cregit-Linux how code gets into the kernel

Release 4.11 net/6lowpan/iphc.c

Directory: net/6lowpan
/*
 * 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[1] = 0x80;
		ipaddr->s6_addr[11] = 0xFF;
		ipaddr->s6_addr[12] = 0xFE;
		ieee802154_le16_to_be16(&ipaddr->s6_addr16[7],
					&addr->short_addr);
		break;
	default:
		/* should never handled and filtered by 802154 6lowpan */
		WARN_ON_ONCE(1);
		break;
	}
}


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static struct lowpan_iphc_ctx *

lowpan_iphc_ctx_get_by_id(const struct net_device *dev, u8 id)
{
	struct lowpan_iphc_ctx *ret = &lowpan_dev(dev)->ctx.table[id];

	if (!lowpan_iphc_ctx_is_active(ret))
		return NULL;

	return ret;
}


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static struct lowpan_iphc_ctx *

lowpan_iphc_ctx_get_by_addr(const struct net_device *dev,
			    const struct in6_addr *addr)
{
	struct lowpan_iphc_ctx *table = lowpan_dev(dev)->ctx.table;
	struct lowpan_iphc_ctx *ret = NULL;
	struct in6_addr addr_pfx;
	u8 addr_plen;
	int i;

	for (i = 0; i < LOWPAN_IPHC_CTX_TABLE_SIZE; i++) {
		/* Check if context is valid. A context that is not valid
                 * MUST NOT be used for compression.
                 */
		if (!lowpan_iphc_ctx_is_active(&table[i]) ||
		    !lowpan_iphc_ctx_is_compression(&table[i]))
			continue;

		ipv6_addr_prefix(&addr_pfx, addr, table[i].plen);

		/* if prefix len < 64, the remaining bits until 64th bit is
                 * zero. Otherwise we use table[i]->plen.
                 */
		if (table[i].plen < 64)
			addr_plen = 64;
		else
			addr_plen = table[i].plen;

		if (ipv6_prefix_equal(&addr_pfx, &table[i].pfx, addr_plen)) {
			/* remember first match */
			if (!ret) {
				ret = &table[i];
				continue;
			}

			/* get the context with longest prefix len */
			if (table[i].plen > ret->plen)
				ret = &table[i];
		}
	}

	return ret;
}


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static struct lowpan_iphc_ctx *

lowpan_iphc_ctx_get_by_mcast_addr(const struct net_device *dev,
				  const struct in6_addr *addr)
{
	struct lowpan_iphc_ctx *table = lowpan_dev(dev)->ctx.table;
	struct lowpan_iphc_ctx *ret = NULL;
	struct in6_addr addr_mcast, network_pfx = {};
	int i;

	/* init mcast address with  */
	memcpy(&addr_mcast, addr, sizeof(*addr));

	for (i = 0; i < LOWPAN_IPHC_CTX_TABLE_SIZE; i++) {
		/* Check if context is valid. A context that is not valid
                 * MUST NOT be used for compression.
                 */
		if (!lowpan_iphc_ctx_is_active(&table[i]) ||
		    !lowpan_iphc_ctx_is_compression(&table[i]))
			continue;

		/* setting plen */
		addr_mcast.s6_addr[3] = table[i].plen;
		/* get network prefix to copy into multicast address */
		ipv6_addr_prefix(&network_pfx, &table[i].pfx,
				 table[i].plen);
		/* setting network prefix */
		memcpy(&addr_mcast.s6_addr[4], &network_pfx, 8);

		if (ipv6_addr_equal(addr, &addr_mcast)) {
			ret = &table[i];
			break;
		}
	}

	return ret;
}


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/* Uncompress address function for source and
 * destination address(non-multicast).
 *
 * address_mode is the masked value for sam or dam value
 */



static int lowpan_iphc_uncompress_addr(struct sk_buff *skb,
				       const struct net_device *dev,
				       struct in6_addr *ipaddr,
				       u8 address_mode, const void *lladdr)
{
	bool fail;

	switch (address_mode) {
	/* SAM and DAM are the same here */
	case LOWPAN_IPHC_DAM_00:
		/* for global link addresses */
		fail = lowpan_fetch_skb(skb, ipaddr->s6_addr, 16);
		break;
	case LOWPAN_IPHC_SAM_01:
	case LOWPAN_IPHC_DAM_01:
		/* fe:80::XXXX:XXXX:XXXX:XXXX */
		ipaddr->s6_addr[0] = 0xFE;
		ipaddr->s6_addr[1] = 0x80;
		fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[8], 8);
		break;
	case LOWPAN_IPHC_SAM_10:
	case LOWPAN_IPHC_DAM_10:
		/* fe:80::ff:fe00:XXXX */
		ipaddr->s6_addr[0] = 0xFE;
		ipaddr->s6_addr[1] = 0x80;
		ipaddr->s6_addr[11] = 0xFF;
		ipaddr->s6_addr[12] = 0xFE;
		fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[14], 2);
		break;
	case LOWPAN_IPHC_SAM_11:
	case LOWPAN_IPHC_DAM_11:
		fail = false;
		switch (lowpan_dev(dev)->lltype) {
		case LOWPAN_LLTYPE_IEEE802154:
			lowpan_iphc_uncompress_802154_lladdr(ipaddr, lladdr);
			break;
		default:
			lowpan_iphc_uncompress_eui64_lladdr(ipaddr, lladdr);
			break;
		}
		break;
	default:
		pr_debug("Invalid address mode value: 0x%x\n", address_mode);
		return -EINVAL;
	}

	if (fail) {
		pr_debug("Failed to fetch skb data\n");
		return -EIO;
	}

	raw_dump_inline(NULL, "Reconstructed ipv6 addr is",
			ipaddr->s6_addr, 16);

	return 0;
}


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/* Uncompress address function for source context
 * based address(non-multicast).
 */



static int lowpan_iphc_uncompress_ctx_addr(struct sk_buff *skb,
					   const struct net_device *dev,
					   const struct lowpan_iphc_ctx *ctx,
					   struct in6_addr *ipaddr,
					   u8 address_mode, const void *lladdr)
{
	bool fail;

	switch (address_mode) {
	/* SAM and DAM are the same here */
	case LOWPAN_IPHC_DAM_00:
		fail = false;
		/* SAM_00 -> unspec address ::
                 * Do nothing, address is already ::
                 *
                 * DAM 00 -> reserved should never occur.
                 */
		break;
	case LOWPAN_IPHC_SAM_01:
	case LOWPAN_IPHC_DAM_01:
		fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[8], 8);
		ipv6_addr_prefix_copy(ipaddr, &ctx->pfx, ctx->plen);
		break;
	case LOWPAN_IPHC_SAM_10:
	case LOWPAN_IPHC_DAM_10:
		ipaddr->s6_addr[11] = 0xFF;
		ipaddr->s6_addr[12] = 0xFE;
		fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[14], 2);
		ipv6_addr_prefix_copy(ipaddr, &ctx->pfx, ctx->plen);
		break;
	case LOWPAN_IPHC_SAM_11:
	case LOWPAN_IPHC_DAM_11:
		fail = false;
		switch (lowpan_dev(dev)->lltype) {
		case LOWPAN_LLTYPE_IEEE802154:
			lowpan_iphc_uncompress_802154_lladdr(ipaddr, lladdr);
			break;
		default:
			lowpan_iphc_uncompress_eui64_lladdr(ipaddr, lladdr);
			break;
		}
		ipv6_addr_prefix_copy(ipaddr, &ctx->pfx, ctx->plen);
		break;
	default:
		pr_debug("Invalid sam value: 0x%x\n", address_mode);
		return -EINVAL;
	}

	if (fail) {
		pr_debug("Failed to fetch skb data\n");
		return -EIO;
	}

	raw_dump_inline(NULL,
			"Reconstructed context based ipv6 src addr is",
			ipaddr->s6_addr, 16);

	return 0;
}


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/* Uncompress function for multicast destination address,
 * when M bit is set.
 */



static int lowpan_uncompress_multicast_daddr(struct sk_buff *skb,
					     struct in6_addr *ipaddr,
					     u8 address_mode)
{
	bool fail;

	switch (address_mode) {
	case LOWPAN_IPHC_DAM_00:
		/* 00:  128 bits.  The full address
                 * is carried in-line.
                 */
		fail = lowpan_fetch_skb(skb, ipaddr->s6_addr, 16);
		break;
	case LOWPAN_IPHC_DAM_01:
		/* 01:  48 bits.  The address takes
                 * the form ffXX::00XX:XXXX:XXXX.
                 */
		ipaddr->s6_addr[0] = 0xFF;
		fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[1], 1);
		fail |= lowpan_fetch_skb(skb, &ipaddr->s6_addr[11], 5);
		break;
	case LOWPAN_IPHC_DAM_10:
		/* 10:  32 bits.  The address takes
                 * the form ffXX::00XX:XXXX.
                 */
		ipaddr->s6_addr[0] = 0xFF;
		fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[1], 1);
		fail |= lowpan_fetch_skb(skb, &ipaddr->s6_addr[13], 3);
		break;
	case LOWPAN_IPHC_DAM_11:
		/* 11:  8 bits.  The address takes
                 * the form ff02::00XX.
                 */
		ipaddr->s6_addr[0] = 0xFF;
		ipaddr->s6_addr[1] = 0x02;
		fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[15], 1);
		break;
	default:
		pr_debug("DAM value has a wrong value: 0x%x\n", address_mode);
		return -EINVAL;
	}

	if (fail) {
		pr_debug("Failed to fetch skb data\n");
		return -EIO;
	}

	raw_dump_inline(NULL, "Reconstructed ipv6 multicast addr is",
			ipaddr->s6_addr, 16);

	return 0;
}


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static int lowpan_uncompress_multicast_ctx_daddr(struct sk_buff *skb,
						 struct lowpan_iphc_ctx *ctx,
						 struct in6_addr *ipaddr,
						 u8 address_mode)
{
	struct in6_addr network_pfx = {};
	bool fail;

	ipaddr->s6_addr[0] = 0xFF;
	fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[1], 2);
	fail |= lowpan_fetch_skb(skb, &ipaddr->s6_addr[12], 4);
	if (fail)
		return -EIO;

	/* take prefix_len and network prefix from the context */
	ipaddr->s6_addr[3] = ctx->plen;
	/* get network prefix to copy into multicast address */
	ipv6_addr_prefix(&network_pfx, &ctx->pfx, ctx->plen);
	/* setting network prefix */
	memcpy(&ipaddr->s6_addr[4], &network_pfx, 8);

	return 0;
}


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/* get the ecn values from iphc tf format and set it to ipv6hdr */



static inline void lowpan_iphc_tf_set_ecn(struct ipv6hdr *hdr, const u8 *tf)
{
	/* get the two higher bits which is ecn */
	u8 ecn = tf[0] & 0xc0;

	/* ECN takes 0x30 in hdr->flow_lbl[0] */
	hdr->flow_lbl[0] |= (ecn >> 2);
}


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/* get the dscp values from iphc tf format and set it to ipv6hdr */



static inline void lowpan_iphc_tf_set_dscp(struct ipv6hdr *hdr, const u8 *tf)
{
	/* DSCP is at place after ECN */
	u8 dscp = tf[0] & 0x3f;

	/* The four highest bits need to be set at hdr->priority */
	hdr->priority |= ((dscp & 0x3c) >> 2);
	/* The two lower bits is part of hdr->flow_lbl[0] */
	hdr->flow_lbl[0] |= ((dscp & 0x03) << 6);
}


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/* get the flow label values from iphc tf format and set it to ipv6hdr */



static inline void lowpan_iphc_tf_set_lbl(struct ipv6hdr *hdr, const u8 *lbl)
{
	/* flow label is always some array started with lower nibble of
         * flow_lbl[0] and followed with two bytes afterwards. Inside inline
         * data the flow_lbl position can be different, which will be handled
         * by lbl pointer. E.g. case "01" vs "00" the traffic class is 8 bit
         * shifted, the different lbl pointer will handle that.
         *
         * The flow label will started at lower nibble of flow_lbl[0], the
         * higher nibbles are part of DSCP + ECN.
         */
	hdr->flow_lbl[0] |= lbl[0] & 0x0f;
	memcpy(&hdr->flow_lbl[1], &lbl[1], 2);
}


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/* lowpan_iphc_tf_decompress - decompress the traffic class.
 *      This function will return zero on success, a value lower than zero if
 *      failed.
 */



static int lowpan_iphc_tf_decompress(struct sk_buff *skb, struct ipv6hdr *hdr,
				     u8 val)
{
	u8 tf[4];

	/* Traffic Class and Flow Label */
	switch (val) {
	case LOWPAN_IPHC_TF_00:
		/* ECN + DSCP + 4-bit Pad + Flow Label (4 bytes) */
		if (lowpan_fetch_skb(skb, tf, 4))
			return -EINVAL;

		/*                      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
                 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                 * |ECN|   DSCP    |  rsv  |             Flow Label                |
                 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                 */
		lowpan_iphc_tf_set_ecn(hdr, tf);
		lowpan_iphc_tf_set_dscp(hdr, tf);
		lowpan_iphc_tf_set_lbl(hdr, &tf[1]);
		break;
	case LOWPAN_IPHC_TF_01:
		/* ECN + 2-bit Pad + Flow Label (3 bytes), DSCP is elided. */
		if (lowpan_fetch_skb(skb, tf, 3))
			return -EINVAL;

		/*                     1                   2
                 * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3
                 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                 * |ECN|rsv|             Flow Label                |
                 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                 */
		lowpan_iphc_tf_set_ecn(hdr, tf);
		lowpan_iphc_tf_set_lbl(hdr, &tf[0]);
		break;
	case LOWPAN_IPHC_TF_10:
		/* ECN + DSCP (1 byte), Flow Label is elided. */
		if (lowpan_fetch_skb(skb, tf, 1))
			return -EINVAL;

		/*  0 1 2 3 4 5 6 7
                 * +-+-+-+-+-+-+-+-+
                 * |ECN|   DSCP    |
                 * +-+-+-+-+-+-+-+-+
                 */
		lowpan_iphc_tf_set_ecn(hdr, tf);
		lowpan_iphc_tf_set_dscp(hdr, tf);
		break;
	case LOWPAN_IPHC_TF_11:
		/* Traffic Class and Flow Label are elided */
		break;
	default:
		WARN_ON_ONCE(1);
		return -EINVAL;
	}

	return 0;
}


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Alexander Aring170100.00%1100.00%


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/* TTL uncompression values */

static const u8 lowpan_ttl_values[] = {
	[LOWPAN_IPHC_HLIM_01] = 1,
	[LOWPAN_IPHC_HLIM_10] = 64,
	[LOWPAN_IPHC_HLIM_11] = 255,
};




int lowpan_header_decompress(struct sk_buff *skb, const struct net_device *dev,
			     const void *daddr, const void *saddr)
{
	struct ipv6hdr hdr = {};
	struct lowpan_iphc_ctx *ci;
	u8 iphc0, iphc1, cid = 0;
	int err;

	raw_dump_table(__func__, "raw skb data dump uncompressed",
		       skb->data, skb->len);

	if (lowpan_fetch_skb(skb, &iphc0, sizeof(iphc0)) ||
	    lowpan_fetch_skb(skb, &iphc1, sizeof(iphc1)))
		return -EINVAL;

	hdr.version = 6;

	/* default CID = 0, another if the CID flag is set */
	if (iphc1 & LOWPAN_IPHC_CID) {
		if (lowpan_fetch_skb(skb, &cid, sizeof(cid)))
			return -EINVAL;
	}

	err = lowpan_iphc_tf_decompress(skb, &hdr,
					iphc0 & LOWPAN_IPHC_TF_MASK);
	if (err < 0)
		return err;

	/* Next Header */
	if (!(iphc0 & LOWPAN_IPHC_NH)) {
		/* Next header is carried inline */
		if (lowpan_fetch_skb(skb, &hdr.nexthdr, sizeof(hdr.nexthdr)))
			return -EINVAL;

		pr_debug("NH flag is set, next header carried inline: %02x\n",
			 hdr.nexthdr);
	}

	/* Hop Limit */
	if ((iphc0 & LOWPAN_IPHC_HLIM_MASK) != LOWPAN_IPHC_HLIM_00) {
		hdr.hop_limit = lowpan_ttl_values[iphc0 & LOWPAN_IPHC_HLIM_MASK];
	} else {
		if (lowpan_fetch_skb(skb, &hdr.hop_limit,
				     sizeof(hdr.hop_limit)))
			return -EINVAL;
	}

	if (iphc1 & LOWPAN_IPHC_SAC) {
		spin_lock_bh(&lowpan_dev(dev)->ctx.lock);
		ci = lowpan_iphc_ctx_get_by_id(dev, LOWPAN_IPHC_CID_SCI(cid));
		if (!ci) {
			spin_unlock_bh(&lowpan_dev(dev)->ctx.lock);
			return -EINVAL;
		}

		pr_debug("SAC bit is set. Handle context based source address.\n");
		err = lowpan_iphc_uncompress_ctx_addr(skb, dev, ci, &hdr.saddr,
						      iphc1 & LOWPAN_IPHC_SAM_MASK,
						      saddr);
		spin_unlock_bh(&lowpan_dev(dev)->ctx.lock);
	} else {
		/* Source address uncompression */
		pr_debug("source address stateless compression\n");
		err = lowpan_iphc_uncompress_addr(skb, dev, &hdr.saddr,
						  iphc1 & LOWPAN_IPHC_SAM_MASK,
						  saddr);
	}

	/* Check on error of previous branch */
	if (err)
		return -EINVAL;

	switch (iphc1 & (LOWPAN_IPHC_M | LOWPAN_IPHC_DAC)) {
	case LOWPAN_IPHC_M | LOWPAN_IPHC_DAC:
		spin_lock_bh(&lowpan_dev(dev)->ctx.lock);
		ci = lowpan_iphc_ctx_get_by_id(dev, LOWPAN_IPHC_CID_DCI(cid));
		if (!ci) {
			spin_unlock_bh(&lowpan_dev(dev)->ctx.lock);
			return -EINVAL;
		}

		/* multicast with context */
		pr_debug("dest: context-based mcast compression\n");
		err = lowpan_uncompress_multicast_ctx_daddr(skb, ci,
							    &hdr.daddr,
							    iphc1 & LOWPAN_IPHC_DAM_MASK);
		spin_unlock_bh(&lowpan_dev(dev)->ctx.lock);
		break;
	case LOWPAN_IPHC_M:
		/* multicast */
		err = lowpan_uncompress_multicast_daddr(skb, &hdr.daddr,
							iphc1 & LOWPAN_IPHC_DAM_MASK);
		break;
	case LOWPAN_IPHC_DAC:
		spin_lock_bh(&lowpan_dev(dev)->ctx.lock);
		ci = lowpan_iphc_ctx_get_by_id(dev, LOWPAN_IPHC_CID_DCI(cid));
		if (!ci) {
			spin_unlock_bh(&lowpan_dev(dev)->ctx.lock);
			return -EINVAL;
		}

		/* Destination address context based uncompression */
		pr_debug("DAC bit is set. Handle context based destination address.\n");
		err = lowpan_iphc_uncompress_ctx_addr(skb, dev, ci, &hdr.daddr,
						      iphc1 & LOWPAN_IPHC_DAM_MASK,
						      daddr);
		spin_unlock_bh(&lowpan_dev(dev)->ctx.lock);
		break;
	default:
		err = lowpan_iphc_uncompress_addr(skb, dev, &hdr.daddr,
						  iphc1 & LOWPAN_IPHC_DAM_MASK,
						  daddr);
		pr_debug("dest: stateless compression mode %d dest %pI6c\n",
			 iphc1 & LOWPAN_IPHC_DAM_MASK, &hdr.daddr);
		break;
	}

	if (err)
		return -EINVAL;

	/* Next header data uncompression */
	if (iphc0 & LOWPAN_IPHC_NH) {
		err = lowpan_nhc_do_uncompression(skb, dev, &hdr);
		if (err < 0)
			return err;
	} else {
		err = skb_cow(skb, sizeof(hdr));
		if (unlikely(err))
			return err;
	}

	switch (lowpan_dev(dev)->lltype) {
	case LOWPAN_LLTYPE_IEEE802154:
		if (lowpan_802154_cb(skb)->d_size)
			hdr.payload_len = htons(lowpan_802154_cb(skb)->d_size -
						sizeof(struct ipv6hdr));
		else
			hdr.payload_len = htons(skb->len);
		break;
	default:
		hdr.payload_len = htons(skb->len);
		break;
	}

	pr_debug("skb headroom size = %d, data length = %d\n",
		 skb_headroom(skb), skb->len);

	pr_debug("IPv6 header dump:\n\tversion = %d\n\tlength  = %d\n\t"
		 "nexthdr = 0x%02x\n\thop_lim = %d\n\tdest    = %pI6c\n",
		hdr.version, ntohs(hdr.payload_len), hdr.nexthdr,
		hdr.hop_limit, &hdr.daddr);

	skb_push(skb, sizeof(hdr));
	skb_reset_network_header(skb);
	skb_copy_to_linear_data(skb, &hdr, sizeof(hdr));

	raw_dump_table(__func__, "raw header dump", (u8 *)&hdr, sizeof(hdr));

	return 0;
}

Contributors
PersonTokensPropCommitsCommitProp
Alexander Aring84798.03%571.43%


Jukka Rissanen91.04%114.29%


Simon Vincent80.93%114.29%


Total864100.00%7100.00%




EXPORT_SYMBOL_GPL(lowpan_header_decompress);


static const u8 lowpan_iphc_dam_to_sam_value[] = {
	[LOWPAN_IPHC_DAM_00] = LOWPAN_IPHC_SAM_00,
	[LOWPAN_IPHC_DAM_01] = LOWPAN_IPHC_SAM_01,
	[LOWPAN_IPHC_DAM_10] = LOWPAN_IPHC_SAM_10,
	[LOWPAN_IPHC_DAM_11] = LOWPAN_IPHC_SAM_11,
};



static inline bool

lowpan_iphc_compress_ctx_802154_lladdr(const struct in6_addr *ipaddr,
				       const struct lowpan_iphc_ctx *ctx,
				       const void *lladdr)
{
	const struct ieee802154_addr *addr = lladdr;
	unsigned char extended_addr[EUI64_ADDR_LEN];
	bool lladdr_compress = false;
	struct in6_addr tmp = {};

	switch (addr->mode) {
	case IEEE802154_ADDR_LONG:
		ieee802154_le64_to_be64(&extended_addr, &addr->extended_addr);
		/* check for SAM/DAM = 11 */
		memcpy(&tmp.s6_addr[8], &extended_addr, EUI64_ADDR_LEN);
		/* second bit-flip (Universe/Local) is done according RFC2464 */
		tmp.s6_addr[