path: root/net/6lowpan/iphc.c

/*
 * Copyright 2011, Siemens AG
 * written by Alexander Smirnov <alex.bluesman.smirnov@gmail.com>
 */

/* Based on patches from Jon Smirl <jonsmirl@gmail.com>
 * Copyright (c) 2011 Jon Smirl <jonsmirl@gmail.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2
 * as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 */

/* Jon's code is based on 6lowpan implementation for Contiki which is:
 * 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.
 */

#include <linux/bitops.h>
#include <linux/if_arp.h>
#include <linux/netdevice.h>

#include <net/6lowpan.h>
#include <net/ipv6.h>

#include "6lowpan_i.h"
#include "nhc.h"

/* Values of fields within the IPHC encoding first byte */
#define LOWPAN_IPHC_TF_MASK	0x18
#define LOWPAN_IPHC_TF_00	0x00
#define LOWPAN_IPHC_TF_01	0x08
#define LOWPAN_IPHC_TF_10	0x10
#define LOWPAN_IPHC_TF_11	0x18

#define LOWPAN_IPHC_NH		0x04

#define LOWPAN_IPHC_HLIM_MASK	0x03
#define LOWPAN_IPHC_HLIM_00	0x00
#define LOWPAN_IPHC_HLIM_01	0x01
#define LOWPAN_IPHC_HLIM_10	0x02
#define LOWPAN_IPHC_HLIM_11	0x03

/* Values of fields within the IPHC encoding second byte */
#define LOWPAN_IPHC_CID		0x80

#define LOWPAN_IPHC_SAC		0x40

#define LOWPAN_IPHC_SAM_MASK	0x30
#define LOWPAN_IPHC_SAM_00	0x00
#define LOWPAN_IPHC_SAM_01	0x10
#define LOWPAN_IPHC_SAM_10	0x20
#define LOWPAN_IPHC_SAM_11	0x30

#define LOWPAN_IPHC_M		0x08

#define LOWPAN_IPHC_DAC		0x04

#define LOWPAN_IPHC_DAM_MASK	0x03
#define LOWPAN_IPHC_DAM_00	0x00
#define LOWPAN_IPHC_DAM_01	0x01
#define LOWPAN_IPHC_DAM_10	0x02
#define LOWPAN_IPHC_DAM_11	0x03

/* ipv6 address based on mac
 * second bit-flip (Universe/Local) is done according RFC2464
 */
#define is_addr_mac_addr_based(a, m) \
	((((a)->s6_addr[8])  == (((m)[0]) ^ 0x02)) &&	\
	 (((a)->s6_addr[9])  == (m)[1]) &&		\
	 (((a)->s6_addr[10]) == (m)[2]) &&		\
	 (((a)->s6_addr[11]) == (m)[3]) &&		\
	 (((a)->s6_addr[12]) == (m)[4]) &&		\
	 (((a)->s6_addr[13]) == (m)[5]) &&		\
	 (((a)->s6_addr[14]) == (m)[6]) &&		\
	 (((a)->s6_addr[15]) == (m)[7]))

/* check whether we can compress the IID to 16 bits,
 * it's possible for unicast addresses with first 49 bits are zero only.
 */
#define lowpan_is_iid_16_bit_compressable(a)	\
	((((a)->s6_addr16[4]) == 0) &&		\
	 (((a)->s6_addr[10]) == 0) &&		\
	 (((a)->s6_addr[11]) == 0xff) &&	\
	 (((a)->s6_addr[12]) == 0xfe) &&	\
	 (((a)->s6_addr[13]) == 0))

/* check whether the 112-bit gid of the multicast address is mappable to: */

/* 48 bits, FFXX::00XX:XXXX:XXXX */
#define lowpan_is_mcast_addr_compressable48(a)	\
	((((a)->s6_addr16[1]) == 0) &&		\
	 (((a)->s6_addr16[2]) == 0) &&		\
	 (((a)->s6_addr16[3]) == 0) &&		\
	 (((a)->s6_addr16[4]) == 0) &&		\
	 (((a)->s6_addr[10]) == 0))

/* 32 bits, FFXX::00XX:XXXX */
#define lowpan_is_mcast_addr_compressable32(a)	\
	((((a)->s6_addr16[1]) == 0) &&		\
	 (((a)->s6_addr16[2]) == 0) &&		\
	 (((a)->s6_addr16[3]) == 0) &&		\
	 (((a)->s6_addr16[4]) == 0) &&		\
	 (((a)->s6_addr16[5]) == 0) &&		\
	 (((a)->s6_addr[12]) == 0))

/* 8 bits, FF02::00XX */
#define lowpan_is_mcast_addr_compressable8(a)	\
	((((a)->s6_addr[1])  == 2) &&		\
	 (((a)->s6_addr16[1]) == 0) &&		\
	 (((a)->s6_addr16[2]) == 0) &&		\
	 (((a)->s6_addr16[3]) == 0) &&		\
	 (((a)->s6_addr16[4]) == 0) &&		\
	 (((a)->s6_addr16[5]) == 0) &&		\
	 (((a)->s6_addr16[6]) == 0) &&		\
	 (((a)->s6_addr[14]) == 0))

#define lowpan_is_linklocal_zero_padded(a)	\
	(!(hdr->saddr.s6_addr[1] & 0x3f) &&	\
	 !hdr->saddr.s6_addr16[1] &&		\
	 !hdr->saddr.s6_addr32[1])

#define LOWPAN_IPHC_CID_DCI(cid)	(cid & 0x0f)
#define LOWPAN_IPHC_CID_SCI(cid)	((cid & 0xf0) >> 4)

static inline void
lowpan_iphc_uncompress_802154_lladdr(struct in6_addr *ipaddr,
				     const void *lladdr)
{
	const struct ieee802154_addr *addr = lladdr;
	u8 eui64[EUI64_ADDR_LEN];

	switch (addr->mode) {
	case IEEE802154_ADDR_LONG:
		ieee802154_le64_to_be64(eui64, &addr->extended_addr);
		lowpan_iphc_uncompress_eui64_lladdr(ipaddr, eui64);
		break;
	case IEEE802154_ADDR_SHORT:
		/* fe:80::ff:fe00:XXXX
		 *                \__/
		 *             short_addr
		 *
		 * Universe/Local bit is zero.
		 */
		ipaddr->s6_addr[0] = 0xFE;
		ipaddr->s6_addr[