sicslowpan.c

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/*
 * Copyright (c) 2008, Swedish Institute of Computer Science.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the Institute nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * This file is part of the Contiki operating system.
 *
 */

/**
 * \file
 *         6lowpan implementation (RFC4944 and draft-ietf-6lowpan-hc-06)
 *
 * \author Adam Dunkels <adam@sics.se>
 * \author Nicolas Tsiftes <nvt@sics.se>
 * \author Niclas Finne <nfi@sics.se>
 * \author Mathilde Durvy <mdurvy@cisco.com>
 * \author Julien Abeille <jabeille@cisco.com>
 * \author Joakim Eriksson <joakime@sics.se>
 * \author Joel Hoglund <joel@sics.se>
 */

/**
 * \addtogroup sicslowpan
 * @{
 */

/**
 * FOR HC-06 COMPLIANCE TODO:
 * -Add compression options to UDP, currently only supports
 *  both ports compressed or both ports elided
 *  
 * -Verify TC/FL compression works
 *  
 * -Add stateless multicast option
 */

#include <string.h>

#include "contiki.h"
#include "dev/watchdog.h"
#include "net/ip/tcpip.h"
#include "net/ip/uip.h"
#include "net/ipv6/uip-ds6.h"
#include "net/rime/rime.h"
#include "net/ipv6/sicslowpan.h"
#include "net/netstack.h"

#if UIP_CONF_IPV6

#include <stdio.h>

#define DEBUG DEBUG_NONE
#include "net/ip/uip-debug.h"
#if DEBUG
/* PRINTFI and PRINTFO are defined for input and output to debug one without changing the timing of the other */
uint8_t p;
#include <stdio.h>
#define PRINTFI(...) PRINTF(__VA_ARGS__)
#define PRINTFO(...) PRINTF(__VA_ARGS__)
#define PRINTPACKETBUF() PRINTF("packetbuf buffer: "); for(p = 0; p < packetbuf_datalen(); p++){PRINTF("%.2X", *(packetbuf_ptr + p));} PRINTF("\n")
#define PRINTUIPBUF() PRINTF("UIP buffer: "); for(p = 0; p < uip_len; p++){PRINTF("%.2X", uip_buf[p]);}PRINTF("\n")
#define PRINTSICSLOWPANBUF() PRINTF("SICSLOWPAN buffer: "); for(p = 0; p < sicslowpan_len; p++){PRINTF("%.2X", sicslowpan_buf[p]);}PRINTF("\n")
#else
#define PRINTFI(...)
#define PRINTFO(...)
#define PRINTPACKETBUF()
#define PRINTUIPBUF()
#define PRINTSICSLOWPANBUF()
#endif /* DEBUG == 1*/

#if UIP_LOGGING
#include <stdio.h>
void uip_log(char *msg);
#define UIP_LOG(m) uip_log(m)
#else
#define UIP_LOG(m)
#endif /* UIP_LOGGING == 1 */

#ifdef SICSLOWPAN_CONF_MAX_MAC_TRANSMISSIONS
#define SICSLOWPAN_MAX_MAC_TRANSMISSIONS SICSLOWPAN_CONF_MAX_MAC_TRANSMISSIONS
#else
#define SICSLOWPAN_MAX_MAC_TRANSMISSIONS 4
#endif

#ifndef SICSLOWPAN_COMPRESSION
#ifdef SICSLOWPAN_CONF_COMPRESSION
#define SICSLOWPAN_COMPRESSION SICSLOWPAN_CONF_COMPRESSION
#else
#define SICSLOWPAN_COMPRESSION SICSLOWPAN_COMPRESSION_IPV6
#endif /* SICSLOWPAN_CONF_COMPRESSION */
#endif /* SICSLOWPAN_COMPRESSION */

#define GET16(ptr,index) (((uint16_t)((ptr)[index] << 8)) | ((ptr)[(index) + 1]))
#define SET16(ptr,index,value) do {     \
  (ptr)[index] = ((value) >> 8) & 0xff; \
  (ptr)[index + 1] = (value) & 0xff;    \
} while(0)

/** \name Pointers in the packetbuf buffer
 *  @{
 */
#define PACKETBUF_FRAG_PTR           (packetbuf_ptr)
#define PACKETBUF_FRAG_DISPATCH_SIZE 0   /* 16 bit */
#define PACKETBUF_FRAG_TAG           2   /* 16 bit */
#define PACKETBUF_FRAG_OFFSET        4   /* 8 bit */

/* define the buffer as a byte array */
#define PACKETBUF_IPHC_BUF              ((uint8_t *)(packetbuf_ptr + packetbuf_hdr_len))

#define PACKETBUF_HC1_PTR            (packetbuf_ptr + packetbuf_hdr_len)
#define PACKETBUF_HC1_DISPATCH       0 /* 8 bit */
#define PACKETBUF_HC1_ENCODING       1 /* 8 bit */
#define PACKETBUF_HC1_TTL            2 /* 8 bit */

#define PACKETBUF_HC1_HC_UDP_PTR           (packetbuf_ptr + packetbuf_hdr_len)
#define PACKETBUF_HC1_HC_UDP_DISPATCH      0 /* 8 bit */
#define PACKETBUF_HC1_HC_UDP_HC1_ENCODING  1 /* 8 bit */
#define PACKETBUF_HC1_HC_UDP_UDP_ENCODING  2 /* 8 bit */
#define PACKETBUF_HC1_HC_UDP_TTL           3 /* 8 bit */
#define PACKETBUF_HC1_HC_UDP_PORTS         4 /* 8 bit */
#define PACKETBUF_HC1_HC_UDP_CHKSUM        5 /* 16 bit */

/** \name Pointers in the sicslowpan and uip buffer
 *  @{
 */
#define SICSLOWPAN_IP_BUF   ((struct uip_ip_hdr *)&sicslowpan_buf[UIP_LLH_LEN])
#define SICSLOWPAN_UDP_BUF ((struct uip_udp_hdr *)&sicslowpan_buf[UIP_LLIPH_LEN])

#define UIP_IP_BUF          ((struct uip_ip_hdr *)&uip_buf[UIP_LLH_LEN])
#define UIP_UDP_BUF          ((struct uip_udp_hdr *)&uip_buf[UIP_LLIPH_LEN])
#define UIP_TCP_BUF          ((struct uip_tcp_hdr *)&uip_buf[UIP_LLIPH_LEN])
#define UIP_ICMP_BUF          ((struct uip_icmp_hdr *)&uip_buf[UIP_LLIPH_LEN])
/** @} */


/** \brief Maximum available size for frame headers,
           link layer security-related overhead, as well as
           6LoWPAN payload. */
#ifdef SICSLOWPAN_CONF_MAC_MAX_PAYLOAD
#define MAC_MAX_PAYLOAD SICSLOWPAN_CONF_MAC_MAX_PAYLOAD
#else /* SICSLOWPAN_CONF_MAC_MAX_PAYLOAD */
#define MAC_MAX_PAYLOAD (127 - 2)
#endif /* SICSLOWPAN_CONF_MAC_MAX_PAYLOAD */


/** \brief Some MAC layers need a minimum payload, which is
    configurable through the SICSLOWPAN_CONF_MIN_MAC_PAYLOAD
    option. */
#ifdef SICSLOWPAN_CONF_COMPRESSION_THRESHOLD
#define COMPRESSION_THRESHOLD SICSLOWPAN_CONF_COMPRESSION_THRESHOLD
#else
#define COMPRESSION_THRESHOLD 0
#endif

/** \name General variables
 *  @{
 */
#ifdef SICSLOWPAN_NH_COMPRESSOR
/** A pointer to the additional compressor */
extern struct sicslowpan_nh_compressor SICSLOWPAN_NH_COMPRESSOR;
#endif

/**
 * A pointer to the packetbuf buffer.
 * We initialize it to the beginning of the packetbuf buffer, then
 * access different fields by updating the offset packetbuf_hdr_len.
 */
static uint8_t *packetbuf_ptr;

/**
 * packetbuf_hdr_len is the total length of (the processed) 6lowpan headers
 * (fragment headers, IPV6 or HC1, HC2, and HC1 and HC2 non compressed
 * fields).
 */
static uint8_t packetbuf_hdr_len;

/**
 * The length of the payload in the Packetbuf buffer.
 * The payload is what comes after the compressed or uncompressed
 * headers (can be the IP payload if the IP header only is compressed
 * or the UDP payload if the UDP header is also compressed)
 */
static int packetbuf_payload_len;

/**
 * uncomp_hdr_len is the length of the headers before compression (if HC2
 * is used this includes the UDP header in addition to the IP header).
 */
static uint8_t uncomp_hdr_len;

/**
 * the result of the last transmitted fragment
 */
static int last_tx_status;
/** @} */

#if SICSLOWPAN_CONF_FRAG
/** \name Fragmentation related variables
 *  @{
 */

static uint16_t sicslowpan_len;

/**
 * The buffer used for the 6lowpan reassembly.
 * This buffer contains only the IPv6 packet (no MAC header, 6lowpan, etc).
 * It has a fix size as we do not use dynamic memory allocation.
 */
static uip_buf_t sicslowpan_aligned_buf;
#define sicslowpan_buf (sicslowpan_aligned_buf.u8)

/** The total length of the IPv6 packet in the sicslowpan_buf. */

/**
 * length of the ip packet already sent / received.
 * It includes IP and transport headers.
 */
static uint16_t processed_ip_in_len;

/** Datagram tag to be put in the fragments I send. */
static uint16_t my_tag;

/** When reassembling, the tag in the fragments being merged. */
static uint16_t reass_tag;

/** When reassembling, the source address of the fragments being merged */
linkaddr_t frag_sender;

/** Reassembly %process %timer. */
static struct timer reass_timer;

/** @} */
#else /* SICSLOWPAN_CONF_FRAG */
/** The buffer used for the 6lowpan processing is uip_buf.
    We do not use any additional buffer.*/
#define sicslowpan_buf uip_buf
#define sicslowpan_len uip_len
#endif /* SICSLOWPAN_CONF_FRAG */

static int last_rssi;

/*-------------------------------------------------------------------------*/
/* Rime Sniffer support for one single listener to enable powertrace of IP */
/*-------------------------------------------------------------------------*/
static struct rime_sniffer *callback = NULL;

void
rime_sniffer_add(struct rime_sniffer *s)
{
  callback = s;
}

void
rime_sniffer_remove(struct rime_sniffer *s)
{
  callback = NULL;
}

static void
set_packet_attrs()
{
  int c = 0;
  /* set protocol in NETWORK_ID */
  packetbuf_set_attr(PACKETBUF_ATTR_NETWORK_ID, UIP_IP_BUF->proto);

  /* assign values to the channel attribute (port or type + code) */
  if(UIP_IP_BUF->proto == UIP_PROTO_UDP) {
    c = UIP_UDP_BUF->srcport;
    if(UIP_UDP_BUF->destport < c) {
      c = UIP_UDP_BUF->destport;
    }
  } else if(UIP_IP_BUF->proto == UIP_PROTO_TCP) {
    c = UIP_TCP_BUF->srcport;
    if(UIP_TCP_BUF->destport < c) {
      c = UIP_TCP_BUF->destport;
    }
  } else if(UIP_IP_BUF->proto == UIP_PROTO_ICMP6) {
    c = UIP_ICMP_BUF->type << 8 | UIP_ICMP_BUF->icode;
  }

  packetbuf_set_attr(PACKETBUF_ATTR_CHANNEL, c);

/*   if(uip_ds6_is_my_addr(&UIP_IP_BUF->srcipaddr)) { */
/*     own = 1; */
/*   } */

}



#if SICSLOWPAN_COMPRESSION == SICSLOWPAN_COMPRESSION_HC06
/** \name HC06 specific variables
 *  @{
 */

/** Addresses contexts for IPHC. */
#if SICSLOWPAN_CONF_MAX_ADDR_CONTEXTS > 0
static struct sicslowpan_addr_context 
addr_contexts[SICSLOWPAN_CONF_MAX_ADDR_CONTEXTS];
#endif

/** pointer to an address context. */
static struct sicslowpan_addr_context *context;

/** pointer to the byte where to write next inline field. */
static uint8_t *hc06_ptr;

/* Uncompression of linklocal */
/*   0 -> 16 bytes from packet  */
/*   1 -> 2 bytes from prefix - bunch of zeroes and 8 from packet */
/*   2 -> 2 bytes from prefix - 0000::00ff:fe00:XXXX from packet */
/*   3 -> 2 bytes from prefix - infer 8 bytes from lladdr */
/*   NOTE: => the uncompress function does change 0xf to 0x10 */
/*   NOTE: 0x00 => no-autoconfig => unspecified */
const uint8_t unc_llconf[] = {0x0f,0x28,0x22,0x20};

/* Uncompression of ctx-based */
/*   0 -> 0 bits from packet [unspecified / reserved] */
/*   1 -> 8 bytes from prefix - bunch of zeroes and 8 from packet */
/*   2 -> 8 bytes from prefix - 0000::00ff:fe00:XXXX + 2 from packet */
/*   3 -> 8 bytes from prefix - infer 8 bytes from lladdr */
const uint8_t unc_ctxconf[] = {0x00,0x88,0x82,0x80};

/* Uncompression of ctx-based */
/*   0 -> 0 bits from packet  */
/*   1 -> 2 bytes from prefix - bunch of zeroes 5 from packet */
/*   2 -> 2 bytes from prefix - zeroes + 3 from packet */
/*   3 -> 2 bytes from prefix - infer 1 bytes from lladdr */
const uint8_t unc_mxconf[] = {0x0f, 0x25, 0x23, 0x21};

/* Link local prefix */
const uint8_t llprefix[] = {0xfe, 0x80};

/* TTL uncompression values */
static const uint8_t ttl_values[] = {0, 1, 64, 255};

/*--------------------------------------------------------------------*/
/** \name HC06 related functions
 * @{                                                                 */
/*--------------------------------------------------------------------*/
/** \brief find the context corresponding to prefix ipaddr */
static struct sicslowpan_addr_context*
addr_context_lookup_by_prefix(uip_ipaddr_t *ipaddr)
{
/* Remove code to avoid warnings and save flash if no context is used */
#if SICSLOWPAN_CONF_MAX_ADDR_CONTEXTS > 0
  int i;
  for(i = 0; i < SICSLOWPAN_CONF_MAX_ADDR_CONTEXTS; i++) {
    if((addr_contexts[i].used == 1) &&
       uip_ipaddr_prefixcmp(&addr_contexts[i].prefix, ipaddr, 64)) {
      return &addr_contexts[i];
    }
  }
#endif /* SICSLOWPAN_CONF_MAX_ADDR_CONTEXTS > 0 */
  return NULL;
}
/*--------------------------------------------------------------------*/
/** \brief find the context with the given number */
static struct sicslowpan_addr_context*
addr_context_lookup_by_number(uint8_t number)
{
/* Remove code to avoid warnings and save flash if no context is used */ 
#if SICSLOWPAN_CONF_MAX_ADDR_CONTEXTS > 0
  int i;
  for(i = 0; i < SICSLOWPAN_CONF_MAX_ADDR_CONTEXTS; i++) {
    if((addr_contexts[i].used == 1) &&
       addr_contexts[i].number == number) {
      return &addr_contexts[i];
    }
  }
#endif /* SICSLOWPAN_CONF_MAX_ADDR_CONTEXTS > 0 */
  return NULL;
}
/*--------------------------------------------------------------------*/
static uint8_t
compress_addr_64(uint8_t bitpos, uip_ipaddr_t *ipaddr, uip_lladdr_t *lladdr)
{
  if(uip_is_addr_mac_addr_based(ipaddr, lladdr)) {
    return 3 << bitpos; /* 0-bits */
  } else if(sicslowpan_is_iid_16_bit_compressable(ipaddr)) {
    /* compress IID to 16 bits xxxx::0000:00ff:fe00:XXXX */
    memcpy(hc06_ptr, &ipaddr->u16[7], 2);
    hc06_ptr += 2;
    return 2 << bitpos; /* 16-bits */
  } else {
    /* do not compress IID => xxxx::IID */
    memcpy(hc06_ptr, &ipaddr->u16[4], 8);
    hc06_ptr += 8;
    return 1 << bitpos; /* 64-bits */
  }
}

/*-------------------------------------------------------------------- */
/* Uncompress addresses based on a prefix and a postfix with zeroes in
 * between. If the postfix is zero in length it will use the link address
 * to configure the IP address (autoconf style).
 * pref_post_count takes a byte where the first nibble specify prefix count
 * and the second postfix count (NOTE: 15/0xf => 16 bytes copy).
 */
static void
uncompress_addr(uip_ipaddr_t *ipaddr, uint8_t const prefix[],
                uint8_t pref_post_count, uip_lladdr_t *lladdr)
{
  uint8_t prefcount = pref_post_count >> 4;
  uint8_t postcount = pref_post_count & 0x0f;
  /* full nibble 15 => 16 */
  prefcount = prefcount == 15 ? 16 : prefcount;
  postcount = postcount == 15 ? 16 : postcount;

  PRINTF("Uncompressing %d + %d => ", prefcount, postcount);

  if(prefcount > 0) {
    memcpy(ipaddr, prefix, prefcount);
  }
  if(prefcount + postcount < 16) {
    memset(&ipaddr->u8[prefcount], 0, 16 - (prefcount + postcount));
  }
  if(postcount > 0) {
    memcpy(&ipaddr->u8[16 - postcount], hc06_ptr, postcount);
    if(postcount == 2 && prefcount < 11) {
      /* 16 bits uncompression => 0000:00ff:fe00:XXXX */
      ipaddr->u8[11] = 0xff;
      ipaddr->u8[12] = 0xfe;
    }
    hc06_ptr += postcount;
  } else if (prefcount > 0) {
    /* no IID based configuration if no prefix and no data => unspec */
    uip_ds6_set_addr_iid(ipaddr, lladdr);
  }

  PRINT6ADDR(ipaddr);
  PRINTF("\n");
}

/*--------------------------------------------------------------------*/
/**
 * \brief Compress IP/UDP header
 *
 * This function is called by the 6lowpan code to create a compressed
 * 6lowpan packet in the packetbuf buffer from a full IPv6 packet in the
 * uip_buf buffer.
 *
 *
 * HC-06 (draft-ietf-6lowpan-hc, version 6)\n
 * http://tools.ietf.org/html/draft-ietf-6lowpan-hc-06
 *
 * \note We do not support ISA100_UDP header compression
 *
 * For LOWPAN_UDP compression, we either compress both ports or none.
 * General format with LOWPAN_UDP compression is
 * \verbatim
 *                      1                   2                   3
 *  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |0|1|1|TF |N|HLI|C|S|SAM|M|D|DAM| SCI   | DCI   | comp. IPv6 hdr|
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * | compressed IPv6 fields .....                                  |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * | LOWPAN_UDP    | non compressed UDP fields ...                 |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * | L4 data ...                                                   |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * \endverbatim
 * \note The context number 00 is reserved for the link local prefix.
 * For unicast addresses, if we cannot compress the prefix, we neither
 * compress the IID.
 * \param link_destaddr L2 destination address, needed to compress IP
 * dest
 */
static void
compress_hdr_hc06(linkaddr_t *link_destaddr)
{
  uint8_t tmp, iphc0, iphc1;
#if DEBUG
  { uint16_t ndx;
    PRINTF("before compression (%d): ", UIP_IP_BUF->len[1]);
    for(ndx = 0; ndx < UIP_IP_BUF->len[1] + 40; ndx++) {
      uint8_t data = ((uint8_t *) (UIP_IP_BUF))[ndx];
      PRINTF("%02x", data);
    }
    PRINTF("\n");
  }
#endif

  hc06_ptr = packetbuf_ptr + 2;
  /*
   * As we copy some bit-length fields, in the IPHC encoding bytes,
   * we sometimes use |=
   * If the field is 0, and the current bit value in memory is 1,
   * this does not work. We therefore reset the IPHC encoding here
   */

  iphc0 = SICSLOWPAN_DISPATCH_IPHC;
  iphc1 = 0;
  PACKETBUF_IPHC_BUF[2] = 0; /* might not be used - but needs to be cleared */

  /*
   * Address handling needs to be made first since it might
   * cause an extra byte with [ SCI | DCI ]
   *
   */


  /* check if dest context exists (for allocating third byte) */
  /* TODO: fix this so that it remembers the looked up values for
     avoiding two lookups - or set the lookup values immediately */
  if(addr_context_lookup_by_prefix(&UIP_IP_BUF->destipaddr) != NULL ||
     addr_context_lookup_by_prefix(&UIP_IP_BUF->srcipaddr) != NULL) {
    /* set context flag and increase hc06_ptr */
    PRINTF("IPHC: compressing dest or src ipaddr - setting CID\n");
    iphc1 |= SICSLOWPAN_IPHC_CID;
    hc06_ptr++;
  }

  /*
   * Traffic class, flow label
   * If flow label is 0, compress it. If traffic class is 0, compress it
   * We have to process both in the same time as the offset of traffic class
   * depends on the presence of version and flow label
   */
 
  /* hc06 format of tc is ECN | DSCP , original is DSCP | ECN */
  tmp = (UIP_IP_BUF->vtc << 4) | (UIP_IP_BUF->tcflow >> 4);
  tmp = ((tmp & 0x03) << 6) | (tmp >> 2);
  
  if(((UIP_IP_BUF->tcflow & 0x0F) == 0) &&
     (UIP_IP_BUF->flow == 0)) {
    /* flow label can be compressed */
    iphc0 |= SICSLOWPAN_IPHC_FL_C;
    if(((UIP_IP_BUF->vtc & 0x0F) == 0) &&
       ((UIP_IP_BUF->tcflow & 0xF0) == 0)) {
      /* compress (elide) all */
      iphc0 |= SICSLOWPAN_IPHC_TC_C;
    } else {
      /* compress only the flow label */
     *hc06_ptr = tmp;
      hc06_ptr += 1;
    }
  } else {
    /* Flow label cannot be compressed */
    if(((UIP_IP_BUF->vtc & 0x0F) == 0) &&
       ((UIP_IP_BUF->tcflow & 0xF0) == 0)) {
      /* compress only traffic class */
      iphc0 |= SICSLOWPAN_IPHC_TC_C;
      *hc06_ptr = (tmp & 0xc0) |
        (UIP_IP_BUF->tcflow & 0x0F);
      memcpy(hc06_ptr + 1, &UIP_IP_BUF->flow, 2);
      hc06_ptr += 3;
    } else {
      /* compress nothing */
      memcpy(hc06_ptr, &UIP_IP_BUF->vtc, 4);
      /* but replace the top byte with the new ECN | DSCP format*/
      *hc06_ptr = tmp;
      hc06_ptr += 4;
   }
  }

  /* Note that the payload length is always compressed */

  /* Next header. We compress it if UDP */
#if UIP_CONF_UDP || UIP_CONF_ROUTER
  if(UIP_IP_BUF->proto == UIP_PROTO_UDP) {
    iphc0 |= SICSLOWPAN_IPHC_NH_C;
  }
#endif /*UIP_CONF_UDP*/
#ifdef SICSLOWPAN_NH_COMPRESSOR 
  if(SICSLOWPAN_NH_COMPRESSOR.is_compressable(UIP_IP_BUF->proto)) {
    iphc0 |= SICSLOWPAN_IPHC_NH_C;
  }
#endif
  if ((iphc0 & SICSLOWPAN_IPHC_NH_C) == 0) {
    *hc06_ptr = UIP_IP_BUF->proto;
    hc06_ptr += 1;
  }

  /*
   * Hop limit
   * if 1: compress, encoding is 01
   * if 64: compress, encoding is 10
   * if 255: compress, encoding is 11
   * else do not compress
   */
  switch(UIP_IP_BUF->ttl) {
    case 1:
      iphc0 |= SICSLOWPAN_IPHC_TTL_1;
      break;
    case 64:
      iphc0 |= SICSLOWPAN_IPHC_TTL_64;
      break;
    case 255:
      iphc0 |= SICSLOWPAN_IPHC_TTL_255;
      break;
    default:
      *hc06_ptr = UIP_IP_BUF->ttl;
      hc06_ptr += 1;
      break;
  }

  /* source address - cannot be multicast */
  if(uip_is_addr_unspecified(&UIP_IP_BUF->srcipaddr)) {
    PRINTF("IPHC: compressing unspecified - setting SAC\n");
    iphc1 |= SICSLOWPAN_IPHC_SAC;
    iphc1 |= SICSLOWPAN_IPHC_SAM_00;
  } else if((context = addr_context_lookup_by_prefix(&UIP_IP_BUF->srcipaddr))
     != NULL) {
    /* elide the prefix - indicate by CID and set context + SAC */
    PRINTF("IPHC: compressing src with context - setting CID & SAC ctx: %d\n",
           context->number);
    iphc1 |= SICSLOWPAN_IPHC_CID | SICSLOWPAN_IPHC_SAC;
    PACKETBUF_IPHC_BUF[2] |= context->number << 4;
    /* compession compare with this nodes address (source) */

    iphc1 |= compress_addr_64(SICSLOWPAN_IPHC_SAM_BIT,
                              &UIP_IP_BUF->srcipaddr, &uip_lladdr);
    /* No context found for this address */
  } else if(uip_is_addr_link_local(&UIP_IP_BUF->srcipaddr) &&
            UIP_IP_BUF->destipaddr.u16[1] == 0 &&
            UIP_IP_BUF->destipaddr.u16[2] == 0 &&
            UIP_IP_BUF->destipaddr.u16[3] == 0) {
    iphc1 |= compress_addr_64(SICSLOWPAN_IPHC_SAM_BIT,
                              &UIP_IP_BUF->srcipaddr, &uip_lladdr);
  } else {
    /* send the full address => SAC = 0, SAM = 00 */
    iphc1 |= SICSLOWPAN_IPHC_SAM_00; /* 128-bits */
    memcpy(hc06_ptr, &UIP_IP_BUF->srcipaddr.u16[0], 16);
    hc06_ptr += 16;
  }

  /* dest address*/
  if(uip_is_addr_mcast(&UIP_IP_BUF->destipaddr)) {
    /* Address is multicast, try to compress */
    iphc1 |= SICSLOWPAN_IPHC_M;
    if(sicslowpan_is_mcast_addr_compressable8(&UIP_IP_BUF->destipaddr)) {
      iphc1 |= SICSLOWPAN_IPHC_DAM_11;
      /* use last byte */
      *hc06_ptr = UIP_IP_BUF->destipaddr.u8[15];
      hc06_ptr += 1;
    } else if(sicslowpan_is_mcast_addr_compressable32(&UIP_IP_BUF->destipaddr)) {
      iphc1 |= SICSLOWPAN_IPHC_DAM_10;
      /* second byte + the last three */
      *hc06_ptr = UIP_IP_BUF->destipaddr.u8[1];
      memcpy(hc06_ptr + 1, &UIP_IP_BUF->destipaddr.u8[13], 3);
      hc06_ptr += 4;
    } else if(sicslowpan_is_mcast_addr_compressable48(&UIP_IP_BUF->destipaddr)) {
      iphc1 |= SICSLOWPAN_IPHC_DAM_01;
      /* second byte + the last five */
      *hc06_ptr = UIP_IP_BUF->destipaddr.u8[1];
      memcpy(hc06_ptr + 1, &UIP_IP_BUF->destipaddr.u8[11], 5);
      hc06_ptr += 6;
    } else {
      iphc1 |= SICSLOWPAN_IPHC_DAM_00;
      /* full address */
      memcpy(hc06_ptr, &UIP_IP_BUF->destipaddr.u8[0], 16);
      hc06_ptr += 16;
    }
  } else {
    /* Address is unicast, try to compress */
    if((context = addr_context_lookup_by_prefix(&UIP_IP_BUF->destipaddr)) != NULL) {
      /* elide the prefix */
      iphc1 |= SICSLOWPAN_IPHC_DAC;
      PACKETBUF_IPHC_BUF[2] |= context->number;
      /* compession compare with link adress (destination) */

      iphc1 |= compress_addr_64(SICSLOWPAN_IPHC_DAM_BIT,
               &UIP_IP_BUF->destipaddr, (uip_lladdr_t *)link_destaddr);
      /* No context found for this address */
    } else if(uip_is_addr_link_local(&UIP_IP_BUF->destipaddr) &&
              UIP_IP_BUF->destipaddr.u16[1] == 0 &&
              UIP_IP_BUF->destipaddr.u16[2] == 0 &&
              UIP_IP_BUF->destipaddr.u16[3] == 0) {
      iphc1 |= compress_addr_64(SICSLOWPAN_IPHC_DAM_BIT,
               &UIP_IP_BUF->destipaddr, (uip_lladdr_t *)link_destaddr);
    } else {
      /* send the full address */
      iphc1 |= SICSLOWPAN_IPHC_DAM_00; /* 128-bits */
      memcpy(hc06_ptr, &UIP_IP_BUF->destipaddr.u16[0], 16);
      hc06_ptr += 16;
    }
  }

  uncomp_hdr_len = UIP_IPH_LEN;

#if UIP_CONF_UDP || UIP_CONF_ROUTER
  /* UDP header compression */
  if(UIP_IP_BUF->proto == UIP_PROTO_UDP) {
    PRINTF("IPHC: Uncompressed UDP ports on send side: %x, %x\n",
           UIP_HTONS(UIP_UDP_BUF->srcport), UIP_HTONS(UIP_UDP_BUF->destport));
    /* Mask out the last 4 bits can be used as a mask */
    if(((UIP_HTONS(UIP_UDP_BUF->srcport) & 0xfff0) == SICSLOWPAN_UDP_4_BIT_PORT_MIN) &&
       ((UIP_HTONS(UIP_UDP_BUF->destport) & 0xfff0) == SICSLOWPAN_UDP_4_BIT_PORT_MIN)) {
      /* we can compress 12 bits of both source and dest */
      *hc06_ptr = SICSLOWPAN_NHC_UDP_CS_P_11;
      PRINTF("IPHC: remove 12 b of both source & dest with prefix 0xFOB\n");
      *(hc06_ptr + 1) =
        (uint8_t)((UIP_HTONS(UIP_UDP_BUF->srcport) -
                SICSLOWPAN_UDP_4_BIT_PORT_MIN) << 4) +
        (uint8_t)((UIP_HTONS(UIP_UDP_BUF->destport) -
                SICSLOWPAN_UDP_4_BIT_PORT_MIN));
      hc06_ptr += 2;
    } else if((UIP_HTONS(UIP_UDP_BUF->destport) & 0xff00) == SICSLOWPAN_UDP_8_BIT_PORT_MIN) {
      /* we can compress 8 bits of dest, leave source. */
      *hc06_ptr = SICSLOWPAN_NHC_UDP_CS_P_01;
      PRINTF("IPHC: leave source, remove 8 bits of dest with prefix 0xF0\n");
      memcpy(hc06_ptr + 1, &UIP_UDP_BUF->srcport, 2);
      *(hc06_ptr + 3) =
        (uint8_t)((UIP_HTONS(UIP_UDP_BUF->destport) -
                SICSLOWPAN_UDP_8_BIT_PORT_MIN));
      hc06_ptr += 4;
    } else if((UIP_HTONS(UIP_UDP_BUF->srcport) & 0xff00) == SICSLOWPAN_UDP_8_BIT_PORT_MIN) {
      /* we can compress 8 bits of src, leave dest. Copy compressed port */
      *hc06_ptr = SICSLOWPAN_NHC_UDP_CS_P_10;
      PRINTF("IPHC: remove 8 bits of source with prefix 0xF0, leave dest. hch: %i\n", *hc06_ptr);
      *(hc06_ptr + 1) =
        (uint8_t)((UIP_HTONS(UIP_UDP_BUF->srcport) -
                SICSLOWPAN_UDP_8_BIT_PORT_MIN));
      memcpy(hc06_ptr + 2, &UIP_UDP_BUF->destport, 2);
      hc06_ptr += 4;
    } else {
      /* we cannot compress. Copy uncompressed ports, full checksum  */
      *hc06_ptr = SICSLOWPAN_NHC_UDP_CS_P_00;
      PRINTF("IPHC: cannot compress headers\n");
      memcpy(hc06_ptr + 1, &UIP_UDP_BUF->srcport, 4);
      hc06_ptr += 5;
    }
    /* always inline the checksum  */
    if(1) {
      memcpy(hc06_ptr, &UIP_UDP_BUF->udpchksum, 2);
      hc06_ptr += 2;
    }
    uncomp_hdr_len += UIP_UDPH_LEN;
  }
#endif /*UIP_CONF_UDP*/

#ifdef SICSLOWPAN_NH_COMPRESSOR
  /* if nothing to compress just return zero  */
  hc06_ptr += SICSLOWPAN_NH_COMPRESSOR.compress(hc06_ptr, &uncomp_hdr_len);
#endif

  /* before the packetbuf_hdr_len operation */
  PACKETBUF_IPHC_BUF[0] = iphc0;
  PACKETBUF_IPHC_BUF[1] = iphc1;

  packetbuf_hdr_len = hc06_ptr - packetbuf_ptr;
  return;
}

/*--------------------------------------------------------------------*/
/**
 * \brief Uncompress HC06 (i.e., IPHC and LOWPAN_UDP) headers and put
 * them in sicslowpan_buf
 *
 * This function is called by the input function when the dispatch is
 * HC06.
 * We %process the packet in the packetbuf buffer, uncompress the header
 * fields, and copy the result in the sicslowpan buffer.
 * At the end of the decompression, packetbuf_hdr_len and uncompressed_hdr_len
 * are set to the appropriate values
 *
 * \param ip_len Equal to 0 if the packet is not a fragment (IP length
 * is then inferred from the L2 length), non 0 if the packet is a 1st
 * fragment.
 */
static void
uncompress_hdr_hc06(uint16_t ip_len)
{
  uint8_t tmp, iphc0, iphc1;
  /* at least two byte will be used for the encoding */
  hc06_ptr = packetbuf_ptr + packetbuf_hdr_len + 2;

  iphc0 = PACKETBUF_IPHC_BUF[0];
  iphc1 = PACKETBUF_IPHC_BUF[1];

  /* another if the CID flag is set */
  if(iphc1 & SICSLOWPAN_IPHC_CID) {
    PRINTF("IPHC: CID flag set - increase header with one\n");
    hc06_ptr++;
  }

  /* Traffic class and flow label */
    if((iphc0 & SICSLOWPAN_IPHC_FL_C) == 0) {
      /* Flow label are carried inline */
      if((iphc0 & SICSLOWPAN_IPHC_TC_C) == 0) {
        /* Traffic class is carried inline */
        memcpy(&SICSLOWPAN_IP_BUF->tcflow, hc06_ptr + 1, 3);
        tmp = *hc06_ptr;
        hc06_ptr += 4;
        /* hc06 format of tc is ECN | DSCP , original is DSCP | ECN */
        /* set version, pick highest DSCP bits and set in vtc */
        SICSLOWPAN_IP_BUF->vtc = 0x60 | ((tmp >> 2) & 0x0f);
        /* ECN rolled down two steps + lowest DSCP bits at top two bits */
        SICSLOWPAN_IP_BUF->tcflow = ((tmp >> 2) & 0x30) | (tmp << 6) |
        (SICSLOWPAN_IP_BUF->tcflow & 0x0f);
      } else {
        /* Traffic class is compressed (set version and no TC)*/
        SICSLOWPAN_IP_BUF->vtc = 0x60;
        /* highest flow label bits + ECN bits */
        SICSLOWPAN_IP_BUF->tcflow = (*hc06_ptr & 0x0F) |
        ((*hc06_ptr >> 2) & 0x30);
        memcpy(&SICSLOWPAN_IP_BUF->flow, hc06_ptr + 1, 2);
        hc06_ptr += 3;
      }
    } else {
      /* Version is always 6! */
      /* Version and flow label are compressed */
      if((iphc0 & SICSLOWPAN_IPHC_TC_C) == 0) {
        /* Traffic class is inline */
          SICSLOWPAN_IP_BUF->vtc = 0x60 | ((*hc06_ptr >> 2) & 0x0f);
          SICSLOWPAN_IP_BUF->tcflow = ((*hc06_ptr << 6) & 0xC0) | ((*hc06_ptr >> 2) & 0x30);
          SICSLOWPAN_IP_BUF->flow = 0;
          hc06_ptr += 1;
      } else {
        /* Traffic class is compressed */
        SICSLOWPAN_IP_BUF->vtc = 0x60;
        SICSLOWPAN_IP_BUF->tcflow = 0;
        SICSLOWPAN_IP_BUF->flow = 0;
      }
    }

  /* Next Header */
  if((iphc0 & SICSLOWPAN_IPHC_NH_C) == 0) {
    /* Next header is carried inline */
    SICSLOWPAN_IP_BUF->proto = *hc06_ptr;
    PRINTF("IPHC: next header inline: %d\n", SICSLOWPAN_IP_BUF->proto);
    hc06_ptr += 1;
  }

  /* Hop limit */
  if((iphc0 & 0x03) != SICSLOWPAN_IPHC_TTL_I) {
    SICSLOWPAN_IP_BUF->ttl = ttl_values[iphc0 & 0x03];
  } else {
    SICSLOWPAN_IP_BUF->ttl = *hc06_ptr;
    hc06_ptr += 1;
  }

  /* put the source address compression mode SAM in the tmp var */
  tmp = ((iphc1 & SICSLOWPAN_IPHC_SAM_11) >> SICSLOWPAN_IPHC_SAM_BIT) & 0x03;

  /* context based compression */
  if(iphc1 & SICSLOWPAN_IPHC_SAC) {
    uint8_t sci = (iphc1 & SICSLOWPAN_IPHC_CID) ?
      PACKETBUF_IPHC_BUF[2] >> 4 : 0;

    /* Source address - check context != NULL only if SAM bits are != 0*/
    if (tmp != 0) {
      context = addr_context_lookup_by_number(sci);
      if(context == NULL) {
        PRINTF("sicslowpan uncompress_hdr: error context not found\n");
        return;
      }
    }
    /* if tmp == 0 we do not have a context and therefore no prefix */
    uncompress_addr(&SICSLOWPAN_IP_BUF->srcipaddr,
                    tmp != 0 ? context->prefix : NULL, unc_ctxconf[tmp],
                    (uip_lladdr_t *)packetbuf_addr(PACKETBUF_ADDR_SENDER));
  } else {
    /* no compression and link local */
    uncompress_addr(&SICSLOWPAN_IP_BUF->srcipaddr, llprefix, unc_llconf[tmp],
                    (uip_lladdr_t *)packetbuf_addr(PACKETBUF_ADDR_SENDER));
  }

  /* Destination address */
  /* put the destination address compression mode into tmp */
  tmp = ((iphc1 & SICSLOWPAN_IPHC_DAM_11) >> SICSLOWPAN_IPHC_DAM_BIT) & 0x03;

  /* multicast compression */
  if(iphc1 & SICSLOWPAN_IPHC_M) {
    /* context based multicast compression */
    if(iphc1 & SICSLOWPAN_IPHC_DAC) {
      /* TODO: implement this */
    } else {
      /* non-context based multicast compression - */
      /* DAM_00: 128 bits  */
      /* DAM_01:  48 bits FFXX::00XX:XXXX:XXXX */
      /* DAM_10:  32 bits FFXX::00XX:XXXX */
      /* DAM_11:   8 bits FF02::00XX */
      uint8_t prefix[] = {0xff, 0x02};
      if(tmp > 0 && tmp < 3) {
        prefix[1] = *hc06_ptr;
        hc06_ptr++;
      }

      uncompress_addr(&SICSLOWPAN_IP_BUF->destipaddr, prefix,
                      unc_mxconf[tmp], NULL);
    }
  } else {
    /* no multicast */
    /* Context based */
    if(iphc1 & SICSLOWPAN_IPHC_DAC) {
      uint8_t dci = (iphc1 & SICSLOWPAN_IPHC_CID) ?
        PACKETBUF_IPHC_BUF[2] & 0x0f : 0;
      context = addr_context_lookup_by_number(dci);

      /* all valid cases below need the context! */
      if(context == NULL) {
        PRINTF("sicslowpan uncompress_hdr: error context not found\n");
        return;
      }
      uncompress_addr(&SICSLOWPAN_IP_BUF->destipaddr, context->prefix,
                      unc_ctxconf[tmp],
                      (uip_lladdr_t *)packetbuf_addr(PACKETBUF_ADDR_RECEIVER));
    } else {
      /* not context based => link local M = 0, DAC = 0 - same as SAC */
      uncompress_addr(&SICSLOWPAN_IP_BUF->destipaddr, llprefix,
                      unc_llconf[tmp],
                      (uip_lladdr_t *)packetbuf_addr(PACKETBUF_ADDR_RECEIVER));
    }
  }
  uncomp_hdr_len += UIP_IPH_LEN;

  /* Next header processing - continued */
  if((iphc0 & SICSLOWPAN_IPHC_NH_C)) {
    /* The next header is compressed, NHC is following */
    if((*hc06_ptr & SICSLOWPAN_NHC_UDP_MASK) == SICSLOWPAN_NHC_UDP_ID) {
      uint8_t checksum_compressed;
      SICSLOWPAN_IP_BUF->proto = UIP_PROTO_UDP;
      checksum_compressed = *hc06_ptr & SICSLOWPAN_NHC_UDP_CHECKSUMC;
      PRINTF("IPHC: Incoming header value: %i\n", *hc06_ptr);
      switch(*hc06_ptr & SICSLOWPAN_NHC_UDP_CS_P_11) {
      case SICSLOWPAN_NHC_UDP_CS_P_00:
        /* 1 byte for NHC, 4 byte for ports, 2 bytes chksum */
        memcpy(&SICSLOWPAN_UDP_BUF->srcport, hc06_ptr + 1, 2);
        memcpy(&SICSLOWPAN_UDP_BUF->destport, hc06_ptr + 3, 2);
        PRINTF("IPHC: Uncompressed UDP ports (ptr+5): %x, %x\n",
               UIP_HTONS(SICSLOWPAN_UDP_BUF->srcport), UIP_HTONS(SICSLOWPAN_UDP_BUF->destport));
        hc06_ptr += 5;
        break;

      case SICSLOWPAN_NHC_UDP_CS_P_01:
        /* 1 byte for NHC + source 16bit inline, dest = 0xF0 + 8 bit inline */
        PRINTF("IPHC: Decompressing destination\n");
        memcpy(&SICSLOWPAN_UDP_BUF->srcport, hc06_ptr + 1, 2);
        SICSLOWPAN_UDP_BUF->destport = UIP_HTONS(SICSLOWPAN_UDP_8_BIT_PORT_MIN + (*(hc06_ptr + 3)));
        PRINTF("IPHC: Uncompressed UDP ports (ptr+4): %x, %x\n",
               UIP_HTONS(SICSLOWPAN_UDP_BUF->srcport), UIP_HTONS(SICSLOWPAN_UDP_BUF->destport));
        hc06_ptr += 4;
        break;

      case SICSLOWPAN_NHC_UDP_CS_P_10:
        /* 1 byte for NHC + source = 0xF0 + 8bit inline, dest = 16 bit inline*/
        PRINTF("IPHC: Decompressing source\n");
        SICSLOWPAN_UDP_BUF->srcport = UIP_HTONS(SICSLOWPAN_UDP_8_BIT_PORT_MIN +
                                            (*(hc06_ptr + 1)));
        memcpy(&SICSLOWPAN_UDP_BUF->destport, hc06_ptr + 2, 2);
        PRINTF("IPHC: Uncompressed UDP ports (ptr+4): %x, %x\n",
               UIP_HTONS(SICSLOWPAN_UDP_BUF->srcport), UIP_HTONS(SICSLOWPAN_UDP_BUF->destport));
        hc06_ptr += 4;
        break;

      case SICSLOWPAN_NHC_UDP_CS_P_11:
        /* 1 byte for NHC, 1 byte for ports */
        SICSLOWPAN_UDP_BUF->srcport = UIP_HTONS(SICSLOWPAN_UDP_4_BIT_PORT_MIN +
                                            (*(hc06_ptr + 1) >> 4));
        SICSLOWPAN_UDP_BUF->destport = UIP_HTONS(SICSLOWPAN_UDP_4_BIT_PORT_MIN +
                                             ((*(hc06_ptr + 1)) & 0x0F));
        PRINTF("IPHC: Uncompressed UDP ports (ptr+2): %x, %x\n",
               UIP_HTONS(SICSLOWPAN_UDP_BUF->srcport), UIP_HTONS(SICSLOWPAN_UDP_BUF->destport));
        hc06_ptr += 2;
        break;

      default:
        PRINTF("sicslowpan uncompress_hdr: error unsupported UDP compression\n");
        return;
      }
      if(!checksum_compressed) { /* has_checksum, default  */
        memcpy(&SICSLOWPAN_UDP_BUF->udpchksum, hc06_ptr, 2);
        hc06_ptr += 2;
        PRINTF("IPHC: sicslowpan uncompress_hdr: checksum included\n");
      } else {
        PRINTF("IPHC: sicslowpan uncompress_hdr: checksum *NOT* included\n");
      }
      uncomp_hdr_len += UIP_UDPH_LEN;
    }
#ifdef SICSLOWPAN_NH_COMPRESSOR
    else {
      hc06_ptr += SICSLOWPAN_NH_COMPRESSOR.uncompress(hc06_ptr, sicslowpan_buf, &uncomp_hdr_len);
    }
#endif
  }

  packetbuf_hdr_len = hc06_ptr - packetbuf_ptr;
  
  /* IP length field. */
  if(ip_len == 0) {
    int len = packetbuf_datalen() - packetbuf_hdr_len + uncomp_hdr_len - UIP_IPH_LEN;
    /* This is not a fragmented packet */
    SICSLOWPAN_IP_BUF->len[0] = len >> 8;
    SICSLOWPAN_IP_BUF->len[1] = len & 0x00FF;
  } else {
    /* This is a 1st fragment */
    SICSLOWPAN_IP_BUF->len[0] = (ip_len - UIP_IPH_LEN) >> 8;
    SICSLOWPAN_IP_BUF->len[1] = (ip_len - UIP_IPH_LEN) & 0x00FF;
  }
  
  /* length field in UDP header */
  if(SICSLOWPAN_IP_BUF->proto == UIP_PROTO_UDP) {
    memcpy(&SICSLOWPAN_UDP_BUF->udplen, &SICSLOWPAN_IP_BUF->len[0], 2);
  }

  return;
}
/** @} */
#endif /* SICSLOWPAN_COMPRESSION == SICSLOWPAN_COMPRESSION_HC06 */


#if SICSLOWPAN_COMPRESSION == SICSLOWPAN_COMPRESSION_HC1
/*--------------------------------------------------------------------*/
/** \name HC1 compression and uncompression functions
 *  @{                                                                */
/*--------------------------------------------------------------------*/
/**
 * \brief Compress IP/UDP header using HC1 and HC_UDP
 *
 * This function is called by the 6lowpan code to create a compressed
 * 6lowpan packet in the packetbuf buffer from a full IPv6 packet in the
 * uip_buf buffer.
 *
 *
 * If we can compress everything, we use HC1 dispatch, if not we use
 * IPv6 dispatch.\n
 * We can compress everything if:
 *   - IP version is
 *   - Flow label and traffic class are 0
 *   - Both src and dest ip addresses are link local
 *   - Both src and dest interface ID are recoverable from lower layer
 *     header
 *   - Next header is either ICMP, UDP or TCP
 * Moreover, if next header is UDP, we try to compress it using HC_UDP.
 * This is feasible is both ports are between F0B0 and F0B0 + 15\n\n
 *
 * Resulting header structure:
 * - For ICMP, TCP, non compressed UDP\n
 *   HC1 encoding = 11111010 (UDP) 11111110 (TCP) 11111100 (ICMP)\n
 * \verbatim
 *                      1                   2                   3
 * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * | LoWPAN HC1 Dsp | HC1 encoding  | IPv6 Hop limit| L4 hdr + data|
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * | ...
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * \endverbatim
 *
 * - For compressed UDP
 *   HC1 encoding = 11111011, HC_UDP encoding = 11100000\n
 * \verbatim
 *                      1                   2                   3
 * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * | LoWPAN HC1 Dsp| HC1 encoding  |  HC_UDP encod.| IPv6 Hop limit|
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * | src p.| dst p.| UDP checksum                  | L4 data...
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * \endverbatim
 *
 * \param link_destaddr L2 destination address, needed to compress the
 * IP destination field
 */
static void
compress_hdr_hc1(linkaddr_t *link_destaddr)
{
  /*
   * Check if all the assumptions for full compression
   * are valid :
   */
  if(UIP_IP_BUF->vtc != 0x60 ||
     UIP_IP_BUF->tcflow != 0 ||
     UIP_IP_BUF->flow != 0 ||
     !uip_is_addr_link_local(&UIP_IP_BUF->srcipaddr) ||
     !uip_is_addr_mac_addr_based(&UIP_IP_BUF->srcipaddr, &uip_lladdr) ||
     !uip_is_addr_link_local(&UIP_IP_BUF->destipaddr) ||
     !uip_is_addr_mac_addr_based(&UIP_IP_BUF->destipaddr,
                                 (uip_lladdr_t *)link_destaddr) ||
     (UIP_IP_BUF->proto != UIP_PROTO_ICMP6 &&
      UIP_IP_BUF->proto != UIP_PROTO_UDP &&
      UIP_IP_BUF->proto != UIP_PROTO_TCP))
  {
    /*
     * IPV6 DISPATCH
     * Something cannot be compressed, use IPV6 DISPATCH,
     * compress nothing, copy IPv6 header in packetbuf buffer
     */
    *packetbuf_ptr = SICSLOWPAN_DISPATCH_IPV6;
    packetbuf_hdr_len += SICSLOWPAN_IPV6_HDR_LEN;
    memcpy(packetbuf_ptr + packetbuf_hdr_len, UIP_IP_BUF, UIP_IPH_LEN);
    packetbuf_hdr_len += UIP_IPH_LEN;
    uncomp_hdr_len += UIP_IPH_LEN;
  } else {
    /*
     * HC1 DISPATCH
     * maximum compresssion:
     * All fields in the IP header but Hop Limit are elided
     * If next header is UDP, we compress UDP header using HC2
     */
    PACKETBUF_HC1_PTR[PACKETBUF_HC1_DISPATCH] = SICSLOWPAN_DISPATCH_HC1;
    uncomp_hdr_len += UIP_IPH_LEN;
    switch(UIP_IP_BUF->proto) {
      case UIP_PROTO_ICMP6:
        /* HC1 encoding and ttl */
        PACKETBUF_HC1_PTR[PACKETBUF_HC1_ENCODING] = 0xFC;
        PACKETBUF_HC1_PTR[PACKETBUF_HC1_TTL] = UIP_IP_BUF->ttl;
        packetbuf_hdr_len += SICSLOWPAN_HC1_HDR_LEN;
        break;
#if UIP_CONF_TCP
      case UIP_PROTO_TCP:
        /* HC1 encoding and ttl */
        PACKETBUF_HC1_PTR[PACKETBUF_HC1_ENCODING] = 0xFE;
        PACKETBUF_HC1_PTR[PACKETBUF_HC1_TTL] = UIP_IP_BUF->ttl;
        packetbuf_hdr_len += SICSLOWPAN_HC1_HDR_LEN;
        break;
#endif /* UIP_CONF_TCP */
#if UIP_CONF_UDP
      case UIP_PROTO_UDP:
        /*
         * try to compress UDP header (we do only full compression).
         * This is feasible if both src and dest ports are between
         * SICSLOWPAN_UDP_PORT_MIN and SICSLOWPAN_UDP_PORT_MIN + 15
         */
        PRINTF("local/remote port %u/%u\n",UIP_UDP_BUF->srcport,UIP_UDP_BUF->destport);
        if(UIP_HTONS(UIP_UDP_BUF->srcport)  >= SICSLOWPAN_UDP_PORT_MIN &&
           UIP_HTONS(UIP_UDP_BUF->srcport)  <  SICSLOWPAN_UDP_PORT_MAX &&
           UIP_HTONS(UIP_UDP_BUF->destport) >= SICSLOWPAN_UDP_PORT_MIN &&
           UIP_HTONS(UIP_UDP_BUF->destport) <  SICSLOWPAN_UDP_PORT_MAX) {
          /* HC1 encoding */
          PACKETBUF_HC1_HC_UDP_PTR[PACKETBUF_HC1_HC_UDP_HC1_ENCODING] = 0xFB;
        
          /* HC_UDP encoding, ttl, src and dest ports, checksum */
          PACKETBUF_HC1_HC_UDP_PTR[PACKETBUF_HC1_HC_UDP_UDP_ENCODING] = 0xE0;
          PACKETBUF_HC1_HC_UDP_PTR[PACKETBUF_HC1_HC_UDP_TTL] = UIP_IP_BUF->ttl;

          PACKETBUF_HC1_HC_UDP_PTR[PACKETBUF_HC1_HC_UDP_PORTS] =
               (uint8_t)((UIP_HTONS(UIP_UDP_BUF->srcport) -
                       SICSLOWPAN_UDP_PORT_MIN) << 4) +
               (uint8_t)((UIP_HTONS(UIP_UDP_BUF->destport) - SICSLOWPAN_UDP_PORT_MIN));
          memcpy(&PACKETBUF_HC1_HC_UDP_PTR[PACKETBUF_HC1_HC_UDP_CHKSUM], &UIP_UDP_BUF->udpchksum, 2);
          packetbuf_hdr_len += SICSLOWPAN_HC1_HC_UDP_HDR_LEN;
          uncomp_hdr_len += UIP_UDPH_LEN;
        } else {
          /* HC1 encoding and ttl */
          PACKETBUF_HC1_PTR[PACKETBUF_HC1_ENCODING] = 0xFA;
          PACKETBUF_HC1_PTR[PACKETBUF_HC1_TTL] = UIP_IP_BUF->ttl;
          packetbuf_hdr_len += SICSLOWPAN_HC1_HDR_LEN;
        }
        break;
#endif /*UIP_CONF_UDP*/
    }
  }
  return;
}

/*--------------------------------------------------------------------*/
/**
 * \brief Uncompress HC1 (and HC_UDP) headers and put them in
 * sicslowpan_buf
 *
 * This function is called by the input function when the dispatch is
 * HC1.
 * We %process the packet in the packetbuf buffer, uncompress the header
 * fields, and copy the result in the sicslowpan buffer.
 * At the end of the decompression, packetbuf_hdr_len and uncompressed_hdr_len
 * are set to the appropriate values
 *
 * \param ip_len Equal to 0 if the packet is not a fragment (IP length
 * is then inferred from the L2 length), non 0 if the packet is a 1st
 * fragment.
 */
static void
uncompress_hdr_hc1(uint16_t ip_len)
{
  /* version, traffic class, flow label */
  SICSLOWPAN_IP_BUF->vtc = 0x60;
  SICSLOWPAN_IP_BUF->tcflow = 0;
  SICSLOWPAN_IP_BUF->flow = 0;
  
  /* src and dest ip addresses */
  uip_ip6addr(&SICSLOWPAN_IP_BUF->srcipaddr, 0xfe80, 0, 0, 0, 0, 0, 0, 0);
  uip_ds6_set_addr_iid(&SICSLOWPAN_IP_BUF->srcipaddr,
                       (uip_lladdr_t *)packetbuf_addr(PACKETBUF_ADDR_SENDER));
  uip_ip6addr(&SICSLOWPAN_IP_BUF->destipaddr, 0xfe80, 0, 0, 0, 0, 0, 0, 0);
  uip_ds6_set_addr_iid(&SICSLOWPAN_IP_BUF->destipaddr,
                       (uip_lladdr_t *)packetbuf_addr(PACKETBUF_ADDR_RECEIVER));
  
  uncomp_hdr_len += UIP_IPH_LEN;
  
  /* Next header field */
  switch(PACKETBUF_HC1_PTR[PACKETBUF_HC1_ENCODING] & 0x06) {
    case SICSLOWPAN_HC1_NH_ICMP6:
      SICSLOWPAN_IP_BUF->proto = UIP_PROTO_ICMP6;
      SICSLOWPAN_IP_BUF->ttl = PACKETBUF_HC1_PTR[PACKETBUF_HC1_TTL];
      packetbuf_hdr_len += SICSLOWPAN_HC1_HDR_LEN;
      break;
#if UIP_CONF_TCP
    case SICSLOWPAN_HC1_NH_TCP:
      SICSLOWPAN_IP_BUF->proto = UIP_PROTO_TCP;
      SICSLOWPAN_IP_BUF->ttl = PACKETBUF_HC1_PTR[PACKETBUF_HC1_TTL];
      packetbuf_hdr_len += SICSLOWPAN_HC1_HDR_LEN;
      break;
#endif/* UIP_CONF_TCP */
#if UIP_CONF_UDP
    case SICSLOWPAN_HC1_NH_UDP:
      SICSLOWPAN_IP_BUF->proto = UIP_PROTO_UDP;
      if(PACKETBUF_HC1_HC_UDP_PTR[PACKETBUF_HC1_HC_UDP_HC1_ENCODING] & 0x01) {
        /* UDP header is compressed with HC_UDP */
        if(PACKETBUF_HC1_HC_UDP_PTR[PACKETBUF_HC1_HC_UDP_UDP_ENCODING] !=
           SICSLOWPAN_HC_UDP_ALL_C) {
          PRINTF("sicslowpan (uncompress_hdr), packet not supported");
          return;
        }
        /* IP TTL */
        SICSLOWPAN_IP_BUF->ttl = PACKETBUF_HC1_HC_UDP_PTR[PACKETBUF_HC1_HC_UDP_TTL];
        /* UDP ports, len, checksum */
        SICSLOWPAN_UDP_BUF->srcport =
          UIP_HTONS(SICSLOWPAN_UDP_PORT_MIN +
                (PACKETBUF_HC1_HC_UDP_PTR[PACKETBUF_HC1_HC_UDP_PORTS] >> 4));
        SICSLOWPAN_UDP_BUF->destport =
          UIP_HTONS(SICSLOWPAN_UDP_PORT_MIN +
                (PACKETBUF_HC1_HC_UDP_PTR[PACKETBUF_HC1_HC_UDP_PORTS] & 0x0F));
        memcpy(&SICSLOWPAN_UDP_BUF->udpchksum, &PACKETBUF_HC1_HC_UDP_PTR[PACKETBUF_HC1_HC_UDP_CHKSUM], 2);
        uncomp_hdr_len += UIP_UDPH_LEN;
        packetbuf_hdr_len += SICSLOWPAN_HC1_HC_UDP_HDR_LEN;
      } else {
        packetbuf_hdr_len += SICSLOWPAN_HC1_HDR_LEN;
      }
      break;
#endif/* UIP_CONF_UDP */
    default:
      /* this shouldn't happen, drop */
      return;
  }
  
  /* IP length field. */
  if(ip_len == 0) {
    int len = packetbuf_datalen() - packetbuf_hdr_len + uncomp_hdr_len - UIP_IPH_LEN;
    /* This is not a fragmented packet */
    SICSLOWPAN_IP_BUF->len[0] = len >> 8;
    SICSLOWPAN_IP_BUF->len[1] = len & 0x00FF;
  } else {
    /* This is a 1st fragment */
    SICSLOWPAN_IP_BUF->len[0] = (ip_len - UIP_IPH_LEN) >> 8;
    SICSLOWPAN_IP_BUF->len[1] = (ip_len - UIP_IPH_LEN) & 0x00FF;
  }
  /* length field in UDP header */
  if(SICSLOWPAN_IP_BUF->proto == UIP_PROTO_UDP) {
    memcpy(&SICSLOWPAN_UDP_BUF->udplen, &SICSLOWPAN_IP_BUF->len[0], 2);
  }
  return;
}
/** @} */
#endif /* SICSLOWPAN_COMPRESSION == SICSLOWPAN_COMPRESSION_HC1 */



/*--------------------------------------------------------------------*/
/** \name IPv6 dispatch "compression" function
 * @{                                                                 */
/*--------------------------------------------------------------------*/
/* \brief Packets "Compression" when only IPv6 dispatch is used
 *
 * There is no compression in this case, all fields are sent
 * inline. We just add the IPv6 dispatch byte before the packet.
 * \verbatim
 * 0               1                   2                   3
 * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * | IPv6 Dsp      | IPv6 header and payload ...
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * \endverbatim
 */
static void
compress_hdr_ipv6(linkaddr_t *link_destaddr)
{
  *packetbuf_ptr = SICSLOWPAN_DISPATCH_IPV6;
  packetbuf_hdr_len += SICSLOWPAN_IPV6_HDR_LEN;
  memcpy(packetbuf_ptr + packetbuf_hdr_len, UIP_IP_BUF, UIP_IPH_LEN);
  packetbuf_hdr_len += UIP_IPH_LEN;
  uncomp_hdr_len += UIP_IPH_LEN;
  return;
}
/** @} */

/*--------------------------------------------------------------------*/
/** \name Input/output functions common to all compression schemes
 * @{                                                                 */
/*--------------------------------------------------------------------*/
/**
 * Callback function for the MAC packet sent callback
 */
static void
packet_sent(void *ptr, int status, int transmissions)
{
  uip_ds6_link_neighbor_callback(status, transmissions);

  if(callback != NULL) {
    callback->output_callback(status);
  }
  last_tx_status = status;
}
/*--------------------------------------------------------------------*/
/**
 * \brief This function is called by the 6lowpan code to send out a
 * packet.
 * \param dest the link layer destination address of the packet
 */
static void
send_packet(linkaddr_t *dest)
{
  /* Set the link layer destination address for the packet as a
   * packetbuf attribute. The MAC layer can access the destination
   * address with the function packetbuf_addr(PACKETBUF_ADDR_RECEIVER).
   */
  packetbuf_set_addr(PACKETBUF_ADDR_RECEIVER, dest);

#if NETSTACK_CONF_BRIDGE_MODE
  /* This needs to be explicitly set here for bridge mode to work */
  packetbuf_set_addr(PACKETBUF_ADDR_SENDER,(void*)&uip_lladdr);
#endif

  /* Force acknowledge from sender (test hardware autoacks) */
#if SICSLOWPAN_CONF_ACK_ALL
    packetbuf_set_attr(PACKETBUF_ATTR_RELIABLE, 1);
#endif

  /* Provide a callback function to receive the result of
     a packet transmission. */
  NETSTACK_LLSEC.send(&packet_sent, NULL);

  /* If we are sending multiple packets in a row, we need to let the
     watchdog know that we are still alive. */
  watchdog_periodic();
}
/*--------------------------------------------------------------------*/
/** \brief Take an IP packet and format it to be sent on an 802.15.4
 *  network using 6lowpan.
 *  \param localdest The MAC address of the destination
 *
 *  The IP packet is initially in uip_buf. Its header is compressed
 *  and if necessary it is fragmented. The resulting
 *  packet/fragments are put in packetbuf and delivered to the 802.15.4
 *  MAC.
 */
static uint8_t
output(const uip_lladdr_t *localdest)
{
  int framer_hdrlen;
  int max_payload;

  /* The MAC address of the destination of the packet */
  linkaddr_t dest;

  /* Number of bytes processed. */
  uint16_t processed_ip_out_len;

  /* init */
  uncomp_hdr_len = 0;
  packetbuf_hdr_len = 0;

  /* reset packetbuf buffer */
  packetbuf_clear();
  packetbuf_ptr = packetbuf_dataptr();

  packetbuf_set_attr(PACKETBUF_ATTR_MAX_MAC_TRANSMISSIONS,
                     SICSLOWPAN_MAX_MAC_TRANSMISSIONS);

  if(callback) {
    /* call the attribution when the callback comes, but set attributes
       here ! */
    set_packet_attrs();
  }

#define TCP_FIN 0x01
#define TCP_ACK 0x10
#define TCP_CTL 0x3f
  /* Set stream mode for all TCP packets, except FIN packets. */
  if(UIP_IP_BUF->proto == UIP_PROTO_TCP &&
     (UIP_TCP_BUF->flags & TCP_FIN) == 0 &&
     (UIP_TCP_BUF->flags & TCP_CTL) != TCP_ACK) {
    packetbuf_set_attr(PACKETBUF_ATTR_PACKET_TYPE,
                       PACKETBUF_ATTR_PACKET_TYPE_STREAM);
  } else if(UIP_IP_BUF->proto == UIP_PROTO_TCP &&
            (UIP_TCP_BUF->flags & TCP_FIN) == TCP_FIN) {
    packetbuf_set_attr(PACKETBUF_ATTR_PACKET_TYPE,
                       PACKETBUF_ATTR_PACKET_TYPE_STREAM_END);
  }

  /*
   * The destination address will be tagged to each outbound
   * packet. If the argument localdest is NULL, we are sending a
   * broadcast packet.
   */
  if(localdest == NULL) {
    linkaddr_copy(&dest, &linkaddr_null);
  } else {
    linkaddr_copy(&dest, (const linkaddr_t *)localdest);
  }
  
  PRINTFO("sicslowpan output: sending packet len %d\n", uip_len);

  if(uip_len >= COMPRESSION_THRESHOLD) {
    /* Try to compress the headers */
#if SICSLOWPAN_COMPRESSION == SICSLOWPAN_COMPRESSION_HC1
    compress_hdr_hc1(&dest);
#endif /* SICSLOWPAN_COMPRESSION == SICSLOWPAN_COMPRESSION_HC1 */
#if SICSLOWPAN_COMPRESSION == SICSLOWPAN_COMPRESSION_IPV6
    compress_hdr_ipv6(&dest);
#endif /* SICSLOWPAN_COMPRESSION == SICSLOWPAN_COMPRESSION_IPV6 */
#if SICSLOWPAN_COMPRESSION == SICSLOWPAN_COMPRESSION_HC06
    compress_hdr_hc06(&dest);
#endif /* SICSLOWPAN_COMPRESSION == SICSLOWPAN_COMPRESSION_HC06 */
  } else {
    compress_hdr_ipv6(&dest);
  }
  PRINTFO("sicslowpan output: header of len %d\n", packetbuf_hdr_len);

  /* Calculate NETSTACK_FRAMER's header length, that will be added in the NETSTACK_RDC.
   * We calculate it here only to make a better decision of whether the outgoing packet
   * needs to be fragmented or not. */
#define USE_FRAMER_HDRLEN 1
#if USE_FRAMER_HDRLEN
  packetbuf_set_addr(PACKETBUF_ADDR_RECEIVER, &dest);
  framer_hdrlen = NETSTACK_FRAMER.length();
  if(framer_hdrlen < 0) {
    /* Framing failed, we assume the maximum header length */
    framer_hdrlen = 21;
  }
#else /* USE_FRAMER_HDRLEN */
  framer_hdrlen = 21;
#endif /* USE_FRAMER_HDRLEN */
  max_payload = MAC_MAX_PAYLOAD - framer_hdrlen - NETSTACK_LLSEC.get_overhead();

  if((int)uip_len - (int)uncomp_hdr_len > max_payload - (int)packetbuf_hdr_len) {
#if SICSLOWPAN_CONF_FRAG
    struct queuebuf *q;
    /*
     * The outbound IPv6 packet is too large to fit into a single 15.4
     * packet, so we fragment it into multiple packets and send them.
     * The first fragment contains frag1 dispatch, then
     * IPv6/HC1/HC06/HC_UDP dispatchs/headers.
     * The following fragments contain only the fragn dispatch.
     */
    int estimated_fragments = ((int)uip_len) / ((int)MAC_MAX_PAYLOAD - SICSLOWPAN_FRAGN_HDR_LEN) + 1;
    int freebuf = queuebuf_numfree() - 1;
    PRINTFO("uip_len: %d, fragments: %d, free bufs: %d\n", uip_len, estimated_fragments, freebuf);
    if(freebuf < estimated_fragments) {
      PRINTFO("Dropping packet, not enough free bufs\n");
      return 0;
    }

    PRINTFO("Fragmentation sending packet len %d\n", uip_len);

    /* Create 1st Fragment */
    PRINTFO("sicslowpan output: 1rst fragment ");

    /* move HC1/HC06/IPv6 header */
    memmove(packetbuf_ptr + SICSLOWPAN_FRAG1_HDR_LEN, packetbuf_ptr, packetbuf_hdr_len);

    /*
     * FRAG1 dispatch + header
     * Note that the length is in units of 8 bytes
     */
/*     PACKETBUF_FRAG_BUF->dispatch_size = */
/*       uip_htons((SICSLOWPAN_DISPATCH_FRAG1 << 8) | uip_len); */
    SET16(PACKETBUF_FRAG_PTR, PACKETBUF_FRAG_DISPATCH_SIZE,
          ((SICSLOWPAN_DISPATCH_FRAG1 << 8) | uip_len));
/*     PACKETBUF_FRAG_BUF->tag = uip_htons(my_tag); */
    SET16(PACKETBUF_FRAG_PTR, PACKETBUF_FRAG_TAG, my_tag);
    my_tag++;

    /* Copy payload and send */
    packetbuf_hdr_len += SICSLOWPAN_FRAG1_HDR_LEN;
    packetbuf_payload_len = (max_payload - packetbuf_hdr_len) & 0xfffffff8;
    PRINTFO("(len %d, tag %d)\n", packetbuf_payload_len, my_tag);
    memcpy(packetbuf_ptr + packetbuf_hdr_len,
           (uint8_t *)UIP_IP_BUF + uncomp_hdr_len, packetbuf_payload_len);
    packetbuf_set_datalen(packetbuf_payload_len + packetbuf_hdr_len);
    q = queuebuf_new_from_packetbuf();
    if(q == NULL) {
      PRINTFO("could not allocate queuebuf for first fragment, dropping packet\n");
      return 0;
    }
    send_packet(&dest);
    queuebuf_to_packetbuf(q);
    queuebuf_free(q);
    q = NULL;

    /* Check tx result. */
    if((last_tx_status == MAC_TX_COLLISION) ||
       (last_tx_status == MAC_TX_ERR) ||
       (last_tx_status == MAC_TX_ERR_FATAL)) {
      PRINTFO("error in fragment tx, dropping subsequent fragments.\n");
      return 0;
    }

    /* set processed_ip_out_len to what we already sent from the IP payload*/
    processed_ip_out_len = packetbuf_payload_len + uncomp_hdr_len;
    
    /*
     * Create following fragments
     * Datagram tag is already in the buffer, we need to set the
     * FRAGN dispatch and for each fragment, the offset
     */
    packetbuf_hdr_len = SICSLOWPAN_FRAGN_HDR_LEN;
/*     PACKETBUF_FRAG_BUF->dispatch_size = */
/*       uip_htons((SICSLOWPAN_DISPATCH_FRAGN << 8) | uip_len); */
    SET16(PACKETBUF_FRAG_PTR, PACKETBUF_FRAG_DISPATCH_SIZE,
          ((SICSLOWPAN_DISPATCH_FRAGN << 8) | uip_len));
    packetbuf_payload_len = (max_payload - packetbuf_hdr_len) & 0xfffffff8;
    while(processed_ip_out_len < uip_len) {
      PRINTFO("sicslowpan output: fragment ");
      PACKETBUF_FRAG_PTR[PACKETBUF_FRAG_OFFSET] = processed_ip_out_len >> 3;
      
      /* Copy payload and send */
      if(uip_len - processed_ip_out_len < packetbuf_payload_len) {
        /* last fragment */
        packetbuf_payload_len = uip_len - processed_ip_out_len;
      }
      PRINTFO("(offset %d, len %d, tag %d)\n",
             processed_ip_out_len >> 3, packetbuf_payload_len, my_tag);
      memcpy(packetbuf_ptr + packetbuf_hdr_len,
             (uint8_t *)UIP_IP_BUF + processed_ip_out_len, packetbuf_payload_len);
      packetbuf_set_datalen(packetbuf_payload_len + packetbuf_hdr_len);
      q = queuebuf_new_from_packetbuf();
      if(q == NULL) {
        PRINTFO("could not allocate queuebuf, dropping fragment\n");
        return 0;
      }
      send_packet(&dest);
      queuebuf_to_packetbuf(q);
      queuebuf_free(q);
      q = NULL;
      processed_ip_out_len += packetbuf_payload_len;

      /* Check tx result. */
      if((last_tx_status == MAC_TX_COLLISION) ||
         (last_tx_status == MAC_TX_ERR) ||
         (last_tx_status == MAC_TX_ERR_FATAL)) {
        PRINTFO("error in fragment tx, dropping subsequent fragments.\n");
        return 0;
      }
    }
#else /* SICSLOWPAN_CONF_FRAG */
    PRINTFO("sicslowpan output: Packet too large to be sent without fragmentation support; dropping packet\n");
    return 0;
#endif /* SICSLOWPAN_CONF_FRAG */
  } else {

    /*
     * The packet does not need to be fragmented
     * copy "payload" and send
     */
    memcpy(packetbuf_ptr + packetbuf_hdr_len, (uint8_t *)UIP_IP_BUF + uncomp_hdr_len,
           uip_len - uncomp_hdr_len);
    packetbuf_set_datalen(uip_len - uncomp_hdr_len + packetbuf_hdr_len);
    send_packet(&dest);
  }
  return 1;
}

/*--------------------------------------------------------------------*/
/** \brief Process a received 6lowpan packet.
 *  \param r The MAC layer
 *
 *  The 6lowpan packet is put in packetbuf by the MAC. If its a frag1 or
 *  a non-fragmented packet we first uncompress the IP header. The
 *  6lowpan payload and possibly the uncompressed IP header are then
 *  copied in siclowpan_buf. If the IP packet is complete it is copied
 *  to uip_buf and the IP layer is called.
 *
 * \note We do not check for overlapping sicslowpan fragments
 * (it is a SHALL in the RFC 4944 and should never happen)
 */
static void
input(void)
{
  /* size of the IP packet (read from fragment) */
  uint16_t frag_size = 0;
  /* offset of the fragment in the IP packet */
  uint8_t frag_offset = 0;
  uint8_t is_fragment = 0;
#if SICSLOWPAN_CONF_FRAG
  /* tag of the fragment */
  uint16_t frag_tag = 0;
  uint8_t first_fragment = 0, last_fragment = 0;
#endif /*SICSLOWPAN_CONF_FRAG*/

  /* init */
  uncomp_hdr_len = 0;
  packetbuf_hdr_len = 0;

  /* The MAC puts the 15.4 payload inside the packetbuf data buffer */
  packetbuf_ptr = packetbuf_dataptr();

  /* Save the RSSI of the incoming packet in case the upper layer will
     want to query us for it later. */
  last_rssi = (signed short)packetbuf_attr(PACKETBUF_ATTR_RSSI);
#if SICSLOWPAN_CONF_FRAG
  /* if reassembly timed out, cancel it */
  if(timer_expired(&reass_timer)) {
    sicslowpan_len = 0;
    processed_ip_in_len = 0;
  }
  /*
   * Since we don't support the mesh and broadcast header, the first header
   * we look for is the fragmentation header
   */
  switch((GET16(PACKETBUF_FRAG_PTR, PACKETBUF_FRAG_DISPATCH_SIZE) & 0xf800) >> 8) {
    case SICSLOWPAN_DISPATCH_FRAG1:
      PRINTFI("sicslowpan input: FRAG1 ");
      frag_offset = 0;
/*       frag_size = (uip_ntohs(PACKETBUF_FRAG_BUF->dispatch_size) & 0x07ff); */
      frag_size = GET16(PACKETBUF_FRAG_PTR, PACKETBUF_FRAG_DISPATCH_SIZE) & 0x07ff;
/*       frag_tag = uip_ntohs(PACKETBUF_FRAG_BUF->tag); */
      frag_tag = GET16(PACKETBUF_FRAG_PTR, PACKETBUF_FRAG_TAG);
      PRINTFI("size %d, tag %d, offset %d)\n",
             frag_size, frag_tag, frag_offset);
      packetbuf_hdr_len += SICSLOWPAN_FRAG1_HDR_LEN;
      /*      printf("frag1 %d %d\n", reass_tag, frag_tag);*/
      first_fragment = 1;
      is_fragment = 1;
      break;
    case SICSLOWPAN_DISPATCH_FRAGN:
      /*
       * set offset, tag, size
       * Offset is in units of 8 bytes
       */
      PRINTFI("sicslowpan input: FRAGN ");
      frag_offset = PACKETBUF_FRAG_PTR[PACKETBUF_FRAG_OFFSET];
      frag_tag = GET16(PACKETBUF_FRAG_PTR, PACKETBUF_FRAG_TAG);
      frag_size = GET16(PACKETBUF_FRAG_PTR, PACKETBUF_FRAG_DISPATCH_SIZE) & 0x07ff;
      PRINTFI("size %d, tag %d, offset %d)\n",
             frag_size, frag_tag, frag_offset);
      packetbuf_hdr_len += SICSLOWPAN_FRAGN_HDR_LEN;

      /* If this is the last fragment, we may shave off any extrenous
         bytes at the end. We must be liberal in what we accept. */
      PRINTFI("last_fragment?: processed_ip_in_len %d packetbuf_payload_len %d frag_size %d\n",
              processed_ip_in_len, packetbuf_datalen() - packetbuf_hdr_len, frag_size);

      if(processed_ip_in_len + packetbuf_datalen() - packetbuf_hdr_len >= frag_size) {
        last_fragment = 1;
      }
      is_fragment = 1;
      break;
    default:
      break;
  }

  /* We are currently reassembling a packet, but have just received the first
   * fragment of another packet. We can either ignore it and hope to receive
   * the rest of the under-reassembly packet fragments, or we can discard the
   * previous packet altogether, and start reassembling the new packet.
   *
   * We discard the previous packet, and start reassembling the new packet.
   * This lessens the negative impacts of too high SICSLOWPAN_REASS_MAXAGE.
   */
#define PRIORITIZE_NEW_PACKETS 1
#if PRIORITIZE_NEW_PACKETS

  if(!is_fragment) {
    /* Prioritize non-fragment packets too. */
    sicslowpan_len = 0;
    processed_ip_in_len = 0;
  } else if(processed_ip_in_len > 0 && first_fragment
      && !linkaddr_cmp(&frag_sender, packetbuf_addr(PACKETBUF_ADDR_SENDER))) {
    sicslowpan_len = 0;
    processed_ip_in_len = 0;
  }
#endif /* PRIORITIZE_NEW_PACKETS */

  if(processed_ip_in_len > 0) {
    /* reassembly is ongoing */
    /*    printf("frag %d %d\n", reass_tag, frag_tag);*/
    if((frag_size > 0 &&
        (frag_size != sicslowpan_len ||
         reass_tag  != frag_tag ||
         !linkaddr_cmp(&frag_sender, packetbuf_addr(PACKETBUF_ADDR_SENDER))))  ||
       frag_size == 0) {
      /*
       * the packet is a fragment that does not belong to the packet
       * being reassembled or the packet is not a fragment.
       */
      PRINTFI("sicslowpan input: Dropping 6lowpan packet that is not a fragment of the packet currently being reassembled\n");
      return;
    }
  } else {
    /*
     * reassembly is off
     * start it if we received a fragment
     */
    if((frag_size > 0) && (frag_size <= UIP_BUFSIZE)) {
      /* We are currently not reassembling a packet, but have received a packet fragment
       * that is not the first one. */
      if(is_fragment && !first_fragment) {
        return;
      }

      sicslowpan_len = frag_size;
      reass_tag = frag_tag;
      timer_set(&reass_timer, SICSLOWPAN_REASS_MAXAGE * CLOCK_SECOND);
      PRINTFI("sicslowpan input: INIT FRAGMENTATION (len %d, tag %d)\n",
             sicslowpan_len, reass_tag);
      linkaddr_copy(&frag_sender, packetbuf_addr(PACKETBUF_ADDR_SENDER));
    }
  }

  if(packetbuf_hdr_len == SICSLOWPAN_FRAGN_HDR_LEN) {
    /* this is a FRAGN, skip the header compression dispatch section */
    goto copypayload;
  }
#endif /* SICSLOWPAN_CONF_FRAG */

  /* Process next dispatch and headers */
#if SICSLOWPAN_COMPRESSION == SICSLOWPAN_COMPRESSION_HC06
  if((PACKETBUF_HC1_PTR[PACKETBUF_HC1_DISPATCH] & 0xe0) == SICSLOWPAN_DISPATCH_IPHC) {
    PRINTFI("sicslowpan input: IPHC\n");
    uncompress_hdr_hc06(frag_size);
  } else
#endif /* SICSLOWPAN_COMPRESSION == SICSLOWPAN_COMPRESSION_HC06 */
    switch(PACKETBUF_HC1_PTR[PACKETBUF_HC1_DISPATCH]) {
#if SICSLOWPAN_COMPRESSION == SICSLOWPAN_COMPRESSION_HC1
    case SICSLOWPAN_DISPATCH_HC1:
      PRINTFI("sicslowpan input: HC1\n");
      uncompress_hdr_hc1(frag_size);
      break;
#endif /* SICSLOWPAN_COMPRESSION == SICSLOWPAN_COMPRESSION_HC1 */
    case SICSLOWPAN_DISPATCH_IPV6:
      PRINTFI("sicslowpan input: IPV6\n");
      packetbuf_hdr_len += SICSLOWPAN_IPV6_HDR_LEN;

      /* Put uncompressed IP header in sicslowpan_buf. */
      memcpy(SICSLOWPAN_IP_BUF, packetbuf_ptr + packetbuf_hdr_len, UIP_IPH_LEN);

      /* Update uncomp_hdr_len and packetbuf_hdr_len. */
      packetbuf_hdr_len += UIP_IPH_LEN;
      uncomp_hdr_len += UIP_IPH_LEN;
      break;
    default:
      /* unknown header */
      PRINTFI("sicslowpan input: unknown dispatch: %u\n",
             PACKETBUF_HC1_PTR[PACKETBUF_HC1_DISPATCH]);
      return;
  }
   
    
#if SICSLOWPAN_CONF_FRAG
 copypayload:
#endif /*SICSLOWPAN_CONF_FRAG*/
  /*
   * copy "payload" from the packetbuf buffer to the sicslowpan_buf
   * if this is a first fragment or not fragmented packet,
   * we have already copied the compressed headers, uncomp_hdr_len
   * and packetbuf_hdr_len are non 0, frag_offset is.
   * If this is a subsequent fragment, this is the contrary.
   */
  if(packetbuf_datalen() < packetbuf_hdr_len) {
    PRINTF("SICSLOWPAN: packet dropped due to header > total packet\n");
    return;
  }
  packetbuf_payload_len = packetbuf_datalen() - packetbuf_hdr_len;

  /* Sanity-check size of incoming packet to avoid buffer overflow */
  {
    int req_size = UIP_LLH_LEN + uncomp_hdr_len + (uint16_t)(frag_offset << 3)
        + packetbuf_payload_len;
    if(req_size > sizeof(sicslowpan_buf)) {
      PRINTF(
          "SICSLOWPAN: packet dropped, minimum required SICSLOWPAN_IP_BUF size: %d+%d+%d+%d=%d (current size: %d)\n",
          UIP_LLH_LEN, uncomp_hdr_len, (uint16_t)(frag_offset << 3),
          packetbuf_payload_len, req_size, sizeof(sicslowpan_buf));
      return;
    }
  }

  memcpy((uint8_t *)SICSLOWPAN_IP_BUF + uncomp_hdr_len + (uint16_t)(frag_offset << 3), packetbuf_ptr + packetbuf_hdr_len, packetbuf_payload_len);
  
  /* update processed_ip_in_len if fragment, sicslowpan_len otherwise */

#if SICSLOWPAN_CONF_FRAG
  if(frag_size > 0) {
    /* Add the size of the header only for the first fragment. */
    if(first_fragment != 0) {
      processed_ip_in_len += uncomp_hdr_len;
    }
    /* For the last fragment, we are OK if there is extrenous bytes at
       the end of the packet. */
    if(last_fragment != 0) {
      processed_ip_in_len = frag_size;
    } else {
      processed_ip_in_len += packetbuf_payload_len;
    }
    PRINTF("processed_ip_in_len %d, packetbuf_payload_len %d\n", processed_ip_in_len, packetbuf_payload_len);

  } else {
#endif /* SICSLOWPAN_CONF_FRAG */
    sicslowpan_len = packetbuf_payload_len + uncomp_hdr_len;
#if SICSLOWPAN_CONF_FRAG
  }

  /*
   * If we have a full IP packet in sicslowpan_buf, deliver it to
   * the IP stack
   */
  PRINTF("sicslowpan_init processed_ip_in_len %d, sicslowpan_len %d\n",
         processed_ip_in_len, sicslowpan_len);
  if(processed_ip_in_len == 0 || (processed_ip_in_len == sicslowpan_len)) {
    PRINTFI("sicslowpan input: IP packet ready (length %d)\n",
           sicslowpan_len);
    memcpy((uint8_t *)UIP_IP_BUF, (uint8_t *)SICSLOWPAN_IP_BUF, sicslowpan_len);
    uip_len = sicslowpan_len;
    sicslowpan_len = 0;
    processed_ip_in_len = 0;
#endif /* SICSLOWPAN_CONF_FRAG */

#if DEBUG
    {
      uint16_t ndx;
      PRINTF("after decompression %u:", SICSLOWPAN_IP_BUF->len[1]);
      for (ndx = 0; ndx < SICSLOWPAN_IP_BUF->len[1] + 40; ndx++) {
        uint8_t data = ((uint8_t *) (SICSLOWPAN_IP_BUF))[ndx];
        PRINTF("%02x", data);
      }
      PRINTF("\n");
    }
#endif

    /* if callback is set then set attributes and call */
    if(callback) {
      set_packet_attrs();
      callback->input_callback();
    }

    tcpip_input();
#if SICSLOWPAN_CONF_FRAG
  }
#endif /* SICSLOWPAN_CONF_FRAG */
}
/** @} */

/*--------------------------------------------------------------------*/
/* \brief 6lowpan init function (called by the MAC layer)             */
/*--------------------------------------------------------------------*/
void
sicslowpan_init(void)
{
  /*
   * Set out output function as the function to be called from uIP to
   * send a packet.
   */
  tcpip_set_outputfunc(output);

#if SICSLOWPAN_COMPRESSION == SICSLOWPAN_COMPRESSION_HC06
/* Preinitialize any address contexts for better header compression
 * (Saves up to 13 bytes per 6lowpan packet)
 * The platform contiki-conf.h file can override this using e.g.
 * #define SICSLOWPAN_CONF_ADDR_CONTEXT_0 {addr_contexts[0].prefix[0]=0xbb;addr_contexts[0].prefix[1]=0xbb;}
 */
#if SICSLOWPAN_CONF_MAX_ADDR_CONTEXTS > 0 
  addr_contexts[0].used   = 1;
  addr_contexts[0].number = 0;
#ifdef SICSLOWPAN_CONF_ADDR_CONTEXT_0
        SICSLOWPAN_CONF_ADDR_CONTEXT_0;
#else
  addr_contexts[0].prefix[0] = 0xaa; 
  addr_contexts[0].prefix[1] = 0xaa;
#endif
#endif /* SICSLOWPAN_CONF_MAX_ADDR_CONTEXTS > 0 */

#if SICSLOWPAN_CONF_MAX_ADDR_CONTEXTS > 1
  {
    int i;
    for(i = 1; i < SICSLOWPAN_CONF_MAX_ADDR_CONTEXTS; i++) {
#ifdef SICSLOWPAN_CONF_ADDR_CONTEXT_1
          if (i==1) {
            addr_contexts[1].used   = 1;
                addr_contexts[1].number = 1;
                SICSLOWPAN_CONF_ADDR_CONTEXT_1;
#ifdef SICSLOWPAN_CONF_ADDR_CONTEXT_2
      } else if (i==2) {
                addr_contexts[2].used   = 1;
                addr_contexts[2].number = 2;
                SICSLOWPAN_CONF_ADDR_CONTEXT_2;
#endif
      } else {
        addr_contexts[i].used = 0;
      }   
#else
      addr_contexts[i].used = 0;
#endif /* SICSLOWPAN_CONF_ADDR_CONTEXT_1 */

    }
  }
#endif /* SICSLOWPAN_CONF_MAX_ADDR_CONTEXTS > 1 */

#endif /* SICSLOWPAN_COMPRESSION == SICSLOWPAN_COMPRESSION_HC06 */
}
/*--------------------------------------------------------------------*/
int
sicslowpan_get_last_rssi(void)
{
  return last_rssi;
}
/*--------------------------------------------------------------------*/
const struct network_driver sicslowpan_driver = {
  "sicslowpan",
  sicslowpan_init,
  input
};
/*--------------------------------------------------------------------*/
/** @} */
#endif /* UIP_CONF_IPV6 */