net/6lowpan/iphc.c

   1 /*
   2  * Copyright 2011, Siemens AG
   3  * written by Alexander Smirnov <alex.bluesman.smirnov@gmail.com>
   4  */
   5
   6 /*
   7  * Based on patches from Jon Smirl <jonsmirl@gmail.com>
   8  * Copyright (c) 2011 Jon Smirl <jonsmirl@gmail.com>
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License version 2
  12  * as published by the Free Software Foundation.
  13  *
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17  * GNU General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU General Public License along
  20  * with this program; if not, write to the Free Software Foundation, Inc.,
  21  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  22  */
  23
  24 /* Jon's code is based on 6lowpan implementation for Contiki which is:
  25  * Copyright (c) 2008, Swedish Institute of Computer Science.
  26  * All rights reserved.
  27  *
  28  * Redistribution and use in source and binary forms, with or without
  29  * modification, are permitted provided that the following conditions
  30  * are met:
  31  * 1. Redistributions of source code must retain the above copyright
  32  *    notice, this list of conditions and the following disclaimer.
  33  * 2. Redistributions in binary form must reproduce the above copyright
  34  *    notice, this list of conditions and the following disclaimer in the
  35  *    documentation and/or other materials provided with the distribution.
  36  * 3. Neither the name of the Institute nor the names of its contributors
  37  *    may be used to endorse or promote products derived from this software
  38  *    without specific prior written permission.
  39  *
  40  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
  41  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  42  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  43  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
  44  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  45  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  46  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  47  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  48  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  49  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  50  * SUCH DAMAGE.
  51  */
  52
  53 #include <linux/bitops.h>
  54 #include <linux/if_arp.h>
  55 #include <linux/module.h>
  56 #include <linux/netdevice.h>
  57 #include <net/6lowpan.h>
  58 #include <net/ipv6.h>
  59 #include <net/af_ieee802154.h>
  60
  61 /*
  62  * Uncompress address function for source and
  63  * destination address(non-multicast).
  64  *
  65  * address_mode is sam value or dam value.
  66  */
  67 static int uncompress_addr(struct sk_buff *skb,
  68                                 struct in6_addr *ipaddr, const u8 address_mode,
  69                                 const u8 *lladdr, const u8 addr_type,
  70                                 const u8 addr_len)
  71 {
  72         bool fail;
  73
  74         switch (address_mode) {
  75         case LOWPAN_IPHC_ADDR_00:
  76                 /* for global link addresses */
  77                 fail = lowpan_fetch_skb(skb, ipaddr->s6_addr, 16);
  78                 break;
  79         case LOWPAN_IPHC_ADDR_01:
  80                 /* fe:80::XXXX:XXXX:XXXX:XXXX */
  81                 ipaddr->s6_addr[0] = 0xFE;
  82                 ipaddr->s6_addr[1] = 0x80;
  83                 fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[8], 8);
  84                 break;
  85         case LOWPAN_IPHC_ADDR_02:
  86                 /* fe:80::ff:fe00:XXXX */
  87                 ipaddr->s6_addr[0] = 0xFE;
  88                 ipaddr->s6_addr[1] = 0x80;
  89                 ipaddr->s6_addr[11] = 0xFF;
  90                 ipaddr->s6_addr[12] = 0xFE;
  91                 fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[14], 2);
  92                 break;
  93         case LOWPAN_IPHC_ADDR_03:
  94                 fail = false;
  95                 switch (addr_type) {
  96                 case IEEE802154_ADDR_LONG:
  97                         /* fe:80::XXXX:XXXX:XXXX:XXXX
  98                          *        \_________________/
  99                          *              hwaddr
 100                          */
 101                         ipaddr->s6_addr[0] = 0xFE;
 102                         ipaddr->s6_addr[1] = 0x80;
 103                         memcpy(&ipaddr->s6_addr[8], lladdr, addr_len);
 104                         /* second bit-flip (Universe/Local)
 105                          * is done according RFC2464
 106                          */
 107                         ipaddr->s6_addr[8] ^= 0x02;
 108                         break;
 109                 case IEEE802154_ADDR_SHORT:
 110                         /* fe:80::ff:fe00:XXXX
 111                          *                \__/
 112                          *             short_addr
 113                          *
 114                          * Universe/Local bit is zero.
 115                          */
 116                         ipaddr->s6_addr[0] = 0xFE;
 117                         ipaddr->s6_addr[1] = 0x80;
 118                         ipaddr->s6_addr[11] = 0xFF;
 119                         ipaddr->s6_addr[12] = 0xFE;
 120                         ipaddr->s6_addr16[7] = htons(*((u16 *)lladdr));
 121                         break;
 122                 default:
 123                         pr_debug("Invalid addr_type set\n");
 124                         return -EINVAL;
 125                 }
 126                 break;
 127         default:
 128                 pr_debug("Invalid address mode value: 0x%x\n", address_mode);
 129                 return -EINVAL;
 130         }
 131
 132         if (fail) {
 133                 pr_debug("Failed to fetch skb data\n");
 134                 return -EIO;
 135         }
 136
 137         raw_dump_inline(NULL, "Reconstructed ipv6 addr is",
 138                         ipaddr->s6_addr, 16);
 139
 140         return 0;
 141 }
 142
 143 /*
 144  * Uncompress address function for source context
 145  * based address(non-multicast).
 146  */
 147 static int uncompress_context_based_src_addr(struct sk_buff *skb,
 148                                                 struct in6_addr *ipaddr,
 149                                                 const u8 sam)
 150 {
 151         switch (sam) {
 152         case LOWPAN_IPHC_ADDR_00:
 153                 /* unspec address ::
 154                  * Do nothing, address is already ::
 155                  */
 156                 break;
 157         case LOWPAN_IPHC_ADDR_01:
 158                 /* TODO */
 159         case LOWPAN_IPHC_ADDR_02:
 160                 /* TODO */
 161         case LOWPAN_IPHC_ADDR_03:
 162                 /* TODO */
 163                 netdev_warn(skb->dev, "SAM value 0x%x not supported\n", sam);
 164                 return -EINVAL;
 165         default:
 166                 pr_debug("Invalid sam value: 0x%x\n", sam);
 167                 return -EINVAL;
 168         }
 169
 170         raw_dump_inline(NULL,
 171                         "Reconstructed context based ipv6 src addr is",
 172                         ipaddr->s6_addr, 16);
 173
 174         return 0;
 175 }
 176
 177 static int skb_deliver(struct sk_buff *skb, struct ipv6hdr *hdr,
 178                 struct net_device *dev, skb_delivery_cb deliver_skb)
 179 {
 180         struct sk_buff *new;
 181         int stat;
 182
 183         new = skb_copy_expand(skb, sizeof(struct ipv6hdr), skb_tailroom(skb),
 184                                                                 GFP_ATOMIC);
 185         kfree_skb(skb);
 186
 187         if (!new)
 188                 return -ENOMEM;
 189
 190         skb_push(new, sizeof(struct ipv6hdr));
 191         skb_reset_network_header(new);
 192         skb_copy_to_linear_data(new, hdr, sizeof(struct ipv6hdr));
 193
 194         new->protocol = htons(ETH_P_IPV6);
 195         new->pkt_type = PACKET_HOST;
 196         new->dev = dev;
 197
 198         raw_dump_table(__func__, "raw skb data dump before receiving",
 199                         new->data, new->len);
 200
 201         stat = deliver_skb(new, dev);
 202
 203         kfree_skb(new);
 204
 205         return stat;
 206 }
 207
 208 /* Uncompress function for multicast destination address,
 209  * when M bit is set.
 210  */
 211 static int
 212 lowpan_uncompress_multicast_daddr(struct sk_buff *skb,
 213                 struct in6_addr *ipaddr,
 214                 const u8 dam)
 215 {
 216         bool fail;
 217
 218         switch (dam) {
 219         case LOWPAN_IPHC_DAM_00:
 220                 /* 00:  128 bits.  The full address
 221                  * is carried in-line.
 222                  */
 223                 fail = lowpan_fetch_skb(skb, ipaddr->s6_addr, 16);
 224                 break;
 225         case LOWPAN_IPHC_DAM_01:
 226                 /* 01:  48 bits.  The address takes
 227                  * the form ffXX::00XX:XXXX:XXXX.
 228                  */
 229                 ipaddr->s6_addr[0] = 0xFF;
 230                 fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[1], 1);
 231                 fail |= lowpan_fetch_skb(skb, &ipaddr->s6_addr[11], 5);
 232                 break;
 233         case LOWPAN_IPHC_DAM_10:
 234                 /* 10:  32 bits.  The address takes
 235                  * the form ffXX::00XX:XXXX.
 236                  */
 237                 ipaddr->s6_addr[0] = 0xFF;
 238                 fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[1], 1);
 239                 fail |= lowpan_fetch_skb(skb, &ipaddr->s6_addr[13], 3);
 240                 break;
 241         case LOWPAN_IPHC_DAM_11:
 242                 /* 11:  8 bits.  The address takes
 243                  * the form ff02::00XX.
 244                  */
 245                 ipaddr->s6_addr[0] = 0xFF;
 246                 ipaddr->s6_addr[1] = 0x02;
 247                 fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[15], 1);
 248                 break;
 249         default:
 250                 pr_debug("DAM value has a wrong value: 0x%x\n", dam);
 251                 return -EINVAL;
 252         }
 253
 254         if (fail) {
 255                 pr_debug("Failed to fetch skb data\n");
 256                 return -EIO;
 257         }
 258
 259         raw_dump_inline(NULL, "Reconstructed ipv6 multicast addr is",
 260                                 ipaddr->s6_addr, 16);
 261
 262         return 0;
 263 }
 264
 265 static int
 266 uncompress_udp_header(struct sk_buff *skb, struct udphdr *uh)
 267 {
 268         bool fail;
 269         u8 tmp = 0, val = 0;
 270
 271         if (!uh)
 272                 goto err;
 273
 274         fail = lowpan_fetch_skb(skb, &tmp, sizeof(tmp));
 275
 276         if ((tmp & LOWPAN_NHC_UDP_MASK) == LOWPAN_NHC_UDP_ID) {
 277                 pr_debug("UDP header uncompression\n");
 278                 switch (tmp & LOWPAN_NHC_UDP_CS_P_11) {
 279                 case LOWPAN_NHC_UDP_CS_P_00:
 280                         fail |= lowpan_fetch_skb(skb, &uh->source,
 281                                                  sizeof(uh->source));
 282                         fail |= lowpan_fetch_skb(skb, &uh->dest,
 283                                                  sizeof(uh->dest));
 284                         break;
 285                 case LOWPAN_NHC_UDP_CS_P_01:
 286                         fail |= lowpan_fetch_skb(skb, &uh->source,
 287                                                  sizeof(uh->source));
 288                         fail |= lowpan_fetch_skb(skb, &val, sizeof(val));
 289                         uh->dest = htons(val + LOWPAN_NHC_UDP_8BIT_PORT);
 290                         break;
 291                 case LOWPAN_NHC_UDP_CS_P_10:
 292                         fail |= lowpan_fetch_skb(skb, &val, sizeof(val));
 293                         uh->source = htons(val + LOWPAN_NHC_UDP_8BIT_PORT);
 294                         fail |= lowpan_fetch_skb(skb, &uh->dest,
 295                                                  sizeof(uh->dest));
 296                         break;
 297                 case LOWPAN_NHC_UDP_CS_P_11:
 298                         fail |= lowpan_fetch_skb(skb, &val, sizeof(val));
 299                         uh->source = htons(LOWPAN_NHC_UDP_4BIT_PORT +
 300                                            (val >> 4));
 301                         uh->dest = htons(LOWPAN_NHC_UDP_4BIT_PORT +
 302                                          (val & 0x0f));
 303                         break;
 304                 default:
 305                         pr_debug("ERROR: unknown UDP format\n");
 306                         goto err;
 307                         break;
 308                 }
 309
 310                 pr_debug("uncompressed UDP ports: src = %d, dst = %d\n",
 311                          ntohs(uh->source), ntohs(uh->dest));
 312
 313                 /* checksum */
 314                 if (tmp & LOWPAN_NHC_UDP_CS_C) {
 315                         pr_debug_ratelimited("checksum elided currently not supported\n");
 316                         goto err;
 317                 } else {
 318                         fail |= lowpan_fetch_skb(skb, &uh->check,
 319                                                  sizeof(uh->check));
 320                 }
 321
 322                 /*
 323                  * UDP lenght needs to be infered from the lower layers
 324                  * here, we obtain the hint from the remaining size of the
 325                  * frame
 326                  */
 327                 uh->len = htons(skb->len + sizeof(struct udphdr));
 328                 pr_debug("uncompressed UDP length: src = %d", ntohs(uh->len));
 329         } else {
 330                 pr_debug("ERROR: unsupported NH format\n");
 331                 goto err;
 332         }
 333
 334         if (fail)
 335                 goto err;
 336
 337         return 0;
 338 err:
 339         return -EINVAL;
 340 }
 341
 342 /* TTL uncompression values */
 343 static const u8 lowpan_ttl_values[] = { 0, 1, 64, 255 };
 344
 345 int lowpan_process_data(struct sk_buff *skb, struct net_device *dev,
 346                 const u8 *saddr, const u8 saddr_type, const u8 saddr_len,
 347                 const u8 *daddr, const u8 daddr_type, const u8 daddr_len,
 348                 u8 iphc0, u8 iphc1, skb_delivery_cb deliver_skb)
 349 {
 350         struct ipv6hdr hdr = {};
 351         u8 tmp, num_context = 0;
 352         int err;
 353
 354         raw_dump_table(__func__, "raw skb data dump uncompressed",
 355                                 skb->data, skb->len);
 356
 357         /* another if the CID flag is set */
 358         if (iphc1 & LOWPAN_IPHC_CID) {
 359                 pr_debug("CID flag is set, increase header with one\n");
 360                 if (lowpan_fetch_skb(skb, &num_context, sizeof(num_context)))
 361                         goto drop;
 362         }
 363
 364         hdr.version = 6;
 365
 366         /* Traffic Class and Flow Label */
 367         switch ((iphc0 & LOWPAN_IPHC_TF) >> 3) {
 368         /*
 369          * Traffic Class and FLow Label carried in-line
 370          * ECN + DSCP + 4-bit Pad + Flow Label (4 bytes)
 371          */
 372         case 0: /* 00b */
 373                 if (lowpan_fetch_skb(skb, &tmp, sizeof(tmp)))
 374                         goto drop;
 375
 376                 memcpy(&hdr.flow_lbl, &skb->data[0], 3);
 377                 skb_pull(skb, 3);
 378                 hdr.priority = ((tmp >> 2) & 0x0f);
 379                 hdr.flow_lbl[0] = ((tmp >> 2) & 0x30) | (tmp << 6) |
 380                                         (hdr.flow_lbl[0] & 0x0f);
 381                 break;
 382         /*
 383          * Traffic class carried in-line
 384          * ECN + DSCP (1 byte), Flow Label is elided
 385          */
 386         case 2: /* 10b */
 387                 if (lowpan_fetch_skb(skb, &tmp, sizeof(tmp)))
 388                         goto drop;
 389
 390                 hdr.priority = ((tmp >> 2) & 0x0f);
 391                 hdr.flow_lbl[0] = ((tmp << 6) & 0xC0) | ((tmp >> 2) & 0x30);
 392                 break;
 393         /*
 394          * Flow Label carried in-line
 395          * ECN + 2-bit Pad + Flow Label (3 bytes), DSCP is elided
 396          */
 397         case 1: /* 01b */
 398                 if (lowpan_fetch_skb(skb, &tmp, sizeof(tmp)))
 399                         goto drop;
 400
 401                 hdr.flow_lbl[0] = (skb->data[0] & 0x0F) | ((tmp >> 2) & 0x30);
 402                 memcpy(&hdr.flow_lbl[1], &skb->data[0], 2);
 403                 skb_pull(skb, 2);
 404                 break;
 405         /* Traffic Class and Flow Label are elided */
 406         case 3: /* 11b */
 407                 break;
 408         default:
 409                 break;
 410         }
 411
 412         /* Next Header */
 413         if ((iphc0 & LOWPAN_IPHC_NH_C) == 0) {
 414                 /* Next header is carried inline */
 415                 if (lowpan_fetch_skb(skb, &hdr.nexthdr, sizeof(hdr.nexthdr)))
 416                         goto drop;
 417
 418                 pr_debug("NH flag is set, next header carried inline: %02x\n",
 419                          hdr.nexthdr);
 420         }
 421
 422         /* Hop Limit */
 423         if ((iphc0 & 0x03) != LOWPAN_IPHC_TTL_I)
 424                 hdr.hop_limit = lowpan_ttl_values[iphc0 & 0x03];
 425         else {
 426                 if (lowpan_fetch_skb(skb, &hdr.hop_limit,
 427                                      sizeof(hdr.hop_limit)))
 428                         goto drop;
 429         }
 430
 431         /* Extract SAM to the tmp variable */
 432         tmp = ((iphc1 & LOWPAN_IPHC_SAM) >> LOWPAN_IPHC_SAM_BIT) & 0x03;
 433
 434         if (iphc1 & LOWPAN_IPHC_SAC) {
 435                 /* Source address context based uncompression */
 436                 pr_debug("SAC bit is set. Handle context based source address.\n");
 437                 err = uncompress_context_based_src_addr(
 438                                 skb, &hdr.saddr, tmp);
 439         } else {
 440                 /* Source address uncompression */
 441                 pr_debug("source address stateless compression\n");
 442                 err = uncompress_addr(skb, &hdr.saddr, tmp, saddr,
 443                                         saddr_type, saddr_len);
 444         }
 445
 446         /* Check on error of previous branch */
 447         if (err)
 448                 goto drop;
 449
 450         /* Extract DAM to the tmp variable */
 451         tmp = ((iphc1 & LOWPAN_IPHC_DAM_11) >> LOWPAN_IPHC_DAM_BIT) & 0x03;
 452
 453         /* check for Multicast Compression */
 454         if (iphc1 & LOWPAN_IPHC_M) {
 455                 if (iphc1 & LOWPAN_IPHC_DAC) {
 456                         pr_debug("dest: context-based mcast compression\n");
 457                         /* TODO: implement this */
 458                 } else {
 459                         err = lowpan_uncompress_multicast_daddr(
 460                                                 skb, &hdr.daddr, tmp);
 461                         if (err)
 462                                 goto drop;
 463                 }
 464         } else {
 465                 err = uncompress_addr(skb, &hdr.daddr, tmp, daddr,
 466                                         daddr_type, daddr_len);
 467                 pr_debug("dest: stateless compression mode %d dest %pI6c\n",
 468                         tmp, &hdr.daddr);
 469                 if (err)
 470                         goto drop;
 471         }
 472
 473         /* UDP data uncompression */
 474         if (iphc0 & LOWPAN_IPHC_NH_C) {
 475                 struct udphdr uh;
 476                 struct sk_buff *new;
 477                 if (uncompress_udp_header(skb, &uh))
 478                         goto drop;
 479
 480                 /*
 481                  * replace the compressed UDP head by the uncompressed UDP
 482                  * header
 483                  */
 484                 new = skb_copy_expand(skb, sizeof(struct udphdr),
 485                                       skb_tailroom(skb), GFP_ATOMIC);
 486                 kfree_skb(skb);
 487
 488                 if (!new)
 489                         return -ENOMEM;
 490
 491                 skb = new;
 492
 493                 skb_push(skb, sizeof(struct udphdr));
 494                 skb_reset_transport_header(skb);
 495                 skb_copy_to_linear_data(skb, &uh, sizeof(struct udphdr));
 496
 497                 raw_dump_table(__func__, "raw UDP header dump",
 498                                       (u8 *)&uh, sizeof(uh));
 499
 500                 hdr.nexthdr = UIP_PROTO_UDP;
 501         }
 502
 503         hdr.payload_len = htons(skb->len);
 504
 505         pr_debug("skb headroom size = %d, data length = %d\n",
 506                  skb_headroom(skb), skb->len);
 507
 508         pr_debug("IPv6 header dump:\n\tversion = %d\n\tlength  = %d\n\t"
 509                  "nexthdr = 0x%02x\n\thop_lim = %d\n\tdest    = %pI6c\n",
 510                 hdr.version, ntohs(hdr.payload_len), hdr.nexthdr,
 511                 hdr.hop_limit, &hdr.daddr);
 512
 513         raw_dump_table(__func__, "raw header dump", (u8 *)&hdr,
 514                                                         sizeof(hdr));
 515
 516         return skb_deliver(skb, &hdr, dev, deliver_skb);
 517
 518 drop:
 519         kfree_skb(skb);
 520         return -EINVAL;
 521 }
 522 EXPORT_SYMBOL_GPL(lowpan_process_data);
 523
 524 static u8 lowpan_compress_addr_64(u8 **hc_ptr, u8 shift,
 525                                   const struct in6_addr *ipaddr,
 526                                   const unsigned char *lladdr)
 527 {
 528         u8 val = 0;
 529
 530         if (is_addr_mac_addr_based(ipaddr, lladdr)) {
 531                 val = 3; /* 0-bits */
 532                 pr_debug("address compression 0 bits\n");
 533         } else if (lowpan_is_iid_16_bit_compressable(ipaddr)) {
 534                 /* compress IID to 16 bits xxxx::XXXX */
 535                 memcpy(*hc_ptr, &ipaddr->s6_addr16[7], 2);
 536                 *hc_ptr += 2;
 537                 val = 2; /* 16-bits */
 538                 raw_dump_inline(NULL, "Compressed ipv6 addr is (16 bits)",
 539                                 *hc_ptr - 2, 2);
 540         } else {
 541                 /* do not compress IID => xxxx::IID */
 542                 memcpy(*hc_ptr, &ipaddr->s6_addr16[4], 8);
 543                 *hc_ptr += 8;
 544                 val = 1; /* 64-bits */
 545                 raw_dump_inline(NULL, "Compressed ipv6 addr is (64 bits)",
 546                                 *hc_ptr - 8, 8);
 547         }
 548
 549         return rol8(val, shift);
 550 }
 551
 552 static void compress_udp_header(u8 **hc_ptr, struct sk_buff *skb)
 553 {
 554         struct udphdr *uh = udp_hdr(skb);
 555         u8 tmp;
 556
 557         if (((ntohs(uh->source) & LOWPAN_NHC_UDP_4BIT_MASK) ==
 558              LOWPAN_NHC_UDP_4BIT_PORT) &&
 559             ((ntohs(uh->dest) & LOWPAN_NHC_UDP_4BIT_MASK) ==
 560              LOWPAN_NHC_UDP_4BIT_PORT)) {
 561                 pr_debug("UDP header: both ports compression to 4 bits\n");
 562                 /* compression value */
 563                 tmp = LOWPAN_NHC_UDP_CS_P_11;
 564                 lowpan_push_hc_data(hc_ptr, &tmp, sizeof(tmp));
 565                 /* source and destination port */
 566                 tmp = ntohs(uh->dest) - LOWPAN_NHC_UDP_4BIT_PORT +
 567                       ((ntohs(uh->source) - LOWPAN_NHC_UDP_4BIT_PORT) << 4);
 568                 lowpan_push_hc_data(hc_ptr, &tmp, sizeof(tmp));
 569         } else if ((ntohs(uh->dest) & LOWPAN_NHC_UDP_8BIT_MASK) ==
 570                         LOWPAN_NHC_UDP_8BIT_PORT) {
 571                 pr_debug("UDP header: remove 8 bits of dest\n");
 572                 /* compression value */
 573                 tmp = LOWPAN_NHC_UDP_CS_P_01;
 574                 lowpan_push_hc_data(hc_ptr, &tmp, sizeof(tmp));
 575                 /* source port */
 576                 lowpan_push_hc_data(hc_ptr, &uh->source, sizeof(uh->source));
 577                 /* destination port */
 578                 tmp = ntohs(uh->dest) - LOWPAN_NHC_UDP_8BIT_PORT;
 579                 lowpan_push_hc_data(hc_ptr, &tmp, sizeof(tmp));
 580         } else if ((ntohs(uh->source) & LOWPAN_NHC_UDP_8BIT_MASK) ==
 581                         LOWPAN_NHC_UDP_8BIT_PORT) {
 582                 pr_debug("UDP header: remove 8 bits of source\n");
 583                 /* compression value */
 584                 tmp = LOWPAN_NHC_UDP_CS_P_10;
 585                 lowpan_push_hc_data(hc_ptr, &tmp, sizeof(tmp));
 586                 /* source port */
 587                 tmp = ntohs(uh->source) - LOWPAN_NHC_UDP_8BIT_PORT;
 588                 lowpan_push_hc_data(hc_ptr, &tmp, sizeof(tmp));
 589                 /* destination port */
 590                 lowpan_push_hc_data(hc_ptr, &uh->dest, sizeof(uh->dest));
 591         } else {
 592                 pr_debug("UDP header: can't compress\n");
 593                 /* compression value */
 594                 tmp = LOWPAN_NHC_UDP_CS_P_00;
 595                 lowpan_push_hc_data(hc_ptr, &tmp, sizeof(tmp));
 596                 /* source port */
 597                 lowpan_push_hc_data(hc_ptr, &uh->source, sizeof(uh->source));
 598                 /* destination port */
 599                 lowpan_push_hc_data(hc_ptr, &uh->dest, sizeof(uh->dest));
 600         }
 601
 602         /* checksum is always inline */
 603         lowpan_push_hc_data(hc_ptr, &uh->check, sizeof(uh->check));
 604
 605         /* skip the UDP header */
 606         skb_pull(skb, sizeof(struct udphdr));
 607 }
 608
 609 int lowpan_header_compress(struct sk_buff *skb, struct net_device *dev,
 610                         unsigned short type, const void *_daddr,
 611                         const void *_saddr, unsigned int len)
 612 {
 613         u8 tmp, iphc0, iphc1, *hc_ptr;
 614         struct ipv6hdr *hdr;
 615         u8 head[100] = {};
 616
 617         if (type != ETH_P_IPV6)
 618                 return -EINVAL;
 619
 620         hdr = ipv6_hdr(skb);
 621         hc_ptr = head + 2;
 622
 623         pr_debug("IPv6 header dump:\n\tversion = %d\n\tlength  = %d\n"
 624                  "\tnexthdr = 0x%02x\n\thop_lim = %d\n\tdest    = %pI6c\n",
 625                 hdr->version, ntohs(hdr->payload_len), hdr->nexthdr,
 626                 hdr->hop_limit, &hdr->daddr);
 627
 628         raw_dump_table(__func__, "raw skb network header dump",
 629                 skb_network_header(skb), sizeof(struct ipv6hdr));
 630
 631         /*
 632          * As we copy some bit-length fields, in the IPHC encoding bytes,
 633          * we sometimes use |=
 634          * If the field is 0, and the current bit value in memory is 1,
 635          * this does not work. We therefore reset the IPHC encoding here
 636          */
 637         iphc0 = LOWPAN_DISPATCH_IPHC;
 638         iphc1 = 0;
 639
 640         /* TODO: context lookup */
 641
 642         raw_dump_inline(__func__, "saddr",
 643                         (unsigned char *)_saddr, IEEE802154_ADDR_LEN);
 644         raw_dump_inline(__func__, "daddr",
 645                         (unsigned char *)_daddr, IEEE802154_ADDR_LEN);
 646
 647         raw_dump_table(__func__,
 648                         "sending raw skb network uncompressed packet",
 649                         skb->data, skb->len);
 650
 651         /*
 652          * Traffic class, flow label
 653          * If flow label is 0, compress it. If traffic class is 0, compress it
 654          * We have to process both in the same time as the offset of traffic
 655          * class depends on the presence of version and flow label
 656          */
 657
 658         /* hc format of TC is ECN | DSCP , original one is DSCP | ECN */
 659         tmp = (hdr->priority << 4) | (hdr->flow_lbl[0] >> 4);
 660         tmp = ((tmp & 0x03) << 6) | (tmp >> 2);
 661
 662         if (((hdr->flow_lbl[0] & 0x0F) == 0) &&
 663              (hdr->flow_lbl[1] == 0) && (hdr->flow_lbl[2] == 0)) {
 664                 /* flow label can be compressed */
 665                 iphc0 |= LOWPAN_IPHC_FL_C;
 666                 if ((hdr->priority == 0) &&
 667                    ((hdr->flow_lbl[0] & 0xF0) == 0)) {
 668                         /* compress (elide) all */
 669                         iphc0 |= LOWPAN_IPHC_TC_C;
 670                 } else {
 671                         /* compress only the flow label */
 672                         *hc_ptr = tmp;
 673                         hc_ptr += 1;
 674                 }
 675         } else {
 676                 /* Flow label cannot be compressed */
 677                 if ((hdr->priority == 0) &&
 678                    ((hdr->flow_lbl[0] & 0xF0) == 0)) {
 679                         /* compress only traffic class */
 680                         iphc0 |= LOWPAN_IPHC_TC_C;
 681                         *hc_ptr = (tmp & 0xc0) | (hdr->flow_lbl[0] & 0x0F);
 682                         memcpy(hc_ptr + 1, &hdr->flow_lbl[1], 2);
 683                         hc_ptr += 3;
 684                 } else {
 685                         /* compress nothing */
 686                         memcpy(hc_ptr, hdr, 4);
 687                         /* replace the top byte with new ECN | DSCP format */
 688                         *hc_ptr = tmp;
 689                         hc_ptr += 4;
 690                 }
 691         }
 692
 693         /* NOTE: payload length is always compressed */
 694
 695         /* Next Header is compress if UDP */
 696         if (hdr->nexthdr == UIP_PROTO_UDP)
 697                 iphc0 |= LOWPAN_IPHC_NH_C;
 698
 699         if ((iphc0 & LOWPAN_IPHC_NH_C) == 0) {
 700                 *hc_ptr = hdr->nexthdr;
 701                 hc_ptr += 1;
 702         }
 703
 704         /*
 705          * Hop limit
 706          * if 1:   compress, encoding is 01
 707          * if 64:  compress, encoding is 10
 708          * if 255: compress, encoding is 11
 709          * else do not compress
 710          */
 711         switch (hdr->hop_limit) {
 712         case 1:
 713                 iphc0 |= LOWPAN_IPHC_TTL_1;
 714                 break;
 715         case 64:
 716                 iphc0 |= LOWPAN_IPHC_TTL_64;
 717                 break;
 718         case 255:
 719                 iphc0 |= LOWPAN_IPHC_TTL_255;
 720                 break;
 721         default:
 722                 *hc_ptr = hdr->hop_limit;
 723                 hc_ptr += 1;
 724                 break;
 725         }
 726
 727         /* source address compression */
 728         if (is_addr_unspecified(&hdr->saddr)) {
 729                 pr_debug("source address is unspecified, setting SAC\n");
 730                 iphc1 |= LOWPAN_IPHC_SAC;
 731         /* TODO: context lookup */
 732         } else if (is_addr_link_local(&hdr->saddr)) {
 733                 iphc1 |= lowpan_compress_addr_64(&hc_ptr,
 734                                 LOWPAN_IPHC_SAM_BIT, &hdr->saddr, _saddr);
 735                 pr_debug("source address unicast link-local %pI6c "
 736                         "iphc1 0x%02x\n", &hdr->saddr, iphc1);
 737         } else {
 738                 pr_debug("send the full source address\n");
 739                 memcpy(hc_ptr, &hdr->saddr.s6_addr16[0], 16);
 740                 hc_ptr += 16;
 741         }
 742
 743         /* destination address compression */
 744         if (is_addr_mcast(&hdr->daddr)) {
 745                 pr_debug("destination address is multicast: ");
 746                 iphc1 |= LOWPAN_IPHC_M;
 747                 if (lowpan_is_mcast_addr_compressable8(&hdr->daddr)) {
 748                         pr_debug("compressed to 1 octet\n");
 749                         iphc1 |= LOWPAN_IPHC_DAM_11;
 750                         /* use last byte */
 751                         *hc_ptr = hdr->daddr.s6_addr[15];
 752                         hc_ptr += 1;
 753                 } else if (lowpan_is_mcast_addr_compressable32(&hdr->daddr)) {
 754                         pr_debug("compressed to 4 octets\n");
 755                         iphc1 |= LOWPAN_IPHC_DAM_10;
 756                         /* second byte + the last three */
 757                         *hc_ptr = hdr->daddr.s6_addr[1];
 758                         memcpy(hc_ptr + 1, &hdr->daddr.s6_addr[13], 3);
 759                         hc_ptr += 4;
 760                 } else if (lowpan_is_mcast_addr_compressable48(&hdr->daddr)) {
 761                         pr_debug("compressed to 6 octets\n");
 762                         iphc1 |= LOWPAN_IPHC_DAM_01;
 763                         /* second byte + the last five */
 764                         *hc_ptr = hdr->daddr.s6_addr[1];
 765                         memcpy(hc_ptr + 1, &hdr->daddr.s6_addr[11], 5);
 766                         hc_ptr += 6;
 767                 } else {
 768                         pr_debug("using full address\n");
 769                         iphc1 |= LOWPAN_IPHC_DAM_00;
 770                         memcpy(hc_ptr, &hdr->daddr.s6_addr[0], 16);
 771                         hc_ptr += 16;
 772                 }
 773         } else {
 774                 /* TODO: context lookup */
 775                 if (is_addr_link_local(&hdr->daddr)) {
 776                         iphc1 |= lowpan_compress_addr_64(&hc_ptr,
 777                                 LOWPAN_IPHC_DAM_BIT, &hdr->daddr, _daddr);
 778                         pr_debug("dest address unicast link-local %pI6c "
 779                                 "iphc1 0x%02x\n", &hdr->daddr, iphc1);
 780                 } else {
 781                         pr_debug("dest address unicast %pI6c\n", &hdr->daddr);
 782                         memcpy(hc_ptr, &hdr->daddr.s6_addr16[0], 16);
 783                         hc_ptr += 16;
 784                 }
 785         }
 786
 787         /* UDP header compression */
 788         if (hdr->nexthdr == UIP_PROTO_UDP)
 789                 compress_udp_header(&hc_ptr, skb);
 790
 791         head[0] = iphc0;
 792         head[1] = iphc1;
 793
 794         skb_pull(skb, sizeof(struct ipv6hdr));
 795         skb_reset_transport_header(skb);
 796         memcpy(skb_push(skb, hc_ptr - head), head, hc_ptr - head);
 797         skb_reset_network_header(skb);
 798
 799         pr_debug("header len %d skb %u\n", (int)(hc_ptr - head), skb->len);
 800
 801         raw_dump_table(__func__, "raw skb data dump compressed",
 802                                 skb->data, skb->len);
 803         return 0;
 804 }
 805 EXPORT_SYMBOL_GPL(lowpan_header_compress);
 806
 807 MODULE_LICENSE("GPL");