Adding upstream version 4.19.249.upstream/4.19.249upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1313 insertions, 0 deletions

diff --git a/net/6lowpan/iphc.c b/net/6lowpan/iphc.c
new file mode 100644
index 000000000..52fad5dad
--- /dev/null
+++ b/net/6lowpan/iphc.c
@@ -0,0 +1,1313 @@
+/*
+ * 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;
+	}
+}
+
+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;
+}
+
+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;
+}
+
+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;
+}
+
+static void lowpan_iphc_uncompress_lladdr(const struct net_device *dev,
+					  struct in6_addr *ipaddr,
+					  const void *lladdr)
+{
+	switch (dev->addr_len) {
+	case ETH_ALEN:
+		lowpan_iphc_uncompress_eui48_lladdr(ipaddr, lladdr);
+		break;
+	case EUI64_ADDR_LEN:
+		lowpan_iphc_uncompress_eui64_lladdr(ipaddr, lladdr);
+		break;
+	default:
+		WARN_ON_ONCE(1);
+		break;
+	}
+}
+
+/* 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_lladdr(dev, 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;
+}
+
+/* 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_lladdr(dev, 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;
+}
+
+/* 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;
+}
+
+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;
+}
+
+/* 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);
+}
+
+/* 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);
+}
+
+/* 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);
+}
+
+/* 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;
+}
+
+/* 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:
+		skb->pkt_type = PACKET_BROADCAST;
+
+		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:
+		skb->pkt_type = PACKET_BROADCAST;
+
+		/* multicast */
+		err = lowpan_uncompress_multicast_daddr(skb, &hdr.daddr,
+							iphc1 & LOWPAN_IPHC_DAM_MASK);
+		break;
+	case LOWPAN_IPHC_DAC:
+		skb->pkt_type = PACKET_HOST;
+
+		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:
+		skb->pkt_type = PACKET_HOST;
+
+		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_mac_header(skb);
+	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;
+}
+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[8] ^= 0x02;
+		/* context information are always used */
+		ipv6_addr_prefix_copy(&tmp, &ctx->pfx, ctx->plen);
+		if (ipv6_addr_equal(&tmp, ipaddr))
+			lladdr_compress = true;
+		break;
+	case IEEE802154_ADDR_SHORT:
+		tmp.s6_addr[11] = 0xFF;
+		tmp.s6_addr[12] = 0xFE;
+		ieee802154_le16_to_be16(&tmp.s6_addr16[7],
+					&addr->short_addr);
+		/* context information are always used */
+		ipv6_addr_prefix_copy(&tmp, &ctx->pfx, ctx->plen);
+		if (ipv6_addr_equal(&tmp, ipaddr))
+			lladdr_compress = true;
+		break;
+	default:
+		/* should never handled and filtered by 802154 6lowpan */
+		WARN_ON_ONCE(1);
+		break;
+	}
+
+	return lladdr_compress;
+}
+
+static bool lowpan_iphc_addr_equal(const struct net_device *dev,
+				   const struct lowpan_iphc_ctx *ctx,
+				   const struct in6_addr *ipaddr,
+				   const void *lladdr)
+{
+	struct in6_addr tmp = {};
+
+	lowpan_iphc_uncompress_lladdr(dev, &tmp, lladdr);
+
+	if (ctx)
+		ipv6_addr_prefix_copy(&tmp, &ctx->pfx, ctx->plen);
+
+	return ipv6_addr_equal(&tmp, ipaddr);
+}
+
+static u8 lowpan_compress_ctx_addr(u8 **hc_ptr, const struct net_device *dev,
+				   const struct in6_addr *ipaddr,
+				   const struct lowpan_iphc_ctx *ctx,
+				   const unsigned char *lladdr, bool sam)
+{
+	struct in6_addr tmp = {};
+	u8 dam;
+
+	switch (lowpan_dev(dev)->lltype) {
+	case LOWPAN_LLTYPE_IEEE802154:
+		if (lowpan_iphc_compress_ctx_802154_lladdr(ipaddr, ctx,
+							   lladdr)) {
+			dam = LOWPAN_IPHC_DAM_11;
+			goto out;
+		}
+		break;
+	default:
+		if (lowpan_iphc_addr_equal(dev, ctx, ipaddr, lladdr)) {
+			dam = LOWPAN_IPHC_DAM_11;
+			goto out;
+		}
+		break;
+	}
+
+	memset(&tmp, 0, sizeof(tmp));
+	/* check for SAM/DAM = 10 */
+	tmp.s6_addr[11] = 0xFF;
+	tmp.s6_addr[12] = 0xFE;
+	memcpy(&tmp.s6_addr[14], &ipaddr->s6_addr[14], 2);
+	/* context information are always used */
+	ipv6_addr_prefix_copy(&tmp, &ctx->pfx, ctx->plen);
+	if (ipv6_addr_equal(&tmp, ipaddr)) {
+		lowpan_push_hc_data(hc_ptr, &ipaddr->s6_addr[14], 2);
+		dam = LOWPAN_IPHC_DAM_10;
+		goto out;
+	}
+
+	memset(&tmp, 0, sizeof(tmp));
+	/* check for SAM/DAM = 01, should always match */
+	memcpy(&tmp.s6_addr[8], &ipaddr->s6_addr[8], 8);
+	/* context information are always used */
+	ipv6_addr_prefix_copy(&tmp, &ctx->pfx, ctx->plen);
+	if (ipv6_addr_equal(&tmp, ipaddr)) {
+		lowpan_push_hc_data(hc_ptr, &ipaddr->s6_addr[8], 8);
+		dam = LOWPAN_IPHC_DAM_01;
+		goto out;
+	}
+
+	WARN_ONCE(1, "context found but no address mode matched\n");
+	return LOWPAN_IPHC_DAM_00;
+out:
+
+	if (sam)
+		return lowpan_iphc_dam_to_sam_value[dam];
+	else
+		return dam;
+}
+
+static inline bool
+lowpan_iphc_compress_802154_lladdr(const struct in6_addr *ipaddr,
+				   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);
+		if (is_addr_mac_addr_based(ipaddr, extended_addr))
+			lladdr_compress = true;
+		break;
+	case IEEE802154_ADDR_SHORT:
+		/* fe:80::ff:fe00:XXXX
+		 *                \__/
+		 *             short_addr
+		 *
+		 * Universe/Local bit is zero.
+		 */
+		tmp.s6_addr[0] = 0xFE;
+		tmp.s6_addr[1] = 0x80;
+		tmp.s6_addr[11] = 0xFF;
+		tmp.s6_addr[12] = 0xFE;
+		ieee802154_le16_to_be16(&tmp.s6_addr16[7],
+					&addr->short_addr);
+		if (ipv6_addr_equal(&tmp, ipaddr))
+			lladdr_compress = true;
+		break;
+	default:
+		/* should never handled and filtered by 802154 6lowpan */
+		WARN_ON_ONCE(1);
+		break;
+	}
+
+	return lladdr_compress;
+}
+
+static u8 lowpan_compress_addr_64(u8 **hc_ptr, const struct net_device *dev,
+				  const struct in6_addr *ipaddr,
+				  const unsigned char *lladdr, bool sam)
+{
+	u8 dam = LOWPAN_IPHC_DAM_01;
+
+	switch (lowpan_dev(dev)->lltype) {
+	case LOWPAN_LLTYPE_IEEE802154:
+		if (lowpan_iphc_compress_802154_lladdr(ipaddr, lladdr)) {
+			dam = LOWPAN_IPHC_DAM_11; /* 0-bits */
+			pr_debug("address compression 0 bits\n");
+			goto out;
+		}
+		break;
+	default:
+		if (lowpan_iphc_addr_equal(dev, NULL, ipaddr, lladdr)) {
+			dam = LOWPAN_IPHC_DAM_11;
+			pr_debug("address compression 0 bits\n");
+			goto out;
+		}
+
+		break;
+	}
+
+	if (lowpan_is_iid_16_bit_compressable(ipaddr)) {
+		/* compress IID to 16 bits xxxx::XXXX */
+		lowpan_push_hc_data(hc_ptr, &ipaddr->s6_addr16[7], 2);
+		dam = LOWPAN_IPHC_DAM_10; /* 16-bits */
+		raw_dump_inline(NULL, "Compressed ipv6 addr is (16 bits)",
+				*hc_ptr - 2, 2);
+		goto out;
+	}
+
+	/* do not compress IID => xxxx::IID */
+	lowpan_push_hc_data(hc_ptr, &ipaddr->s6_addr16[4], 8);
+	raw_dump_inline(NULL, "Compressed ipv6 addr is (64 bits)",
+			*hc_ptr - 8, 8);
+
+out:
+
+	if (sam)
+		return lowpan_iphc_dam_to_sam_value[dam];
+	else
+		return dam;
+}
+
+/* lowpan_iphc_get_tc - get the ECN + DCSP fields in hc format */
+static inline u8 lowpan_iphc_get_tc(const struct ipv6hdr *hdr)
+{
+	u8 dscp, ecn;
+
+	/* hdr->priority contains the higher bits of dscp, lower are part of
+	 * flow_lbl[0]. Note ECN, DCSP is swapped in ipv6 hdr.
+	 */
+	dscp = (hdr->priority << 2) | ((hdr->flow_lbl[0] & 0xc0) >> 6);
+	/* ECN is at the two lower bits from first nibble of flow_lbl[0] */
+	ecn = (hdr->flow_lbl[0] & 0x30);
+	/* for pretty debug output, also shift ecn to get the ecn value */
+	pr_debug("ecn 0x%02x dscp 0x%02x\n", ecn >> 4, dscp);
+	/* ECN is at 0x30 now, shift it to have ECN + DCSP */
+	return (ecn << 2) | dscp;
+}
+
+/* lowpan_iphc_is_flow_lbl_zero - check if flow label is zero */
+static inline bool lowpan_iphc_is_flow_lbl_zero(const struct ipv6hdr *hdr)
+{
+	return ((!(hdr->flow_lbl[0] & 0x0f)) &&
+		!hdr->flow_lbl[1] && !hdr->flow_lbl[2]);
+}
+
+/* lowpan_iphc_tf_compress - compress the traffic class which is set by
+ *	ipv6hdr. Return the corresponding format identifier which is used.
+ */
+static u8 lowpan_iphc_tf_compress(u8 **hc_ptr, const struct ipv6hdr *hdr)
+{
+	/* get ecn dscp data in a byteformat as: ECN(hi) + DSCP(lo) */
+	u8 tc = lowpan_iphc_get_tc(hdr), tf[4], val;
+
+	/* printout the traffic class in hc format */
+	pr_debug("tc 0x%02x\n", tc);
+
+	if (lowpan_iphc_is_flow_lbl_zero(hdr)) {
+		if (!tc) {
+			/* 11:  Traffic Class and Flow Label are elided. */
+			val = LOWPAN_IPHC_TF_11;
+		} else {
+			/* 10:  ECN + DSCP (1 byte), Flow Label is elided.
+			 *
+			 *  0 1 2 3 4 5 6 7
+			 * +-+-+-+-+-+-+-+-+
+			 * |ECN|   DSCP    |
+			 * +-+-+-+-+-+-+-+-+
+			 */
+			lowpan_push_hc_data(hc_ptr, &tc, sizeof(tc));
+			val = LOWPAN_IPHC_TF_10;
+		}
+	} else {
+		/* check if dscp is zero, it's after the first two bit */
+		if (!(tc & 0x3f)) {
+			/* 01:  ECN + 2-bit Pad + Flow Label (3 bytes), DSCP is elided
+			 *
+			 *                     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                |
+			 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+			 */
+			memcpy(&tf[0], &hdr->flow_lbl[0], 3);
+			/* zero the highest 4-bits, contains DCSP + ECN */
+			tf[0] &= ~0xf0;
+			/* set ECN */
+			tf[0] |= (tc & 0xc0);
+
+			lowpan_push_hc_data(hc_ptr, tf, 3);
+			val = LOWPAN_IPHC_TF_01;
+		} else {
+			/* 00:  ECN + DSCP + 4-bit Pad + Flow Label (4 bytes)
+			 *
+			 *                      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                |
+			 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+			 */
+			memcpy(&tf[0], &tc, sizeof(tc));
+			/* highest nibble of flow_lbl[0] is part of DSCP + ECN
+			 * which will be the 4-bit pad and will be filled with
+			 * zeros afterwards.
+			 */
+			memcpy(&tf[1], &hdr->flow_lbl[0], 3);
+			/* zero the 4-bit pad, which is reserved */
+			tf[1] &= ~0xf0;
+
+			lowpan_push_hc_data(hc_ptr, tf, 4);
+			val = LOWPAN_IPHC_TF_00;
+		}
+	}
+
+	return val;
+}
+
+static u8 lowpan_iphc_mcast_ctx_addr_compress(u8 **hc_ptr,
+					      const struct lowpan_iphc_ctx *ctx,
+					      const struct in6_addr *ipaddr)
+{
+	u8 data[6];
+
+	/* flags/scope, reserved (RIID) */
+	memcpy(data, &ipaddr->s6_addr[1], 2);
+	/* group ID */
+	memcpy(&data[1], &ipaddr->s6_addr[11], 4);
+	lowpan_push_hc_data(hc_ptr, data, 6);
+
+	return LOWPAN_IPHC_DAM_00;
+}
+
+static u8 lowpan_iphc_mcast_addr_compress(u8 **hc_ptr,
+					  const struct in6_addr *ipaddr)
+{
+	u8 val;
+
+	if (lowpan_is_mcast_addr_compressable8(ipaddr)) {
+		pr_debug("compressed to 1 octet\n");
+		/* use last byte */
+		lowpan_push_hc_data(hc_ptr, &ipaddr->s6_addr[15], 1);
+		val = LOWPAN_IPHC_DAM_11;
+	} else if (lowpan_is_mcast_addr_compressable32(ipaddr)) {
+		pr_debug("compressed to 4 octets\n");
+		/* second byte + the last three */
+		lowpan_push_hc_data(hc_ptr, &ipaddr->s6_addr[1], 1);
+		lowpan_push_hc_data(hc_ptr, &ipaddr->s6_addr[13], 3);
+		val = LOWPAN_IPHC_DAM_10;
+	} else if (lowpan_is_mcast_addr_compressable48(ipaddr)) {
+		pr_debug("compressed to 6 octets\n");
+		/* second byte + the last five */
+		lowpan_push_hc_data(hc_ptr, &ipaddr->s6_addr[1], 1);
+		lowpan_push_hc_data(hc_ptr, &ipaddr->s6_addr[11], 5);
+		val = LOWPAN_IPHC_DAM_01;
+	} else {
+		pr_debug("using full address\n");
+		lowpan_push_hc_data(hc_ptr, ipaddr->s6_addr, 16);
+		val = LOWPAN_IPHC_DAM_00;
+	}
+
+	return val;
+}
+
+int lowpan_header_compress(struct sk_buff *skb, const struct net_device *dev,
+			   const void *daddr, const void *saddr)
+{
+	u8 iphc0, iphc1, *hc_ptr, cid = 0;
+	struct ipv6hdr *hdr;
+	u8 head[LOWPAN_IPHC_MAX_HC_BUF_LEN] = {};
+	struct lowpan_iphc_ctx *dci, *sci, dci_entry, sci_entry;
+	int ret, ipv6_daddr_type, ipv6_saddr_type;
+
+	if (skb->protocol != htons(ETH_P_IPV6))
+		return -EINVAL;
+
+	hdr = ipv6_hdr(skb);
+	hc_ptr = head + 2;
+
+	pr_debug("IPv6 header dump:\n\tversion = %d\n\tlength  = %d\n"
+		 "\tnexthdr = 0x%02x\n\thop_lim = %d\n\tdest    = %pI6c\n",
+		 hdr->version, ntohs(hdr->payload_len), hdr->nexthdr,
+		 hdr->hop_limit, &hdr->daddr);
+
+	raw_dump_table(__func__, "raw skb network header dump",
+		       skb_network_header(skb), sizeof(struct ipv6hdr));
+
+	/* 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 = LOWPAN_DISPATCH_IPHC;
+	iphc1 = 0;
+
+	raw_dump_table(__func__, "sending raw skb network uncompressed packet",
+		       skb->data, skb->len);
+
+	ipv6_daddr_type = ipv6_addr_type(&hdr->daddr);
+	spin_lock_bh(&lowpan_dev(dev)->ctx.lock);
+	if (ipv6_daddr_type & IPV6_ADDR_MULTICAST)
+		dci = lowpan_iphc_ctx_get_by_mcast_addr(dev, &hdr->daddr);
+	else
+		dci = lowpan_iphc_ctx_get_by_addr(dev, &hdr->daddr);
+	if (dci) {
+		memcpy(&dci_entry, dci, sizeof(*dci));
+		cid |= dci->id;
+	}
+	spin_unlock_bh(&lowpan_dev(dev)->ctx.lock);
+
+	spin_lock_bh(&lowpan_dev(dev)->ctx.lock);
+	sci = lowpan_iphc_ctx_get_by_addr(dev, &hdr->saddr);
+	if (sci) {
+		memcpy(&sci_entry, sci, sizeof(*sci));
+		cid |= (sci->id << 4);
+	}
+	spin_unlock_bh(&lowpan_dev(dev)->ctx.lock);
+
+	/* if cid is zero it will be compressed */
+	if (cid) {
+		iphc1 |= LOWPAN_IPHC_CID;
+		lowpan_push_hc_data(&hc_ptr, &cid, sizeof(cid));
+	}
+
+	/* Traffic Class, Flow Label compression */
+	iphc0 |= lowpan_iphc_tf_compress(&hc_ptr, hdr);
+
+	/* NOTE: payload length is always compressed */
+
+	/* Check if we provide the nhc format for nexthdr and compression
+	 * functionality. If not nexthdr is handled inline and not compressed.
+	 */
+	ret = lowpan_nhc_check_compression(skb, hdr, &hc_ptr);
+	if (ret == -ENOENT)
+		lowpan_push_hc_data(&hc_ptr, &hdr->nexthdr,
+				    sizeof(hdr->nexthdr));
+	else
+		iphc0 |= LOWPAN_IPHC_NH;
+
+	/* 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 (hdr->hop_limit) {
+	case 1:
+		iphc0 |= LOWPAN_IPHC_HLIM_01;
+		break;
+	case 64:
+		iphc0 |= LOWPAN_IPHC_HLIM_10;
+		break;
+	case 255:
+		iphc0 |= LOWPAN_IPHC_HLIM_11;
+		break;
+	default:
+		lowpan_push_hc_data(&hc_ptr, &hdr->hop_limit,
+				    sizeof(hdr->hop_limit));
+	}
+
+	ipv6_saddr_type = ipv6_addr_type(&hdr->saddr);
+	/* source address compression */
+	if (ipv6_saddr_type == IPV6_ADDR_ANY) {
+		pr_debug("source address is unspecified, setting SAC\n");
+		iphc1 |= LOWPAN_IPHC_SAC;
+	} else {
+		if (sci) {
+			iphc1 |= lowpan_compress_ctx_addr(&hc_ptr, dev,
+							  &hdr->saddr,
+							  &sci_entry, saddr,
+							  true);
+			iphc1 |= LOWPAN_IPHC_SAC;
+		} else {
+			if (ipv6_saddr_type & IPV6_ADDR_LINKLOCAL &&
+			    lowpan_is_linklocal_zero_padded(hdr->saddr)) {
+				iphc1 |= lowpan_compress_addr_64(&hc_ptr, dev,
+								 &hdr->saddr,
+								 saddr, true);
+				pr_debug("source address unicast link-local %pI6c iphc1 0x%02x\n",
+					 &hdr->saddr, iphc1);
+			} else {
+				pr_debug("send the full source address\n");
+				lowpan_push_hc_data(&hc_ptr,
+						    hdr->saddr.s6_addr, 16);
+			}
+		}
+	}
+
+	/* destination address compression */
+	if (ipv6_daddr_type & IPV6_ADDR_MULTICAST) {
+		pr_debug("destination address is multicast: ");
+		iphc1 |= LOWPAN_IPHC_M;
+		if (dci) {
+			iphc1 |= lowpan_iphc_mcast_ctx_addr_compress(&hc_ptr,
+								     &dci_entry,
+								     &hdr->daddr);
+			iphc1 |= LOWPAN_IPHC_DAC;
+		} else {
+			iphc1 |= lowpan_iphc_mcast_addr_compress(&hc_ptr,
+								 &hdr->daddr);
+		}
+	} else {
+		if (dci) {
+			iphc1 |= lowpan_compress_ctx_addr(&hc_ptr, dev,
+							  &hdr->daddr,
+							  &dci_entry, daddr,
+							  false);
+			iphc1 |= LOWPAN_IPHC_DAC;
+		} else {
+			if (ipv6_daddr_type & IPV6_ADDR_LINKLOCAL &&
+			    lowpan_is_linklocal_zero_padded(hdr->daddr)) {
+				iphc1 |= lowpan_compress_addr_64(&hc_ptr, dev,
+								 &hdr->daddr,
+								 daddr, false);
+				pr_debug("dest address unicast link-local %pI6c iphc1 0x%02x\n",
+					 &hdr->daddr, iphc1);
+			} else {
+				pr_debug("dest address unicast %pI6c\n",
+					 &hdr->daddr);
+				lowpan_push_hc_data(&hc_ptr,
+						    hdr->daddr.s6_addr, 16);
+			}
+		}
+	}
+
+	/* next header compression */
+	if (iphc0 & LOWPAN_IPHC_NH) {
+		ret = lowpan_nhc_do_compression(skb, hdr, &hc_ptr);
+		if (ret < 0)
+			return ret;
+	}
+
+	head[0] = iphc0;
+	head[1] = iphc1;
+
+	skb_pull(skb, sizeof(struct ipv6hdr));
+	skb_reset_transport_header(skb);
+	memcpy(skb_push(skb, hc_ptr - head), head, hc_ptr - head);
+	skb_reset_network_header(skb);
+
+	pr_debug("header len %d skb %u\n", (int)(hc_ptr - head), skb->len);
+
+	raw_dump_table(__func__, "raw skb data dump compressed",
+		       skb->data, skb->len);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(lowpan_header_compress);