net/ieee802154/6lowpan_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/netdevice.h>
  56 #include <net/ipv6.h>
  57 #include <net/af_ieee802154.h>
  58
  59 #include "6lowpan.h"
  60
  61 /* print data in line */
  62 static inline void raw_dump_inline(const char *caller, char *msg,
  63                                    unsigned char *buf, int len)
  64 {
  65         if (msg)
  66                 pr_debug("%s():%s: ", caller, msg);
  67         print_hex_dump_debug("", DUMP_PREFIX_NONE,
  68                        16, 1, buf, len, false);
  69 }
  70
  71 /*
  72  * print data in a table format:
  73  *
  74  * addr: xx xx xx xx xx xx
  75  * addr: xx xx xx xx xx xx
  76  * ...
  77  */
  78 static inline void raw_dump_table(const char *caller, char *msg,
  79                                 unsigned char *buf, int len)
  80 {
  81         if (msg)
  82                 pr_debug("%s():%s:\n", caller, msg);
  83         print_hex_dump_debug("\t", DUMP_PREFIX_OFFSET,
  84                        16, 1, buf, len, false);
  85 }
  86
  87 /*
  88  * Uncompress address function for source and
  89  * destination address(non-multicast).
  90  *
  91  * address_mode is sam value or dam value.
  92  */
  93 static int uncompress_addr(struct sk_buff *skb,
  94                                 struct in6_addr *ipaddr, const u8 address_mode,
  95                                 const u8 *lladdr, const u8 addr_type,
  96                                 const u8 addr_len)
  97 {
  98         bool fail;
  99
 100         switch (address_mode) {
 101         case LOWPAN_IPHC_ADDR_00:
 102                 /* for global link addresses */
 103                 fail = lowpan_fetch_skb(skb, ipaddr->s6_addr, 16);
 104                 break;
 105         case LOWPAN_IPHC_ADDR_01:
 106                 /* fe:80::XXXX:XXXX:XXXX:XXXX */
 107                 ipaddr->s6_addr[0] = 0xFE;
 108                 ipaddr->s6_addr[1] = 0x80;
 109                 fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[8], 8);
 110                 break;
 111         case LOWPAN_IPHC_ADDR_02:
 112                 /* fe:80::ff:fe00:XXXX */
 113                 ipaddr->s6_addr[0] = 0xFE;
 114                 ipaddr->s6_addr[1] = 0x80;
 115                 ipaddr->s6_addr[11] = 0xFF;
 116                 ipaddr->s6_addr[12] = 0xFE;
 117                 fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[14], 2);
 118                 break;
 119         case LOWPAN_IPHC_ADDR_03:
 120                 fail = false;
 121                 switch (addr_type) {
 122                 case IEEE802154_ADDR_LONG:
 123                         /* fe:80::XXXX:XXXX:XXXX:XXXX
 124                          *        \_________________/
 125                          *              hwaddr
 126                          */
 127                         ipaddr->s6_addr[0] = 0xFE;
 128                         ipaddr->s6_addr[1] = 0x80;
 129                         memcpy(&ipaddr->s6_addr[8], lladdr, addr_len);
 130                         /* second bit-flip (Universe/Local)
 131                          * is done according RFC2464
 132                          */
 133                         ipaddr->s6_addr[8] ^= 0x02;
 134                         break;
 135                 case IEEE802154_ADDR_SHORT:
 136                         /* fe:80::ff:fe00:XXXX
 137                          *                \__/
 138                          *             short_addr
 139                          *
 140                          * Universe/Local bit is zero.
 141                          */
 142                         ipaddr->s6_addr[0] = 0xFE;
 143                         ipaddr->s6_addr[1] = 0x80;
 144                         ipaddr->s6_addr[11] = 0xFF;
 145                         ipaddr->s6_addr[12] = 0xFE;
 146                         ipaddr->s6_addr16[7] = htons(*((u16 *)lladdr));
 147                         break;
 148                 default:
 149                         pr_debug("Invalid addr_type set\n");
 150                         return -EINVAL;
 151                 }
 152                 break;
 153         default:
 154                 pr_debug("Invalid address mode value: 0x%x\n", address_mode);
 155                 return -EINVAL;
 156         }
 157
 158         if (fail) {
 159                 pr_debug("Failed to fetch skb data\n");
 160                 return -EIO;
 161         }
 162
 163         raw_dump_inline(NULL, "Reconstructed ipv6 addr is",
 164                         ipaddr->s6_addr, 16);
 165
 166         return 0;
 167 }
 168
 169 /*
 170  * Uncompress address function for source context
 171  * based address(non-multicast).
 172  */
 173 static int uncompress_context_based_src_addr(struct sk_buff *skb,
 174                                                 struct in6_addr *ipaddr,
 175                                                 const u8 sam)
 176 {
 177         switch (sam) {
 178         case LOWPAN_IPHC_ADDR_00:
 179                 /* unspec address ::
 180                  * Do nothing, address is already ::
 181                  */
 182                 break;
 183         case LOWPAN_IPHC_ADDR_01:
 184                 /* TODO */
 185         case LOWPAN_IPHC_ADDR_02:
 186                 /* TODO */
 187         case LOWPAN_IPHC_ADDR_03:
 188                 /* TODO */
 189                 netdev_warn(skb->dev, "SAM value 0x%x not supported\n", sam);
 190                 return -EINVAL;
 191         default:
 192                 pr_debug("Invalid sam value: 0x%x\n", sam);
 193                 return -EINVAL;
 194         }
 195
 196         raw_dump_inline(NULL,
 197                         "Reconstructed context based ipv6 src addr is",
 198                         ipaddr->s6_addr, 16);
 199
 200         return 0;
 201 }
 202
 203 static int skb_deliver(struct sk_buff *skb, struct ipv6hdr *hdr,
 204                 struct net_device *dev, skb_delivery_cb deliver_skb)
 205 {
 206         struct sk_buff *new;
 207         int stat;
 208
 209         new = skb_copy_expand(skb, sizeof(struct ipv6hdr), skb_tailroom(skb),
 210                                                                 GFP_ATOMIC);
 211         kfree_skb(skb);
 212
 213         if (!new)
 214                 return -ENOMEM;
 215
 216         skb_push(new, sizeof(struct ipv6hdr));
 217         skb_reset_network_header(new);
 218         skb_copy_to_linear_data(new, hdr, sizeof(struct ipv6hdr));
 219
 220         new->protocol = htons(ETH_P_IPV6);
 221         new->pkt_type = PACKET_HOST;
 222         new->dev = dev;
 223
 224         raw_dump_table(__func__, "raw skb data dump before receiving",
 225                         new->data, new->len);
 226
 227         stat = deliver_skb(new, dev);
 228
 229         kfree_skb(new);
 230
 231         return stat;
 232 }
 233
 234 /* Uncompress function for multicast destination address,
 235  * when M bit is set.
 236  */
 237 static int
 238 lowpan_uncompress_multicast_daddr(struct sk_buff *skb,
 239                 struct in6_addr *ipaddr,
 240                 const u8 dam)
 241 {
 242         bool fail;
 243
 244         switch (dam) {
 245         case LOWPAN_IPHC_DAM_00:
 246                 /* 00:  128 bits.  The full address
 247                  * is carried in-line.
 248                  */
 249                 fail = lowpan_fetch_skb(skb, ipaddr->s6_addr, 16);
 250                 break;
 251         case LOWPAN_IPHC_DAM_01:
 252                 /* 01:  48 bits.  The address takes
 253                  * the form ffXX::00XX:XXXX:XXXX.
 254                  */
 255                 ipaddr->s6_addr[0] = 0xFF;
 256                 fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[1], 1);
 257                 fail |= lowpan_fetch_skb(skb, &ipaddr->s6_addr[11], 5);
 258                 break;
 259         case LOWPAN_IPHC_DAM_10:
 260                 /* 10:  32 bits.  The address takes
 261                  * the form ffXX::00XX:XXXX.
 262                  */
 263                 ipaddr->s6_addr[0] = 0xFF;
 264                 fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[1], 1);
 265                 fail |= lowpan_fetch_skb(skb, &ipaddr->s6_addr[13], 3);
 266                 break;
 267         case LOWPAN_IPHC_DAM_11:
 268                 /* 11:  8 bits.  The address takes
 269                  * the form ff02::00XX.
 270                  */
 271                 ipaddr->s6_addr[0] = 0xFF;
 272                 ipaddr->s6_addr[1] = 0x02;
 273                 fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[15], 1);
 274                 break;
 275         default:
 276                 pr_debug("DAM value has a wrong value: 0x%x\n", dam);
 277                 return -EINVAL;
 278         }
 279
 280         if (fail) {
 281                 pr_debug("Failed to fetch skb data\n");
 282                 return -EIO;
 283         }
 284
 285         raw_dump_inline(NULL, "Reconstructed ipv6 multicast addr is",
 286                                 ipaddr->s6_addr, 16);
 287
 288         return 0;
 289 }
 290
 291 static int
 292 uncompress_udp_header(struct sk_buff *skb, struct udphdr *uh)
 293 {
 294         u8 tmp;
 295
 296         if (!uh)
 297                 goto err;
 298
 299         if (lowpan_fetch_skb_u8(skb, &tmp))
 300                 goto err;
 301
 302         if ((tmp & LOWPAN_NHC_UDP_MASK) == LOWPAN_NHC_UDP_ID) {
 303                 pr_debug("UDP header uncompression\n");
 304                 switch (tmp & LOWPAN_NHC_UDP_CS_P_11) {
 305                 case LOWPAN_NHC_UDP_CS_P_00:
 306                         memcpy(&uh->source, &skb->data[0], 2);
 307                         memcpy(&uh->dest, &skb->data[2], 2);
 308                         skb_pull(skb, 4);
 309                         break;
 310                 case LOWPAN_NHC_UDP_CS_P_01:
 311                         memcpy(&uh->source, &skb->data[0], 2);
 312                         uh->dest =
 313                            skb->data[2] + LOWPAN_NHC_UDP_8BIT_PORT;
 314                         skb_pull(skb, 3);
 315                         break;
 316                 case LOWPAN_NHC_UDP_CS_P_10:
 317                         uh->source = skb->data[0] + LOWPAN_NHC_UDP_8BIT_PORT;
 318                         memcpy(&uh->dest, &skb->data[1], 2);
 319                         skb_pull(skb, 3);
 320                         break;
 321                 case LOWPAN_NHC_UDP_CS_P_11:
 322                         uh->source =
 323                            LOWPAN_NHC_UDP_4BIT_PORT + (skb->data[0] >> 4);
 324                         uh->dest =
 325                            LOWPAN_NHC_UDP_4BIT_PORT + (skb->data[0] & 0x0f);
 326                         skb_pull(skb, 1);
 327                         break;
 328                 default:
 329                         pr_debug("ERROR: unknown UDP format\n");
 330                         goto err;
 331                         break;
 332                 }
 333
 334                 pr_debug("uncompressed UDP ports: src = %d, dst = %d\n",
 335                          uh->source, uh->dest);
 336
 337                 /* copy checksum */
 338                 memcpy(&uh->check, &skb->data[0], 2);
 339                 skb_pull(skb, 2);
 340
 341                 /*
 342                  * UDP lenght needs to be infered from the lower layers
 343                  * here, we obtain the hint from the remaining size of the
 344                  * frame
 345                  */
 346                 uh->len = htons(skb->len + sizeof(struct udphdr));
 347                 pr_debug("uncompressed UDP length: src = %d", uh->len);
 348         } else {
 349                 pr_debug("ERROR: unsupported NH format\n");
 350                 goto err;
 351         }
 352
 353         return 0;
 354 err:
 355         return -EINVAL;
 356 }
 357
 358 /* TTL uncompression values */
 359 static const u8 lowpan_ttl_values[] = { 0, 1, 64, 255 };
 360
 361 int lowpan_process_data(struct sk_buff *skb, struct net_device *dev,
 362                 const u8 *saddr, const u8 saddr_type, const u8 saddr_len,
 363                 const u8 *daddr, const u8 daddr_type, const u8 daddr_len,
 364                 u8 iphc0, u8 iphc1, skb_delivery_cb deliver_skb)
 365 {
 366         struct ipv6hdr hdr = {};
 367         u8 tmp, num_context = 0;
 368         int err;
 369
 370         raw_dump_table(__func__, "raw skb data dump uncompressed",
 371                                 skb->data, skb->len);
 372
 373         /* another if the CID flag is set */
 374         if (iphc1 & LOWPAN_IPHC_CID) {
 375                 pr_debug("CID flag is set, increase header with one\n");
 376                 if (lowpan_fetch_skb_u8(skb, &num_context))
 377                         goto drop;
 378         }
 379
 380         hdr.version = 6;
 381
 382         /* Traffic Class and Flow Label */
 383         switch ((iphc0 & LOWPAN_IPHC_TF) >> 3) {
 384         /*
 385          * Traffic Class and FLow Label carried in-line
 386          * ECN + DSCP + 4-bit Pad + Flow Label (4 bytes)
 387          */
 388         case 0: /* 00b */
 389                 if (lowpan_fetch_skb_u8(skb, &tmp))
 390                         goto drop;
 391
 392                 memcpy(&hdr.flow_lbl, &skb->data[0], 3);
 393                 skb_pull(skb, 3);
 394                 hdr.priority = ((tmp >> 2) & 0x0f);
 395                 hdr.flow_lbl[0] = ((tmp >> 2) & 0x30) | (tmp << 6) |
 396                                         (hdr.flow_lbl[0] & 0x0f);
 397                 break;
 398         /*
 399          * Traffic class carried in-line
 400          * ECN + DSCP (1 byte), Flow Label is elided
 401          */
 402         case 2: /* 10b */
 403                 if (lowpan_fetch_skb_u8(skb, &tmp))
 404                         goto drop;
 405
 406                 hdr.priority = ((tmp >> 2) & 0x0f);
 407                 hdr.flow_lbl[0] = ((tmp << 6) & 0xC0) | ((tmp >> 2) & 0x30);
 408                 break;
 409         /*
 410          * Flow Label carried in-line
 411          * ECN + 2-bit Pad + Flow Label (3 bytes), DSCP is elided
 412          */
 413         case 1: /* 01b */
 414                 if (lowpan_fetch_skb_u8(skb, &tmp))
 415                         goto drop;
 416
 417                 hdr.flow_lbl[0] = (skb->data[0] & 0x0F) | ((tmp >> 2) & 0x30);
 418                 memcpy(&hdr.flow_lbl[1], &skb->data[0], 2);
 419                 skb_pull(skb, 2);
 420                 break;
 421         /* Traffic Class and Flow Label are elided */
 422         case 3: /* 11b */
 423                 break;
 424         default:
 425                 break;
 426         }
 427
 428         /* Next Header */
 429         if ((iphc0 & LOWPAN_IPHC_NH_C) == 0) {
 430                 /* Next header is carried inline */
 431                 if (lowpan_fetch_skb_u8(skb, &(hdr.nexthdr)))
 432                         goto drop;
 433
 434                 pr_debug("NH flag is set, next header carried inline: %02x\n",
 435                          hdr.nexthdr);
 436         }
 437
 438         /* Hop Limit */
 439         if ((iphc0 & 0x03) != LOWPAN_IPHC_TTL_I)
 440                 hdr.hop_limit = lowpan_ttl_values[iphc0 & 0x03];
 441         else {
 442                 if (lowpan_fetch_skb_u8(skb, &(hdr.hop_limit)))
 443                         goto drop;
 444         }
 445
 446         /* Extract SAM to the tmp variable */
 447         tmp = ((iphc1 & LOWPAN_IPHC_SAM) >> LOWPAN_IPHC_SAM_BIT) & 0x03;
 448
 449         if (iphc1 & LOWPAN_IPHC_SAC) {
 450                 /* Source address context based uncompression */
 451                 pr_debug("SAC bit is set. Handle context based source address.\n");
 452                 err = uncompress_context_based_src_addr(
 453                                 skb, &hdr.saddr, tmp);
 454         } else {
 455                 /* Source address uncompression */
 456                 pr_debug("source address stateless compression\n");
 457                 err = uncompress_addr(skb, &hdr.saddr, tmp, saddr,
 458                                         saddr_type, saddr_len);
 459         }
 460
 461         /* Check on error of previous branch */
 462         if (err)
 463                 goto drop;
 464
 465         /* Extract DAM to the tmp variable */
 466         tmp = ((iphc1 & LOWPAN_IPHC_DAM_11) >> LOWPAN_IPHC_DAM_BIT) & 0x03;
 467
 468         /* check for Multicast Compression */
 469         if (iphc1 & LOWPAN_IPHC_M) {
 470                 if (iphc1 & LOWPAN_IPHC_DAC) {
 471                         pr_debug("dest: context-based mcast compression\n");
 472                         /* TODO: implement this */
 473                 } else {
 474                         err = lowpan_uncompress_multicast_daddr(
 475                                                 skb, &hdr.daddr, tmp);
 476                         if (err)
 477                                 goto drop;
 478                 }
 479         } else {
 480                 err = uncompress_addr(skb, &hdr.daddr, tmp, daddr,
 481                                         daddr_type, daddr_len);
 482                 pr_debug("dest: stateless compression mode %d dest %pI6c\n",
 483                         tmp, &hdr.daddr);
 484                 if (err)
 485                         goto drop;
 486         }
 487
 488         /* UDP data uncompression */
 489         if (iphc0 & LOWPAN_IPHC_NH_C) {
 490                 struct udphdr uh;
 491                 struct sk_buff *new;
 492                 if (uncompress_udp_header(skb, &uh))
 493                         goto drop;
 494
 495                 /*
 496                  * replace the compressed UDP head by the uncompressed UDP
 497                  * header
 498                  */
 499                 new = skb_copy_expand(skb, sizeof(struct udphdr),
 500                                       skb_tailroom(skb), GFP_ATOMIC);
 501                 kfree_skb(skb);
 502
 503                 if (!new)
 504                         return -ENOMEM;
 505
 506                 skb = new;
 507
 508                 skb_push(skb, sizeof(struct udphdr));
 509                 skb_reset_transport_header(skb);
 510                 skb_copy_to_linear_data(skb, &uh, sizeof(struct udphdr));
 511
 512                 raw_dump_table(__func__, "raw UDP header dump",
 513                                       (u8 *)&uh, sizeof(uh));
 514
 515                 hdr.nexthdr = UIP_PROTO_UDP;
 516         }
 517
 518         hdr.payload_len = htons(skb->len);
 519
 520         pr_debug("skb headroom size = %d, data length = %d\n",
 521                  skb_headroom(skb), skb->len);
 522
 523         pr_debug("IPv6 header dump:\n\tversion = %d\n\tlength  = %d\n\t"
 524                  "nexthdr = 0x%02x\n\thop_lim = %d\n\tdest    = %pI6c\n",
 525                 hdr.version, ntohs(hdr.payload_len), hdr.nexthdr,
 526                 hdr.hop_limit, &hdr.daddr);
 527
 528         raw_dump_table(__func__, "raw header dump", (u8 *)&hdr,
 529                                                         sizeof(hdr));
 530
 531         return skb_deliver(skb, &hdr, dev, deliver_skb);
 532
 533 drop:
 534         kfree_skb(skb);
 535         return -EINVAL;
 536 }
 537 EXPORT_SYMBOL_GPL(lowpan_process_data);
 538
 539 static u8 lowpan_compress_addr_64(u8 **hc06_ptr, u8 shift,
 540                                 const struct in6_addr *ipaddr,
 541                                 const unsigned char *lladdr)
 542 {
 543         u8 val = 0;
 544
 545         if (is_addr_mac_addr_based(ipaddr, lladdr)) {
 546                 val = 3; /* 0-bits */
 547                 pr_debug("address compression 0 bits\n");
 548         } else if (lowpan_is_iid_16_bit_compressable(ipaddr)) {
 549                 /* compress IID to 16 bits xxxx::XXXX */
 550                 memcpy(*hc06_ptr, &ipaddr->s6_addr16[7], 2);
 551                 *hc06_ptr += 2;
 552                 val = 2; /* 16-bits */
 553                 raw_dump_inline(NULL, "Compressed ipv6 addr is (16 bits)",
 554                         *hc06_ptr - 2, 2);
 555         } else {
 556                 /* do not compress IID => xxxx::IID */
 557                 memcpy(*hc06_ptr, &ipaddr->s6_addr16[4], 8);
 558                 *hc06_ptr += 8;
 559                 val = 1; /* 64-bits */
 560                 raw_dump_inline(NULL, "Compressed ipv6 addr is (64 bits)",
 561                         *hc06_ptr - 8, 8);
 562         }
 563
 564         return rol8(val, shift);
 565 }
 566
 567 static void compress_udp_header(u8 **hc06_ptr, struct sk_buff *skb)
 568 {
 569         struct udphdr *uh = udp_hdr(skb);
 570
 571         if (((uh->source & LOWPAN_NHC_UDP_4BIT_MASK) ==
 572                                 LOWPAN_NHC_UDP_4BIT_PORT) &&
 573             ((uh->dest & LOWPAN_NHC_UDP_4BIT_MASK) ==
 574                                 LOWPAN_NHC_UDP_4BIT_PORT)) {
 575                 pr_debug("UDP header: both ports compression to 4 bits\n");
 576                 **hc06_ptr = LOWPAN_NHC_UDP_CS_P_11;
 577                 **(hc06_ptr + 1) = /* subtraction is faster */
 578                    (u8)((uh->dest - LOWPAN_NHC_UDP_4BIT_PORT) +
 579                        ((uh->source & LOWPAN_NHC_UDP_4BIT_PORT) << 4));
 580                 *hc06_ptr += 2;
 581         } else if ((uh->dest & LOWPAN_NHC_UDP_8BIT_MASK) ==
 582                         LOWPAN_NHC_UDP_8BIT_PORT) {
 583                 pr_debug("UDP header: remove 8 bits of dest\n");
 584                 **hc06_ptr = LOWPAN_NHC_UDP_CS_P_01;
 585                 memcpy(*hc06_ptr + 1, &uh->source, 2);
 586                 **(hc06_ptr + 3) = (u8)(uh->dest - LOWPAN_NHC_UDP_8BIT_PORT);
 587                 *hc06_ptr += 4;
 588         } else if ((uh->source & LOWPAN_NHC_UDP_8BIT_MASK) ==
 589                         LOWPAN_NHC_UDP_8BIT_PORT) {
 590                 pr_debug("UDP header: remove 8 bits of source\n");
 591                 **hc06_ptr = LOWPAN_NHC_UDP_CS_P_10;
 592                 memcpy(*hc06_ptr + 1, &uh->dest, 2);
 593                 **(hc06_ptr + 3) = (u8)(uh->source - LOWPAN_NHC_UDP_8BIT_PORT);
 594                 *hc06_ptr += 4;
 595         } else {
 596                 pr_debug("UDP header: can't compress\n");
 597                 **hc06_ptr = LOWPAN_NHC_UDP_CS_P_00;
 598                 memcpy(*hc06_ptr + 1, &uh->source, 2);
 599                 memcpy(*hc06_ptr + 3, &uh->dest, 2);
 600                 *hc06_ptr += 5;
 601         }
 602
 603         /* checksum is always inline */
 604         memcpy(*hc06_ptr, &uh->check, 2);
 605         *hc06_ptr += 2;
 606
 607         /* skip the UDP header */
 608         skb_pull(skb, sizeof(struct udphdr));
 609 }
 610
 611 int lowpan_header_compress(struct sk_buff *skb, struct net_device *dev,
 612                         unsigned short type, const void *_daddr,
 613                         const void *_saddr, unsigned int len)
 614 {
 615         u8 tmp, iphc0, iphc1, *hc06_ptr;
 616         struct ipv6hdr *hdr;
 617         u8 head[100] = {};
 618
 619         if (type != ETH_P_IPV6)
 620                 return -EINVAL;
 621
 622         hdr = ipv6_hdr(skb);
 623         hc06_ptr = head + 2;
 624
 625         pr_debug("IPv6 header dump:\n\tversion = %d\n\tlength  = %d\n"
 626                  "\tnexthdr = 0x%02x\n\thop_lim = %d\n\tdest    = %pI6c\n",
 627                 hdr->version, ntohs(hdr->payload_len), hdr->nexthdr,
 628                 hdr->hop_limit, &hdr->daddr);
 629
 630         raw_dump_table(__func__, "raw skb network header dump",
 631                 skb_network_header(skb), sizeof(struct ipv6hdr));
 632
 633         /*
 634          * As we copy some bit-length fields, in the IPHC encoding bytes,
 635          * we sometimes use |=
 636          * If the field is 0, and the current bit value in memory is 1,
 637          * this does not work. We therefore reset the IPHC encoding here
 638          */
 639         iphc0 = LOWPAN_DISPATCH_IPHC;
 640         iphc1 = 0;
 641
 642         /* TODO: context lookup */
 643
 644         raw_dump_inline(__func__, "saddr",
 645                         (unsigned char *)_saddr, IEEE802154_ADDR_LEN);
 646         raw_dump_inline(__func__, "daddr",
 647                         (unsigned char *)_daddr, IEEE802154_ADDR_LEN);
 648
 649         raw_dump_table(__func__,
 650                         "sending raw skb network uncompressed packet",
 651                         skb->data, skb->len);
 652
 653         /*
 654          * Traffic class, flow label
 655          * If flow label is 0, compress it. If traffic class is 0, compress it
 656          * We have to process both in the same time as the offset of traffic
 657          * class depends on the presence of version and flow label
 658          */
 659
 660         /* hc06 format of TC is ECN | DSCP , original one is DSCP | ECN */
 661         tmp = (hdr->priority << 4) | (hdr->flow_lbl[0] >> 4);
 662         tmp = ((tmp & 0x03) << 6) | (tmp >> 2);
 663
 664         if (((hdr->flow_lbl[0] & 0x0F) == 0) &&
 665              (hdr->flow_lbl[1] == 0) && (hdr->flow_lbl[2] == 0)) {
 666                 /* flow label can be compressed */
 667                 iphc0 |= LOWPAN_IPHC_FL_C;
 668                 if ((hdr->priority == 0) &&
 669                    ((hdr->flow_lbl[0] & 0xF0) == 0)) {
 670                         /* compress (elide) all */
 671                         iphc0 |= LOWPAN_IPHC_TC_C;
 672                 } else {
 673                         /* compress only the flow label */
 674                         *hc06_ptr = tmp;
 675                         hc06_ptr += 1;
 676                 }
 677         } else {
 678                 /* Flow label cannot be compressed */
 679                 if ((hdr->priority == 0) &&
 680                    ((hdr->flow_lbl[0] & 0xF0) == 0)) {
 681                         /* compress only traffic class */
 682                         iphc0 |= LOWPAN_IPHC_TC_C;
 683                         *hc06_ptr = (tmp & 0xc0) | (hdr->flow_lbl[0] & 0x0F);
 684                         memcpy(hc06_ptr + 1, &hdr->flow_lbl[1], 2);
 685                         hc06_ptr += 3;
 686                 } else {
 687                         /* compress nothing */
 688                         memcpy(hc06_ptr, &hdr, 4);
 689                         /* replace the top byte with new ECN | DSCP format */
 690                         *hc06_ptr = tmp;
 691                         hc06_ptr += 4;
 692                 }
 693         }
 694
 695         /* NOTE: payload length is always compressed */
 696
 697         /* Next Header is compress if UDP */
 698         if (hdr->nexthdr == UIP_PROTO_UDP)
 699                 iphc0 |= LOWPAN_IPHC_NH_C;
 700
 701         if ((iphc0 & LOWPAN_IPHC_NH_C) == 0) {
 702                 *hc06_ptr = hdr->nexthdr;
 703                 hc06_ptr += 1;
 704         }
 705
 706         /*
 707          * Hop limit
 708          * if 1:   compress, encoding is 01
 709          * if 64:  compress, encoding is 10
 710          * if 255: compress, encoding is 11
 711          * else do not compress
 712          */
 713         switch (hdr->hop_limit) {
 714         case 1:
 715                 iphc0 |= LOWPAN_IPHC_TTL_1;
 716                 break;
 717         case 64:
 718                 iphc0 |= LOWPAN_IPHC_TTL_64;
 719                 break;
 720         case 255:
 721                 iphc0 |= LOWPAN_IPHC_TTL_255;
 722                 break;
 723         default:
 724                 *hc06_ptr = hdr->hop_limit;
 725                 hc06_ptr += 1;
 726                 break;
 727         }
 728
 729         /* source address compression */
 730         if (is_addr_unspecified(&hdr->saddr)) {
 731                 pr_debug("source address is unspecified, setting SAC\n");
 732                 iphc1 |= LOWPAN_IPHC_SAC;
 733         /* TODO: context lookup */
 734         } else if (is_addr_link_local(&hdr->saddr)) {
 735                 iphc1 |= lowpan_compress_addr_64(&hc06_ptr,
 736                                 LOWPAN_IPHC_SAM_BIT, &hdr->saddr, _saddr);
 737                 pr_debug("source address unicast link-local %pI6c "
 738                         "iphc1 0x%02x\n", &hdr->saddr, iphc1);
 739         } else {
 740                 pr_debug("send the full source address\n");
 741                 memcpy(hc06_ptr, &hdr->saddr.s6_addr16[0], 16);
 742                 hc06_ptr += 16;
 743         }
 744
 745         /* destination address compression */
 746         if (is_addr_mcast(&hdr->daddr)) {
 747                 pr_debug("destination address is multicast: ");
 748                 iphc1 |= LOWPAN_IPHC_M;
 749                 if (lowpan_is_mcast_addr_compressable8(&hdr->daddr)) {
 750                         pr_debug("compressed to 1 octet\n");
 751                         iphc1 |= LOWPAN_IPHC_DAM_11;
 752                         /* use last byte */
 753                         *hc06_ptr = hdr->daddr.s6_addr[15];
 754                         hc06_ptr += 1;
 755                 } else if (lowpan_is_mcast_addr_compressable32(&hdr->daddr)) {
 756                         pr_debug("compressed to 4 octets\n");
 757                         iphc1 |= LOWPAN_IPHC_DAM_10;
 758                         /* second byte + the last three */
 759                         *hc06_ptr = hdr->daddr.s6_addr[1];
 760                         memcpy(hc06_ptr + 1, &hdr->daddr.s6_addr[13], 3);
 761                         hc06_ptr += 4;
 762                 } else if (lowpan_is_mcast_addr_compressable48(&hdr->daddr)) {
 763                         pr_debug("compressed to 6 octets\n");
 764                         iphc1 |= LOWPAN_IPHC_DAM_01;
 765                         /* second byte + the last five */
 766                         *hc06_ptr = hdr->daddr.s6_addr[1];
 767                         memcpy(hc06_ptr + 1, &hdr->daddr.s6_addr[11], 5);
 768                         hc06_ptr += 6;
 769                 } else {
 770                         pr_debug("using full address\n");
 771                         iphc1 |= LOWPAN_IPHC_DAM_00;
 772                         memcpy(hc06_ptr, &hdr->daddr.s6_addr[0], 16);
 773                         hc06_ptr += 16;
 774                 }
 775         } else {
 776                 /* TODO: context lookup */
 777                 if (is_addr_link_local(&hdr->daddr)) {
 778                         iphc1 |= lowpan_compress_addr_64(&hc06_ptr,
 779                                 LOWPAN_IPHC_DAM_BIT, &hdr->daddr, _daddr);
 780                         pr_debug("dest address unicast link-local %pI6c "
 781                                 "iphc1 0x%02x\n", &hdr->daddr, iphc1);
 782                 } else {
 783                         pr_debug("dest address unicast %pI6c\n", &hdr->daddr);
 784                         memcpy(hc06_ptr, &hdr->daddr.s6_addr16[0], 16);
 785                         hc06_ptr += 16;
 786                 }
 787         }
 788
 789         /* UDP header compression */
 790         if (hdr->nexthdr == UIP_PROTO_UDP)
 791                 compress_udp_header(&hc06_ptr, skb);
 792
 793         head[0] = iphc0;
 794         head[1] = iphc1;
 795
 796         skb_pull(skb, sizeof(struct ipv6hdr));
 797         skb_reset_transport_header(skb);
 798         memcpy(skb_push(skb, hc06_ptr - head), head, hc06_ptr - head);
 799         skb_reset_network_header(skb);
 800
 801         pr_debug("header len %d skb %u\n", (int)(hc06_ptr - head), skb->len);
 802
 803         raw_dump_table(__func__, "raw skb data dump compressed",
 804                                 skb->data, skb->len);
 805         return 0;
 806 }
 807 EXPORT_SYMBOL_GPL(lowpan_header_compress);