IEEE802.15.4: 6LoWPAN basic support
[pandora-kernel.git] / net / ieee802154 / 6lowpan.c
diff --git a/net/ieee802154/6lowpan.c b/net/ieee802154/6lowpan.c
new file mode 100644 (file)
index 0000000..cf304cc
--- /dev/null
@@ -0,0 +1,885 @@
+/*
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/* 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.
+ */
+
+#define DEBUG
+
+#include <linux/bitops.h>
+#include <linux/if_arp.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/netdevice.h>
+#include <net/af_ieee802154.h>
+#include <net/ieee802154.h>
+#include <net/ieee802154_netdev.h>
+#include <net/ipv6.h>
+
+#include "6lowpan.h"
+
+/* TTL uncompression values */
+static const u8 lowpan_ttl_values[] = {0, 1, 64, 255};
+
+static LIST_HEAD(lowpan_devices);
+
+/*
+ * 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 - zeroes + 2 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
+ */
+static const u8 lowpan_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 - zeroes + 2 from packet
+ *   3 -> 8 bytes from prefix - infer 8 bytes from lladdr
+ */
+static const u8 lowpan_unc_ctxconf[] = {0x00, 0x88, 0x82, 0x80};
+
+/*
+ * Uncompression of ctx-base
+ *   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
+ */
+static const u8 lowpan_unc_mxconf[] = {0x0f, 0x25, 0x23, 0x21};
+
+/* Link local prefix */
+static const u8 lowpan_llprefix[] = {0xfe, 0x80};
+
+/* private device info */
+struct lowpan_dev_info {
+       struct net_device       *real_dev; /* real WPAN device ptr */
+       struct mutex            dev_list_mtx; /* mutex for list ops */
+};
+
+struct lowpan_dev_record {
+       struct net_device *ldev;
+       struct list_head list;
+};
+
+static inline struct
+lowpan_dev_info *lowpan_dev_info(const struct net_device *dev)
+{
+       return netdev_priv(dev);
+}
+
+static inline void lowpan_address_flip(u8 *src, u8 *dest)
+{
+       int i;
+       for (i = 0; i < IEEE802154_ADDR_LEN; i++)
+               (dest)[IEEE802154_ADDR_LEN - i - 1] = (src)[i];
+}
+
+/* list of all 6lowpan devices, uses for package delivering */
+/* print data in line */
+static inline void lowpan_raw_dump_inline(const char *caller, char *msg,
+                                  unsigned char *buf, int len)
+{
+#ifdef DEBUG
+       if (msg)
+               pr_debug("(%s) %s: ", caller, msg);
+       print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_NONE,
+                      16, 1, buf, len, false);
+#endif /* DEBUG */
+}
+
+/*
+ * print data in a table format:
+ *
+ * addr: xx xx xx xx xx xx
+ * addr: xx xx xx xx xx xx
+ * ...
+ */
+static inline void lowpan_raw_dump_table(const char *caller, char *msg,
+                                  unsigned char *buf, int len)
+{
+#ifdef DEBUG
+       if (msg)
+               pr_debug("(%s) %s:\n", caller, msg);
+       print_hex_dump(KERN_DEBUG, "\t", DUMP_PREFIX_OFFSET,
+                      16, 1, buf, len, false);
+#endif /* DEBUG */
+}
+
+static u8
+lowpan_compress_addr_64(u8 **hc06_ptr, u8 shift, const struct in6_addr *ipaddr,
+                const unsigned char *lladdr)
+{
+       u8 val = 0;
+
+       if (is_addr_mac_addr_based(ipaddr, lladdr))
+               val = 3; /* 0-bits */
+       else if (lowpan_is_iid_16_bit_compressable(ipaddr)) {
+               /* compress IID to 16 bits xxxx::XXXX */
+               memcpy(*hc06_ptr, &ipaddr->s6_addr16[7], 2);
+               *hc06_ptr += 2;
+               val = 2; /* 16-bits */
+       } else {
+               /* do not compress IID => xxxx::IID */
+               memcpy(*hc06_ptr, &ipaddr->s6_addr16[4], 8);
+               *hc06_ptr += 8;
+               val = 1; /* 64-bits */
+       }
+
+       return rol8(val, shift);
+}
+
+static void
+lowpan_uip_ds6_set_addr_iid(struct in6_addr *ipaddr, unsigned char *lladdr)
+{
+       memcpy(&ipaddr->s6_addr[8], lladdr, IEEE802154_ALEN);
+       /* second bit-flip (Universe/Local) is done according RFC2464 */
+       ipaddr->s6_addr[8] ^= 0x02;
+}
+
+/*
+ * 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 int
+lowpan_uncompress_addr(struct sk_buff *skb, struct in6_addr *ipaddr,
+       u8 const *prefix, u8 pref_post_count, unsigned char *lladdr)
+{
+       u8 prefcount = pref_post_count >> 4;
+       u8 postcount = pref_post_count & 0x0f;
+
+       /* full nibble 15 => 16 */
+       prefcount = (prefcount == 15 ? 16 : prefcount);
+       postcount = (postcount == 15 ? 16 : postcount);
+
+       if (lladdr)
+               lowpan_raw_dump_inline(__func__, "linklocal address",
+                                               lladdr, IEEE802154_ALEN);
+       if (prefcount > 0)
+               memcpy(ipaddr, prefix, prefcount);
+
+       if (prefcount + postcount < 16)
+               memset(&ipaddr->s6_addr[prefcount], 0,
+                                       16 - (prefcount + postcount));
+
+       if (postcount > 0) {
+               memcpy(&ipaddr->s6_addr[16 - postcount], skb->data, postcount);
+               skb_pull(skb, postcount);
+       } else if (prefcount > 0) {
+               if (lladdr == NULL)
+                       return -EINVAL;
+
+               /* no IID based configuration if no prefix and no data */
+               lowpan_uip_ds6_set_addr_iid(ipaddr, lladdr);
+       }
+
+       pr_debug("(%s): uncompressing %d + %d => ", __func__, prefcount,
+                                                               postcount);
+       lowpan_raw_dump_inline(NULL, NULL, ipaddr->s6_addr, 16);
+
+       return 0;
+}
+
+static u8 lowpan_fetch_skb_u8(struct sk_buff *skb)
+{
+       u8 ret;
+
+       ret = skb->data[0];
+       skb_pull(skb, 1);
+
+       return ret;
+}
+
+static int lowpan_header_create(struct sk_buff *skb,
+                          struct net_device *dev,
+                          unsigned short type, const void *_daddr,
+                          const void *_saddr, unsigned len)
+{
+       u8 tmp, iphc0, iphc1, *hc06_ptr;
+       struct ipv6hdr *hdr;
+       const u8 *saddr = _saddr;
+       const u8 *daddr = _daddr;
+       u8 *head;
+       struct ieee802154_addr sa, da;
+
+       if (type != ETH_P_IPV6)
+               return 0;
+               /* TODO:
+                * if this package isn't ipv6 one, where should it be routed?
+                */
+       head = kzalloc(100, GFP_KERNEL);
+       if (head == NULL)
+               return -ENOMEM;
+
+       hdr = ipv6_hdr(skb);
+       hc06_ptr = head + 2;
+
+       pr_debug("(%s): IPv6 header dump:\n\tversion = %d\n\tlength  = %d\n"
+                "\tnexthdr = 0x%02x\n\thop_lim = %d\n", __func__,
+               hdr->version, ntohs(hdr->payload_len), hdr->nexthdr,
+               hdr->hop_limit);
+
+       lowpan_raw_dump_table(__func__, "raw skb network header dump",
+               skb_network_header(skb), sizeof(struct ipv6hdr));
+
+       if (!saddr)
+               saddr = dev->dev_addr;
+
+       lowpan_raw_dump_inline(__func__, "saddr", (unsigned char *)saddr, 8);
+
+       /*
+        * 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;
+
+       /* TODO: context lookup */
+
+       lowpan_raw_dump_inline(__func__, "daddr", (unsigned char *)daddr, 8);
+
+       /*
+        * 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 one is DSCP | ECN */
+       tmp = (hdr->priority << 4) | (hdr->flow_lbl[0] >> 4);
+       tmp = ((tmp & 0x03) << 6) | (tmp >> 2);
+
+       if (((hdr->flow_lbl[0] & 0x0F) == 0) &&
+            (hdr->flow_lbl[1] == 0) && (hdr->flow_lbl[2] == 0)) {
+               /* flow label can be compressed */
+               iphc0 |= LOWPAN_IPHC_FL_C;
+               if ((hdr->priority == 0) &&
+                  ((hdr->flow_lbl[0] & 0xF0) == 0)) {
+                       /* compress (elide) all */
+                       iphc0 |= LOWPAN_IPHC_TC_C;
+               } else {
+                       /* compress only the flow label */
+                       *hc06_ptr = tmp;
+                       hc06_ptr += 1;
+               }
+       } else {
+               /* Flow label cannot be compressed */
+               if ((hdr->priority == 0) &&
+                  ((hdr->flow_lbl[0] & 0xF0) == 0)) {
+                       /* compress only traffic class */
+                       iphc0 |= LOWPAN_IPHC_TC_C;
+                       *hc06_ptr = (tmp & 0xc0) | (hdr->flow_lbl[0] & 0x0F);
+                       memcpy(hc06_ptr + 1, &hdr->flow_lbl[1], 2);
+                       hc06_ptr += 3;
+               } else {
+                       /* compress nothing */
+                       memcpy(hc06_ptr, &hdr, 4);
+                       /* replace the top byte with new ECN | DSCP format */
+                       *hc06_ptr = tmp;
+                       hc06_ptr += 4;
+               }
+       }
+
+       /* NOTE: payload length is always compressed */
+
+       /* Next Header is compress if UDP */
+       if (hdr->nexthdr == UIP_PROTO_UDP)
+               iphc0 |= LOWPAN_IPHC_NH_C;
+
+/* TODO: next header compression */
+
+       if ((iphc0 & LOWPAN_IPHC_NH_C) == 0) {
+               *hc06_ptr = hdr->nexthdr;
+               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 (hdr->hop_limit) {
+       case 1:
+               iphc0 |= LOWPAN_IPHC_TTL_1;
+               break;
+       case 64:
+               iphc0 |= LOWPAN_IPHC_TTL_64;
+               break;
+       case 255:
+               iphc0 |= LOWPAN_IPHC_TTL_255;
+               break;
+       default:
+               *hc06_ptr = hdr->hop_limit;
+               break;
+       }
+
+       /* source address compression */
+       if (is_addr_unspecified(&hdr->saddr)) {
+               pr_debug("(%s): source address is unspecified, setting SAC\n",
+                                                               __func__);
+               iphc1 |= LOWPAN_IPHC_SAC;
+       /* TODO: context lookup */
+       } else if (is_addr_link_local(&hdr->saddr)) {
+               pr_debug("(%s): source address is link-local\n", __func__);
+               iphc1 |= lowpan_compress_addr_64(&hc06_ptr,
+                               LOWPAN_IPHC_SAM_BIT, &hdr->saddr, saddr);
+       } else {
+               pr_debug("(%s): send the full source address\n", __func__);
+               memcpy(hc06_ptr, &hdr->saddr.s6_addr16[0], 16);
+               hc06_ptr += 16;
+       }
+
+       /* destination address compression */
+       if (is_addr_mcast(&hdr->daddr)) {
+               pr_debug("(%s): destination address is multicast", __func__);
+               iphc1 |= LOWPAN_IPHC_M;
+               if (lowpan_is_mcast_addr_compressable8(&hdr->daddr)) {
+                       pr_debug("compressed to 1 octet\n");
+                       iphc1 |= LOWPAN_IPHC_DAM_11;
+                       /* use last byte */
+                       *hc06_ptr = hdr->daddr.s6_addr[15];
+                       hc06_ptr += 1;
+               } else if (lowpan_is_mcast_addr_compressable32(&hdr->daddr)) {
+                       pr_debug("compressed to 4 octets\n");
+                       iphc1 |= LOWPAN_IPHC_DAM_10;
+                       /* second byte + the last three */
+                       *hc06_ptr = hdr->daddr.s6_addr[1];
+                       memcpy(hc06_ptr + 1, &hdr->daddr.s6_addr[13], 3);
+                       hc06_ptr += 4;
+               } else if (lowpan_is_mcast_addr_compressable48(&hdr->daddr)) {
+                       pr_debug("compressed to 6 octets\n");
+                       iphc1 |= LOWPAN_IPHC_DAM_01;
+                       /* second byte + the last five */
+                       *hc06_ptr = hdr->daddr.s6_addr[1];
+                       memcpy(hc06_ptr + 1, &hdr->daddr.s6_addr[11], 5);
+                       hc06_ptr += 6;
+               } else {
+                       pr_debug("using full address\n");
+                       iphc1 |= LOWPAN_IPHC_DAM_00;
+                       memcpy(hc06_ptr, &hdr->daddr.s6_addr[0], 16);
+                       hc06_ptr += 16;
+               }
+       } else {
+               pr_debug("(%s): destination address is unicast: ", __func__);
+               /* TODO: context lookup */
+               if (is_addr_link_local(&hdr->daddr)) {
+                       pr_debug("destination address is link-local\n");
+                       iphc1 |= lowpan_compress_addr_64(&hc06_ptr,
+                               LOWPAN_IPHC_DAM_BIT, &hdr->daddr, daddr);
+               } else {
+                       pr_debug("using full address\n");
+                       memcpy(hc06_ptr, &hdr->daddr.s6_addr16[0], 16);
+                       hc06_ptr += 16;
+               }
+       }
+
+       /* TODO: UDP header compression */
+       /* TODO: Next Header compression */
+
+       head[0] = iphc0;
+       head[1] = iphc1;
+
+       skb_pull(skb, sizeof(struct ipv6hdr));
+       memcpy(skb_push(skb, hc06_ptr - head), head, hc06_ptr - head);
+
+       kfree(head);
+
+       lowpan_raw_dump_table(__func__, "raw skb data dump", skb->data,
+                               skb->len);
+
+       /*
+        * NOTE1: I'm still unsure about the fact that compression and WPAN
+        * header are created here and not later in the xmit. So wait for
+        * an opinion of net maintainers.
+        */
+       /*
+        * NOTE2: to be absolutely correct, we must derive PANid information
+        * from MAC subif of the 'dev' and 'real_dev' network devices, but
+        * this isn't implemented in mainline yet, so currently we assign 0xff
+        */
+       {
+               /* prepare wpan address data */
+               sa.addr_type = IEEE802154_ADDR_LONG;
+               sa.pan_id = 0xff;
+
+               da.addr_type = IEEE802154_ADDR_LONG;
+               da.pan_id = 0xff;
+
+               memcpy(&(da.hwaddr), daddr, 8);
+               memcpy(&(sa.hwaddr), saddr, 8);
+
+               mac_cb(skb)->flags = IEEE802154_FC_TYPE_DATA;
+               return dev_hard_header(skb, lowpan_dev_info(dev)->real_dev,
+                               type, (void *)&da, (void *)&sa, skb->len);
+       }
+}
+
+static int lowpan_skb_deliver(struct sk_buff *skb, struct ipv6hdr *hdr)
+{
+       struct sk_buff *new;
+       struct lowpan_dev_record *entry;
+       int stat = NET_RX_SUCCESS;
+
+       new = skb_copy_expand(skb, sizeof(struct ipv6hdr), skb_tailroom(skb),
+                                                               GFP_KERNEL);
+       kfree_skb(skb);
+
+       if (NULL == new)
+               return -ENOMEM;
+
+       skb_push(new, sizeof(struct ipv6hdr));
+       skb_reset_network_header(new);
+       skb_copy_to_linear_data(new, hdr, sizeof(struct ipv6hdr));
+
+       new->protocol = htons(ETH_P_IPV6);
+       new->pkt_type = PACKET_HOST;
+
+       rcu_read_lock();
+       list_for_each_entry_rcu(entry, &lowpan_devices, list)
+               if (lowpan_dev_info(entry->ldev)->real_dev == new->dev) {
+                       skb = skb_copy(new, GFP_KERNEL);
+                       skb->dev = entry->ldev;
+
+                       if (in_interrupt())
+                               stat = netif_rx(skb);
+                       else
+                               stat = netif_rx_ni(skb);
+               }
+       rcu_read_unlock();
+
+       kfree_skb(new);
+
+       return stat;
+}
+
+static int
+lowpan_process_data(struct sk_buff *skb)
+{
+       struct ipv6hdr hdr;
+       u8 tmp, iphc0, iphc1, num_context = 0;
+       u8 *_saddr, *_daddr;
+       int err;
+
+       lowpan_raw_dump_table(__func__, "raw skb data dump", skb->data,
+                               skb->len);
+       /* at least two bytes will be used for the encoding */
+       if (skb->len < 2)
+               goto drop;
+       iphc0 = lowpan_fetch_skb_u8(skb);
+       iphc1 = lowpan_fetch_skb_u8(skb);
+
+       _saddr = mac_cb(skb)->sa.hwaddr;
+       _daddr = mac_cb(skb)->da.hwaddr;
+
+       pr_debug("(%s): iphc0 = %02x, iphc1 = %02x\n", __func__, iphc0, iphc1);
+
+       /* another if the CID flag is set */
+       if (iphc1 & LOWPAN_IPHC_CID) {
+               pr_debug("(%s): CID flag is set, increase header with one\n",
+                                                               __func__);
+               if (!skb->len)
+                       goto drop;
+               num_context = lowpan_fetch_skb_u8(skb);
+       }
+
+       hdr.version = 6;
+
+       /* Traffic Class and Flow Label */
+       switch ((iphc0 & LOWPAN_IPHC_TF) >> 3) {
+       /*
+        * Traffic Class and FLow Label carried in-line
+        * ECN + DSCP + 4-bit Pad + Flow Label (4 bytes)
+        */
+       case 0: /* 00b */
+               if (!skb->len)
+                       goto drop;
+               tmp = lowpan_fetch_skb_u8(skb);
+               memcpy(&hdr.flow_lbl, &skb->data[0], 3);
+               skb_pull(skb, 3);
+               hdr.priority = ((tmp >> 2) & 0x0f);
+               hdr.flow_lbl[0] = ((tmp >> 2) & 0x30) | (tmp << 6) |
+                                       (hdr.flow_lbl[0] & 0x0f);
+               break;
+       /*
+        * Traffic class carried in-line
+        * ECN + DSCP (1 byte), Flow Label is elided
+        */
+       case 1: /* 10b */
+               if (!skb->len)
+                       goto drop;
+               tmp = lowpan_fetch_skb_u8(skb);
+               hdr.priority = ((tmp >> 2) & 0x0f);
+               hdr.flow_lbl[0] = ((tmp << 6) & 0xC0) | ((tmp >> 2) & 0x30);
+               hdr.flow_lbl[1] = 0;
+               hdr.flow_lbl[2] = 0;
+               break;
+       /*
+        * Flow Label carried in-line
+        * ECN + 2-bit Pad + Flow Label (3 bytes), DSCP is elided
+        */
+       case 2: /* 01b */
+               if (!skb->len)
+                       goto drop;
+               tmp = lowpan_fetch_skb_u8(skb);
+               hdr.flow_lbl[0] = (skb->data[0] & 0x0F) | ((tmp >> 2) & 0x30);
+               memcpy(&hdr.flow_lbl[1], &skb->data[0], 2);
+               skb_pull(skb, 2);
+               break;
+       /* Traffic Class and Flow Label are elided */
+       case 3: /* 11b */
+               hdr.priority = 0;
+               hdr.flow_lbl[0] = 0;
+               hdr.flow_lbl[1] = 0;
+               hdr.flow_lbl[2] = 0;
+               break;
+       default:
+               break;
+       }
+
+       /* Next Header */
+       if ((iphc0 & LOWPAN_IPHC_NH_C) == 0) {
+               /* Next header is carried inline */
+               if (!skb->len)
+                       goto drop;
+               hdr.nexthdr = lowpan_fetch_skb_u8(skb);
+               pr_debug("(%s): NH flag is set, next header is carried "
+                        "inline: %02x\n", __func__, hdr.nexthdr);
+       }
+
+       /* Hop Limit */
+       if ((iphc0 & 0x03) != LOWPAN_IPHC_TTL_I)
+               hdr.hop_limit = lowpan_ttl_values[iphc0 & 0x03];
+       else {
+               if (!skb->len)
+                       goto drop;
+               hdr.hop_limit = lowpan_fetch_skb_u8(skb);
+       }
+
+       /* Extract SAM to the tmp variable */
+       tmp = ((iphc1 & LOWPAN_IPHC_SAM) >> LOWPAN_IPHC_SAM_BIT) & 0x03;
+
+       /* Source address uncompression */
+       pr_debug("(%s): source address stateless compression\n", __func__);
+       err = lowpan_uncompress_addr(skb, &hdr.saddr, lowpan_llprefix,
+                               lowpan_unc_llconf[tmp], skb->data);
+       if (err)
+               goto drop;
+
+       /* Extract DAM to the tmp variable */
+       tmp = ((iphc1 & LOWPAN_IPHC_DAM_11) >> LOWPAN_IPHC_DAM_BIT) & 0x03;
+
+       /* check for Multicast Compression */
+       if (iphc1 & LOWPAN_IPHC_M) {
+               if (iphc1 & LOWPAN_IPHC_DAC) {
+                       pr_debug("(%s): destination address context-based "
+                                "multicast compression\n", __func__);
+                       /* TODO: implement this */
+               } else {
+                       u8 prefix[] = {0xff, 0x02};
+
+                       pr_debug("(%s): destination address non-context-based"
+                                " multicast compression\n", __func__);
+                       if (0 < tmp && tmp < 3) {
+                               if (!skb->len)
+                                       goto drop;
+                               else
+                                       prefix[1] = lowpan_fetch_skb_u8(skb);
+                       }
+
+                       err = lowpan_uncompress_addr(skb, &hdr.daddr, prefix,
+                                       lowpan_unc_mxconf[tmp], NULL);
+                       if (err)
+                               goto drop;
+               }
+       } else {
+               pr_debug("(%s): destination address stateless compression\n",
+                                                               __func__);
+               err = lowpan_uncompress_addr(skb, &hdr.daddr, lowpan_llprefix,
+                               lowpan_unc_llconf[tmp], skb->data);
+               if (err)
+                       goto drop;
+       }
+
+       /* TODO: UDP header parse */
+
+       /* Not fragmented package */
+       hdr.payload_len = htons(skb->len);
+
+       pr_debug("(%s): skb headroom size = %d, data length = %d\n", __func__,
+                                               skb_headroom(skb), skb->len);
+
+       pr_debug("(%s): IPv6 header dump:\n\tversion = %d\n\tlength  = %d\n\t"
+                "nexthdr = 0x%02x\n\thop_lim = %d\n", __func__, hdr.version,
+                ntohs(hdr.payload_len), hdr.nexthdr, hdr.hop_limit);
+
+       lowpan_raw_dump_table(__func__, "raw header dump", (u8 *)&hdr,
+                                                       sizeof(hdr));
+       return lowpan_skb_deliver(skb, &hdr);
+drop:
+       kfree(skb);
+       return -EINVAL;
+}
+
+static int lowpan_set_address(struct net_device *dev, void *p)
+{
+       struct sockaddr *sa = p;
+
+       if (netif_running(dev))
+               return -EBUSY;
+
+       /* TODO: validate addr */
+       memcpy(dev->dev_addr, sa->sa_data, dev->addr_len);
+
+       return 0;
+}
+
+static netdev_tx_t lowpan_xmit(struct sk_buff *skb, struct net_device *dev)
+{
+       int err = 0;
+
+       pr_debug("(%s): package xmit\n", __func__);
+
+       skb->dev = lowpan_dev_info(dev)->real_dev;
+       if (skb->dev == NULL) {
+               pr_debug("(%s) ERROR: no real wpan device found\n", __func__);
+               dev_kfree_skb(skb);
+       } else
+               err = dev_queue_xmit(skb);
+
+       return (err < 0 ? NETDEV_TX_BUSY : NETDEV_TX_OK);
+}
+
+static void lowpan_dev_free(struct net_device *dev)
+{
+       dev_put(lowpan_dev_info(dev)->real_dev);
+       free_netdev(dev);
+}
+
+static struct header_ops lowpan_header_ops = {
+       .create = lowpan_header_create,
+};
+
+static const struct net_device_ops lowpan_netdev_ops = {
+       .ndo_start_xmit         = lowpan_xmit,
+       .ndo_set_mac_address    = lowpan_set_address,
+};
+
+static void lowpan_setup(struct net_device *dev)
+{
+       pr_debug("(%s)\n", __func__);
+
+       dev->addr_len           = IEEE802154_ADDR_LEN;
+       memset(dev->broadcast, 0xff, IEEE802154_ADDR_LEN);
+       dev->type               = ARPHRD_IEEE802154;
+       dev->features           = NETIF_F_NO_CSUM;
+       /* Frame Control + Sequence Number + Address fields + Security Header */
+       dev->hard_header_len    = 2 + 1 + 20 + 14;
+       dev->needed_tailroom    = 2; /* FCS */
+       dev->mtu                = 1281;
+       dev->tx_queue_len       = 0;
+       dev->flags              = IFF_NOARP | IFF_BROADCAST;
+       dev->watchdog_timeo     = 0;
+
+       dev->netdev_ops         = &lowpan_netdev_ops;
+       dev->header_ops         = &lowpan_header_ops;
+       dev->destructor         = lowpan_dev_free;
+}
+
+static int lowpan_validate(struct nlattr *tb[], struct nlattr *data[])
+{
+       pr_debug("(%s)\n", __func__);
+
+       if (tb[IFLA_ADDRESS]) {
+               if (nla_len(tb[IFLA_ADDRESS]) != IEEE802154_ADDR_LEN)
+                       return -EINVAL;
+       }
+       return 0;
+}
+
+static int lowpan_rcv(struct sk_buff *skb, struct net_device *dev,
+       struct packet_type *pt, struct net_device *orig_dev)
+{
+       if (!netif_running(dev))
+               goto drop;
+
+       if (dev->type != ARPHRD_IEEE802154)
+               goto drop;
+
+       /* check that it's our buffer */
+       if ((skb->data[0] & 0xe0) == 0x60)
+               lowpan_process_data(skb);
+
+       return NET_RX_SUCCESS;
+
+drop:
+       kfree_skb(skb);
+       return NET_RX_DROP;
+}
+
+static int lowpan_newlink(struct net *src_net, struct net_device *dev,
+                         struct nlattr *tb[], struct nlattr *data[])
+{
+       struct net_device *real_dev;
+       struct lowpan_dev_record *entry;
+
+       pr_debug("(%s)\n", __func__);
+
+       if (!tb[IFLA_LINK])
+               return -EINVAL;
+       /* find and hold real wpan device */
+       real_dev = dev_get_by_index(src_net, nla_get_u32(tb[IFLA_LINK]));
+       if (!real_dev)
+               return -ENODEV;
+
+       lowpan_dev_info(dev)->real_dev = real_dev;
+       mutex_init(&lowpan_dev_info(dev)->dev_list_mtx);
+
+       entry = kzalloc(sizeof(struct lowpan_dev_record), GFP_KERNEL);
+       if (!entry)
+               return -ENOMEM;
+
+       entry->ldev = dev;
+
+       mutex_lock(&lowpan_dev_info(dev)->dev_list_mtx);
+       INIT_LIST_HEAD(&entry->list);
+       list_add_tail(&entry->list, &lowpan_devices);
+       mutex_unlock(&lowpan_dev_info(dev)->dev_list_mtx);
+
+       register_netdevice(dev);
+
+       return 0;
+}
+
+static void lowpan_dellink(struct net_device *dev, struct list_head *head)
+{
+       struct lowpan_dev_info *lowpan_dev = lowpan_dev_info(dev);
+       struct net_device *real_dev = lowpan_dev->real_dev;
+       struct lowpan_dev_record *entry;
+
+       ASSERT_RTNL();
+
+       mutex_lock(&lowpan_dev_info(dev)->dev_list_mtx);
+       list_for_each_entry(entry, &lowpan_devices, list)
+               if (entry->ldev == dev) {
+                       list_del(&entry->list);
+                       kfree(entry);
+               }
+       mutex_unlock(&lowpan_dev_info(dev)->dev_list_mtx);
+
+       mutex_destroy(&lowpan_dev_info(dev)->dev_list_mtx);
+
+       unregister_netdevice_queue(dev, head);
+
+       dev_put(real_dev);
+}
+
+static struct rtnl_link_ops lowpan_link_ops __read_mostly = {
+       .kind           = "lowpan",
+       .priv_size      = sizeof(struct lowpan_dev_info),
+       .setup          = lowpan_setup,
+       .newlink        = lowpan_newlink,
+       .dellink        = lowpan_dellink,
+       .validate       = lowpan_validate,
+};
+
+static inline int __init lowpan_netlink_init(void)
+{
+       return rtnl_link_register(&lowpan_link_ops);
+}
+
+static inline void __init lowpan_netlink_fini(void)
+{
+       rtnl_link_unregister(&lowpan_link_ops);
+}
+
+static struct packet_type lowpan_packet_type = {
+       .type = __constant_htons(ETH_P_IEEE802154),
+       .func = lowpan_rcv,
+};
+
+static int __init lowpan_init_module(void)
+{
+       int err = 0;
+
+       pr_debug("(%s)\n", __func__);
+
+       err = lowpan_netlink_init();
+       if (err < 0)
+               goto out;
+
+       dev_add_pack(&lowpan_packet_type);
+out:
+       return err;
+}
+
+static void __exit lowpan_cleanup_module(void)
+{
+       pr_debug("(%s)\n", __func__);
+
+       lowpan_netlink_fini();
+
+       dev_remove_pack(&lowpan_packet_type);
+}
+
+module_init(lowpan_init_module);
+module_exit(lowpan_cleanup_module);
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_RTNL_LINK("lowpan");