kernel/net/6lowpan/iphc.c

   1 /*
   2  * Copyright 2011, Siemens AG
   3  * written by Alexander Smirnov <alex.bluesman.smirnov@gmail.com>
   4  */
   5
   6 /* Based on patches from Jon Smirl <jonsmirl@gmail.com>
   7  * Copyright (c) 2011 Jon Smirl <jonsmirl@gmail.com>
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License version 2
  11  * as published by the Free Software Foundation.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  */
  19
  20 /* Jon's code is based on 6lowpan implementation for Contiki which is:
  21  * Copyright (c) 2008, Swedish Institute of Computer Science.
  22  * All rights reserved.
  23  *
  24  * Redistribution and use in source and binary forms, with or without
  25  * modification, are permitted provided that the following conditions
  26  * are met:
  27  * 1. Redistributions of source code must retain the above copyright
  28  *    notice, this list of conditions and the following disclaimer.
  29  * 2. Redistributions in binary form must reproduce the above copyright
  30  *    notice, this list of conditions and the following disclaimer in the
  31  *    documentation and/or other materials provided with the distribution.
  32  * 3. Neither the name of the Institute nor the names of its contributors
  33  *    may be used to endorse or promote products derived from this software
  34  *    without specific prior written permission.
  35  *
  36  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
  37  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  38  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  39  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
  40  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  41  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  42  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  43  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  44  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  45  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  46  * SUCH DAMAGE.
  47  */
  48
  49 #include <linux/bitops.h>
  50 #include <linux/if_arp.h>
  51 #include <linux/module.h>
  52 #include <linux/netdevice.h>
  53 #include <net/6lowpan.h>
  54 #include <net/ipv6.h>
  55 #include <net/af_ieee802154.h>
  56
  57 #include "nhc.h"
  58
  59 /* Uncompress address function for source and
  60  * destination address(non-multicast).
  61  *
  62  * address_mode is sam value or dam value.
  63  */
  64 static int uncompress_addr(struct sk_buff *skb,
  65                            struct in6_addr *ipaddr, const u8 address_mode,
  66                            const u8 *lladdr, const u8 addr_type,
  67                            const u8 addr_len)
  68 {
  69         bool fail;
  70
  71         switch (address_mode) {
  72         case LOWPAN_IPHC_ADDR_00:
  73                 /* for global link addresses */
  74                 fail = lowpan_fetch_skb(skb, ipaddr->s6_addr, 16);
  75                 break;
  76         case LOWPAN_IPHC_ADDR_01:
  77                 /* fe:80::XXXX:XXXX:XXXX:XXXX */
  78                 ipaddr->s6_addr[0] = 0xFE;
  79                 ipaddr->s6_addr[1] = 0x80;
  80                 fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[8], 8);
  81                 break;
  82         case LOWPAN_IPHC_ADDR_02:
  83                 /* fe:80::ff:fe00:XXXX */
  84                 ipaddr->s6_addr[0] = 0xFE;
  85                 ipaddr->s6_addr[1] = 0x80;
  86                 ipaddr->s6_addr[11] = 0xFF;
  87                 ipaddr->s6_addr[12] = 0xFE;
  88                 fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[14], 2);
  89                 break;
  90         case LOWPAN_IPHC_ADDR_03:
  91                 fail = false;
  92                 switch (addr_type) {
  93                 case IEEE802154_ADDR_LONG:
  94                         /* fe:80::XXXX:XXXX:XXXX:XXXX
  95                          *        \_________________/
  96                          *              hwaddr
  97                          */
  98                         ipaddr->s6_addr[0] = 0xFE;
  99                         ipaddr->s6_addr[1] = 0x80;
 100                         memcpy(&ipaddr->s6_addr[8], lladdr, addr_len);
 101                         /* second bit-flip (Universe/Local)
 102                          * is done according RFC2464
 103                          */
 104                         ipaddr->s6_addr[8] ^= 0x02;
 105                         break;
 106                 case IEEE802154_ADDR_SHORT:
 107                         /* fe:80::ff:fe00:XXXX
 108                          *                \__/
 109                          *             short_addr
 110                          *
 111                          * Universe/Local bit is zero.
 112                          */
 113                         ipaddr->s6_addr[0] = 0xFE;
 114                         ipaddr->s6_addr[1] = 0x80;
 115                         ipaddr->s6_addr[11] = 0xFF;
 116                         ipaddr->s6_addr[12] = 0xFE;
 117                         ipaddr->s6_addr16[7] = htons(*((u16 *)lladdr));
 118                         break;
 119                 default:
 120                         pr_debug("Invalid addr_type set\n");
 121                         return -EINVAL;
 122                 }
 123                 break;
 124         default:
 125                 pr_debug("Invalid address mode value: 0x%x\n", address_mode);
 126                 return -EINVAL;
 127         }
 128
 129         if (fail) {
 130                 pr_debug("Failed to fetch skb data\n");
 131                 return -EIO;
 132         }
 133
 134         raw_dump_inline(NULL, "Reconstructed ipv6 addr is",
 135                         ipaddr->s6_addr, 16);
 136
 137         return 0;
 138 }
 139
 140 /* Uncompress address function for source context
 141  * based address(non-multicast).
 142  */
 143 static int uncompress_context_based_src_addr(struct sk_buff *skb,
 144                                              struct in6_addr *ipaddr,
 145                                              const u8 sam)
 146 {
 147         switch (sam) {
 148         case LOWPAN_IPHC_ADDR_00:
 149                 /* unspec address ::
 150                  * Do nothing, address is already ::
 151                  */
 152                 break;
 153         case LOWPAN_IPHC_ADDR_01:
 154                 /* TODO */
 155         case LOWPAN_IPHC_ADDR_02:
 156                 /* TODO */
 157         case LOWPAN_IPHC_ADDR_03:
 158                 /* TODO */
 159                 netdev_warn(skb->dev, "SAM value 0x%x not supported\n", sam);
 160                 return -EINVAL;
 161         default:
 162                 pr_debug("Invalid sam value: 0x%x\n", sam);
 163                 return -EINVAL;
 164         }
 165
 166         raw_dump_inline(NULL,
 167                         "Reconstructed context based ipv6 src addr is",
 168                         ipaddr->s6_addr, 16);
 169
 170         return 0;
 171 }
 172
 173 /* Uncompress function for multicast destination address,
 174  * when M bit is set.
 175  */
 176 static int lowpan_uncompress_multicast_daddr(struct sk_buff *skb,
 177                                              struct in6_addr *ipaddr,
 178                                              const u8 dam)
 179 {
 180         bool fail;
 181
 182         switch (dam) {
 183         case LOWPAN_IPHC_DAM_00:
 184                 /* 00:  128 bits.  The full address
 185                  * is carried in-line.
 186                  */
 187                 fail = lowpan_fetch_skb(skb, ipaddr->s6_addr, 16);
 188                 break;
 189         case LOWPAN_IPHC_DAM_01:
 190                 /* 01:  48 bits.  The address takes
 191                  * the form ffXX::00XX:XXXX:XXXX.
 192                  */
 193                 ipaddr->s6_addr[0] = 0xFF;
 194                 fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[1], 1);
 195                 fail |= lowpan_fetch_skb(skb, &ipaddr->s6_addr[11], 5);
 196                 break;
 197         case LOWPAN_IPHC_DAM_10:
 198                 /* 10:  32 bits.  The address takes
 199                  * the form ffXX::00XX:XXXX.
 200                  */
 201                 ipaddr->s6_addr[0] = 0xFF;
 202                 fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[1], 1);
 203                 fail |= lowpan_fetch_skb(skb, &ipaddr->s6_addr[13], 3);
 204                 break;
 205         case LOWPAN_IPHC_DAM_11:
 206                 /* 11:  8 bits.  The address takes
 207                  * the form ff02::00XX.
 208                  */
 209                 ipaddr->s6_addr[0] = 0xFF;
 210                 ipaddr->s6_addr[1] = 0x02;
 211                 fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[15], 1);
 212                 break;
 213         default:
 214                 pr_debug("DAM value has a wrong value: 0x%x\n", dam);
 215                 return -EINVAL;
 216         }
 217
 218         if (fail) {
 219                 pr_debug("Failed to fetch skb data\n");
 220                 return -EIO;
 221         }
 222
 223         raw_dump_inline(NULL, "Reconstructed ipv6 multicast addr is",
 224                         ipaddr->s6_addr, 16);
 225
 226         return 0;
 227 }
 228
 229 /* TTL uncompression values */
 230 static const u8 lowpan_ttl_values[] = { 0, 1, 64, 255 };
 231
 232 int
 233 lowpan_header_decompress(struct sk_buff *skb, struct net_device *dev,
 234                          const u8 *saddr, const u8 saddr_type,
 235                          const u8 saddr_len, const u8 *daddr,
 236                          const u8 daddr_type, const u8 daddr_len,
 237                          u8 iphc0, u8 iphc1)
 238 {
 239         struct ipv6hdr hdr = {};
 240         u8 tmp, num_context = 0;
 241         int err;
 242
 243         raw_dump_table(__func__, "raw skb data dump uncompressed",
 244                        skb->data, skb->len);
 245
 246         /* another if the CID flag is set */
 247         if (iphc1 & LOWPAN_IPHC_CID) {
 248                 pr_debug("CID flag is set, increase header with one\n");
 249                 if (lowpan_fetch_skb(skb, &num_context, sizeof(num_context)))
 250                         return -EINVAL;
 251         }
 252
 253         hdr.version = 6;
 254
 255         /* Traffic Class and Flow Label */
 256         switch ((iphc0 & LOWPAN_IPHC_TF) >> 3) {
 257         /* Traffic Class and FLow Label carried in-line
 258          * ECN + DSCP + 4-bit Pad + Flow Label (4 bytes)
 259          */
 260         case 0: /* 00b */
 261                 if (lowpan_fetch_skb(skb, &tmp, sizeof(tmp)))
 262                         return -EINVAL;
 263
 264                 memcpy(&hdr.flow_lbl, &skb->data[0], 3);
 265                 skb_pull(skb, 3);
 266                 hdr.priority = ((tmp >> 2) & 0x0f);
 267                 hdr.flow_lbl[0] = ((tmp >> 2) & 0x30) | (tmp << 6) |
 268                                         (hdr.flow_lbl[0] & 0x0f);
 269                 break;
 270         /* Traffic class carried in-line
 271          * ECN + DSCP (1 byte), Flow Label is elided
 272          */
 273         case 2: /* 10b */
 274                 if (lowpan_fetch_skb(skb, &tmp, sizeof(tmp)))
 275                         return -EINVAL;
 276
 277                 hdr.priority = ((tmp >> 2) & 0x0f);
 278                 hdr.flow_lbl[0] = ((tmp << 6) & 0xC0) | ((tmp >> 2) & 0x30);
 279                 break;
 280         /* Flow Label carried in-line
 281          * ECN + 2-bit Pad + Flow Label (3 bytes), DSCP is elided
 282          */
 283         case 1: /* 01b */
 284                 if (lowpan_fetch_skb(skb, &tmp, sizeof(tmp)))
 285                         return -EINVAL;
 286
 287                 hdr.flow_lbl[0] = (skb->data[0] & 0x0F) | ((tmp >> 2) & 0x30);
 288                 memcpy(&hdr.flow_lbl[1], &skb->data[0], 2);
 289                 skb_pull(skb, 2);
 290                 break;
 291         /* Traffic Class and Flow Label are elided */
 292         case 3: /* 11b */
 293                 break;
 294         default:
 295                 break;
 296         }
 297
 298         /* Next Header */
 299         if ((iphc0 & LOWPAN_IPHC_NH_C) == 0) {
 300                 /* Next header is carried inline */
 301                 if (lowpan_fetch_skb(skb, &hdr.nexthdr, sizeof(hdr.nexthdr)))
 302                         return -EINVAL;
 303
 304                 pr_debug("NH flag is set, next header carried inline: %02x\n",
 305                          hdr.nexthdr);
 306         }
 307
 308         /* Hop Limit */
 309         if ((iphc0 & 0x03) != LOWPAN_IPHC_TTL_I) {
 310                 hdr.hop_limit = lowpan_ttl_values[iphc0 & 0x03];
 311         } else {
 312                 if (lowpan_fetch_skb(skb, &hdr.hop_limit,
 313                                      sizeof(hdr.hop_limit)))
 314                         return -EINVAL;
 315         }
 316
 317         /* Extract SAM to the tmp variable */
 318         tmp = ((iphc1 & LOWPAN_IPHC_SAM) >> LOWPAN_IPHC_SAM_BIT) & 0x03;
 319
 320         if (iphc1 & LOWPAN_IPHC_SAC) {
 321                 /* Source address context based uncompression */
 322                 pr_debug("SAC bit is set. Handle context based source address.\n");
 323                 err = uncompress_context_based_src_addr(skb, &hdr.saddr, tmp);
 324         } else {
 325                 /* Source address uncompression */
 326                 pr_debug("source address stateless compression\n");
 327                 err = uncompress_addr(skb, &hdr.saddr, tmp, saddr,
 328                                       saddr_type, saddr_len);
 329         }
 330
 331         /* Check on error of previous branch */
 332         if (err)
 333                 return -EINVAL;
 334
 335         /* Extract DAM to the tmp variable */
 336         tmp = ((iphc1 & LOWPAN_IPHC_DAM_11) >> LOWPAN_IPHC_DAM_BIT) & 0x03;
 337
 338         /* check for Multicast Compression */
 339         if (iphc1 & LOWPAN_IPHC_M) {
 340                 if (iphc1 & LOWPAN_IPHC_DAC) {
 341                         pr_debug("dest: context-based mcast compression\n");
 342                         /* TODO: implement this */
 343                 } else {
 344                         err = lowpan_uncompress_multicast_daddr(skb, &hdr.daddr,
 345                                                                 tmp);
 346
 347                         if (err)
 348                                 return -EINVAL;
 349                 }
 350         } else {
 351                 err = uncompress_addr(skb, &hdr.daddr, tmp, daddr,
 352                                       daddr_type, daddr_len);
 353                 pr_debug("dest: stateless compression mode %d dest %pI6c\n",
 354                          tmp, &hdr.daddr);
 355                 if (err)
 356                         return -EINVAL;
 357         }
 358
 359         /* Next header data uncompression */
 360         if (iphc0 & LOWPAN_IPHC_NH_C) {
 361                 err = lowpan_nhc_do_uncompression(skb, dev, &hdr);
 362                 if (err < 0)
 363                         return err;
 364         } else {
 365                 err = skb_cow(skb, sizeof(hdr));
 366                 if (unlikely(err))
 367                         return err;
 368         }
 369
 370         hdr.payload_len = htons(skb->len);
 371
 372         pr_debug("skb headroom size = %d, data length = %d\n",
 373                  skb_headroom(skb), skb->len);
 374
 375         pr_debug("IPv6 header dump:\n\tversion = %d\n\tlength  = %d\n\t"
 376                  "nexthdr = 0x%02x\n\thop_lim = %d\n\tdest    = %pI6c\n",
 377                 hdr.version, ntohs(hdr.payload_len), hdr.nexthdr,
 378                 hdr.hop_limit, &hdr.daddr);
 379
 380         skb_push(skb, sizeof(hdr));
 381         skb_reset_network_header(skb);
 382         skb_copy_to_linear_data(skb, &hdr, sizeof(hdr));
 383
 384         raw_dump_table(__func__, "raw header dump", (u8 *)&hdr, sizeof(hdr));
 385
 386         return 0;
 387 }
 388 EXPORT_SYMBOL_GPL(lowpan_header_decompress);
 389
 390 static u8 lowpan_compress_addr_64(u8 **hc_ptr, u8 shift,
 391                                   const struct in6_addr *ipaddr,
 392                                   const unsigned char *lladdr)
 393 {
 394         u8 val = 0;
 395
 396         if (is_addr_mac_addr_based(ipaddr, lladdr)) {
 397                 val = 3; /* 0-bits */
 398                 pr_debug("address compression 0 bits\n");
 399         } else if (lowpan_is_iid_16_bit_compressable(ipaddr)) {
 400                 /* compress IID to 16 bits xxxx::XXXX */
 401                 lowpan_push_hc_data(hc_ptr, &ipaddr->s6_addr16[7], 2);
 402                 val = 2; /* 16-bits */
 403                 raw_dump_inline(NULL, "Compressed ipv6 addr is (16 bits)",
 404                                 *hc_ptr - 2, 2);
 405         } else {
 406                 /* do not compress IID => xxxx::IID */
 407                 lowpan_push_hc_data(hc_ptr, &ipaddr->s6_addr16[4], 8);
 408                 val = 1; /* 64-bits */
 409                 raw_dump_inline(NULL, "Compressed ipv6 addr is (64 bits)",
 410                                 *hc_ptr - 8, 8);
 411         }
 412
 413         return rol8(val, shift);
 414 }
 415
 416 int lowpan_header_compress(struct sk_buff *skb, struct net_device *dev,
 417                            unsigned short type, const void *_daddr,
 418                            const void *_saddr, unsigned int len)
 419 {
 420         u8 tmp, iphc0, iphc1, *hc_ptr;
 421         struct ipv6hdr *hdr;
 422         u8 head[100] = {};
 423         int ret, addr_type;
 424
 425         if (type != ETH_P_IPV6)
 426                 return -EINVAL;
 427
 428         hdr = ipv6_hdr(skb);
 429         hc_ptr = head + 2;
 430
 431         pr_debug("IPv6 header dump:\n\tversion = %d\n\tlength  = %d\n"
 432                  "\tnexthdr = 0x%02x\n\thop_lim = %d\n\tdest    = %pI6c\n",
 433                  hdr->version, ntohs(hdr->payload_len), hdr->nexthdr,
 434                  hdr->hop_limit, &hdr->daddr);
 435
 436         raw_dump_table(__func__, "raw skb network header dump",
 437                        skb_network_header(skb), sizeof(struct ipv6hdr));
 438
 439         /* As we copy some bit-length fields, in the IPHC encoding bytes,
 440          * we sometimes use |=
 441          * If the field is 0, and the current bit value in memory is 1,
 442          * this does not work. We therefore reset the IPHC encoding here
 443          */
 444         iphc0 = LOWPAN_DISPATCH_IPHC;
 445         iphc1 = 0;
 446
 447         /* TODO: context lookup */
 448
 449         raw_dump_inline(__func__, "saddr",
 450                         (unsigned char *)_saddr, IEEE802154_ADDR_LEN);
 451         raw_dump_inline(__func__, "daddr",
 452                         (unsigned char *)_daddr, IEEE802154_ADDR_LEN);
 453
 454         raw_dump_table(__func__, "sending raw skb network uncompressed packet",
 455                        skb->data, skb->len);
 456
 457         /* Traffic class, flow label
 458          * If flow label is 0, compress it. If traffic class is 0, compress it
 459          * We have to process both in the same time as the offset of traffic
 460          * class depends on the presence of version and flow label
 461          */
 462
 463         /* hc format of TC is ECN | DSCP , original one is DSCP | ECN */
 464         tmp = (hdr->priority << 4) | (hdr->flow_lbl[0] >> 4);
 465         tmp = ((tmp & 0x03) << 6) | (tmp >> 2);
 466
 467         if (((hdr->flow_lbl[0] & 0x0F) == 0) &&
 468             (hdr->flow_lbl[1] == 0) && (hdr->flow_lbl[2] == 0)) {
 469                 /* flow label can be compressed */
 470                 iphc0 |= LOWPAN_IPHC_FL_C;
 471                 if ((hdr->priority == 0) &&
 472                     ((hdr->flow_lbl[0] & 0xF0) == 0)) {
 473                         /* compress (elide) all */
 474                         iphc0 |= LOWPAN_IPHC_TC_C;
 475                 } else {
 476                         /* compress only the flow label */
 477                         *hc_ptr = tmp;
 478                         hc_ptr += 1;
 479                 }
 480         } else {
 481                 /* Flow label cannot be compressed */
 482                 if ((hdr->priority == 0) &&
 483                     ((hdr->flow_lbl[0] & 0xF0) == 0)) {
 484                         /* compress only traffic class */
 485                         iphc0 |= LOWPAN_IPHC_TC_C;
 486                         *hc_ptr = (tmp & 0xc0) | (hdr->flow_lbl[0] & 0x0F);
 487                         memcpy(hc_ptr + 1, &hdr->flow_lbl[1], 2);
 488                         hc_ptr += 3;
 489                 } else {
 490                         /* compress nothing */
 491                         memcpy(hc_ptr, hdr, 4);
 492                         /* replace the top byte with new ECN | DSCP format */
 493                         *hc_ptr = tmp;
 494                         hc_ptr += 4;
 495                 }
 496         }
 497
 498         /* NOTE: payload length is always compressed */
 499
 500         /* Check if we provide the nhc format for nexthdr and compression
 501          * functionality. If not nexthdr is handled inline and not compressed.
 502          */
 503         ret = lowpan_nhc_check_compression(skb, hdr, &hc_ptr, &iphc0);
 504         if (ret < 0)
 505                 return ret;
 506
 507         /* Hop limit
 508          * if 1:   compress, encoding is 01
 509          * if 64:  compress, encoding is 10
 510          * if 255: compress, encoding is 11
 511          * else do not compress
 512          */
 513         switch (hdr->hop_limit) {
 514         case 1:
 515                 iphc0 |= LOWPAN_IPHC_TTL_1;
 516                 break;
 517         case 64:
 518                 iphc0 |= LOWPAN_IPHC_TTL_64;
 519                 break;
 520         case 255:
 521                 iphc0 |= LOWPAN_IPHC_TTL_255;
 522                 break;
 523         default:
 524                 lowpan_push_hc_data(&hc_ptr, &hdr->hop_limit,
 525                                     sizeof(hdr->hop_limit));
 526         }
 527
 528         addr_type = ipv6_addr_type(&hdr->saddr);
 529         /* source address compression */
 530         if (addr_type == IPV6_ADDR_ANY) {
 531                 pr_debug("source address is unspecified, setting SAC\n");
 532                 iphc1 |= LOWPAN_IPHC_SAC;
 533         } else {
 534                 if (addr_type & IPV6_ADDR_LINKLOCAL) {
 535                         iphc1 |= lowpan_compress_addr_64(&hc_ptr,
 536                                                          LOWPAN_IPHC_SAM_BIT,
 537                                                          &hdr->saddr, _saddr);
 538                         pr_debug("source address unicast link-local %pI6c iphc1 0x%02x\n",
 539                                  &hdr->saddr, iphc1);
 540                 } else {
 541                         pr_debug("send the full source address\n");
 542                         lowpan_push_hc_data(&hc_ptr, hdr->saddr.s6_addr, 16);
 543                 }
 544         }
 545
 546         addr_type = ipv6_addr_type(&hdr->daddr);
 547         /* destination address compression */
 548         if (addr_type & IPV6_ADDR_MULTICAST) {
 549                 pr_debug("destination address is multicast: ");
 550                 iphc1 |= LOWPAN_IPHC_M;
 551                 if (lowpan_is_mcast_addr_compressable8(&hdr->daddr)) {
 552                         pr_debug("compressed to 1 octet\n");
 553                         iphc1 |= LOWPAN_IPHC_DAM_11;
 554                         /* use last byte */
 555                         lowpan_push_hc_data(&hc_ptr,
 556                                             &hdr->daddr.s6_addr[15], 1);
 557                 } else if (lowpan_is_mcast_addr_compressable32(&hdr->daddr)) {
 558                         pr_debug("compressed to 4 octets\n");
 559                         iphc1 |= LOWPAN_IPHC_DAM_10;
 560                         /* second byte + the last three */
 561                         lowpan_push_hc_data(&hc_ptr,
 562                                             &hdr->daddr.s6_addr[1], 1);
 563                         lowpan_push_hc_data(&hc_ptr,
 564                                             &hdr->daddr.s6_addr[13], 3);
 565                 } else if (lowpan_is_mcast_addr_compressable48(&hdr->daddr)) {
 566                         pr_debug("compressed to 6 octets\n");
 567                         iphc1 |= LOWPAN_IPHC_DAM_01;
 568                         /* second byte + the last five */
 569                         lowpan_push_hc_data(&hc_ptr,
 570                                             &hdr->daddr.s6_addr[1], 1);
 571                         lowpan_push_hc_data(&hc_ptr,
 572                                             &hdr->daddr.s6_addr[11], 5);
 573                 } else {
 574                         pr_debug("using full address\n");
 575                         iphc1 |= LOWPAN_IPHC_DAM_00;
 576                         lowpan_push_hc_data(&hc_ptr, hdr->daddr.s6_addr, 16);
 577                 }
 578         } else {
 579                 if (addr_type & IPV6_ADDR_LINKLOCAL) {
 580                         /* TODO: context lookup */
 581                         iphc1 |= lowpan_compress_addr_64(&hc_ptr,
 582                                 LOWPAN_IPHC_DAM_BIT, &hdr->daddr, _daddr);
 583                         pr_debug("dest address unicast link-local %pI6c "
 584                                  "iphc1 0x%02x\n", &hdr->daddr, iphc1);
 585                 } else {
 586                         pr_debug("dest address unicast %pI6c\n", &hdr->daddr);
 587                         lowpan_push_hc_data(&hc_ptr, hdr->daddr.s6_addr, 16);
 588                 }
 589         }
 590
 591         /* next header compression */
 592         if (iphc0 & LOWPAN_IPHC_NH_C) {
 593                 ret = lowpan_nhc_do_compression(skb, hdr, &hc_ptr);
 594                 if (ret < 0)
 595                         return ret;
 596         }
 597
 598         head[0] = iphc0;
 599         head[1] = iphc1;
 600
 601         skb_pull(skb, sizeof(struct ipv6hdr));
 602         skb_reset_transport_header(skb);
 603         memcpy(skb_push(skb, hc_ptr - head), head, hc_ptr - head);
 604         skb_reset_network_header(skb);
 605
 606         pr_debug("header len %d skb %u\n", (int)(hc_ptr - head), skb->len);
 607
 608         raw_dump_table(__func__, "raw skb data dump compressed",
 609                        skb->data, skb->len);
 610         return 0;
 611 }
 612 EXPORT_SYMBOL_GPL(lowpan_header_compress);
 613
 614 static int __init lowpan_module_init(void)
 615 {
 616         request_module_nowait("nhc_dest");
 617         request_module_nowait("nhc_fragment");
 618         request_module_nowait("nhc_hop");
 619         request_module_nowait("nhc_ipv6");
 620         request_module_nowait("nhc_mobility");
 621         request_module_nowait("nhc_routing");
 622         request_module_nowait("nhc_udp");
 623
 624         return 0;
 625 }
 626 module_init(lowpan_module_init);
 627
 628 MODULE_LICENSE("GPL");