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  * You should have received a copy of the GNU General Public License along
  19  * with this program; if not, write to the Free Software Foundation, Inc.,
  20  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  21  */
  22
  23 /* Jon's code is based on 6lowpan implementation for Contiki which is:
  24  * Copyright (c) 2008, Swedish Institute of Computer Science.
  25  * All rights reserved.
  26  *
  27  * Redistribution and use in source and binary forms, with or without
  28  * modification, are permitted provided that the following conditions
  29  * are met:
  30  * 1. Redistributions of source code must retain the above copyright
  31  *    notice, this list of conditions and the following disclaimer.
  32  * 2. Redistributions in binary form must reproduce the above copyright
  33  *    notice, this list of conditions and the following disclaimer in the
  34  *    documentation and/or other materials provided with the distribution.
  35  * 3. Neither the name of the Institute nor the names of its contributors
  36  *    may be used to endorse or promote products derived from this software
  37  *    without specific prior written permission.
  38  *
  39  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
  40  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  41  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  42  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
  43  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  44  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  45  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  46  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  47  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  48  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  49  * SUCH DAMAGE.
  50  */
  51
  52 #include <linux/bitops.h>
  53 #include <linux/if_arp.h>
  54 #include <linux/module.h>
  55 #include <linux/netdevice.h>
  56 #include <net/6lowpan.h>
  57 #include <net/ipv6.h>
  58 #include <net/af_ieee802154.h>
  59
  60 /* Uncompress address function for source and
  61  * destination address(non-multicast).
  62  *
  63  * address_mode is sam value or dam value.
  64  */
  65 static int uncompress_addr(struct sk_buff *skb,
  66                            struct in6_addr *ipaddr, const u8 address_mode,
  67                            const u8 *lladdr, const u8 addr_type,
  68                            const u8 addr_len)
  69 {
  70         bool fail;
  71
  72         switch (address_mode) {
  73         case LOWPAN_IPHC_ADDR_00:
  74                 /* for global link addresses */
  75                 fail = lowpan_fetch_skb(skb, ipaddr->s6_addr, 16);
  76                 break;
  77         case LOWPAN_IPHC_ADDR_01:
  78                 /* fe:80::XXXX:XXXX:XXXX:XXXX */
  79                 ipaddr->s6_addr[0] = 0xFE;
  80                 ipaddr->s6_addr[1] = 0x80;
  81                 fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[8], 8);
  82                 break;
  83         case LOWPAN_IPHC_ADDR_02:
  84                 /* fe:80::ff:fe00:XXXX */
  85                 ipaddr->s6_addr[0] = 0xFE;
  86                 ipaddr->s6_addr[1] = 0x80;
  87                 ipaddr->s6_addr[11] = 0xFF;
  88                 ipaddr->s6_addr[12] = 0xFE;
  89                 fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[14], 2);
  90                 break;
  91         case LOWPAN_IPHC_ADDR_03:
  92                 fail = false;
  93                 switch (addr_type) {
  94                 case IEEE802154_ADDR_LONG:
  95                         /* fe:80::XXXX:XXXX:XXXX:XXXX
  96                          *        \_________________/
  97                          *              hwaddr
  98                          */
  99                         ipaddr->s6_addr[0] = 0xFE;
 100                         ipaddr->s6_addr[1] = 0x80;
 101                         memcpy(&ipaddr->s6_addr[8], lladdr, addr_len);
 102                         /* second bit-flip (Universe/Local)
 103                          * is done according RFC2464
 104                          */
 105                         ipaddr->s6_addr[8] ^= 0x02;
 106                         break;
 107                 case IEEE802154_ADDR_SHORT:
 108                         /* fe:80::ff:fe00:XXXX
 109                          *                \__/
 110                          *             short_addr
 111                          *
 112                          * Universe/Local bit is zero.
 113                          */
 114                         ipaddr->s6_addr[0] = 0xFE;
 115                         ipaddr->s6_addr[1] = 0x80;
 116                         ipaddr->s6_addr[11] = 0xFF;
 117                         ipaddr->s6_addr[12] = 0xFE;
 118                         ipaddr->s6_addr16[7] = htons(*((u16 *)lladdr));
 119                         break;
 120                 default:
 121                         pr_debug("Invalid addr_type set\n");
 122                         return -EINVAL;
 123                 }
 124                 break;
 125         default:
 126                 pr_debug("Invalid address mode value: 0x%x\n", address_mode);
 127                 return -EINVAL;
 128         }
 129
 130         if (fail) {
 131                 pr_debug("Failed to fetch skb data\n");
 132                 return -EIO;
 133         }
 134
 135         raw_dump_inline(NULL, "Reconstructed ipv6 addr is",
 136                         ipaddr->s6_addr, 16);
 137
 138         return 0;
 139 }
 140
 141 /* Uncompress address function for source context
 142  * based address(non-multicast).
 143  */
 144 static int uncompress_context_based_src_addr(struct sk_buff *skb,
 145                                              struct in6_addr *ipaddr,
 146                                              const u8 sam)
 147 {
 148         switch (sam) {
 149         case LOWPAN_IPHC_ADDR_00:
 150                 /* unspec address ::
 151                  * Do nothing, address is already ::
 152                  */
 153                 break;
 154         case LOWPAN_IPHC_ADDR_01:
 155                 /* TODO */
 156         case LOWPAN_IPHC_ADDR_02:
 157                 /* TODO */
 158         case LOWPAN_IPHC_ADDR_03:
 159                 /* TODO */
 160                 netdev_warn(skb->dev, "SAM value 0x%x not supported\n", sam);
 161                 return -EINVAL;
 162         default:
 163                 pr_debug("Invalid sam value: 0x%x\n", sam);
 164                 return -EINVAL;
 165         }
 166
 167         raw_dump_inline(NULL,
 168                         "Reconstructed context based ipv6 src addr is",
 169                         ipaddr->s6_addr, 16);
 170
 171         return 0;
 172 }
 173
 174 static int skb_deliver(struct sk_buff *skb, struct ipv6hdr *hdr,
 175                        struct net_device *dev, skb_delivery_cb deliver_skb)
 176 {
 177         struct sk_buff *new;
 178         int stat;
 179
 180         new = skb_copy_expand(skb, sizeof(struct ipv6hdr),
 181                               skb_tailroom(skb), GFP_ATOMIC);
 182         kfree_skb(skb);
 183
 184         if (!new)
 185                 return -ENOMEM;
 186
 187         skb_push(new, sizeof(struct ipv6hdr));
 188         skb_reset_network_header(new);
 189         skb_copy_to_linear_data(new, hdr, sizeof(struct ipv6hdr));
 190
 191         new->protocol = htons(ETH_P_IPV6);
 192         new->pkt_type = PACKET_HOST;
 193         new->dev = dev;
 194
 195         raw_dump_table(__func__, "raw skb data dump before receiving",
 196                        new->data, new->len);
 197
 198         stat = deliver_skb(new, dev);
 199
 200         kfree_skb(new);
 201
 202         return stat;
 203 }
 204
 205 /* Uncompress function for multicast destination address,
 206  * when M bit is set.
 207  */
 208 static int
 209 lowpan_uncompress_multicast_daddr(struct sk_buff *skb,
 210                                   struct in6_addr *ipaddr,
 211                                   const u8 dam)
 212 {
 213         bool fail;
 214
 215         switch (dam) {
 216         case LOWPAN_IPHC_DAM_00:
 217                 /* 00:  128 bits.  The full address
 218                  * is carried in-line.
 219                  */
 220                 fail = lowpan_fetch_skb(skb, ipaddr->s6_addr, 16);
 221                 break;
 222         case LOWPAN_IPHC_DAM_01:
 223                 /* 01:  48 bits.  The address takes
 224                  * the form ffXX::00XX:XXXX:XXXX.
 225                  */
 226                 ipaddr->s6_addr[0] = 0xFF;
 227                 fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[1], 1);
 228                 fail |= lowpan_fetch_skb(skb, &ipaddr->s6_addr[11], 5);
 229                 break;
 230         case LOWPAN_IPHC_DAM_10:
 231                 /* 10:  32 bits.  The address takes
 232                  * the form ffXX::00XX:XXXX.
 233                  */
 234                 ipaddr->s6_addr[0] = 0xFF;
 235                 fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[1], 1);
 236                 fail |= lowpan_fetch_skb(skb, &ipaddr->s6_addr[13], 3);
 237                 break;
 238         case LOWPAN_IPHC_DAM_11:
 239                 /* 11:  8 bits.  The address takes
 240                  * the form ff02::00XX.
 241                  */
 242                 ipaddr->s6_addr[0] = 0xFF;
 243                 ipaddr->s6_addr[1] = 0x02;
 244                 fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[15], 1);
 245                 break;
 246         default:
 247                 pr_debug("DAM value has a wrong value: 0x%x\n", dam);
 248                 return -EINVAL;
 249         }
 250
 251         if (fail) {
 252                 pr_debug("Failed to fetch skb data\n");
 253                 return -EIO;
 254         }
 255
 256         raw_dump_inline(NULL, "Reconstructed ipv6 multicast addr is",
 257                                 ipaddr->s6_addr, 16);
 258
 259         return 0;
 260 }
 261
 262 static int
 263 uncompress_udp_header(struct sk_buff *skb, struct udphdr *uh)
 264 {
 265         bool fail;
 266         u8 tmp = 0, val = 0;
 267
 268         if (!uh)
 269                 goto err;
 270
 271         fail = lowpan_fetch_skb(skb, &tmp, 1);
 272
 273         if ((tmp & LOWPAN_NHC_UDP_MASK) == LOWPAN_NHC_UDP_ID) {
 274                 pr_debug("UDP header uncompression\n");
 275                 switch (tmp & LOWPAN_NHC_UDP_CS_P_11) {
 276                 case LOWPAN_NHC_UDP_CS_P_00:
 277                         fail |= lowpan_fetch_skb(skb, &uh->source, 2);
 278                         fail |= lowpan_fetch_skb(skb, &uh->dest, 2);
 279                         break;
 280                 case LOWPAN_NHC_UDP_CS_P_01:
 281                         fail |= lowpan_fetch_skb(skb, &uh->source, 2);
 282                         fail |= lowpan_fetch_skb(skb, &val, 1);
 283                         uh->dest = htons(val + LOWPAN_NHC_UDP_8BIT_PORT);
 284                         break;
 285                 case LOWPAN_NHC_UDP_CS_P_10:
 286                         fail |= lowpan_fetch_skb(skb, &val, 1);
 287                         uh->source = htons(val + LOWPAN_NHC_UDP_8BIT_PORT);
 288                         fail |= lowpan_fetch_skb(skb, &uh->dest, 2);
 289                         break;
 290                 case LOWPAN_NHC_UDP_CS_P_11:
 291                         fail |= lowpan_fetch_skb(skb, &val, 1);
 292                         uh->source = htons(LOWPAN_NHC_UDP_4BIT_PORT +
 293                                            (val >> 4));
 294                         uh->dest = htons(LOWPAN_NHC_UDP_4BIT_PORT +
 295                                          (val & 0x0f));
 296                         break;
 297                 default:
 298                         pr_debug("ERROR: unknown UDP format\n");
 299                         goto err;
 300                 }
 301
 302                 pr_debug("uncompressed UDP ports: src = %d, dst = %d\n",
 303                          ntohs(uh->source), ntohs(uh->dest));
 304
 305                 /* checksum */
 306                 if (tmp & LOWPAN_NHC_UDP_CS_C) {
 307                         pr_debug_ratelimited("checksum elided currently not supported\n");
 308                         goto err;
 309                 } else {
 310                         fail |= lowpan_fetch_skb(skb, &uh->check, 2);
 311                 }
 312
 313                 /* UDP lenght needs to be infered from the lower layers
 314                  * here, we obtain the hint from the remaining size of the
 315                  * frame
 316                  */
 317                 uh->len = htons(skb->len + sizeof(struct udphdr));
 318                 pr_debug("uncompressed UDP length: src = %d", ntohs(uh->len));
 319         } else {
 320                 pr_debug("ERROR: unsupported NH format\n");
 321                 goto err;
 322         }
 323
 324         if (fail)
 325                 goto err;
 326
 327         return 0;
 328 err:
 329         return -EINVAL;
 330 }
 331
 332 /* TTL uncompression values */
 333 static const u8 lowpan_ttl_values[] = { 0, 1, 64, 255 };
 334
 335 int lowpan_process_data(struct sk_buff *skb, struct net_device *dev,
 336                         const u8 *saddr, const u8 saddr_type,
 337                         const u8 saddr_len, const u8 *daddr,
 338                         const u8 daddr_type, const u8 daddr_len,
 339                         u8 iphc0, u8 iphc1, skb_delivery_cb deliver_skb)
 340 {
 341         struct ipv6hdr hdr = {};
 342         u8 tmp, num_context = 0;
 343         int err;
 344
 345         raw_dump_table(__func__, "raw skb data dump uncompressed",
 346                        skb->data, skb->len);
 347
 348         /* another if the CID flag is set */
 349         if (iphc1 & LOWPAN_IPHC_CID) {
 350                 pr_debug("CID flag is set, increase header with one\n");
 351                 if (lowpan_fetch_skb_u8(skb, &num_context))
 352                         goto drop;
 353         }
 354
 355         hdr.version = 6;
 356
 357         /* Traffic Class and Flow Label */
 358         switch ((iphc0 & LOWPAN_IPHC_TF) >> 3) {
 359         /* Traffic Class and FLow Label carried in-line
 360          * ECN + DSCP + 4-bit Pad + Flow Label (4 bytes)
 361          */
 362         case 0: /* 00b */
 363                 if (lowpan_fetch_skb_u8(skb, &tmp))
 364                         goto drop;
 365
 366                 memcpy(&hdr.flow_lbl, &skb->data[0], 3);
 367                 skb_pull(skb, 3);
 368                 hdr.priority = ((tmp >> 2) & 0x0f);
 369                 hdr.flow_lbl[0] = ((tmp >> 2) & 0x30) | (tmp << 6) |
 370                                         (hdr.flow_lbl[0] & 0x0f);
 371                 break;
 372         /* Traffic class carried in-line
 373          * ECN + DSCP (1 byte), Flow Label is elided
 374          */
 375         case 2: /* 10b */
 376                 if (lowpan_fetch_skb_u8(skb, &tmp))
 377                         goto drop;
 378
 379                 hdr.priority = ((tmp >> 2) & 0x0f);
 380                 hdr.flow_lbl[0] = ((tmp << 6) & 0xC0) | ((tmp >> 2) & 0x30);
 381                 break;
 382         /* Flow Label carried in-line
 383          * ECN + 2-bit Pad + Flow Label (3 bytes), DSCP is elided
 384          */
 385         case 1: /* 01b */
 386                 if (lowpan_fetch_skb_u8(skb, &tmp))
 387                         goto drop;
 388
 389                 hdr.flow_lbl[0] = (skb->data[0] & 0x0F) | ((tmp >> 2) & 0x30);
 390                 memcpy(&hdr.flow_lbl[1], &skb->data[0], 2);
 391                 skb_pull(skb, 2);
 392                 break;
 393         /* Traffic Class and Flow Label are elided */
 394         case 3: /* 11b */
 395                 break;
 396         default:
 397                 break;
 398         }
 399
 400         /* Next Header */
 401         if ((iphc0 & LOWPAN_IPHC_NH_C) == 0) {
 402                 /* Next header is carried inline */
 403                 if (lowpan_fetch_skb_u8(skb, &(hdr.nexthdr)))
 404                         goto drop;
 405
 406                 pr_debug("NH flag is set, next header carried inline: %02x\n",
 407                          hdr.nexthdr);
 408         }
 409
 410         /* Hop Limit */
 411         if ((iphc0 & 0x03) != LOWPAN_IPHC_TTL_I) {
 412                 hdr.hop_limit = lowpan_ttl_values[iphc0 & 0x03];
 413         } else {
 414                 if (lowpan_fetch_skb_u8(skb, &(hdr.hop_limit)))
 415                         goto drop;
 416         }
 417
 418         /* Extract SAM to the tmp variable */
 419         tmp = ((iphc1 & LOWPAN_IPHC_SAM) >> LOWPAN_IPHC_SAM_BIT) & 0x03;
 420
 421         if (iphc1 & LOWPAN_IPHC_SAC) {
 422                 /* Source address context based uncompression */
 423                 pr_debug("SAC bit is set. Handle context based source address.\n");
 424                 err = uncompress_context_based_src_addr(
 425                                                 skb, &hdr.saddr, tmp);
 426         } else {
 427                 /* Source address uncompression */
 428                 pr_debug("source address stateless compression\n");
 429                 err = uncompress_addr(skb, &hdr.saddr, tmp, saddr,
 430                                       saddr_type, saddr_len);
 431         }
 432
 433         /* Check on error of previous branch */
 434         if (err)
 435                 goto drop;
 436
 437         /* Extract DAM to the tmp variable */
 438         tmp = ((iphc1 & LOWPAN_IPHC_DAM_11) >> LOWPAN_IPHC_DAM_BIT) & 0x03;
 439
 440         /* check for Multicast Compression */
 441         if (iphc1 & LOWPAN_IPHC_M) {
 442                 if (iphc1 & LOWPAN_IPHC_DAC) {
 443                         pr_debug("dest: context-based mcast compression\n");
 444                         /* TODO: implement this */
 445                 } else {
 446                         err = lowpan_uncompress_multicast_daddr(
 447                                                 skb, &hdr.daddr, tmp);
 448                         if (err)
 449                                 goto drop;
 450                 }
 451         } else {
 452                 err = uncompress_addr(skb, &hdr.daddr, tmp, daddr,
 453                                       daddr_type, daddr_len);
 454                 pr_debug("dest: stateless compression mode %d dest %pI6c\n",
 455                          tmp, &hdr.daddr);
 456                 if (err)
 457                         goto drop;
 458         }
 459
 460         /* UDP data uncompression */
 461         if (iphc0 & LOWPAN_IPHC_NH_C) {
 462                 struct udphdr uh;
 463                 struct sk_buff *new;
 464
 465                 if (uncompress_udp_header(skb, &uh))
 466                         goto drop;
 467
 468                 /* replace the compressed UDP head by the uncompressed UDP
 469                  * header
 470                  */
 471                 new = skb_copy_expand(skb, sizeof(struct udphdr),
 472                                       skb_tailroom(skb), GFP_ATOMIC);
 473                 kfree_skb(skb);
 474
 475                 if (!new)
 476                         return -ENOMEM;
 477
 478                 skb = new;
 479
 480                 skb_push(skb, sizeof(struct udphdr));
 481                 skb_reset_transport_header(skb);
 482                 skb_copy_to_linear_data(skb, &uh, sizeof(struct udphdr));
 483
 484                 raw_dump_table(__func__, "raw UDP header dump",
 485                                (u8 *)&uh, sizeof(uh));
 486
 487                 hdr.nexthdr = UIP_PROTO_UDP;
 488         }
 489
 490         hdr.payload_len = htons(skb->len);
 491
 492         pr_debug("skb headroom size = %d, data length = %d\n",
 493                  skb_headroom(skb), skb->len);
 494
 495         pr_debug("IPv6 header dump:\n\tversion = %d\n\tlength  = %d\n\t"
 496                  "nexthdr = 0x%02x\n\thop_lim = %d\n\tdest    = %pI6c\n",
 497                 hdr.version, ntohs(hdr.payload_len), hdr.nexthdr,
 498                 hdr.hop_limit, &hdr.daddr);
 499
 500         raw_dump_table(__func__, "raw header dump",
 501                        (u8 *)&hdr, sizeof(hdr));
 502
 503         return skb_deliver(skb, &hdr, dev, deliver_skb);
 504
 505 drop:
 506         kfree_skb(skb);
 507         return -EINVAL;
 508 }
 509 EXPORT_SYMBOL_GPL(lowpan_process_data);
 510
 511 static u8 lowpan_compress_addr_64(u8 **hc06_ptr, u8 shift,
 512                                   const struct in6_addr *ipaddr,
 513                                   const unsigned char *lladdr)
 514 {
 515         u8 val = 0;
 516
 517         if (is_addr_mac_addr_based(ipaddr, lladdr)) {
 518                 val = 3; /* 0-bits */
 519                 pr_debug("address compression 0 bits\n");
 520         } else if (lowpan_is_iid_16_bit_compressable(ipaddr)) {
 521                 /* compress IID to 16 bits xxxx::XXXX */
 522                 memcpy(*hc06_ptr, &ipaddr->s6_addr16[7], 2);
 523                 *hc06_ptr += 2;
 524                 val = 2; /* 16-bits */
 525                 raw_dump_inline(NULL, "Compressed ipv6 addr is (16 bits)",
 526                                 *hc06_ptr - 2, 2);
 527         } else {
 528                 /* do not compress IID => xxxx::IID */
 529                 memcpy(*hc06_ptr, &ipaddr->s6_addr16[4], 8);
 530                 *hc06_ptr += 8;
 531                 val = 1; /* 64-bits */
 532                 raw_dump_inline(NULL, "Compressed ipv6 addr is (64 bits)",
 533                                 *hc06_ptr - 8, 8);
 534         }
 535
 536         return rol8(val, shift);
 537 }
 538
 539 static void compress_udp_header(u8 **hc06_ptr, struct sk_buff *skb)
 540 {
 541         struct udphdr *uh = udp_hdr(skb);
 542         u8 tmp;
 543
 544         if (((ntohs(uh->source) & LOWPAN_NHC_UDP_4BIT_MASK) ==
 545              LOWPAN_NHC_UDP_4BIT_PORT) &&
 546             ((ntohs(uh->dest) & LOWPAN_NHC_UDP_4BIT_MASK) ==
 547              LOWPAN_NHC_UDP_4BIT_PORT)) {
 548                 pr_debug("UDP header: both ports compression to 4 bits\n");
 549                 /* compression value */
 550                 tmp = LOWPAN_NHC_UDP_CS_P_11;
 551                 lowpan_push_hc_data(hc06_ptr, &tmp, sizeof(tmp));
 552                 /* source and destination port */
 553                 tmp = ntohs(uh->dest) - LOWPAN_NHC_UDP_4BIT_PORT +
 554                       ((ntohs(uh->source) - LOWPAN_NHC_UDP_4BIT_PORT) << 4);
 555                 lowpan_push_hc_data(hc06_ptr, &tmp, sizeof(tmp));
 556         } else if ((ntohs(uh->dest) & LOWPAN_NHC_UDP_8BIT_MASK) ==
 557                         LOWPAN_NHC_UDP_8BIT_PORT) {
 558                 pr_debug("UDP header: remove 8 bits of dest\n");
 559                 /* compression value */
 560                 tmp = LOWPAN_NHC_UDP_CS_P_01;
 561                 lowpan_push_hc_data(hc06_ptr, &tmp, sizeof(tmp));
 562                 /* source port */
 563                 lowpan_push_hc_data(hc06_ptr, &uh->source, sizeof(uh->source));
 564                 /* destination port */
 565                 tmp = ntohs(uh->dest) - LOWPAN_NHC_UDP_8BIT_PORT;
 566                 lowpan_push_hc_data(hc06_ptr, &tmp, sizeof(tmp));
 567         } else if ((ntohs(uh->source) & LOWPAN_NHC_UDP_8BIT_MASK) ==
 568                         LOWPAN_NHC_UDP_8BIT_PORT) {
 569                 pr_debug("UDP header: remove 8 bits of source\n");
 570                 /* compression value */
 571                 tmp = LOWPAN_NHC_UDP_CS_P_10;
 572                 lowpan_push_hc_data(hc06_ptr, &tmp, sizeof(tmp));
 573                 /* source port */
 574                 tmp = ntohs(uh->source) - LOWPAN_NHC_UDP_8BIT_PORT;
 575                 lowpan_push_hc_data(hc06_ptr, &tmp, sizeof(tmp));
 576                 /* destination port */
 577                 lowpan_push_hc_data(hc06_ptr, &uh->dest, sizeof(uh->dest));
 578         } else {
 579                 pr_debug("UDP header: can't compress\n");
 580                 /* compression value */
 581                 tmp = LOWPAN_NHC_UDP_CS_P_00;
 582                 lowpan_push_hc_data(hc06_ptr, &tmp, sizeof(tmp));
 583                 /* source port */
 584                 lowpan_push_hc_data(hc06_ptr, &uh->source, sizeof(uh->source));
 585                 /* destination port */
 586                 lowpan_push_hc_data(hc06_ptr, &uh->dest, sizeof(uh->dest));
 587         }
 588
 589         /* checksum is always inline */
 590         lowpan_push_hc_data(hc06_ptr, &uh->check, sizeof(uh->check));
 591
 592         /* skip the UDP header */
 593         skb_pull(skb, sizeof(struct udphdr));
 594 }
 595
 596 int lowpan_header_compress(struct sk_buff *skb, struct net_device *dev,
 597                            unsigned short type, const void *_daddr,
 598                            const void *_saddr, unsigned int len)
 599 {
 600         u8 tmp, iphc0, iphc1, *hc06_ptr;
 601         struct ipv6hdr *hdr;
 602         u8 head[100] = {};
 603
 604         if (type != ETH_P_IPV6)
 605                 return -EINVAL;
 606
 607         hdr = ipv6_hdr(skb);
 608         hc06_ptr = head + 2;
 609
 610         pr_debug("IPv6 header dump:\n\tversion = %d\n\tlength  = %d\n"
 611                  "\tnexthdr = 0x%02x\n\thop_lim = %d\n\tdest    = %pI6c\n",
 612                  hdr->version, ntohs(hdr->payload_len), hdr->nexthdr,
 613                  hdr->hop_limit, &hdr->daddr);
 614
 615         raw_dump_table(__func__, "raw skb network header dump",
 616                        skb_network_header(skb), sizeof(struct ipv6hdr));
 617
 618         /* As we copy some bit-length fields, in the IPHC encoding bytes,
 619          * we sometimes use |=
 620          * If the field is 0, and the current bit value in memory is 1,
 621          * this does not work. We therefore reset the IPHC encoding here
 622          */
 623         iphc0 = LOWPAN_DISPATCH_IPHC;
 624         iphc1 = 0;
 625
 626         /* TODO: context lookup */
 627
 628         raw_dump_inline(__func__, "saddr",
 629                         (unsigned char *)_saddr, IEEE802154_ADDR_LEN);
 630         raw_dump_inline(__func__, "daddr",
 631                         (unsigned char *)_daddr, IEEE802154_ADDR_LEN);
 632
 633         raw_dump_table(__func__,
 634                        "sending raw skb network uncompressed packet",
 635                        skb->data, skb->len);
 636
 637         /* Traffic class, flow label
 638          * If flow label is 0, compress it. If traffic class is 0, compress it
 639          * We have to process both in the same time as the offset of traffic
 640          * class depends on the presence of version and flow label
 641          */
 642
 643         /* hc06 format of TC is ECN | DSCP , original one is DSCP | ECN */
 644         tmp = (hdr->priority << 4) | (hdr->flow_lbl[0] >> 4);
 645         tmp = ((tmp & 0x03) << 6) | (tmp >> 2);
 646
 647         if (((hdr->flow_lbl[0] & 0x0F) == 0) &&
 648             (hdr->flow_lbl[1] == 0) && (hdr->flow_lbl[2] == 0)) {
 649                 /* flow label can be compressed */
 650                 iphc0 |= LOWPAN_IPHC_FL_C;
 651                 if ((hdr->priority == 0) &&
 652                     ((hdr->flow_lbl[0] & 0xF0) == 0)) {
 653                         /* compress (elide) all */
 654                         iphc0 |= LOWPAN_IPHC_TC_C;
 655                 } else {
 656                         /* compress only the flow label */
 657                         *hc06_ptr = tmp;
 658                         hc06_ptr += 1;
 659                 }
 660         } else {
 661                 /* Flow label cannot be compressed */
 662                 if ((hdr->priority == 0) &&
 663                     ((hdr->flow_lbl[0] & 0xF0) == 0)) {
 664                         /* compress only traffic class */
 665                         iphc0 |= LOWPAN_IPHC_TC_C;
 666                         *hc06_ptr = (tmp & 0xc0) | (hdr->flow_lbl[0] & 0x0F);
 667                         memcpy(hc06_ptr + 1, &hdr->flow_lbl[1], 2);
 668                         hc06_ptr += 3;
 669                 } else {
 670                         /* compress nothing */
 671                         memcpy(hc06_ptr, hdr, 4);
 672                         /* replace the top byte with new ECN | DSCP format */
 673                         *hc06_ptr = tmp;
 674                         hc06_ptr += 4;
 675                 }
 676         }
 677
 678         /* NOTE: payload length is always compressed */
 679
 680         /* Next Header is compress if UDP */
 681         if (hdr->nexthdr == UIP_PROTO_UDP)
 682                 iphc0 |= LOWPAN_IPHC_NH_C;
 683
 684         if ((iphc0 & LOWPAN_IPHC_NH_C) == 0) {
 685                 *hc06_ptr = hdr->nexthdr;
 686                 hc06_ptr += 1;
 687         }
 688
 689         /* Hop limit
 690          * if 1:   compress, encoding is 01
 691          * if 64:  compress, encoding is 10
 692          * if 255: compress, encoding is 11
 693          * else do not compress
 694          */
 695         switch (hdr->hop_limit) {
 696         case 1:
 697                 iphc0 |= LOWPAN_IPHC_TTL_1;
 698                 break;
 699         case 64:
 700                 iphc0 |= LOWPAN_IPHC_TTL_64;
 701                 break;
 702         case 255:
 703                 iphc0 |= LOWPAN_IPHC_TTL_255;
 704                 break;
 705         default:
 706                 *hc06_ptr = hdr->hop_limit;
 707                 hc06_ptr += 1;
 708                 break;
 709         }
 710
 711         /* source address compression */
 712         if (is_addr_unspecified(&hdr->saddr)) {
 713                 pr_debug("source address is unspecified, setting SAC\n");
 714                 iphc1 |= LOWPAN_IPHC_SAC;
 715         /* TODO: context lookup */
 716         } else if (is_addr_link_local(&hdr->saddr)) {
 717                 iphc1 |= lowpan_compress_addr_64(&hc06_ptr,
 718                                 LOWPAN_IPHC_SAM_BIT, &hdr->saddr, _saddr);
 719                 pr_debug("source address unicast link-local %pI6c "
 720                         "iphc1 0x%02x\n", &hdr->saddr, iphc1);
 721         } else {
 722                 pr_debug("send the full source address\n");
 723                 memcpy(hc06_ptr, &hdr->saddr.s6_addr16[0], 16);
 724                 hc06_ptr += 16;
 725         }
 726
 727         /* destination address compression */
 728         if (is_addr_mcast(&hdr->daddr)) {
 729                 pr_debug("destination address is multicast: ");
 730                 iphc1 |= LOWPAN_IPHC_M;
 731                 if (lowpan_is_mcast_addr_compressable8(&hdr->daddr)) {
 732                         pr_debug("compressed to 1 octet\n");
 733                         iphc1 |= LOWPAN_IPHC_DAM_11;
 734                         /* use last byte */
 735                         *hc06_ptr = hdr->daddr.s6_addr[15];
 736                         hc06_ptr += 1;
 737                 } else if (lowpan_is_mcast_addr_compressable32(&hdr->daddr)) {
 738                         pr_debug("compressed to 4 octets\n");
 739                         iphc1 |= LOWPAN_IPHC_DAM_10;
 740                         /* second byte + the last three */
 741                         *hc06_ptr = hdr->daddr.s6_addr[1];
 742                         memcpy(hc06_ptr + 1, &hdr->daddr.s6_addr[13], 3);
 743                         hc06_ptr += 4;
 744                 } else if (lowpan_is_mcast_addr_compressable48(&hdr->daddr)) {
 745                         pr_debug("compressed to 6 octets\n");
 746                         iphc1 |= LOWPAN_IPHC_DAM_01;
 747                         /* second byte + the last five */
 748                         *hc06_ptr = hdr->daddr.s6_addr[1];
 749                         memcpy(hc06_ptr + 1, &hdr->daddr.s6_addr[11], 5);
 750                         hc06_ptr += 6;
 751                 } else {
 752                         pr_debug("using full address\n");
 753                         iphc1 |= LOWPAN_IPHC_DAM_00;
 754                         memcpy(hc06_ptr, &hdr->daddr.s6_addr[0], 16);
 755                         hc06_ptr += 16;
 756                 }
 757         } else {
 758                 /* TODO: context lookup */
 759                 if (is_addr_link_local(&hdr->daddr)) {
 760                         iphc1 |= lowpan_compress_addr_64(&hc06_ptr,
 761                                 LOWPAN_IPHC_DAM_BIT, &hdr->daddr, _daddr);
 762                         pr_debug("dest address unicast link-local %pI6c "
 763                                 "iphc1 0x%02x\n", &hdr->daddr, iphc1);
 764                 } else {
 765                         pr_debug("dest address unicast %pI6c\n", &hdr->daddr);
 766                         memcpy(hc06_ptr, &hdr->daddr.s6_addr16[0], 16);
 767                         hc06_ptr += 16;
 768                 }
 769         }
 770
 771         /* UDP header compression */
 772         if (hdr->nexthdr == UIP_PROTO_UDP)
 773                 compress_udp_header(&hc06_ptr, skb);
 774
 775         head[0] = iphc0;
 776         head[1] = iphc1;
 777
 778         skb_pull(skb, sizeof(struct ipv6hdr));
 779         skb_reset_transport_header(skb);
 780         memcpy(skb_push(skb, hc06_ptr - head), head, hc06_ptr - head);
 781         skb_reset_network_header(skb);
 782
 783         pr_debug("header len %d skb %u\n", (int)(hc06_ptr - head), skb->len);
 784
 785         raw_dump_table(__func__, "raw skb data dump compressed",
 786                        skb->data, skb->len);
 787         return 0;
 788 }
 789 EXPORT_SYMBOL_GPL(lowpan_header_compress);
 790
 791 MODULE_LICENSE("GPL");