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 /* Uncompress address function for source and
  58  * destination address(non-multicast).
  59  *
  60  * address_mode is sam value or dam value.
  61  */
  62 static int uncompress_addr(struct sk_buff *skb,
  63                            struct in6_addr *ipaddr, const u8 address_mode,
  64                            const u8 *lladdr, const u8 addr_type,
  65                            const u8 addr_len)
  66 {
  67         bool fail;
  68
  69         switch (address_mode) {
  70         case LOWPAN_IPHC_ADDR_00:
  71                 /* for global link addresses */
  72                 fail = lowpan_fetch_skb(skb, ipaddr->s6_addr, 16);
  73                 break;
  74         case LOWPAN_IPHC_ADDR_01:
  75                 /* fe:80::XXXX:XXXX:XXXX:XXXX */
  76                 ipaddr->s6_addr[0] = 0xFE;
  77                 ipaddr->s6_addr[1] = 0x80;
  78                 fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[8], 8);
  79                 break;
  80         case LOWPAN_IPHC_ADDR_02:
  81                 /* fe:80::ff:fe00:XXXX */
  82                 ipaddr->s6_addr[0] = 0xFE;
  83                 ipaddr->s6_addr[1] = 0x80;
  84                 ipaddr->s6_addr[11] = 0xFF;
  85                 ipaddr->s6_addr[12] = 0xFE;
  86                 fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[14], 2);
  87                 break;
  88         case LOWPAN_IPHC_ADDR_03:
  89                 fail = false;
  90                 switch (addr_type) {
  91                 case IEEE802154_ADDR_LONG:
  92                         /* fe:80::XXXX:XXXX:XXXX:XXXX
  93                          *        \_________________/
  94                          *              hwaddr
  95                          */
  96                         ipaddr->s6_addr[0] = 0xFE;
  97                         ipaddr->s6_addr[1] = 0x80;
  98                         memcpy(&ipaddr->s6_addr[8], lladdr, addr_len);
  99                         /* second bit-flip (Universe/Local)
 100                          * is done according RFC2464
 101                          */
 102                         ipaddr->s6_addr[8] ^= 0x02;
 103                         break;
 104                 case IEEE802154_ADDR_SHORT:
 105                         /* fe:80::ff:fe00:XXXX
 106                          *                \__/
 107                          *             short_addr
 108                          *
 109                          * Universe/Local bit is zero.
 110                          */
 111                         ipaddr->s6_addr[0] = 0xFE;
 112                         ipaddr->s6_addr[1] = 0x80;
 113                         ipaddr->s6_addr[11] = 0xFF;
 114                         ipaddr->s6_addr[12] = 0xFE;
 115                         ipaddr->s6_addr16[7] = htons(*((u16 *)lladdr));
 116                         break;
 117                 default:
 118                         pr_debug("Invalid addr_type set\n");
 119                         return -EINVAL;
 120                 }
 121                 break;
 122         default:
 123                 pr_debug("Invalid address mode value: 0x%x\n", address_mode);
 124                 return -EINVAL;
 125         }
 126
 127         if (fail) {
 128                 pr_debug("Failed to fetch skb data\n");
 129                 return -EIO;
 130         }
 131
 132         raw_dump_inline(NULL, "Reconstructed ipv6 addr is",
 133                         ipaddr->s6_addr, 16);
 134
 135         return 0;
 136 }
 137
 138 /* Uncompress address function for source context
 139  * based address(non-multicast).
 140  */
 141 static int uncompress_context_based_src_addr(struct sk_buff *skb,
 142                                              struct in6_addr *ipaddr,
 143                                              const u8 sam)
 144 {
 145         switch (sam) {
 146         case LOWPAN_IPHC_ADDR_00:
 147                 /* unspec address ::
 148                  * Do nothing, address is already ::
 149                  */
 150                 break;
 151         case LOWPAN_IPHC_ADDR_01:
 152                 /* TODO */
 153         case LOWPAN_IPHC_ADDR_02:
 154                 /* TODO */
 155         case LOWPAN_IPHC_ADDR_03:
 156                 /* TODO */
 157                 netdev_warn(skb->dev, "SAM value 0x%x not supported\n", sam);
 158                 return -EINVAL;
 159         default:
 160                 pr_debug("Invalid sam value: 0x%x\n", sam);
 161                 return -EINVAL;
 162         }
 163
 164         raw_dump_inline(NULL,
 165                         "Reconstructed context based ipv6 src addr is",
 166                         ipaddr->s6_addr, 16);
 167
 168         return 0;
 169 }
 170
 171 /* Uncompress function for multicast destination address,
 172  * when M bit is set.
 173  */
 174 static int lowpan_uncompress_multicast_daddr(struct sk_buff *skb,
 175                                              struct in6_addr *ipaddr,
 176                                              const u8 dam)
 177 {
 178         bool fail;
 179
 180         switch (dam) {
 181         case LOWPAN_IPHC_DAM_00:
 182                 /* 00:  128 bits.  The full address
 183                  * is carried in-line.
 184                  */
 185                 fail = lowpan_fetch_skb(skb, ipaddr->s6_addr, 16);
 186                 break;
 187         case LOWPAN_IPHC_DAM_01:
 188                 /* 01:  48 bits.  The address takes
 189                  * the form ffXX::00XX:XXXX:XXXX.
 190                  */
 191                 ipaddr->s6_addr[0] = 0xFF;
 192                 fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[1], 1);
 193                 fail |= lowpan_fetch_skb(skb, &ipaddr->s6_addr[11], 5);
 194                 break;
 195         case LOWPAN_IPHC_DAM_10:
 196                 /* 10:  32 bits.  The address takes
 197                  * the form ffXX::00XX:XXXX.
 198                  */
 199                 ipaddr->s6_addr[0] = 0xFF;
 200                 fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[1], 1);
 201                 fail |= lowpan_fetch_skb(skb, &ipaddr->s6_addr[13], 3);
 202                 break;
 203         case LOWPAN_IPHC_DAM_11:
 204                 /* 11:  8 bits.  The address takes
 205                  * the form ff02::00XX.
 206                  */
 207                 ipaddr->s6_addr[0] = 0xFF;
 208                 ipaddr->s6_addr[1] = 0x02;
 209                 fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[15], 1);
 210                 break;
 211         default:
 212                 pr_debug("DAM value has a wrong value: 0x%x\n", dam);
 213                 return -EINVAL;
 214         }
 215
 216         if (fail) {
 217                 pr_debug("Failed to fetch skb data\n");
 218                 return -EIO;
 219         }
 220
 221         raw_dump_inline(NULL, "Reconstructed ipv6 multicast addr is",
 222                         ipaddr->s6_addr, 16);
 223
 224         return 0;
 225 }
 226
 227 static int uncompress_udp_header(struct sk_buff *skb, struct udphdr *uh)
 228 {
 229         bool fail;
 230         u8 tmp = 0, val = 0;
 231
 232         fail = lowpan_fetch_skb(skb, &tmp, sizeof(tmp));
 233
 234         if ((tmp & LOWPAN_NHC_UDP_MASK) == LOWPAN_NHC_UDP_ID) {
 235                 pr_debug("UDP header uncompression\n");
 236                 switch (tmp & LOWPAN_NHC_UDP_CS_P_11) {
 237                 case LOWPAN_NHC_UDP_CS_P_00:
 238                         fail |= lowpan_fetch_skb(skb, &uh->source,
 239                                                  sizeof(uh->source));
 240                         fail |= lowpan_fetch_skb(skb, &uh->dest,
 241                                                  sizeof(uh->dest));
 242                         break;
 243                 case LOWPAN_NHC_UDP_CS_P_01:
 244                         fail |= lowpan_fetch_skb(skb, &uh->source,
 245                                                  sizeof(uh->source));
 246                         fail |= lowpan_fetch_skb(skb, &val, sizeof(val));
 247                         uh->dest = htons(val + LOWPAN_NHC_UDP_8BIT_PORT);
 248                         break;
 249                 case LOWPAN_NHC_UDP_CS_P_10:
 250                         fail |= lowpan_fetch_skb(skb, &val, sizeof(val));
 251                         uh->source = htons(val + LOWPAN_NHC_UDP_8BIT_PORT);
 252                         fail |= lowpan_fetch_skb(skb, &uh->dest,
 253                                                  sizeof(uh->dest));
 254                         break;
 255                 case LOWPAN_NHC_UDP_CS_P_11:
 256                         fail |= lowpan_fetch_skb(skb, &val, sizeof(val));
 257                         uh->source = htons(LOWPAN_NHC_UDP_4BIT_PORT +
 258                                            (val >> 4));
 259                         uh->dest = htons(LOWPAN_NHC_UDP_4BIT_PORT +
 260                                          (val & 0x0f));
 261                         break;
 262                 default:
 263                         pr_debug("ERROR: unknown UDP format\n");
 264                         goto err;
 265                 }
 266
 267                 pr_debug("uncompressed UDP ports: src = %d, dst = %d\n",
 268                          ntohs(uh->source), ntohs(uh->dest));
 269
 270                 /* checksum */
 271                 if (tmp & LOWPAN_NHC_UDP_CS_C) {
 272                         pr_debug_ratelimited("checksum elided currently not supported\n");
 273                         goto err;
 274                 } else {
 275                         fail |= lowpan_fetch_skb(skb, &uh->check,
 276                                                  sizeof(uh->check));
 277                 }
 278
 279                 /* UDP length needs to be infered from the lower layers
 280                  * here, we obtain the hint from the remaining size of the
 281                  * frame
 282                  */
 283                 uh->len = htons(skb->len + sizeof(struct udphdr));
 284                 pr_debug("uncompressed UDP length: src = %d", ntohs(uh->len));
 285         } else {
 286                 pr_debug("ERROR: unsupported NH format\n");
 287                 goto err;
 288         }
 289
 290         if (fail)
 291                 goto err;
 292
 293         return 0;
 294 err:
 295         return -EINVAL;
 296 }
 297
 298 /* TTL uncompression values */
 299 static const u8 lowpan_ttl_values[] = { 0, 1, 64, 255 };
 300
 301 int
 302 lowpan_header_decompress(struct sk_buff *skb, struct net_device *dev,
 303                          const u8 *saddr, const u8 saddr_type,
 304                          const u8 saddr_len, const u8 *daddr,
 305                          const u8 daddr_type, const u8 daddr_len,
 306                          u8 iphc0, u8 iphc1)
 307 {
 308         struct ipv6hdr hdr = {};
 309         u8 tmp, num_context = 0;
 310         int err;
 311
 312         raw_dump_table(__func__, "raw skb data dump uncompressed",
 313                        skb->data, skb->len);
 314
 315         /* another if the CID flag is set */
 316         if (iphc1 & LOWPAN_IPHC_CID) {
 317                 pr_debug("CID flag is set, increase header with one\n");
 318                 if (lowpan_fetch_skb(skb, &num_context, sizeof(num_context)))
 319                         return -EINVAL;
 320         }
 321
 322         hdr.version = 6;
 323
 324         /* Traffic Class and Flow Label */
 325         switch ((iphc0 & LOWPAN_IPHC_TF) >> 3) {
 326         /* Traffic Class and FLow Label carried in-line
 327          * ECN + DSCP + 4-bit Pad + Flow Label (4 bytes)
 328          */
 329         case 0: /* 00b */
 330                 if (lowpan_fetch_skb(skb, &tmp, sizeof(tmp)))
 331                         return -EINVAL;
 332
 333                 memcpy(&hdr.flow_lbl, &skb->data[0], 3);
 334                 skb_pull(skb, 3);
 335                 hdr.priority = ((tmp >> 2) & 0x0f);
 336                 hdr.flow_lbl[0] = ((tmp >> 2) & 0x30) | (tmp << 6) |
 337                                         (hdr.flow_lbl[0] & 0x0f);
 338                 break;
 339         /* Traffic class carried in-line
 340          * ECN + DSCP (1 byte), Flow Label is elided
 341          */
 342         case 2: /* 10b */
 343                 if (lowpan_fetch_skb(skb, &tmp, sizeof(tmp)))
 344                         return -EINVAL;
 345
 346                 hdr.priority = ((tmp >> 2) & 0x0f);
 347                 hdr.flow_lbl[0] = ((tmp << 6) & 0xC0) | ((tmp >> 2) & 0x30);
 348                 break;
 349         /* Flow Label carried in-line
 350          * ECN + 2-bit Pad + Flow Label (3 bytes), DSCP is elided
 351          */
 352         case 1: /* 01b */
 353                 if (lowpan_fetch_skb(skb, &tmp, sizeof(tmp)))
 354                         return -EINVAL;
 355
 356                 hdr.flow_lbl[0] = (skb->data[0] & 0x0F) | ((tmp >> 2) & 0x30);
 357                 memcpy(&hdr.flow_lbl[1], &skb->data[0], 2);
 358                 skb_pull(skb, 2);
 359                 break;
 360         /* Traffic Class and Flow Label are elided */
 361         case 3: /* 11b */
 362                 break;
 363         default:
 364                 break;
 365         }
 366
 367         /* Next Header */
 368         if ((iphc0 & LOWPAN_IPHC_NH_C) == 0) {
 369                 /* Next header is carried inline */
 370                 if (lowpan_fetch_skb(skb, &hdr.nexthdr, sizeof(hdr.nexthdr)))
 371                         return -EINVAL;
 372
 373                 pr_debug("NH flag is set, next header carried inline: %02x\n",
 374                          hdr.nexthdr);
 375         }
 376
 377         /* Hop Limit */
 378         if ((iphc0 & 0x03) != LOWPAN_IPHC_TTL_I) {
 379                 hdr.hop_limit = lowpan_ttl_values[iphc0 & 0x03];
 380         } else {
 381                 if (lowpan_fetch_skb(skb, &hdr.hop_limit,
 382                                      sizeof(hdr.hop_limit)))
 383                         return -EINVAL;
 384         }
 385
 386         /* Extract SAM to the tmp variable */
 387         tmp = ((iphc1 & LOWPAN_IPHC_SAM) >> LOWPAN_IPHC_SAM_BIT) & 0x03;
 388
 389         if (iphc1 & LOWPAN_IPHC_SAC) {
 390                 /* Source address context based uncompression */
 391                 pr_debug("SAC bit is set. Handle context based source address.\n");
 392                 err = uncompress_context_based_src_addr(skb, &hdr.saddr, tmp);
 393         } else {
 394                 /* Source address uncompression */
 395                 pr_debug("source address stateless compression\n");
 396                 err = uncompress_addr(skb, &hdr.saddr, tmp, saddr,
 397                                       saddr_type, saddr_len);
 398         }
 399
 400         /* Check on error of previous branch */
 401         if (err)
 402                 return -EINVAL;
 403
 404         /* Extract DAM to the tmp variable */
 405         tmp = ((iphc1 & LOWPAN_IPHC_DAM_11) >> LOWPAN_IPHC_DAM_BIT) & 0x03;
 406
 407         /* check for Multicast Compression */
 408         if (iphc1 & LOWPAN_IPHC_M) {
 409                 if (iphc1 & LOWPAN_IPHC_DAC) {
 410                         pr_debug("dest: context-based mcast compression\n");
 411                         /* TODO: implement this */
 412                 } else {
 413                         err = lowpan_uncompress_multicast_daddr(skb, &hdr.daddr,
 414                                                                 tmp);
 415
 416                         if (err)
 417                                 return -EINVAL;
 418                 }
 419         } else {
 420                 err = uncompress_addr(skb, &hdr.daddr, tmp, daddr,
 421                                       daddr_type, daddr_len);
 422                 pr_debug("dest: stateless compression mode %d dest %pI6c\n",
 423                          tmp, &hdr.daddr);
 424                 if (err)
 425                         return -EINVAL;
 426         }
 427
 428         /* UDP data uncompression */
 429         if (iphc0 & LOWPAN_IPHC_NH_C) {
 430                 struct udphdr uh;
 431                 const int needed = sizeof(struct udphdr) + sizeof(hdr);
 432
 433                 if (uncompress_udp_header(skb, &uh))
 434                         return -EINVAL;
 435
 436                 /* replace the compressed UDP head by the uncompressed UDP
 437                  * header
 438                  */
 439                 err = skb_cow(skb, needed);
 440                 if (unlikely(err))
 441                         return err;
 442
 443                 skb_push(skb, sizeof(struct udphdr));
 444                 skb_reset_transport_header(skb);
 445                 skb_copy_to_linear_data(skb, &uh, sizeof(struct udphdr));
 446
 447                 raw_dump_table(__func__, "raw UDP header dump",
 448                                (u8 *)&uh, sizeof(uh));
 449
 450                 hdr.nexthdr = UIP_PROTO_UDP;
 451         } else {
 452                 err = skb_cow(skb, sizeof(hdr));
 453                 if (unlikely(err))
 454                         return err;
 455         }
 456
 457         hdr.payload_len = htons(skb->len);
 458
 459         pr_debug("skb headroom size = %d, data length = %d\n",
 460                  skb_headroom(skb), skb->len);
 461
 462         pr_debug("IPv6 header dump:\n\tversion = %d\n\tlength  = %d\n\t"
 463                  "nexthdr = 0x%02x\n\thop_lim = %d\n\tdest    = %pI6c\n",
 464                 hdr.version, ntohs(hdr.payload_len), hdr.nexthdr,
 465                 hdr.hop_limit, &hdr.daddr);
 466
 467         skb_push(skb, sizeof(hdr));
 468         skb_reset_network_header(skb);
 469         skb_copy_to_linear_data(skb, &hdr, sizeof(hdr));
 470
 471         raw_dump_table(__func__, "raw header dump", (u8 *)&hdr, sizeof(hdr));
 472
 473         return 0;
 474 }
 475 EXPORT_SYMBOL_GPL(lowpan_header_decompress);
 476
 477 static u8 lowpan_compress_addr_64(u8 **hc_ptr, u8 shift,
 478                                   const struct in6_addr *ipaddr,
 479                                   const unsigned char *lladdr)
 480 {
 481         u8 val = 0;
 482
 483         if (is_addr_mac_addr_based(ipaddr, lladdr)) {
 484                 val = 3; /* 0-bits */
 485                 pr_debug("address compression 0 bits\n");
 486         } else if (lowpan_is_iid_16_bit_compressable(ipaddr)) {
 487                 /* compress IID to 16 bits xxxx::XXXX */
 488                 lowpan_push_hc_data(hc_ptr, &ipaddr->s6_addr16[7], 2);
 489                 val = 2; /* 16-bits */
 490                 raw_dump_inline(NULL, "Compressed ipv6 addr is (16 bits)",
 491                                 *hc_ptr - 2, 2);
 492         } else {
 493                 /* do not compress IID => xxxx::IID */
 494                 lowpan_push_hc_data(hc_ptr, &ipaddr->s6_addr16[4], 8);
 495                 val = 1; /* 64-bits */
 496                 raw_dump_inline(NULL, "Compressed ipv6 addr is (64 bits)",
 497                                 *hc_ptr - 8, 8);
 498         }
 499
 500         return rol8(val, shift);
 501 }
 502
 503 static void compress_udp_header(u8 **hc_ptr, struct sk_buff *skb)
 504 {
 505         struct udphdr *uh;
 506         u8 tmp;
 507
 508         /* In the case of RAW sockets the transport header is not set by
 509          * the ip6 stack so we must set it ourselves
 510          */
 511         if (skb->transport_header == skb->network_header)
 512                 skb_set_transport_header(skb, sizeof(struct ipv6hdr));
 513
 514         uh = udp_hdr(skb);
 515
 516         if (((ntohs(uh->source) & LOWPAN_NHC_UDP_4BIT_MASK) ==
 517              LOWPAN_NHC_UDP_4BIT_PORT) &&
 518             ((ntohs(uh->dest) & LOWPAN_NHC_UDP_4BIT_MASK) ==
 519              LOWPAN_NHC_UDP_4BIT_PORT)) {
 520                 pr_debug("UDP header: both ports compression to 4 bits\n");
 521                 /* compression value */
 522                 tmp = LOWPAN_NHC_UDP_CS_P_11;
 523                 lowpan_push_hc_data(hc_ptr, &tmp, sizeof(tmp));
 524                 /* source and destination port */
 525                 tmp = ntohs(uh->dest) - LOWPAN_NHC_UDP_4BIT_PORT +
 526                       ((ntohs(uh->source) - LOWPAN_NHC_UDP_4BIT_PORT) << 4);
 527                 lowpan_push_hc_data(hc_ptr, &tmp, sizeof(tmp));
 528         } else if ((ntohs(uh->dest) & LOWPAN_NHC_UDP_8BIT_MASK) ==
 529                         LOWPAN_NHC_UDP_8BIT_PORT) {
 530                 pr_debug("UDP header: remove 8 bits of dest\n");
 531                 /* compression value */
 532                 tmp = LOWPAN_NHC_UDP_CS_P_01;
 533                 lowpan_push_hc_data(hc_ptr, &tmp, sizeof(tmp));
 534                 /* source port */
 535                 lowpan_push_hc_data(hc_ptr, &uh->source, sizeof(uh->source));
 536                 /* destination port */
 537                 tmp = ntohs(uh->dest) - LOWPAN_NHC_UDP_8BIT_PORT;
 538                 lowpan_push_hc_data(hc_ptr, &tmp, sizeof(tmp));
 539         } else if ((ntohs(uh->source) & LOWPAN_NHC_UDP_8BIT_MASK) ==
 540                         LOWPAN_NHC_UDP_8BIT_PORT) {
 541                 pr_debug("UDP header: remove 8 bits of source\n");
 542                 /* compression value */
 543                 tmp = LOWPAN_NHC_UDP_CS_P_10;
 544                 lowpan_push_hc_data(hc_ptr, &tmp, sizeof(tmp));
 545                 /* source port */
 546                 tmp = ntohs(uh->source) - LOWPAN_NHC_UDP_8BIT_PORT;
 547                 lowpan_push_hc_data(hc_ptr, &tmp, sizeof(tmp));
 548                 /* destination port */
 549                 lowpan_push_hc_data(hc_ptr, &uh->dest, sizeof(uh->dest));
 550         } else {
 551                 pr_debug("UDP header: can't compress\n");
 552                 /* compression value */
 553                 tmp = LOWPAN_NHC_UDP_CS_P_00;
 554                 lowpan_push_hc_data(hc_ptr, &tmp, sizeof(tmp));
 555                 /* source port */
 556                 lowpan_push_hc_data(hc_ptr, &uh->source, sizeof(uh->source));
 557                 /* destination port */
 558                 lowpan_push_hc_data(hc_ptr, &uh->dest, sizeof(uh->dest));
 559         }
 560
 561         /* checksum is always inline */
 562         lowpan_push_hc_data(hc_ptr, &uh->check, sizeof(uh->check));
 563
 564         /* skip the UDP header */
 565         skb_pull(skb, sizeof(struct udphdr));
 566 }
 567
 568 int lowpan_header_compress(struct sk_buff *skb, struct net_device *dev,
 569                            unsigned short type, const void *_daddr,
 570                            const void *_saddr, unsigned int len)
 571 {
 572         u8 tmp, iphc0, iphc1, *hc_ptr;
 573         struct ipv6hdr *hdr;
 574         u8 head[100] = {};
 575         int addr_type;
 576
 577         if (type != ETH_P_IPV6)
 578                 return -EINVAL;
 579
 580         hdr = ipv6_hdr(skb);
 581         hc_ptr = head + 2;
 582
 583         pr_debug("IPv6 header dump:\n\tversion = %d\n\tlength  = %d\n"
 584                  "\tnexthdr = 0x%02x\n\thop_lim = %d\n\tdest    = %pI6c\n",
 585                  hdr->version, ntohs(hdr->payload_len), hdr->nexthdr,
 586                  hdr->hop_limit, &hdr->daddr);
 587
 588         raw_dump_table(__func__, "raw skb network header dump",
 589                        skb_network_header(skb), sizeof(struct ipv6hdr));
 590
 591         /* As we copy some bit-length fields, in the IPHC encoding bytes,
 592          * we sometimes use |=
 593          * If the field is 0, and the current bit value in memory is 1,
 594          * this does not work. We therefore reset the IPHC encoding here
 595          */
 596         iphc0 = LOWPAN_DISPATCH_IPHC;
 597         iphc1 = 0;
 598
 599         /* TODO: context lookup */
 600
 601         raw_dump_inline(__func__, "saddr",
 602                         (unsigned char *)_saddr, IEEE802154_ADDR_LEN);
 603         raw_dump_inline(__func__, "daddr",
 604                         (unsigned char *)_daddr, IEEE802154_ADDR_LEN);
 605
 606         raw_dump_table(__func__, "sending raw skb network uncompressed packet",
 607                        skb->data, skb->len);
 608
 609         /* Traffic class, flow label
 610          * If flow label is 0, compress it. If traffic class is 0, compress it
 611          * We have to process both in the same time as the offset of traffic
 612          * class depends on the presence of version and flow label
 613          */
 614
 615         /* hc format of TC is ECN | DSCP , original one is DSCP | ECN */
 616         tmp = (hdr->priority << 4) | (hdr->flow_lbl[0] >> 4);
 617         tmp = ((tmp & 0x03) << 6) | (tmp >> 2);
 618
 619         if (((hdr->flow_lbl[0] & 0x0F) == 0) &&
 620             (hdr->flow_lbl[1] == 0) && (hdr->flow_lbl[2] == 0)) {
 621                 /* flow label can be compressed */
 622                 iphc0 |= LOWPAN_IPHC_FL_C;
 623                 if ((hdr->priority == 0) &&
 624                     ((hdr->flow_lbl[0] & 0xF0) == 0)) {
 625                         /* compress (elide) all */
 626                         iphc0 |= LOWPAN_IPHC_TC_C;
 627                 } else {
 628                         /* compress only the flow label */
 629                         *hc_ptr = tmp;
 630                         hc_ptr += 1;
 631                 }
 632         } else {
 633                 /* Flow label cannot be compressed */
 634                 if ((hdr->priority == 0) &&
 635                     ((hdr->flow_lbl[0] & 0xF0) == 0)) {
 636                         /* compress only traffic class */
 637                         iphc0 |= LOWPAN_IPHC_TC_C;
 638                         *hc_ptr = (tmp & 0xc0) | (hdr->flow_lbl[0] & 0x0F);
 639                         memcpy(hc_ptr + 1, &hdr->flow_lbl[1], 2);
 640                         hc_ptr += 3;
 641                 } else {
 642                         /* compress nothing */
 643                         memcpy(hc_ptr, hdr, 4);
 644                         /* replace the top byte with new ECN | DSCP format */
 645                         *hc_ptr = tmp;
 646                         hc_ptr += 4;
 647                 }
 648         }
 649
 650         /* NOTE: payload length is always compressed */
 651
 652         /* Next Header is compress if UDP */
 653         if (hdr->nexthdr == UIP_PROTO_UDP)
 654                 iphc0 |= LOWPAN_IPHC_NH_C;
 655
 656         if ((iphc0 & LOWPAN_IPHC_NH_C) == 0)
 657                 lowpan_push_hc_data(&hc_ptr, &hdr->nexthdr,
 658                                     sizeof(hdr->nexthdr));
 659
 660         /* Hop limit
 661          * if 1:   compress, encoding is 01
 662          * if 64:  compress, encoding is 10
 663          * if 255: compress, encoding is 11
 664          * else do not compress
 665          */
 666         switch (hdr->hop_limit) {
 667         case 1:
 668                 iphc0 |= LOWPAN_IPHC_TTL_1;
 669                 break;
 670         case 64:
 671                 iphc0 |= LOWPAN_IPHC_TTL_64;
 672                 break;
 673         case 255:
 674                 iphc0 |= LOWPAN_IPHC_TTL_255;
 675                 break;
 676         default:
 677                 lowpan_push_hc_data(&hc_ptr, &hdr->hop_limit,
 678                                     sizeof(hdr->hop_limit));
 679         }
 680
 681         addr_type = ipv6_addr_type(&hdr->saddr);
 682         /* source address compression */
 683         if (addr_type == IPV6_ADDR_ANY) {
 684                 pr_debug("source address is unspecified, setting SAC\n");
 685                 iphc1 |= LOWPAN_IPHC_SAC;
 686         } else {
 687                 if (addr_type & IPV6_ADDR_LINKLOCAL) {
 688                         iphc1 |= lowpan_compress_addr_64(&hc_ptr,
 689                                                          LOWPAN_IPHC_SAM_BIT,
 690                                                          &hdr->saddr, _saddr);
 691                         pr_debug("source address unicast link-local %pI6c iphc1 0x%02x\n",
 692                                  &hdr->saddr, iphc1);
 693                 } else {
 694                         pr_debug("send the full source address\n");
 695                         lowpan_push_hc_data(&hc_ptr, hdr->saddr.s6_addr, 16);
 696                 }
 697         }
 698
 699         addr_type = ipv6_addr_type(&hdr->daddr);
 700         /* destination address compression */
 701         if (addr_type & IPV6_ADDR_MULTICAST) {
 702                 pr_debug("destination address is multicast: ");
 703                 iphc1 |= LOWPAN_IPHC_M;
 704                 if (lowpan_is_mcast_addr_compressable8(&hdr->daddr)) {
 705                         pr_debug("compressed to 1 octet\n");
 706                         iphc1 |= LOWPAN_IPHC_DAM_11;
 707                         /* use last byte */
 708                         lowpan_push_hc_data(&hc_ptr,
 709                                             &hdr->daddr.s6_addr[15], 1);
 710                 } else if (lowpan_is_mcast_addr_compressable32(&hdr->daddr)) {
 711                         pr_debug("compressed to 4 octets\n");
 712                         iphc1 |= LOWPAN_IPHC_DAM_10;
 713                         /* second byte + the last three */
 714                         lowpan_push_hc_data(&hc_ptr,
 715                                             &hdr->daddr.s6_addr[1], 1);
 716                         lowpan_push_hc_data(&hc_ptr,
 717                                             &hdr->daddr.s6_addr[13], 3);
 718                 } else if (lowpan_is_mcast_addr_compressable48(&hdr->daddr)) {
 719                         pr_debug("compressed to 6 octets\n");
 720                         iphc1 |= LOWPAN_IPHC_DAM_01;
 721                         /* second byte + the last five */
 722                         lowpan_push_hc_data(&hc_ptr,
 723                                             &hdr->daddr.s6_addr[1], 1);
 724                         lowpan_push_hc_data(&hc_ptr,
 725                                             &hdr->daddr.s6_addr[11], 5);
 726                 } else {
 727                         pr_debug("using full address\n");
 728                         iphc1 |= LOWPAN_IPHC_DAM_00;
 729                         lowpan_push_hc_data(&hc_ptr, hdr->daddr.s6_addr, 16);
 730                 }
 731         } else {
 732                 if (addr_type & IPV6_ADDR_LINKLOCAL) {
 733                         /* TODO: context lookup */
 734                         iphc1 |= lowpan_compress_addr_64(&hc_ptr,
 735                                 LOWPAN_IPHC_DAM_BIT, &hdr->daddr, _daddr);
 736                         pr_debug("dest address unicast link-local %pI6c "
 737                                  "iphc1 0x%02x\n", &hdr->daddr, iphc1);
 738                 } else {
 739                         pr_debug("dest address unicast %pI6c\n", &hdr->daddr);
 740                         lowpan_push_hc_data(&hc_ptr, hdr->daddr.s6_addr, 16);
 741                 }
 742         }
 743
 744         /* UDP header compression */
 745         if (hdr->nexthdr == UIP_PROTO_UDP)
 746                 compress_udp_header(&hc_ptr, skb);
 747
 748         head[0] = iphc0;
 749         head[1] = iphc1;
 750
 751         skb_pull(skb, sizeof(struct ipv6hdr));
 752         skb_reset_transport_header(skb);
 753         memcpy(skb_push(skb, hc_ptr - head), head, hc_ptr - head);
 754         skb_reset_network_header(skb);
 755
 756         pr_debug("header len %d skb %u\n", (int)(hc_ptr - head), skb->len);
 757
 758         raw_dump_table(__func__, "raw skb data dump compressed",
 759                        skb->data, skb->len);
 760         return 0;
 761 }
 762 EXPORT_SYMBOL_GPL(lowpan_header_compress);
 763
 764 MODULE_LICENSE("GPL");