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/netdevice.h>
  52
  53 #include <net/6lowpan.h>
  54 #include <net/ipv6.h>
  55
  56 /* special link-layer handling */
  57 #include <net/mac802154.h>
  58
  59 #include "nhc.h"
  60
  61 /* Values of fields within the IPHC encoding first byte */
  62 #define LOWPAN_IPHC_TF_MASK     0x18
  63 #define LOWPAN_IPHC_TF_00       0x00
  64 #define LOWPAN_IPHC_TF_01       0x08
  65 #define LOWPAN_IPHC_TF_10       0x10
  66 #define LOWPAN_IPHC_TF_11       0x18
  67
  68 #define LOWPAN_IPHC_NH          0x04
  69
  70 #define LOWPAN_IPHC_HLIM_MASK   0x03
  71 #define LOWPAN_IPHC_HLIM_00     0x00
  72 #define LOWPAN_IPHC_HLIM_01     0x01
  73 #define LOWPAN_IPHC_HLIM_10     0x02
  74 #define LOWPAN_IPHC_HLIM_11     0x03
  75
  76 /* Values of fields within the IPHC encoding second byte */
  77 #define LOWPAN_IPHC_CID         0x80
  78
  79 #define LOWPAN_IPHC_SAC         0x40
  80
  81 #define LOWPAN_IPHC_SAM_MASK    0x30
  82 #define LOWPAN_IPHC_SAM_00      0x00
  83 #define LOWPAN_IPHC_SAM_01      0x10
  84 #define LOWPAN_IPHC_SAM_10      0x20
  85 #define LOWPAN_IPHC_SAM_11      0x30
  86
  87 #define LOWPAN_IPHC_M           0x08
  88
  89 #define LOWPAN_IPHC_DAC         0x04
  90
  91 #define LOWPAN_IPHC_DAM_MASK    0x03
  92 #define LOWPAN_IPHC_DAM_00      0x00
  93 #define LOWPAN_IPHC_DAM_01      0x01
  94 #define LOWPAN_IPHC_DAM_10      0x02
  95 #define LOWPAN_IPHC_DAM_11      0x03
  96
  97 /* ipv6 address based on mac
  98  * second bit-flip (Universe/Local) is done according RFC2464
  99  */
 100 #define is_addr_mac_addr_based(a, m) \
 101         ((((a)->s6_addr[8])  == (((m)[0]) ^ 0x02)) &&   \
 102          (((a)->s6_addr[9])  == (m)[1]) &&              \
 103          (((a)->s6_addr[10]) == (m)[2]) &&              \
 104          (((a)->s6_addr[11]) == (m)[3]) &&              \
 105          (((a)->s6_addr[12]) == (m)[4]) &&              \
 106          (((a)->s6_addr[13]) == (m)[5]) &&              \
 107          (((a)->s6_addr[14]) == (m)[6]) &&              \
 108          (((a)->s6_addr[15]) == (m)[7]))
 109
 110 /* check whether we can compress the IID to 16 bits,
 111  * it's possible for unicast addresses with first 49 bits are zero only.
 112  */
 113 #define lowpan_is_iid_16_bit_compressable(a)    \
 114         ((((a)->s6_addr16[4]) == 0) &&          \
 115          (((a)->s6_addr[10]) == 0) &&           \
 116          (((a)->s6_addr[11]) == 0xff) &&        \
 117          (((a)->s6_addr[12]) == 0xfe) &&        \
 118          (((a)->s6_addr[13]) == 0))
 119
 120 /* check whether the 112-bit gid of the multicast address is mappable to: */
 121
 122 /* 48 bits, FFXX::00XX:XXXX:XXXX */
 123 #define lowpan_is_mcast_addr_compressable48(a)  \
 124         ((((a)->s6_addr16[1]) == 0) &&          \
 125          (((a)->s6_addr16[2]) == 0) &&          \
 126          (((a)->s6_addr16[3]) == 0) &&          \
 127          (((a)->s6_addr16[4]) == 0) &&          \
 128          (((a)->s6_addr[10]) == 0))
 129
 130 /* 32 bits, FFXX::00XX:XXXX */
 131 #define lowpan_is_mcast_addr_compressable32(a)  \
 132         ((((a)->s6_addr16[1]) == 0) &&          \
 133          (((a)->s6_addr16[2]) == 0) &&          \
 134          (((a)->s6_addr16[3]) == 0) &&          \
 135          (((a)->s6_addr16[4]) == 0) &&          \
 136          (((a)->s6_addr16[5]) == 0) &&          \
 137          (((a)->s6_addr[12]) == 0))
 138
 139 /* 8 bits, FF02::00XX */
 140 #define lowpan_is_mcast_addr_compressable8(a)   \
 141         ((((a)->s6_addr[1])  == 2) &&           \
 142          (((a)->s6_addr16[1]) == 0) &&          \
 143          (((a)->s6_addr16[2]) == 0) &&          \
 144          (((a)->s6_addr16[3]) == 0) &&          \
 145          (((a)->s6_addr16[4]) == 0) &&          \
 146          (((a)->s6_addr16[5]) == 0) &&          \
 147          (((a)->s6_addr16[6]) == 0) &&          \
 148          (((a)->s6_addr[14]) == 0))
 149
 150 static inline void iphc_uncompress_eui64_lladdr(struct in6_addr *ipaddr,
 151                                                 const void *lladdr)
 152 {
 153         /* fe:80::XXXX:XXXX:XXXX:XXXX
 154          *        \_________________/
 155          *              hwaddr
 156          */
 157         ipaddr->s6_addr[0] = 0xFE;
 158         ipaddr->s6_addr[1] = 0x80;
 159         memcpy(&ipaddr->s6_addr[8], lladdr, EUI64_ADDR_LEN);
 160         /* second bit-flip (Universe/Local)
 161          * is done according RFC2464
 162          */
 163         ipaddr->s6_addr[8] ^= 0x02;
 164 }
 165
 166 static inline void iphc_uncompress_802154_lladdr(struct in6_addr *ipaddr,
 167                                                  const void *lladdr)
 168 {
 169         const struct ieee802154_addr *addr = lladdr;
 170         u8 eui64[EUI64_ADDR_LEN] = { };
 171
 172         switch (addr->mode) {
 173         case IEEE802154_ADDR_LONG:
 174                 ieee802154_le64_to_be64(eui64, &addr->extended_addr);
 175                 iphc_uncompress_eui64_lladdr(ipaddr, eui64);
 176                 break;
 177         case IEEE802154_ADDR_SHORT:
 178                 /* fe:80::ff:fe00:XXXX
 179                  *                \__/
 180                  *             short_addr
 181                  *
 182                  * Universe/Local bit is zero.
 183                  */
 184                 ipaddr->s6_addr[0] = 0xFE;
 185                 ipaddr->s6_addr[1] = 0x80;
 186                 ipaddr->s6_addr[11] = 0xFF;
 187                 ipaddr->s6_addr[12] = 0xFE;
 188                 ieee802154_le16_to_be16(&ipaddr->s6_addr16[7],
 189                                         &addr->short_addr);
 190                 break;
 191         default:
 192                 /* should never handled and filtered by 802154 6lowpan */
 193                 WARN_ON_ONCE(1);
 194                 break;
 195         }
 196 }
 197
 198 /* Uncompress address function for source and
 199  * destination address(non-multicast).
 200  *
 201  * address_mode is the masked value for sam or dam value
 202  */
 203 static int uncompress_addr(struct sk_buff *skb, const struct net_device *dev,
 204                            struct in6_addr *ipaddr, u8 address_mode,
 205                            const void *lladdr)
 206 {
 207         bool fail;
 208
 209         switch (address_mode) {
 210         /* SAM and DAM are the same here */
 211         case LOWPAN_IPHC_DAM_00:
 212                 /* for global link addresses */
 213                 fail = lowpan_fetch_skb(skb, ipaddr->s6_addr, 16);
 214                 break;
 215         case LOWPAN_IPHC_SAM_01:
 216         case LOWPAN_IPHC_DAM_01:
 217                 /* fe:80::XXXX:XXXX:XXXX:XXXX */
 218                 ipaddr->s6_addr[0] = 0xFE;
 219                 ipaddr->s6_addr[1] = 0x80;
 220                 fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[8], 8);
 221                 break;
 222         case LOWPAN_IPHC_SAM_10:
 223         case LOWPAN_IPHC_DAM_10:
 224                 /* fe:80::ff:fe00:XXXX */
 225                 ipaddr->s6_addr[0] = 0xFE;
 226                 ipaddr->s6_addr[1] = 0x80;
 227                 ipaddr->s6_addr[11] = 0xFF;
 228                 ipaddr->s6_addr[12] = 0xFE;
 229                 fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[14], 2);
 230                 break;
 231         case LOWPAN_IPHC_SAM_11:
 232         case LOWPAN_IPHC_DAM_11:
 233                 fail = false;
 234                 switch (lowpan_priv(dev)->lltype) {
 235                 case LOWPAN_LLTYPE_IEEE802154:
 236                         iphc_uncompress_802154_lladdr(ipaddr, lladdr);
 237                         break;
 238                 default:
 239                         iphc_uncompress_eui64_lladdr(ipaddr, lladdr);
 240                         break;
 241                 }
 242                 break;
 243         default:
 244                 pr_debug("Invalid address mode value: 0x%x\n", address_mode);
 245                 return -EINVAL;
 246         }
 247
 248         if (fail) {
 249                 pr_debug("Failed to fetch skb data\n");
 250                 return -EIO;
 251         }
 252
 253         raw_dump_inline(NULL, "Reconstructed ipv6 addr is",
 254                         ipaddr->s6_addr, 16);
 255
 256         return 0;
 257 }
 258
 259 /* Uncompress address function for source context
 260  * based address(non-multicast).
 261  */
 262 static int uncompress_context_based_src_addr(struct sk_buff *skb,
 263                                              struct in6_addr *ipaddr,
 264                                              u8 address_mode)
 265 {
 266         switch (address_mode) {
 267         case LOWPAN_IPHC_SAM_00:
 268                 /* unspec address ::
 269                  * Do nothing, address is already ::
 270                  */
 271                 break;
 272         case LOWPAN_IPHC_SAM_01:
 273                 /* TODO */
 274         case LOWPAN_IPHC_SAM_10:
 275                 /* TODO */
 276         case LOWPAN_IPHC_SAM_11:
 277                 /* TODO */
 278                 netdev_warn(skb->dev, "SAM value 0x%x not supported\n",
 279                             address_mode);
 280                 return -EINVAL;
 281         default:
 282                 pr_debug("Invalid sam value: 0x%x\n", address_mode);
 283                 return -EINVAL;
 284         }
 285
 286         raw_dump_inline(NULL,
 287                         "Reconstructed context based ipv6 src addr is",
 288                         ipaddr->s6_addr, 16);
 289
 290         return 0;
 291 }
 292
 293 /* Uncompress function for multicast destination address,
 294  * when M bit is set.
 295  */
 296 static int lowpan_uncompress_multicast_daddr(struct sk_buff *skb,
 297                                              struct in6_addr *ipaddr,
 298                                              u8 address_mode)
 299 {
 300         bool fail;
 301
 302         switch (address_mode) {
 303         case LOWPAN_IPHC_DAM_00:
 304                 /* 00:  128 bits.  The full address
 305                  * is carried in-line.
 306                  */
 307                 fail = lowpan_fetch_skb(skb, ipaddr->s6_addr, 16);
 308                 break;
 309         case LOWPAN_IPHC_DAM_01:
 310                 /* 01:  48 bits.  The address takes
 311                  * the form ffXX::00XX:XXXX:XXXX.
 312                  */
 313                 ipaddr->s6_addr[0] = 0xFF;
 314                 fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[1], 1);
 315                 fail |= lowpan_fetch_skb(skb, &ipaddr->s6_addr[11], 5);
 316                 break;
 317         case LOWPAN_IPHC_DAM_10:
 318                 /* 10:  32 bits.  The address takes
 319                  * the form ffXX::00XX:XXXX.
 320                  */
 321                 ipaddr->s6_addr[0] = 0xFF;
 322                 fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[1], 1);
 323                 fail |= lowpan_fetch_skb(skb, &ipaddr->s6_addr[13], 3);
 324                 break;
 325         case LOWPAN_IPHC_DAM_11:
 326                 /* 11:  8 bits.  The address takes
 327                  * the form ff02::00XX.
 328                  */
 329                 ipaddr->s6_addr[0] = 0xFF;
 330                 ipaddr->s6_addr[1] = 0x02;
 331                 fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[15], 1);
 332                 break;
 333         default:
 334                 pr_debug("DAM value has a wrong value: 0x%x\n", address_mode);
 335                 return -EINVAL;
 336         }
 337
 338         if (fail) {
 339                 pr_debug("Failed to fetch skb data\n");
 340                 return -EIO;
 341         }
 342
 343         raw_dump_inline(NULL, "Reconstructed ipv6 multicast addr is",
 344                         ipaddr->s6_addr, 16);
 345
 346         return 0;
 347 }
 348
 349 /* get the ecn values from iphc tf format and set it to ipv6hdr */
 350 static inline void lowpan_iphc_tf_set_ecn(struct ipv6hdr *hdr, const u8 *tf)
 351 {
 352         /* get the two higher bits which is ecn */
 353         u8 ecn = tf[0] & 0xc0;
 354
 355         /* ECN takes 0x30 in hdr->flow_lbl[0] */
 356         hdr->flow_lbl[0] |= (ecn >> 2);
 357 }
 358
 359 /* get the dscp values from iphc tf format and set it to ipv6hdr */
 360 static inline void lowpan_iphc_tf_set_dscp(struct ipv6hdr *hdr, const u8 *tf)
 361 {
 362         /* DSCP is at place after ECN */
 363         u8 dscp = tf[0] & 0x3f;
 364
 365         /* The four highest bits need to be set at hdr->priority */
 366         hdr->priority |= ((dscp & 0x3c) >> 2);
 367         /* The two lower bits is part of hdr->flow_lbl[0] */
 368         hdr->flow_lbl[0] |= ((dscp & 0x03) << 6);
 369 }
 370
 371 /* get the flow label values from iphc tf format and set it to ipv6hdr */
 372 static inline void lowpan_iphc_tf_set_lbl(struct ipv6hdr *hdr, const u8 *lbl)
 373 {
 374         /* flow label is always some array started with lower nibble of
 375          * flow_lbl[0] and followed with two bytes afterwards. Inside inline
 376          * data the flow_lbl position can be different, which will be handled
 377          * by lbl pointer. E.g. case "01" vs "00" the traffic class is 8 bit
 378          * shifted, the different lbl pointer will handle that.
 379          *
 380          * The flow label will started at lower nibble of flow_lbl[0], the
 381          * higher nibbles are part of DSCP + ECN.
 382          */
 383         hdr->flow_lbl[0] |= lbl[0] & 0x0f;
 384         memcpy(&hdr->flow_lbl[1], &lbl[1], 2);
 385 }
 386
 387 /* lowpan_iphc_tf_decompress - decompress the traffic class.
 388  *      This function will return zero on success, a value lower than zero if
 389  *      failed.
 390  */
 391 static int lowpan_iphc_tf_decompress(struct sk_buff *skb, struct ipv6hdr *hdr,
 392                                      u8 val)
 393 {
 394         u8 tf[4];
 395
 396         /* Traffic Class and Flow Label */
 397         switch (val) {
 398         case LOWPAN_IPHC_TF_00:
 399                 /* ECN + DSCP + 4-bit Pad + Flow Label (4 bytes) */
 400                 if (lowpan_fetch_skb(skb, tf, 4))
 401                         return -EINVAL;
 402
 403                 /*                      1                   2                   3
 404                  *  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 405                  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 406                  * |ECN|   DSCP    |  rsv  |             Flow Label                |
 407                  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 408                  */
 409                 lowpan_iphc_tf_set_ecn(hdr, tf);
 410                 lowpan_iphc_tf_set_dscp(hdr, tf);
 411                 lowpan_iphc_tf_set_lbl(hdr, &tf[1]);
 412                 break;
 413         case LOWPAN_IPHC_TF_01:
 414                 /* ECN + 2-bit Pad + Flow Label (3 bytes), DSCP is elided. */
 415                 if (lowpan_fetch_skb(skb, tf, 3))
 416                         return -EINVAL;
 417
 418                 /*                     1                   2
 419                  * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3
 420                  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 421                  * |ECN|rsv|             Flow Label                |
 422                  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 423                  */
 424                 lowpan_iphc_tf_set_ecn(hdr, tf);
 425                 lowpan_iphc_tf_set_lbl(hdr, &tf[0]);
 426                 break;
 427         case LOWPAN_IPHC_TF_10:
 428                 /* ECN + DSCP (1 byte), Flow Label is elided. */
 429                 if (lowpan_fetch_skb(skb, tf, 1))
 430                         return -EINVAL;
 431
 432                 /*  0 1 2 3 4 5 6 7
 433                  * +-+-+-+-+-+-+-+-+
 434                  * |ECN|   DSCP    |
 435                  * +-+-+-+-+-+-+-+-+
 436                  */
 437                 lowpan_iphc_tf_set_ecn(hdr, tf);
 438                 lowpan_iphc_tf_set_dscp(hdr, tf);
 439                 break;
 440         case LOWPAN_IPHC_TF_11:
 441                 /* Traffic Class and Flow Label are elided */
 442                 break;
 443         default:
 444                 WARN_ON_ONCE(1);
 445                 return -EINVAL;
 446         }
 447
 448         return 0;
 449 }
 450
 451 /* TTL uncompression values */
 452 static const u8 lowpan_ttl_values[] = {
 453         [LOWPAN_IPHC_HLIM_01] = 1,
 454         [LOWPAN_IPHC_HLIM_10] = 64,
 455         [LOWPAN_IPHC_HLIM_11] = 255,
 456 };
 457
 458 int lowpan_header_decompress(struct sk_buff *skb, const struct net_device *dev,
 459                              const void *daddr, const void *saddr)
 460 {
 461         struct ipv6hdr hdr = {};
 462         u8 iphc0, iphc1;
 463         int err;
 464
 465         raw_dump_table(__func__, "raw skb data dump uncompressed",
 466                        skb->data, skb->len);
 467
 468         if (lowpan_fetch_skb(skb, &iphc0, sizeof(iphc0)) ||
 469             lowpan_fetch_skb(skb, &iphc1, sizeof(iphc1)))
 470                 return -EINVAL;
 471
 472         /* another if the CID flag is set */
 473         if (iphc1 & LOWPAN_IPHC_CID)
 474                 return -ENOTSUPP;
 475
 476         hdr.version = 6;
 477
 478         err = lowpan_iphc_tf_decompress(skb, &hdr,
 479                                         iphc0 & LOWPAN_IPHC_TF_MASK);
 480         if (err < 0)
 481                 return err;
 482
 483         /* Next Header */
 484         if (!(iphc0 & LOWPAN_IPHC_NH)) {
 485                 /* Next header is carried inline */
 486                 if (lowpan_fetch_skb(skb, &hdr.nexthdr, sizeof(hdr.nexthdr)))
 487                         return -EINVAL;
 488
 489                 pr_debug("NH flag is set, next header carried inline: %02x\n",
 490                          hdr.nexthdr);
 491         }
 492
 493         /* Hop Limit */
 494         if ((iphc0 & LOWPAN_IPHC_HLIM_MASK) != LOWPAN_IPHC_HLIM_00) {
 495                 hdr.hop_limit = lowpan_ttl_values[iphc0 & LOWPAN_IPHC_HLIM_MASK];
 496         } else {
 497                 if (lowpan_fetch_skb(skb, &hdr.hop_limit,
 498                                      sizeof(hdr.hop_limit)))
 499                         return -EINVAL;
 500         }
 501
 502         if (iphc1 & LOWPAN_IPHC_SAC) {
 503                 /* Source address context based uncompression */
 504                 pr_debug("SAC bit is set. Handle context based source address.\n");
 505                 err = uncompress_context_based_src_addr(skb, &hdr.saddr,
 506                                                         iphc1 & LOWPAN_IPHC_SAM_MASK);
 507         } else {
 508                 /* Source address uncompression */
 509                 pr_debug("source address stateless compression\n");
 510                 err = uncompress_addr(skb, dev, &hdr.saddr,
 511                                       iphc1 & LOWPAN_IPHC_SAM_MASK, saddr);
 512         }
 513
 514         /* Check on error of previous branch */
 515         if (err)
 516                 return -EINVAL;
 517
 518         /* check for Multicast Compression */
 519         if (iphc1 & LOWPAN_IPHC_M) {
 520                 if (iphc1 & LOWPAN_IPHC_DAC) {
 521                         pr_debug("dest: context-based mcast compression\n");
 522                         /* TODO: implement this */
 523                 } else {
 524                         err = lowpan_uncompress_multicast_daddr(skb, &hdr.daddr,
 525                                                                 iphc1 & LOWPAN_IPHC_DAM_MASK);
 526
 527                         if (err)
 528                                 return -EINVAL;
 529                 }
 530         } else {
 531                 err = uncompress_addr(skb, dev, &hdr.daddr,
 532                                       iphc1 & LOWPAN_IPHC_DAM_MASK, daddr);
 533                 pr_debug("dest: stateless compression mode %d dest %pI6c\n",
 534                          iphc1 & LOWPAN_IPHC_DAM_MASK, &hdr.daddr);
 535                 if (err)
 536                         return -EINVAL;
 537         }
 538
 539         /* Next header data uncompression */
 540         if (iphc0 & LOWPAN_IPHC_NH) {
 541                 err = lowpan_nhc_do_uncompression(skb, dev, &hdr);
 542                 if (err < 0)
 543                         return err;
 544         } else {
 545                 err = skb_cow(skb, sizeof(hdr));
 546                 if (unlikely(err))
 547                         return err;
 548         }
 549
 550         switch (lowpan_priv(dev)->lltype) {
 551         case LOWPAN_LLTYPE_IEEE802154:
 552                 if (lowpan_802154_cb(skb)->d_size)
 553                         hdr.payload_len = htons(lowpan_802154_cb(skb)->d_size -
 554                                                 sizeof(struct ipv6hdr));
 555                 else
 556                         hdr.payload_len = htons(skb->len);
 557                 break;
 558         default:
 559                 hdr.payload_len = htons(skb->len);
 560                 break;
 561         }
 562
 563         pr_debug("skb headroom size = %d, data length = %d\n",
 564                  skb_headroom(skb), skb->len);
 565
 566         pr_debug("IPv6 header dump:\n\tversion = %d\n\tlength  = %d\n\t"
 567                  "nexthdr = 0x%02x\n\thop_lim = %d\n\tdest    = %pI6c\n",
 568                 hdr.version, ntohs(hdr.payload_len), hdr.nexthdr,
 569                 hdr.hop_limit, &hdr.daddr);
 570
 571         skb_push(skb, sizeof(hdr));
 572         skb_reset_network_header(skb);
 573         skb_copy_to_linear_data(skb, &hdr, sizeof(hdr));
 574
 575         raw_dump_table(__func__, "raw header dump", (u8 *)&hdr, sizeof(hdr));
 576
 577         return 0;
 578 }
 579 EXPORT_SYMBOL_GPL(lowpan_header_decompress);
 580
 581 static const u8 lowpan_iphc_dam_to_sam_value[] = {
 582         [LOWPAN_IPHC_DAM_00] = LOWPAN_IPHC_SAM_00,
 583         [LOWPAN_IPHC_DAM_01] = LOWPAN_IPHC_SAM_01,
 584         [LOWPAN_IPHC_DAM_10] = LOWPAN_IPHC_SAM_10,
 585         [LOWPAN_IPHC_DAM_11] = LOWPAN_IPHC_SAM_11,
 586 };
 587
 588 static u8 lowpan_compress_addr_64(u8 **hc_ptr, const struct in6_addr *ipaddr,
 589                                   const unsigned char *lladdr, bool sam)
 590 {
 591         u8 dam = LOWPAN_IPHC_DAM_00;
 592
 593         if (is_addr_mac_addr_based(ipaddr, lladdr)) {
 594                 dam = LOWPAN_IPHC_DAM_11; /* 0-bits */
 595                 pr_debug("address compression 0 bits\n");
 596         } else if (lowpan_is_iid_16_bit_compressable(ipaddr)) {
 597                 /* compress IID to 16 bits xxxx::XXXX */
 598                 lowpan_push_hc_data(hc_ptr, &ipaddr->s6_addr16[7], 2);
 599                 dam = LOWPAN_IPHC_DAM_10; /* 16-bits */
 600                 raw_dump_inline(NULL, "Compressed ipv6 addr is (16 bits)",
 601                                 *hc_ptr - 2, 2);
 602         } else {
 603                 /* do not compress IID => xxxx::IID */
 604                 lowpan_push_hc_data(hc_ptr, &ipaddr->s6_addr16[4], 8);
 605                 dam = LOWPAN_IPHC_DAM_01; /* 64-bits */
 606                 raw_dump_inline(NULL, "Compressed ipv6 addr is (64 bits)",
 607                                 *hc_ptr - 8, 8);
 608         }
 609
 610         if (sam)
 611                 return lowpan_iphc_dam_to_sam_value[dam];
 612         else
 613                 return dam;
 614 }
 615
 616 /* lowpan_iphc_get_tc - get the ECN + DCSP fields in hc format */
 617 static inline u8 lowpan_iphc_get_tc(const struct ipv6hdr *hdr)
 618 {
 619         u8 dscp, ecn;
 620
 621         /* hdr->priority contains the higher bits of dscp, lower are part of
 622          * flow_lbl[0]. Note ECN, DCSP is swapped in ipv6 hdr.
 623          */
 624         dscp = (hdr->priority << 2) | ((hdr->flow_lbl[0] & 0xc0) >> 6);
 625         /* ECN is at the two lower bits from first nibble of flow_lbl[0] */
 626         ecn = (hdr->flow_lbl[0] & 0x30);
 627         /* for pretty debug output, also shift ecn to get the ecn value */
 628         pr_debug("ecn 0x%02x dscp 0x%02x\n", ecn >> 4, dscp);
 629         /* ECN is at 0x30 now, shift it to have ECN + DCSP */
 630         return (ecn << 2) | dscp;
 631 }
 632
 633 /* lowpan_iphc_is_flow_lbl_zero - check if flow label is zero */
 634 static inline bool lowpan_iphc_is_flow_lbl_zero(const struct ipv6hdr *hdr)
 635 {
 636         return ((!(hdr->flow_lbl[0] & 0x0f)) &&
 637                 !hdr->flow_lbl[1] && !hdr->flow_lbl[2]);
 638 }
 639
 640 /* lowpan_iphc_tf_compress - compress the traffic class which is set by
 641  *      ipv6hdr. Return the corresponding format identifier which is used.
 642  */
 643 static u8 lowpan_iphc_tf_compress(u8 **hc_ptr, const struct ipv6hdr *hdr)
 644 {
 645         /* get ecn dscp data in a byteformat as: ECN(hi) + DSCP(lo) */
 646         u8 tc = lowpan_iphc_get_tc(hdr), tf[4], val;
 647
 648         /* printout the traffic class in hc format */
 649         pr_debug("tc 0x%02x\n", tc);
 650
 651         if (lowpan_iphc_is_flow_lbl_zero(hdr)) {
 652                 if (!tc) {
 653                         /* 11:  Traffic Class and Flow Label are elided. */
 654                         val = LOWPAN_IPHC_TF_11;
 655                 } else {
 656                         /* 10:  ECN + DSCP (1 byte), Flow Label is elided.
 657                          *
 658                          *  0 1 2 3 4 5 6 7
 659                          * +-+-+-+-+-+-+-+-+
 660                          * |ECN|   DSCP    |
 661                          * +-+-+-+-+-+-+-+-+
 662                          */
 663                         lowpan_push_hc_data(hc_ptr, &tc, sizeof(tc));
 664                         val = LOWPAN_IPHC_TF_10;
 665                 }
 666         } else {
 667                 /* check if dscp is zero, it's after the first two bit */
 668                 if (!(tc & 0x3f)) {
 669                         /* 01:  ECN + 2-bit Pad + Flow Label (3 bytes), DSCP is elided
 670                          *
 671                          *                     1                   2
 672                          * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3
 673                          * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 674                          * |ECN|rsv|             Flow Label                |
 675                          * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 676                          */
 677                         memcpy(&tf[0], &hdr->flow_lbl[0], 3);
 678                         /* zero the highest 4-bits, contains DCSP + ECN */
 679                         tf[0] &= ~0xf0;
 680                         /* set ECN */
 681                         tf[0] |= (tc & 0xc0);
 682
 683                         lowpan_push_hc_data(hc_ptr, tf, 3);
 684                         val = LOWPAN_IPHC_TF_01;
 685                 } else {
 686                         /* 00:  ECN + DSCP + 4-bit Pad + Flow Label (4 bytes)
 687                          *
 688                          *                      1                   2                   3
 689                          *  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 690                          * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 691                          * |ECN|   DSCP    |  rsv  |             Flow Label                |
 692                          * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 693                          */
 694                         memcpy(&tf[0], &tc, sizeof(tc));
 695                         /* highest nibble of flow_lbl[0] is part of DSCP + ECN
 696                          * which will be the 4-bit pad and will be filled with
 697                          * zeros afterwards.
 698                          */
 699                         memcpy(&tf[1], &hdr->flow_lbl[0], 3);
 700                         /* zero the 4-bit pad, which is reserved */
 701                         tf[1] &= ~0xf0;
 702
 703                         lowpan_push_hc_data(hc_ptr, tf, 4);
 704                         val = LOWPAN_IPHC_TF_00;
 705                 }
 706         }
 707
 708         return val;
 709 }
 710
 711 static u8 lowpan_iphc_mcast_addr_compress(u8 **hc_ptr,
 712                                           const struct in6_addr *ipaddr)
 713 {
 714         u8 val;
 715
 716         if (lowpan_is_mcast_addr_compressable8(ipaddr)) {
 717                 pr_debug("compressed to 1 octet\n");
 718                 /* use last byte */
 719                 lowpan_push_hc_data(hc_ptr, &ipaddr->s6_addr[15], 1);
 720                 val = LOWPAN_IPHC_DAM_11;
 721         } else if (lowpan_is_mcast_addr_compressable32(ipaddr)) {
 722                 pr_debug("compressed to 4 octets\n");
 723                 /* second byte + the last three */
 724                 lowpan_push_hc_data(hc_ptr, &ipaddr->s6_addr[1], 1);
 725                 lowpan_push_hc_data(hc_ptr, &ipaddr->s6_addr[13], 3);
 726                 val = LOWPAN_IPHC_DAM_10;
 727         } else if (lowpan_is_mcast_addr_compressable48(ipaddr)) {
 728                 pr_debug("compressed to 6 octets\n");
 729                 /* second byte + the last five */
 730                 lowpan_push_hc_data(hc_ptr, &ipaddr->s6_addr[1], 1);
 731                 lowpan_push_hc_data(hc_ptr, &ipaddr->s6_addr[11], 5);
 732                 val = LOWPAN_IPHC_DAM_01;
 733         } else {
 734                 pr_debug("using full address\n");
 735                 lowpan_push_hc_data(hc_ptr, ipaddr->s6_addr, 16);
 736                 val = LOWPAN_IPHC_DAM_00;
 737         }
 738
 739         return val;
 740 }
 741
 742 int lowpan_header_compress(struct sk_buff *skb, const struct net_device *dev,
 743                            const void *daddr, const void *saddr)
 744 {
 745         u8 iphc0, iphc1, *hc_ptr;
 746         struct ipv6hdr *hdr;
 747         u8 head[LOWPAN_IPHC_MAX_HC_BUF_LEN] = {};
 748         int ret, addr_type;
 749
 750         if (skb->protocol != htons(ETH_P_IPV6))
 751                 return -EINVAL;
 752
 753         hdr = ipv6_hdr(skb);
 754         hc_ptr = head + 2;
 755
 756         pr_debug("IPv6 header dump:\n\tversion = %d\n\tlength  = %d\n"
 757                  "\tnexthdr = 0x%02x\n\thop_lim = %d\n\tdest    = %pI6c\n",
 758                  hdr->version, ntohs(hdr->payload_len), hdr->nexthdr,
 759                  hdr->hop_limit, &hdr->daddr);
 760
 761         raw_dump_table(__func__, "raw skb network header dump",
 762                        skb_network_header(skb), sizeof(struct ipv6hdr));
 763
 764         /* As we copy some bit-length fields, in the IPHC encoding bytes,
 765          * we sometimes use |=
 766          * If the field is 0, and the current bit value in memory is 1,
 767          * this does not work. We therefore reset the IPHC encoding here
 768          */
 769         iphc0 = LOWPAN_DISPATCH_IPHC;
 770         iphc1 = 0;
 771
 772         /* TODO: context lookup */
 773
 774         raw_dump_inline(__func__, "saddr", saddr, EUI64_ADDR_LEN);
 775         raw_dump_inline(__func__, "daddr", daddr, EUI64_ADDR_LEN);
 776
 777         raw_dump_table(__func__, "sending raw skb network uncompressed packet",
 778                        skb->data, skb->len);
 779
 780         /* Traffic Class, Flow Label compression */
 781         iphc0 |= lowpan_iphc_tf_compress(&hc_ptr, hdr);
 782
 783         /* NOTE: payload length is always compressed */
 784
 785         /* Check if we provide the nhc format for nexthdr and compression
 786          * functionality. If not nexthdr is handled inline and not compressed.
 787          */
 788         ret = lowpan_nhc_check_compression(skb, hdr, &hc_ptr);
 789         if (ret == -ENOENT)
 790                 lowpan_push_hc_data(&hc_ptr, &hdr->nexthdr,
 791                                     sizeof(hdr->nexthdr));
 792         else
 793                 iphc0 |= LOWPAN_IPHC_NH;
 794
 795         /* Hop limit
 796          * if 1:   compress, encoding is 01
 797          * if 64:  compress, encoding is 10
 798          * if 255: compress, encoding is 11
 799          * else do not compress
 800          */
 801         switch (hdr->hop_limit) {
 802         case 1:
 803                 iphc0 |= LOWPAN_IPHC_HLIM_01;
 804                 break;
 805         case 64:
 806                 iphc0 |= LOWPAN_IPHC_HLIM_10;
 807                 break;
 808         case 255:
 809                 iphc0 |= LOWPAN_IPHC_HLIM_11;
 810                 break;
 811         default:
 812                 lowpan_push_hc_data(&hc_ptr, &hdr->hop_limit,
 813                                     sizeof(hdr->hop_limit));
 814         }
 815
 816         addr_type = ipv6_addr_type(&hdr->saddr);
 817         /* source address compression */
 818         if (addr_type == IPV6_ADDR_ANY) {
 819                 pr_debug("source address is unspecified, setting SAC\n");
 820                 iphc1 |= LOWPAN_IPHC_SAC;
 821         } else {
 822                 if (addr_type & IPV6_ADDR_LINKLOCAL) {
 823                         iphc1 |= lowpan_compress_addr_64(&hc_ptr, &hdr->saddr,
 824                                                          saddr, true);
 825                         pr_debug("source address unicast link-local %pI6c iphc1 0x%02x\n",
 826                                  &hdr->saddr, iphc1);
 827                 } else {
 828                         pr_debug("send the full source address\n");
 829                         lowpan_push_hc_data(&hc_ptr, hdr->saddr.s6_addr, 16);
 830                 }
 831         }
 832
 833         addr_type = ipv6_addr_type(&hdr->daddr);
 834         /* destination address compression */
 835         if (addr_type & IPV6_ADDR_MULTICAST) {
 836                 pr_debug("destination address is multicast: ");
 837                 iphc1 |= LOWPAN_IPHC_M;
 838                 iphc1 |= lowpan_iphc_mcast_addr_compress(&hc_ptr, &hdr->daddr);
 839         } else {
 840                 if (addr_type & IPV6_ADDR_LINKLOCAL) {
 841                         /* TODO: context lookup */
 842                         iphc1 |= lowpan_compress_addr_64(&hc_ptr, &hdr->daddr,
 843                                                          daddr, false);
 844                         pr_debug("dest address unicast link-local %pI6c "
 845                                  "iphc1 0x%02x\n", &hdr->daddr, iphc1);
 846                 } else {
 847                         pr_debug("dest address unicast %pI6c\n", &hdr->daddr);
 848                         lowpan_push_hc_data(&hc_ptr, hdr->daddr.s6_addr, 16);
 849                 }
 850         }
 851
 852         /* next header compression */
 853         if (iphc0 & LOWPAN_IPHC_NH) {
 854                 ret = lowpan_nhc_do_compression(skb, hdr, &hc_ptr);
 855                 if (ret < 0)
 856                         return ret;
 857         }
 858
 859         head[0] = iphc0;
 860         head[1] = iphc1;
 861
 862         skb_pull(skb, sizeof(struct ipv6hdr));
 863         skb_reset_transport_header(skb);
 864         memcpy(skb_push(skb, hc_ptr - head), head, hc_ptr - head);
 865         skb_reset_network_header(skb);
 866
 867         pr_debug("header len %d skb %u\n", (int)(hc_ptr - head), skb->len);
 868
 869         raw_dump_table(__func__, "raw skb data dump compressed",
 870                        skb->data, skb->len);
 871         return 0;
 872 }
 873 EXPORT_SYMBOL_GPL(lowpan_header_compress);