this
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shortest size.
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Padded packets will have the wrong ipv6 checksum unless CONTIKIMAC_HEADER
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is used (on both sides) and the receiver will ignore them.
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With no header, reduce to transmit a proper multicast RPL DIS. */
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#ifdef CONTIKIMAC_FRAMER_CONF_SHORTEST_PACKET_SIZE
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#define SHORTEST_PACKET_SIZE CONTIKIMAC_FRAMER_CONF_SHORTEST_PACKET_SIZE
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#else /* CONTIKIMAC_FRAMER_CONF_SHORTEST_PACKET_SIZE */
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#define SHORTEST_PACKET_SIZE 43
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#endif /* CONTIKIMAC_FRAMER_CONF_SHORTEST_PACKET_SIZE */
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#ifdef CONTIKIMAC_FRAMER_CONF_DECORATED_FRAMER
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#define DECORATED_FRAMER CONTIKIMAC_FRAMER_CONF_DECORATED_FRAMER
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#else /* CONTIKIMAC_FRAMER_CONF_DECORATED_FRAMER */
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#define DECORATED_FRAMER framer_802154
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#endif /* CONTIKIMAC_FRAMER_CONF_DECORATED_FRAMER */
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extern const struct framer DECORATED_FRAMER;
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#define DEBUG 0
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#if DEBUG
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#include <stdio.h>
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#define PRINTF(...) printf(__VA_ARGS__)
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#else
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#define PRINTF(...)
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#endif
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static void pad(void);
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/* 2-byte header for recovering padded packets.
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Wireshark will not understand such packets at present. */
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struct hdr {
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uint8_t id;
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uint8_t len;
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};
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/*---------------------------------------------------------------------------*/
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static int
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hdr_length(void)
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{
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return DECORATED_FRAMER.length() + sizeof(struct hdr);
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}
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/*---------------------------------------------------------------------------*/
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static int
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create(void)
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{
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struct hdr *chdr;
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int hdr_len;
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if(packetbuf_hdralloc(sizeof(struct hdr)) == 0) {
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PRINTF("contikimac-framer: too large header\n");
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return FRAMER_FAILED;
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}
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chdr = packetbuf_hdrptr();
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chdr->id = CONTIKIMAC_ID;
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chdr->len = packetbuf_datalen();
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pad();
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hdr_len = DECORATED_FRAMER.create();
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if(hdr_len < 0) {
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PRINTF("contikimac-framer: decorated framer failed\n");
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return FRAMER_FAILED;
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}
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packetbuf_compact();
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return hdr_len + sizeof(struct hdr);
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}
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/*---------------------------------------------------------------------------*/
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static void
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pad(void)
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{
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int transmit_len;
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uint8_t *ptr;
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uint8_t zeroes_count;
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transmit_len = packetbuf_totlen() + hdr_length();
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if(transmit_len < SHORTEST_PACKET_SIZE) {
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/* Padding required */
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zeroes_count = SHORTEST_PACKET_SIZE - transmit_len;
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ptr = packetbuf_dataptr();
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memset(ptr + packetbuf_datalen(), 0, zeroes_count);
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packetbuf_set_datalen(packetbuf_datalen() + zeroes_count);
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}
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}
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/*---------------------------------------------------------------------------*/
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static int
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parse(void)
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{
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int hdr_len;
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struct hdr *chdr;
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hdr_len = DECORATED_FRAMER.parse();
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if(hdr_len < 0) {
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return FRAMER_FAILED;
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}
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chdr = packetbuf_dataptr();
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if(chdr->id != CONTIKIMAC_ID) {
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PRINTF("contikimac-framer: CONTIKIMAC_ID is missing\n");
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return FRAMER_FAILED;
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}
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if(!packetbuf_hdrreduce(sizeof(struct hdr))) {
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PRINTF("contikimac-framer: packetbuf_hdrreduce failed\n");
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return FRAMER_FAILED;
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}
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packetbuf_set_datalen(chdr->len);
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return hdr_len + sizeof(struct hdr);
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}
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/*---------------------------------------------------------------------------*/
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const struct framer contikimac_framer = {
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hdr_length,
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create,
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parse
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};
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/*---------------------------------------------------------------------------*/
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