net/6lowpan/iphc.c

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This source file includes following definitions.
lowpan_iphc_uncompress_802154_lladdr
lowpan_iphc_ctx_get_by_id
lowpan_iphc_ctx_get_by_addr
lowpan_iphc_ctx_get_by_mcast_addr
lowpan_iphc_uncompress_lladdr
lowpan_iphc_uncompress_addr
lowpan_iphc_uncompress_ctx_addr
lowpan_uncompress_multicast_daddr
lowpan_uncompress_multicast_ctx_daddr
lowpan_iphc_tf_set_ecn
lowpan_iphc_tf_set_dscp
lowpan_iphc_tf_set_lbl
lowpan_iphc_tf_decompress
lowpan_header_decompress
lowpan_iphc_compress_ctx_802154_lladdr
lowpan_iphc_addr_equal
lowpan_compress_ctx_addr
lowpan_iphc_compress_802154_lladdr
lowpan_compress_addr_64
lowpan_iphc_get_tc
lowpan_iphc_is_flow_lbl_zero
lowpan_iphc_tf_compress
lowpan_iphc_mcast_ctx_addr_compress
lowpan_iphc_mcast_addr_compress
lowpan_header_compress
   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 #include "6lowpan_i.h"
  57 #include "nhc.h"
  58 
  59 /* Values of fields within the IPHC encoding first byte */
  60 #define LOWPAN_IPHC_TF_MASK     0x18
  61 #define LOWPAN_IPHC_TF_00       0x00
  62 #define LOWPAN_IPHC_TF_01       0x08
  63 #define LOWPAN_IPHC_TF_10       0x10
  64 #define LOWPAN_IPHC_TF_11       0x18
  65 
  66 #define LOWPAN_IPHC_NH          0x04
  67 
  68 #define LOWPAN_IPHC_HLIM_MASK   0x03
  69 #define LOWPAN_IPHC_HLIM_00     0x00
  70 #define LOWPAN_IPHC_HLIM_01     0x01
  71 #define LOWPAN_IPHC_HLIM_10     0x02
  72 #define LOWPAN_IPHC_HLIM_11     0x03
  73 
  74 /* Values of fields within the IPHC encoding second byte */
  75 #define LOWPAN_IPHC_CID         0x80
  76 
  77 #define LOWPAN_IPHC_SAC         0x40
  78 
  79 #define LOWPAN_IPHC_SAM_MASK    0x30
  80 #define LOWPAN_IPHC_SAM_00      0x00
  81 #define LOWPAN_IPHC_SAM_01      0x10
  82 #define LOWPAN_IPHC_SAM_10      0x20
  83 #define LOWPAN_IPHC_SAM_11      0x30
  84 
  85 #define LOWPAN_IPHC_M           0x08
  86 
  87 #define LOWPAN_IPHC_DAC         0x04
  88 
  89 #define LOWPAN_IPHC_DAM_MASK    0x03
  90 #define LOWPAN_IPHC_DAM_00      0x00
  91 #define LOWPAN_IPHC_DAM_01      0x01
  92 #define LOWPAN_IPHC_DAM_10      0x02
  93 #define LOWPAN_IPHC_DAM_11      0x03
  94 
  95 /* ipv6 address based on mac
  96  * second bit-flip (Universe/Local) is done according RFC2464
  97  */
  98 #define is_addr_mac_addr_based(a, m) \
  99         ((((a)->s6_addr[8])  == (((m)[0]) ^ 0x02)) &&   \
 100          (((a)->s6_addr[9])  == (m)[1]) &&              \
 101          (((a)->s6_addr[10]) == (m)[2]) &&              \
 102          (((a)->s6_addr[11]) == (m)[3]) &&              \
 103          (((a)->s6_addr[12]) == (m)[4]) &&              \
 104          (((a)->s6_addr[13]) == (m)[5]) &&              \
 105          (((a)->s6_addr[14]) == (m)[6]) &&              \
 106          (((a)->s6_addr[15]) == (m)[7]))
 107 
 108 /* check whether we can compress the IID to 16 bits,
 109  * it's possible for unicast addresses with first 49 bits are zero only.
 110  */
 111 #define lowpan_is_iid_16_bit_compressable(a)    \
 112         ((((a)->s6_addr16[4]) == 0) &&          \
 113          (((a)->s6_addr[10]) == 0) &&           \
 114          (((a)->s6_addr[11]) == 0xff) &&        \
 115          (((a)->s6_addr[12]) == 0xfe) &&        \
 116          (((a)->s6_addr[13]) == 0))
 117 
 118 /* check whether the 112-bit gid of the multicast address is mappable to: */
 119 
 120 /* 48 bits, FFXX::00XX:XXXX:XXXX */
 121 #define lowpan_is_mcast_addr_compressable48(a)  \
 122         ((((a)->s6_addr16[1]) == 0) &&          \
 123          (((a)->s6_addr16[2]) == 0) &&          \
 124          (((a)->s6_addr16[3]) == 0) &&          \
 125          (((a)->s6_addr16[4]) == 0) &&          \
 126          (((a)->s6_addr[10]) == 0))
 127 
 128 /* 32 bits, FFXX::00XX:XXXX */
 129 #define lowpan_is_mcast_addr_compressable32(a)  \
 130         ((((a)->s6_addr16[1]) == 0) &&          \
 131          (((a)->s6_addr16[2]) == 0) &&          \
 132          (((a)->s6_addr16[3]) == 0) &&          \
 133          (((a)->s6_addr16[4]) == 0) &&          \
 134          (((a)->s6_addr16[5]) == 0) &&          \
 135          (((a)->s6_addr[12]) == 0))
 136 
 137 /* 8 bits, FF02::00XX */
 138 #define lowpan_is_mcast_addr_compressable8(a)   \
 139         ((((a)->s6_addr[1])  == 2) &&           \
 140          (((a)->s6_addr16[1]) == 0) &&          \
 141          (((a)->s6_addr16[2]) == 0) &&          \
 142          (((a)->s6_addr16[3]) == 0) &&          \
 143          (((a)->s6_addr16[4]) == 0) &&          \
 144          (((a)->s6_addr16[5]) == 0) &&          \
 145          (((a)->s6_addr16[6]) == 0) &&          \
 146          (((a)->s6_addr[14]) == 0))
 147 
 148 #define lowpan_is_linklocal_zero_padded(a)      \
 149         (!(hdr->saddr.s6_addr[1] & 0x3f) &&     \
 150          !hdr->saddr.s6_addr16[1] &&            \
 151          !hdr->saddr.s6_addr32[1])
 152 
 153 #define LOWPAN_IPHC_CID_DCI(cid)        (cid & 0x0f)
 154 #define LOWPAN_IPHC_CID_SCI(cid)        ((cid & 0xf0) >> 4)
 155 
 156 static inline void
 157 lowpan_iphc_uncompress_802154_lladdr(struct in6_addr *ipaddr,
 158                                      const void *lladdr)
 159 {
 160         const struct ieee802154_addr *addr = lladdr;
 161         u8 eui64[EUI64_ADDR_LEN];
 162 
 163         switch (addr->mode) {
 164         case IEEE802154_ADDR_LONG:
 165                 ieee802154_le64_to_be64(eui64, &addr->extended_addr);
 166                 lowpan_iphc_uncompress_eui64_lladdr(ipaddr, eui64);
 167                 break;
 168         case IEEE802154_ADDR_SHORT:
 169                 /* fe:80::ff:fe00:XXXX
 170                  *                \__/
 171                  *             short_addr
 172                  *
 173                  * Universe/Local bit is zero.
 174                  */
 175                 ipaddr->s6_addr[0] = 0xFE;
 176                 ipaddr->s6_addr[1] = 0x80;
 177                 ipaddr->s6_addr[11] = 0xFF;
 178                 ipaddr->s6_addr[12] = 0xFE;
 179                 ieee802154_le16_to_be16(&ipaddr->s6_addr16[7],
 180                                         &addr->short_addr);
 181                 break;
 182         default:
 183                 /* should never handled and filtered by 802154 6lowpan */
 184                 WARN_ON_ONCE(1);
 185                 break;
 186         }
 187 }
 188 
 189 static struct lowpan_iphc_ctx *
 190 lowpan_iphc_ctx_get_by_id(const struct net_device *dev, u8 id)
 191 {
 192         struct lowpan_iphc_ctx *ret = &lowpan_dev(dev)->ctx.table[id];
 193 
 194         if (!lowpan_iphc_ctx_is_active(ret))
 195                 return NULL;
 196 
 197         return ret;
 198 }
 199 
 200 static struct lowpan_iphc_ctx *
 201 lowpan_iphc_ctx_get_by_addr(const struct net_device *dev,
 202                             const struct in6_addr *addr)
 203 {
 204         struct lowpan_iphc_ctx *table = lowpan_dev(dev)->ctx.table;
 205         struct lowpan_iphc_ctx *ret = NULL;
 206         struct in6_addr addr_pfx;
 207         u8 addr_plen;
 208         int i;
 209 
 210         for (i = 0; i < LOWPAN_IPHC_CTX_TABLE_SIZE; i++) {
 211                 /* Check if context is valid. A context that is not valid
 212                  * MUST NOT be used for compression.
 213                  */
 214                 if (!lowpan_iphc_ctx_is_active(&table[i]) ||
 215                     !lowpan_iphc_ctx_is_compression(&table[i]))
 216                         continue;
 217 
 218                 ipv6_addr_prefix(&addr_pfx, addr, table[i].plen);
 219 
 220                 /* if prefix len < 64, the remaining bits until 64th bit is
 221                  * zero. Otherwise we use table[i]->plen.
 222                  */
 223                 if (table[i].plen < 64)
 224                         addr_plen = 64;
 225                 else
 226                         addr_plen = table[i].plen;
 227 
 228                 if (ipv6_prefix_equal(&addr_pfx, &table[i].pfx, addr_plen)) {
 229                         /* remember first match */
 230                         if (!ret) {
 231                                 ret = &table[i];
 232                                 continue;
 233                         }
 234 
 235                         /* get the context with longest prefix len */
 236                         if (table[i].plen > ret->plen)
 237                                 ret = &table[i];
 238                 }
 239         }
 240 
 241         return ret;
 242 }
 243 
 244 static struct lowpan_iphc_ctx *
 245 lowpan_iphc_ctx_get_by_mcast_addr(const struct net_device *dev,
 246                                   const struct in6_addr *addr)
 247 {
 248         struct lowpan_iphc_ctx *table = lowpan_dev(dev)->ctx.table;
 249         struct lowpan_iphc_ctx *ret = NULL;
 250         struct in6_addr addr_mcast, network_pfx = {};
 251         int i;
 252 
 253         /* init mcast address with  */
 254         memcpy(&addr_mcast, addr, sizeof(*addr));
 255 
 256         for (i = 0; i < LOWPAN_IPHC_CTX_TABLE_SIZE; i++) {
 257                 /* Check if context is valid. A context that is not valid
 258                  * MUST NOT be used for compression.
 259                  */
 260                 if (!lowpan_iphc_ctx_is_active(&table[i]) ||
 261                     !lowpan_iphc_ctx_is_compression(&table[i]))
 262                         continue;
 263 
 264                 /* setting plen */
 265                 addr_mcast.s6_addr[3] = table[i].plen;
 266                 /* get network prefix to copy into multicast address */
 267                 ipv6_addr_prefix(&network_pfx, &table[i].pfx,
 268                                  table[i].plen);
 269                 /* setting network prefix */
 270                 memcpy(&addr_mcast.s6_addr[4], &network_pfx, 8);
 271 
 272                 if (ipv6_addr_equal(addr, &addr_mcast)) {
 273                         ret = &table[i];
 274                         break;
 275                 }
 276         }
 277 
 278         return ret;
 279 }
 280 
 281 static void lowpan_iphc_uncompress_lladdr(const struct net_device *dev,
 282                                           struct in6_addr *ipaddr,
 283                                           const void *lladdr)
 284 {
 285         switch (dev->addr_len) {
 286         case ETH_ALEN:
 287                 lowpan_iphc_uncompress_eui48_lladdr(ipaddr, lladdr);
 288                 break;
 289         case EUI64_ADDR_LEN:
 290                 lowpan_iphc_uncompress_eui64_lladdr(ipaddr, lladdr);
 291                 break;
 292         default:
 293                 WARN_ON_ONCE(1);
 294                 break;
 295         }
 296 }
 297 
 298 /* Uncompress address function for source and
 299  * destination address(non-multicast).
 300  *
 301  * address_mode is the masked value for sam or dam value
 302  */
 303 static int lowpan_iphc_uncompress_addr(struct sk_buff *skb,
 304                                        const struct net_device *dev,
 305                                        struct in6_addr *ipaddr,
 306                                        u8 address_mode, const void *lladdr)
 307 {
 308         bool fail;
 309 
 310         switch (address_mode) {
 311         /* SAM and DAM are the same here */
 312         case LOWPAN_IPHC_DAM_00:
 313                 /* for global link addresses */
 314                 fail = lowpan_fetch_skb(skb, ipaddr->s6_addr, 16);
 315                 break;
 316         case LOWPAN_IPHC_SAM_01:
 317         case LOWPAN_IPHC_DAM_01:
 318                 /* fe:80::XXXX:XXXX:XXXX:XXXX */
 319                 ipaddr->s6_addr[0] = 0xFE;
 320                 ipaddr->s6_addr[1] = 0x80;
 321                 fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[8], 8);
 322                 break;
 323         case LOWPAN_IPHC_SAM_10:
 324         case LOWPAN_IPHC_DAM_10:
 325                 /* fe:80::ff:fe00:XXXX */
 326                 ipaddr->s6_addr[0] = 0xFE;
 327                 ipaddr->s6_addr[1] = 0x80;
 328                 ipaddr->s6_addr[11] = 0xFF;
 329                 ipaddr->s6_addr[12] = 0xFE;
 330                 fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[14], 2);
 331                 break;
 332         case LOWPAN_IPHC_SAM_11:
 333         case LOWPAN_IPHC_DAM_11:
 334                 fail = false;
 335                 switch (lowpan_dev(dev)->lltype) {
 336                 case LOWPAN_LLTYPE_IEEE802154:
 337                         lowpan_iphc_uncompress_802154_lladdr(ipaddr, lladdr);
 338                         break;
 339                 default:
 340                         lowpan_iphc_uncompress_lladdr(dev, ipaddr, lladdr);
 341                         break;
 342                 }
 343                 break;
 344         default:
 345                 pr_debug("Invalid address mode value: 0x%x\n", address_mode);
 346                 return -EINVAL;
 347         }
 348 
 349         if (fail) {
 350                 pr_debug("Failed to fetch skb data\n");
 351                 return -EIO;
 352         }
 353 
 354         raw_dump_inline(NULL, "Reconstructed ipv6 addr is",
 355                         ipaddr->s6_addr, 16);
 356 
 357         return 0;
 358 }
 359 
 360 /* Uncompress address function for source context
 361  * based address(non-multicast).
 362  */
 363 static int lowpan_iphc_uncompress_ctx_addr(struct sk_buff *skb,
 364                                            const struct net_device *dev,
 365                                            const struct lowpan_iphc_ctx *ctx,
 366                                            struct in6_addr *ipaddr,
 367                                            u8 address_mode, const void *lladdr)
 368 {
 369         bool fail;
 370 
 371         switch (address_mode) {
 372         /* SAM and DAM are the same here */
 373         case LOWPAN_IPHC_DAM_00:
 374                 fail = false;
 375                 /* SAM_00 -> unspec address ::
 376                  * Do nothing, address is already ::
 377                  *
 378                  * DAM 00 -> reserved should never occur.
 379                  */
 380                 break;
 381         case LOWPAN_IPHC_SAM_01:
 382         case LOWPAN_IPHC_DAM_01:
 383                 fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[8], 8);
 384                 ipv6_addr_prefix_copy(ipaddr, &ctx->pfx, ctx->plen);
 385                 break;
 386         case LOWPAN_IPHC_SAM_10:
 387         case LOWPAN_IPHC_DAM_10:
 388                 ipaddr->s6_addr[11] = 0xFF;
 389                 ipaddr->s6_addr[12] = 0xFE;
 390                 fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[14], 2);
 391                 ipv6_addr_prefix_copy(ipaddr, &ctx->pfx, ctx->plen);
 392                 break;
 393         case LOWPAN_IPHC_SAM_11:
 394         case LOWPAN_IPHC_DAM_11:
 395                 fail = false;
 396                 switch (lowpan_dev(dev)->lltype) {
 397                 case LOWPAN_LLTYPE_IEEE802154:
 398                         lowpan_iphc_uncompress_802154_lladdr(ipaddr, lladdr);
 399                         break;
 400                 default:
 401                         lowpan_iphc_uncompress_lladdr(dev, ipaddr, lladdr);
 402                         break;
 403                 }
 404                 ipv6_addr_prefix_copy(ipaddr, &ctx->pfx, ctx->plen);
 405                 break;
 406         default:
 407                 pr_debug("Invalid sam value: 0x%x\n", address_mode);
 408                 return -EINVAL;
 409         }
 410 
 411         if (fail) {
 412                 pr_debug("Failed to fetch skb data\n");
 413                 return -EIO;
 414         }
 415 
 416         raw_dump_inline(NULL,
 417                         "Reconstructed context based ipv6 src addr is",
 418                         ipaddr->s6_addr, 16);
 419 
 420         return 0;
 421 }
 422 
 423 /* Uncompress function for multicast destination address,
 424  * when M bit is set.
 425  */
 426 static int lowpan_uncompress_multicast_daddr(struct sk_buff *skb,
 427                                              struct in6_addr *ipaddr,
 428                                              u8 address_mode)
 429 {
 430         bool fail;
 431 
 432         switch (address_mode) {
 433         case LOWPAN_IPHC_DAM_00:
 434                 /* 00:  128 bits.  The full address
 435                  * is carried in-line.
 436                  */
 437                 fail = lowpan_fetch_skb(skb, ipaddr->s6_addr, 16);
 438                 break;
 439         case LOWPAN_IPHC_DAM_01:
 440                 /* 01:  48 bits.  The address takes
 441                  * the form ffXX::00XX:XXXX:XXXX.
 442                  */
 443                 ipaddr->s6_addr[0] = 0xFF;
 444                 fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[1], 1);
 445                 fail |= lowpan_fetch_skb(skb, &ipaddr->s6_addr[11], 5);
 446                 break;
 447         case LOWPAN_IPHC_DAM_10:
 448                 /* 10:  32 bits.  The address takes
 449                  * the form ffXX::00XX:XXXX.
 450                  */
 451                 ipaddr->s6_addr[0] = 0xFF;
 452                 fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[1], 1);
 453                 fail |= lowpan_fetch_skb(skb, &ipaddr->s6_addr[13], 3);
 454                 break;
 455         case LOWPAN_IPHC_DAM_11:
 456                 /* 11:  8 bits.  The address takes
 457                  * the form ff02::00XX.
 458                  */
 459                 ipaddr->s6_addr[0] = 0xFF;
 460                 ipaddr->s6_addr[1] = 0x02;
 461                 fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[15], 1);
 462                 break;
 463         default:
 464                 pr_debug("DAM value has a wrong value: 0x%x\n", address_mode);
 465                 return -EINVAL;
 466         }
 467 
 468         if (fail) {
 469                 pr_debug("Failed to fetch skb data\n");
 470                 return -EIO;
 471         }
 472 
 473         raw_dump_inline(NULL, "Reconstructed ipv6 multicast addr is",
 474                         ipaddr->s6_addr, 16);
 475 
 476         return 0;
 477 }
 478 
 479 static int lowpan_uncompress_multicast_ctx_daddr(struct sk_buff *skb,
 480                                                  struct lowpan_iphc_ctx *ctx,
 481                                                  struct in6_addr *ipaddr,
 482                                                  u8 address_mode)
 483 {
 484         struct in6_addr network_pfx = {};
 485         bool fail;
 486 
 487         ipaddr->s6_addr[0] = 0xFF;
 488         fail = lowpan_fetch_skb(skb, &ipaddr->s6_addr[1], 2);
 489         fail |= lowpan_fetch_skb(skb, &ipaddr->s6_addr[12], 4);
 490         if (fail)
 491                 return -EIO;
 492 
 493         /* take prefix_len and network prefix from the context */
 494         ipaddr->s6_addr[3] = ctx->plen;
 495         /* get network prefix to copy into multicast address */
 496         ipv6_addr_prefix(&network_pfx, &ctx->pfx, ctx->plen);
 497         /* setting network prefix */
 498         memcpy(&ipaddr->s6_addr[4], &network_pfx, 8);
 499 
 500         return 0;
 501 }
 502 
 503 /* get the ecn values from iphc tf format and set it to ipv6hdr */
 504 static inline void lowpan_iphc_tf_set_ecn(struct ipv6hdr *hdr, const u8 *tf)
 505 {
 506         /* get the two higher bits which is ecn */
 507         u8 ecn = tf[0] & 0xc0;
 508 
 509         /* ECN takes 0x30 in hdr->flow_lbl[0] */
 510         hdr->flow_lbl[0] |= (ecn >> 2);
 511 }
 512 
 513 /* get the dscp values from iphc tf format and set it to ipv6hdr */
 514 static inline void lowpan_iphc_tf_set_dscp(struct ipv6hdr *hdr, const u8 *tf)
 515 {
 516         /* DSCP is at place after ECN */
 517         u8 dscp = tf[0] & 0x3f;
 518 
 519         /* The four highest bits need to be set at hdr->priority */
 520         hdr->priority |= ((dscp & 0x3c) >> 2);
 521         /* The two lower bits is part of hdr->flow_lbl[0] */
 522         hdr->flow_lbl[0] |= ((dscp & 0x03) << 6);
 523 }
 524 
 525 /* get the flow label values from iphc tf format and set it to ipv6hdr */
 526 static inline void lowpan_iphc_tf_set_lbl(struct ipv6hdr *hdr, const u8 *lbl)
 527 {
 528         /* flow label is always some array started with lower nibble of
 529          * flow_lbl[0] and followed with two bytes afterwards. Inside inline
 530          * data the flow_lbl position can be different, which will be handled
 531          * by lbl pointer. E.g. case "01" vs "00" the traffic class is 8 bit
 532          * shifted, the different lbl pointer will handle that.
 533          *
 534          * The flow label will started at lower nibble of flow_lbl[0], the
 535          * higher nibbles are part of DSCP + ECN.
 536          */
 537         hdr->flow_lbl[0] |= lbl[0] & 0x0f;
 538         memcpy(&hdr->flow_lbl[1], &lbl[1], 2);
 539 }
 540 
 541 /* lowpan_iphc_tf_decompress - decompress the traffic class.
 542  *      This function will return zero on success, a value lower than zero if
 543  *      failed.
 544  */
 545 static int lowpan_iphc_tf_decompress(struct sk_buff *skb, struct ipv6hdr *hdr,
 546                                      u8 val)
 547 {
 548         u8 tf[4];
 549 
 550         /* Traffic Class and Flow Label */
 551         switch (val) {
 552         case LOWPAN_IPHC_TF_00:
 553                 /* ECN + DSCP + 4-bit Pad + Flow Label (4 bytes) */
 554                 if (lowpan_fetch_skb(skb, tf, 4))
 555                         return -EINVAL;
 556 
 557                 /*                      1                   2                   3
 558                  *  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
 559                  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 560                  * |ECN|   DSCP    |  rsv  |             Flow Label                |
 561                  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 562                  */
 563                 lowpan_iphc_tf_set_ecn(hdr, tf);
 564                 lowpan_iphc_tf_set_dscp(hdr, tf);
 565                 lowpan_iphc_tf_set_lbl(hdr, &tf[1]);
 566                 break;
 567         case LOWPAN_IPHC_TF_01:
 568                 /* ECN + 2-bit Pad + Flow Label (3 bytes), DSCP is elided. */
 569                 if (lowpan_fetch_skb(skb, tf, 3))
 570                         return -EINVAL;
 571 
 572                 /*                     1                   2
 573                  * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3
 574                  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 575                  * |ECN|rsv|             Flow Label                |
 576                  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 577                  */
 578                 lowpan_iphc_tf_set_ecn(hdr, tf);
 579                 lowpan_iphc_tf_set_lbl(hdr, &tf[0]);
 580                 break;
 581         case LOWPAN_IPHC_TF_10:
 582                 /* ECN + DSCP (1 byte), Flow Label is elided. */
 583                 if (lowpan_fetch_skb(skb, tf, 1))
 584                         return -EINVAL;
 585 
 586                 /*  0 1 2 3 4 5 6 7
 587                  * +-+-+-+-+-+-+-+-+
 588                  * |ECN|   DSCP    |
 589                  * +-+-+-+-+-+-+-+-+
 590                  */
 591                 lowpan_iphc_tf_set_ecn(hdr, tf);
 592                 lowpan_iphc_tf_set_dscp(hdr, tf);
 593                 break;
 594         case LOWPAN_IPHC_TF_11:
 595                 /* Traffic Class and Flow Label are elided */
 596                 break;
 597         default:
 598                 WARN_ON_ONCE(1);
 599                 return -EINVAL;
 600         }
 601 
 602         return 0;
 603 }
 604 
 605 /* TTL uncompression values */
 606 static const u8 lowpan_ttl_values[] = {
 607         [LOWPAN_IPHC_HLIM_01] = 1,
 608         [LOWPAN_IPHC_HLIM_10] = 64,
 609         [LOWPAN_IPHC_HLIM_11] = 255,
 610 };
 611 
 612 int lowpan_header_decompress(struct sk_buff *skb, const struct net_device *dev,
 613                              const void *daddr, const void *saddr)
 614 {
 615         struct ipv6hdr hdr = {};
 616         struct lowpan_iphc_ctx *ci;
 617         u8 iphc0, iphc1, cid = 0;
 618         int err;
 619 
 620         raw_dump_table(__func__, "raw skb data dump uncompressed",
 621                        skb->data, skb->len);
 622 
 623         if (lowpan_fetch_skb(skb, &iphc0, sizeof(iphc0)) ||
 624             lowpan_fetch_skb(skb, &iphc1, sizeof(iphc1)))
 625                 return -EINVAL;
 626 
 627         hdr.version = 6;
 628 
 629         /* default CID = 0, another if the CID flag is set */
 630         if (iphc1 & LOWPAN_IPHC_CID) {
 631                 if (lowpan_fetch_skb(skb, &cid, sizeof(cid)))
 632                         return -EINVAL;
 633         }
 634 
 635         err = lowpan_iphc_tf_decompress(skb, &hdr,
 636                                         iphc0 & LOWPAN_IPHC_TF_MASK);
 637         if (err < 0)
 638                 return err;
 639 
 640         /* Next Header */
 641         if (!(iphc0 & LOWPAN_IPHC_NH)) {
 642                 /* Next header is carried inline */
 643                 if (lowpan_fetch_skb(skb, &hdr.nexthdr, sizeof(hdr.nexthdr)))
 644                         return -EINVAL;
 645 
 646                 pr_debug("NH flag is set, next header carried inline: %02x\n",
 647                          hdr.nexthdr);
 648         }
 649 
 650         /* Hop Limit */
 651         if ((iphc0 & LOWPAN_IPHC_HLIM_MASK) != LOWPAN_IPHC_HLIM_00) {
 652                 hdr.hop_limit = lowpan_ttl_values[iphc0 & LOWPAN_IPHC_HLIM_MASK];
 653         } else {
 654                 if (lowpan_fetch_skb(skb, &hdr.hop_limit,
 655                                      sizeof(hdr.hop_limit)))
 656                         return -EINVAL;
 657         }
 658 
 659         if (iphc1 & LOWPAN_IPHC_SAC) {
 660                 spin_lock_bh(&lowpan_dev(dev)->ctx.lock);
 661                 ci = lowpan_iphc_ctx_get_by_id(dev, LOWPAN_IPHC_CID_SCI(cid));
 662                 if (!ci) {
 663                         spin_unlock_bh(&lowpan_dev(dev)->ctx.lock);
 664                         return -EINVAL;
 665                 }
 666 
 667                 pr_debug("SAC bit is set. Handle context based source address.\n");
 668                 err = lowpan_iphc_uncompress_ctx_addr(skb, dev, ci, &hdr.saddr,
 669                                                       iphc1 & LOWPAN_IPHC_SAM_MASK,
 670                                                       saddr);
 671                 spin_unlock_bh(&lowpan_dev(dev)->ctx.lock);
 672         } else {
 673                 /* Source address uncompression */
 674                 pr_debug("source address stateless compression\n");
 675                 err = lowpan_iphc_uncompress_addr(skb, dev, &hdr.saddr,
 676                                                   iphc1 & LOWPAN_IPHC_SAM_MASK,
 677                                                   saddr);
 678         }
 679 
 680         /* Check on error of previous branch */
 681         if (err)
 682                 return -EINVAL;
 683 
 684         switch (iphc1 & (LOWPAN_IPHC_M | LOWPAN_IPHC_DAC)) {
 685         case LOWPAN_IPHC_M | LOWPAN_IPHC_DAC:
 686                 skb->pkt_type = PACKET_BROADCAST;
 687 
 688                 spin_lock_bh(&lowpan_dev(dev)->ctx.lock);
 689                 ci = lowpan_iphc_ctx_get_by_id(dev, LOWPAN_IPHC_CID_DCI(cid));
 690                 if (!ci) {
 691                         spin_unlock_bh(&lowpan_dev(dev)->ctx.lock);
 692                         return -EINVAL;
 693                 }
 694 
 695                 /* multicast with context */
 696                 pr_debug("dest: context-based mcast compression\n");
 697                 err = lowpan_uncompress_multicast_ctx_daddr(skb, ci,
 698                                                             &hdr.daddr,
 699                                                             iphc1 & LOWPAN_IPHC_DAM_MASK);
 700                 spin_unlock_bh(&lowpan_dev(dev)->ctx.lock);
 701                 break;
 702         case LOWPAN_IPHC_M:
 703                 skb->pkt_type = PACKET_BROADCAST;
 704 
 705                 /* multicast */
 706                 err = lowpan_uncompress_multicast_daddr(skb, &hdr.daddr,
 707                                                         iphc1 & LOWPAN_IPHC_DAM_MASK);
 708                 break;
 709         case LOWPAN_IPHC_DAC:
 710                 skb->pkt_type = PACKET_HOST;
 711 
 712                 spin_lock_bh(&lowpan_dev(dev)->ctx.lock);
 713                 ci = lowpan_iphc_ctx_get_by_id(dev, LOWPAN_IPHC_CID_DCI(cid));
 714                 if (!ci) {
 715                         spin_unlock_bh(&lowpan_dev(dev)->ctx.lock);
 716                         return -EINVAL;
 717                 }
 718 
 719                 /* Destination address context based uncompression */
 720                 pr_debug("DAC bit is set. Handle context based destination address.\n");
 721                 err = lowpan_iphc_uncompress_ctx_addr(skb, dev, ci, &hdr.daddr,
 722                                                       iphc1 & LOWPAN_IPHC_DAM_MASK,
 723                                                       daddr);
 724                 spin_unlock_bh(&lowpan_dev(dev)->ctx.lock);
 725                 break;
 726         default:
 727                 skb->pkt_type = PACKET_HOST;
 728 
 729                 err = lowpan_iphc_uncompress_addr(skb, dev, &hdr.daddr,
 730                                                   iphc1 & LOWPAN_IPHC_DAM_MASK,
 731                                                   daddr);
 732                 pr_debug("dest: stateless compression mode %d dest %pI6c\n",
 733                          iphc1 & LOWPAN_IPHC_DAM_MASK, &hdr.daddr);
 734                 break;
 735         }
 736 
 737         if (err)
 738                 return -EINVAL;
 739 
 740         /* Next header data uncompression */
 741         if (iphc0 & LOWPAN_IPHC_NH) {
 742                 err = lowpan_nhc_do_uncompression(skb, dev, &hdr);
 743                 if (err < 0)
 744                         return err;
 745         } else {
 746                 err = skb_cow(skb, sizeof(hdr));
 747                 if (unlikely(err))
 748                         return err;
 749         }
 750 
 751         switch (lowpan_dev(dev)->lltype) {
 752         case LOWPAN_LLTYPE_IEEE802154:
 753                 if (lowpan_802154_cb(skb)->d_size)
 754                         hdr.payload_len = htons(lowpan_802154_cb(skb)->d_size -
 755                                                 sizeof(struct ipv6hdr));
 756                 else
 757                         hdr.payload_len = htons(skb->len);
 758                 break;
 759         default:
 760                 hdr.payload_len = htons(skb->len);
 761                 break;
 762         }
 763 
 764         pr_debug("skb headroom size = %d, data length = %d\n",
 765                  skb_headroom(skb), skb->len);
 766 
 767         pr_debug("IPv6 header dump:\n\tversion = %d\n\tlength  = %d\n\t"
 768                  "nexthdr = 0x%02x\n\thop_lim = %d\n\tdest    = %pI6c\n",
 769                 hdr.version, ntohs(hdr.payload_len), hdr.nexthdr,
 770                 hdr.hop_limit, &hdr.daddr);
 771 
 772         skb_push(skb, sizeof(hdr));
 773         skb_reset_mac_header(skb);
 774         skb_reset_network_header(skb);
 775         skb_copy_to_linear_data(skb, &hdr, sizeof(hdr));
 776 
 777         raw_dump_table(__func__, "raw header dump", (u8 *)&hdr, sizeof(hdr));
 778 
 779         return 0;
 780 }
 781 EXPORT_SYMBOL_GPL(lowpan_header_decompress);
 782 
 783 static const u8 lowpan_iphc_dam_to_sam_value[] = {
 784         [LOWPAN_IPHC_DAM_00] = LOWPAN_IPHC_SAM_00,
 785         [LOWPAN_IPHC_DAM_01] = LOWPAN_IPHC_SAM_01,
 786         [LOWPAN_IPHC_DAM_10] = LOWPAN_IPHC_SAM_10,
 787         [LOWPAN_IPHC_DAM_11] = LOWPAN_IPHC_SAM_11,
 788 };
 789 
 790 static inline bool
 791 lowpan_iphc_compress_ctx_802154_lladdr(const struct in6_addr *ipaddr,
 792                                        const struct lowpan_iphc_ctx *ctx,
 793                                        const void *lladdr)
 794 {
 795         const struct ieee802154_addr *addr = lladdr;
 796         unsigned char extended_addr[EUI64_ADDR_LEN];
 797         bool lladdr_compress = false;
 798         struct in6_addr tmp = {};
 799 
 800         switch (addr->mode) {
 801         case IEEE802154_ADDR_LONG:
 802                 ieee802154_le64_to_be64(&extended_addr, &addr->extended_addr);
 803                 /* check for SAM/DAM = 11 */
 804                 memcpy(&tmp.s6_addr[8], &extended_addr, EUI64_ADDR_LEN);
 805                 /* second bit-flip (Universe/Local) is done according RFC2464 */
 806                 tmp.s6_addr[8] ^= 0x02;
 807                 /* context information are always used */
 808                 ipv6_addr_prefix_copy(&tmp, &ctx->pfx, ctx->plen);
 809                 if (ipv6_addr_equal(&tmp, ipaddr))
 810                         lladdr_compress = true;
 811                 break;
 812         case IEEE802154_ADDR_SHORT:
 813                 tmp.s6_addr[11] = 0xFF;
 814                 tmp.s6_addr[12] = 0xFE;
 815                 ieee802154_le16_to_be16(&tmp.s6_addr16[7],
 816                                         &addr->short_addr);
 817                 /* context information are always used */
 818                 ipv6_addr_prefix_copy(&tmp, &ctx->pfx, ctx->plen);
 819                 if (ipv6_addr_equal(&tmp, ipaddr))
 820                         lladdr_compress = true;
 821                 break;
 822         default:
 823                 /* should never handled and filtered by 802154 6lowpan */
 824                 WARN_ON_ONCE(1);
 825                 break;
 826         }
 827 
 828         return lladdr_compress;
 829 }
 830 
 831 static bool lowpan_iphc_addr_equal(const struct net_device *dev,
 832                                    const struct lowpan_iphc_ctx *ctx,
 833                                    const struct in6_addr *ipaddr,
 834                                    const void *lladdr)
 835 {
 836         struct in6_addr tmp = {};
 837 
 838         lowpan_iphc_uncompress_lladdr(dev, &tmp, lladdr);
 839 
 840         if (ctx)
 841                 ipv6_addr_prefix_copy(&tmp, &ctx->pfx, ctx->plen);
 842 
 843         return ipv6_addr_equal(&tmp, ipaddr);
 844 }
 845 
 846 static u8 lowpan_compress_ctx_addr(u8 **hc_ptr, const struct net_device *dev,
 847                                    const struct in6_addr *ipaddr,
 848                                    const struct lowpan_iphc_ctx *ctx,
 849                                    const unsigned char *lladdr, bool sam)
 850 {
 851         struct in6_addr tmp = {};
 852         u8 dam;
 853 
 854         switch (lowpan_dev(dev)->lltype) {
 855         case LOWPAN_LLTYPE_IEEE802154:
 856                 if (lowpan_iphc_compress_ctx_802154_lladdr(ipaddr, ctx,
 857                                                            lladdr)) {
 858                         dam = LOWPAN_IPHC_DAM_11;
 859                         goto out;
 860                 }
 861                 break;
 862         default:
 863                 if (lowpan_iphc_addr_equal(dev, ctx, ipaddr, lladdr)) {
 864                         dam = LOWPAN_IPHC_DAM_11;
 865                         goto out;
 866                 }
 867                 break;
 868         }
 869 
 870         memset(&tmp, 0, sizeof(tmp));
 871         /* check for SAM/DAM = 10 */
 872         tmp.s6_addr[11] = 0xFF;
 873         tmp.s6_addr[12] = 0xFE;
 874         memcpy(&tmp.s6_addr[14], &ipaddr->s6_addr[14], 2);
 875         /* context information are always used */
 876         ipv6_addr_prefix_copy(&tmp, &ctx->pfx, ctx->plen);
 877         if (ipv6_addr_equal(&tmp, ipaddr)) {
 878                 lowpan_push_hc_data(hc_ptr, &ipaddr->s6_addr[14], 2);
 879                 dam = LOWPAN_IPHC_DAM_10;
 880                 goto out;
 881         }
 882 
 883         memset(&tmp, 0, sizeof(tmp));
 884         /* check for SAM/DAM = 01, should always match */
 885         memcpy(&tmp.s6_addr[8], &ipaddr->s6_addr[8], 8);
 886         /* context information are always used */
 887         ipv6_addr_prefix_copy(&tmp, &ctx->pfx, ctx->plen);
 888         if (ipv6_addr_equal(&tmp, ipaddr)) {
 889                 lowpan_push_hc_data(hc_ptr, &ipaddr->s6_addr[8], 8);
 890                 dam = LOWPAN_IPHC_DAM_01;
 891                 goto out;
 892         }
 893 
 894         WARN_ONCE(1, "context found but no address mode matched\n");
 895         return LOWPAN_IPHC_DAM_00;
 896 out:
 897 
 898         if (sam)
 899                 return lowpan_iphc_dam_to_sam_value[dam];
 900         else
 901                 return dam;
 902 }
 903 
 904 static inline bool
 905 lowpan_iphc_compress_802154_lladdr(const struct in6_addr *ipaddr,
 906                                    const void *lladdr)
 907 {
 908         const struct ieee802154_addr *addr = lladdr;
 909         unsigned char extended_addr[EUI64_ADDR_LEN];
 910         bool lladdr_compress = false;
 911         struct in6_addr tmp = {};
 912 
 913         switch (addr->mode) {
 914         case IEEE802154_ADDR_LONG:
 915                 ieee802154_le64_to_be64(&extended_addr, &addr->extended_addr);
 916                 if (is_addr_mac_addr_based(ipaddr, extended_addr))
 917                         lladdr_compress = true;
 918                 break;
 919         case IEEE802154_ADDR_SHORT:
 920                 /* fe:80::ff:fe00:XXXX
 921                  *                \__/
 922                  *             short_addr
 923                  *
 924                  * Universe/Local bit is zero.
 925                  */
 926                 tmp.s6_addr[0] = 0xFE;
 927                 tmp.s6_addr[1] = 0x80;
 928                 tmp.s6_addr[11] = 0xFF;
 929                 tmp.s6_addr[12] = 0xFE;
 930                 ieee802154_le16_to_be16(&tmp.s6_addr16[7],
 931                                         &addr->short_addr);
 932                 if (ipv6_addr_equal(&tmp, ipaddr))
 933                         lladdr_compress = true;
 934                 break;
 935         default:
 936                 /* should never handled and filtered by 802154 6lowpan */
 937                 WARN_ON_ONCE(1);
 938                 break;
 939         }
 940 
 941         return lladdr_compress;
 942 }
 943 
 944 static u8 lowpan_compress_addr_64(u8 **hc_ptr, const struct net_device *dev,
 945                                   const struct in6_addr *ipaddr,
 946                                   const unsigned char *lladdr, bool sam)
 947 {
 948         u8 dam = LOWPAN_IPHC_DAM_01;
 949 
 950         switch (lowpan_dev(dev)->lltype) {
 951         case LOWPAN_LLTYPE_IEEE802154:
 952                 if (lowpan_iphc_compress_802154_lladdr(ipaddr, lladdr)) {
 953                         dam = LOWPAN_IPHC_DAM_11; /* 0-bits */
 954                         pr_debug("address compression 0 bits\n");
 955                         goto out;
 956                 }
 957                 break;
 958         default:
 959                 if (lowpan_iphc_addr_equal(dev, NULL, ipaddr, lladdr)) {
 960                         dam = LOWPAN_IPHC_DAM_11;
 961                         pr_debug("address compression 0 bits\n");
 962                         goto out;
 963                 }
 964 
 965                 break;
 966         }
 967 
 968         if (lowpan_is_iid_16_bit_compressable(ipaddr)) {
 969                 /* compress IID to 16 bits xxxx::XXXX */
 970                 lowpan_push_hc_data(hc_ptr, &ipaddr->s6_addr16[7], 2);
 971                 dam = LOWPAN_IPHC_DAM_10; /* 16-bits */
 972                 raw_dump_inline(NULL, "Compressed ipv6 addr is (16 bits)",
 973                                 *hc_ptr - 2, 2);
 974                 goto out;
 975         }
 976 
 977         /* do not compress IID => xxxx::IID */
 978         lowpan_push_hc_data(hc_ptr, &ipaddr->s6_addr16[4], 8);
 979         raw_dump_inline(NULL, "Compressed ipv6 addr is (64 bits)",
 980                         *hc_ptr - 8, 8);
 981 
 982 out:
 983 
 984         if (sam)
 985                 return lowpan_iphc_dam_to_sam_value[dam];
 986         else
 987                 return dam;
 988 }
 989 
 990 /* lowpan_iphc_get_tc - get the ECN + DCSP fields in hc format */
 991 static inline u8 lowpan_iphc_get_tc(const struct ipv6hdr *hdr)
 992 {
 993         u8 dscp, ecn;
 994 
 995         /* hdr->priority contains the higher bits of dscp, lower are part of
 996          * flow_lbl[0]. Note ECN, DCSP is swapped in ipv6 hdr.
 997          */
 998         dscp = (hdr->priority << 2) | ((hdr->flow_lbl[0] & 0xc0) >> 6);
 999         /* ECN is at the two lower bits from first nibble of flow_lbl[0] */
1000         ecn = (hdr->flow_lbl[0] & 0x30);
1001         /* for pretty debug output, also shift ecn to get the ecn value */
1002         pr_debug("ecn 0x%02x dscp 0x%02x\n", ecn >> 4, dscp);
1003         /* ECN is at 0x30 now, shift it to have ECN + DCSP */
1004         return (ecn << 2) | dscp;
1005 }
1006 
1007 /* lowpan_iphc_is_flow_lbl_zero - check if flow label is zero */
1008 static inline bool lowpan_iphc_is_flow_lbl_zero(const struct ipv6hdr *hdr)
1009 {
1010         return ((!(hdr->flow_lbl[0] & 0x0f)) &&
1011                 !hdr->flow_lbl[1] && !hdr->flow_lbl[2]);
1012 }
1013 
1014 /* lowpan_iphc_tf_compress - compress the traffic class which is set by
1015  *      ipv6hdr. Return the corresponding format identifier which is used.
1016  */
1017 static u8 lowpan_iphc_tf_compress(u8 **hc_ptr, const struct ipv6hdr *hdr)
1018 {
1019         /* get ecn dscp data in a byteformat as: ECN(hi) + DSCP(lo) */
1020         u8 tc = lowpan_iphc_get_tc(hdr), tf[4], val;
1021 
1022         /* printout the traffic class in hc format */
1023         pr_debug("tc 0x%02x\n", tc);
1024 
1025         if (lowpan_iphc_is_flow_lbl_zero(hdr)) {
1026                 if (!tc) {
1027                         /* 11:  Traffic Class and Flow Label are elided. */
1028                         val = LOWPAN_IPHC_TF_11;
1029                 } else {
1030                         /* 10:  ECN + DSCP (1 byte), Flow Label is elided.
1031                          *
1032                          *  0 1 2 3 4 5 6 7
1033                          * +-+-+-+-+-+-+-+-+
1034                          * |ECN|   DSCP    |
1035                          * +-+-+-+-+-+-+-+-+
1036                          */
1037                         lowpan_push_hc_data(hc_ptr, &tc, sizeof(tc));
1038                         val = LOWPAN_IPHC_TF_10;
1039                 }
1040         } else {
1041                 /* check if dscp is zero, it's after the first two bit */
1042                 if (!(tc & 0x3f)) {
1043                         /* 01:  ECN + 2-bit Pad + Flow Label (3 bytes), DSCP is elided
1044                          *
1045                          *                     1                   2
1046                          * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3
1047                          * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1048                          * |ECN|rsv|             Flow Label                |
1049                          * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1050                          */
1051                         memcpy(&tf[0], &hdr->flow_lbl[0], 3);
1052                         /* zero the highest 4-bits, contains DCSP + ECN */
1053                         tf[0] &= ~0xf0;
1054                         /* set ECN */
1055                         tf[0] |= (tc & 0xc0);
1056 
1057                         lowpan_push_hc_data(hc_ptr, tf, 3);
1058                         val = LOWPAN_IPHC_TF_01;
1059                 } else {
1060                         /* 00:  ECN + DSCP + 4-bit Pad + Flow Label (4 bytes)
1061                          *
1062                          *                      1                   2                   3
1063                          *  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
1064                          * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1065                          * |ECN|   DSCP    |  rsv  |             Flow Label                |
1066                          * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1067                          */
1068                         memcpy(&tf[0], &tc, sizeof(tc));
1069                         /* highest nibble of flow_lbl[0] is part of DSCP + ECN
1070                          * which will be the 4-bit pad and will be filled with
1071                          * zeros afterwards.
1072                          */
1073                         memcpy(&tf[1], &hdr->flow_lbl[0], 3);
1074                         /* zero the 4-bit pad, which is reserved */
1075                         tf[1] &= ~0xf0;
1076 
1077                         lowpan_push_hc_data(hc_ptr, tf, 4);
1078                         val = LOWPAN_IPHC_TF_00;
1079                 }
1080         }
1081 
1082         return val;
1083 }
1084 
1085 static u8 lowpan_iphc_mcast_ctx_addr_compress(u8 **hc_ptr,
1086                                               const struct lowpan_iphc_ctx *ctx,
1087                                               const struct in6_addr *ipaddr)
1088 {
1089         u8 data[6];
1090 
1091         /* flags/scope, reserved (RIID) */
1092         memcpy(data, &ipaddr->s6_addr[1], 2);
1093         /* group ID */
1094         memcpy(&data[1], &ipaddr->s6_addr[11], 4);
1095         lowpan_push_hc_data(hc_ptr, data, 6);
1096 
1097         return LOWPAN_IPHC_DAM_00;
1098 }
1099 
1100 static u8 lowpan_iphc_mcast_addr_compress(u8 **hc_ptr,
1101                                           const struct in6_addr *ipaddr)
1102 {
1103         u8 val;
1104 
1105         if (lowpan_is_mcast_addr_compressable8(ipaddr)) {
1106                 pr_debug("compressed to 1 octet\n");
1107                 /* use last byte */
1108                 lowpan_push_hc_data(hc_ptr, &ipaddr->s6_addr[15], 1);
1109                 val = LOWPAN_IPHC_DAM_11;
1110         } else if (lowpan_is_mcast_addr_compressable32(ipaddr)) {
1111                 pr_debug("compressed to 4 octets\n");
1112                 /* second byte + the last three */
1113                 lowpan_push_hc_data(hc_ptr, &ipaddr->s6_addr[1], 1);
1114                 lowpan_push_hc_data(hc_ptr, &ipaddr->s6_addr[13], 3);
1115                 val = LOWPAN_IPHC_DAM_10;
1116         } else if (lowpan_is_mcast_addr_compressable48(ipaddr)) {
1117                 pr_debug("compressed to 6 octets\n");
1118                 /* second byte + the last five */
1119                 lowpan_push_hc_data(hc_ptr, &ipaddr->s6_addr[1], 1);
1120                 lowpan_push_hc_data(hc_ptr, &ipaddr->s6_addr[11], 5);
1121                 val = LOWPAN_IPHC_DAM_01;
1122         } else {
1123                 pr_debug("using full address\n");
1124                 lowpan_push_hc_data(hc_ptr, ipaddr->s6_addr, 16);
1125                 val = LOWPAN_IPHC_DAM_00;
1126         }
1127 
1128         return val;
1129 }
1130 
1131 int lowpan_header_compress(struct sk_buff *skb, const struct net_device *dev,
1132                            const void *daddr, const void *saddr)
1133 {
1134         u8 iphc0, iphc1, *hc_ptr, cid = 0;
1135         struct ipv6hdr *hdr;
1136         u8 head[LOWPAN_IPHC_MAX_HC_BUF_LEN] = {};
1137         struct lowpan_iphc_ctx *dci, *sci, dci_entry, sci_entry;
1138         int ret, ipv6_daddr_type, ipv6_saddr_type;
1139 
1140         if (skb->protocol != htons(ETH_P_IPV6))
1141                 return -EINVAL;
1142 
1143         hdr = ipv6_hdr(skb);
1144         hc_ptr = head + 2;
1145 
1146         pr_debug("IPv6 header dump:\n\tversion = %d\n\tlength  = %d\n"
1147                  "\tnexthdr = 0x%02x\n\thop_lim = %d\n\tdest    = %pI6c\n",
1148                  hdr->version, ntohs(hdr->payload_len), hdr->nexthdr,
1149                  hdr->hop_limit, &hdr->daddr);
1150 
1151         raw_dump_table(__func__, "raw skb network header dump",
1152                        skb_network_header(skb), sizeof(struct ipv6hdr));
1153 
1154         /* As we copy some bit-length fields, in the IPHC encoding bytes,
1155          * we sometimes use |=
1156          * If the field is 0, and the current bit value in memory is 1,
1157          * this does not work. We therefore reset the IPHC encoding here
1158          */
1159         iphc0 = LOWPAN_DISPATCH_IPHC;
1160         iphc1 = 0;
1161 
1162         raw_dump_table(__func__, "sending raw skb network uncompressed packet",
1163                        skb->data, skb->len);
1164 
1165         ipv6_daddr_type = ipv6_addr_type(&hdr->daddr);
1166         spin_lock_bh(&lowpan_dev(dev)->ctx.lock);
1167         if (ipv6_daddr_type & IPV6_ADDR_MULTICAST)
1168                 dci = lowpan_iphc_ctx_get_by_mcast_addr(dev, &hdr->daddr);
1169         else
1170                 dci = lowpan_iphc_ctx_get_by_addr(dev, &hdr->daddr);
1171         if (dci) {
1172                 memcpy(&dci_entry, dci, sizeof(*dci));
1173                 cid |= dci->id;
1174         }
1175         spin_unlock_bh(&lowpan_dev(dev)->ctx.lock);
1176 
1177         spin_lock_bh(&lowpan_dev(dev)->ctx.lock);
1178         sci = lowpan_iphc_ctx_get_by_addr(dev, &hdr->saddr);
1179         if (sci) {
1180                 memcpy(&sci_entry, sci, sizeof(*sci));
1181                 cid |= (sci->id << 4);
1182         }
1183         spin_unlock_bh(&lowpan_dev(dev)->ctx.lock);
1184 
1185         /* if cid is zero it will be compressed */
1186         if (cid) {
1187                 iphc1 |= LOWPAN_IPHC_CID;
1188                 lowpan_push_hc_data(&hc_ptr, &cid, sizeof(cid));
1189         }
1190 
1191         /* Traffic Class, Flow Label compression */
1192         iphc0 |= lowpan_iphc_tf_compress(&hc_ptr, hdr);
1193 
1194         /* NOTE: payload length is always compressed */
1195 
1196         /* Check if we provide the nhc format for nexthdr and compression
1197          * functionality. If not nexthdr is handled inline and not compressed.
1198          */
1199         ret = lowpan_nhc_check_compression(skb, hdr, &hc_ptr);
1200         if (ret == -ENOENT)
1201                 lowpan_push_hc_data(&hc_ptr, &hdr->nexthdr,
1202                                     sizeof(hdr->nexthdr));
1203         else
1204                 iphc0 |= LOWPAN_IPHC_NH;
1205 
1206         /* Hop limit
1207          * if 1:   compress, encoding is 01
1208          * if 64:  compress, encoding is 10
1209          * if 255: compress, encoding is 11
1210          * else do not compress
1211          */
1212         switch (hdr->hop_limit) {
1213         case 1:
1214                 iphc0 |= LOWPAN_IPHC_HLIM_01;
1215                 break;
1216         case 64:
1217                 iphc0 |= LOWPAN_IPHC_HLIM_10;
1218                 break;
1219         case 255:
1220                 iphc0 |= LOWPAN_IPHC_HLIM_11;
1221                 break;
1222         default:
1223                 lowpan_push_hc_data(&hc_ptr, &hdr->hop_limit,
1224                                     sizeof(hdr->hop_limit));
1225         }
1226 
1227         ipv6_saddr_type = ipv6_addr_type(&hdr->saddr);
1228         /* source address compression */
1229         if (ipv6_saddr_type == IPV6_ADDR_ANY) {
1230                 pr_debug("source address is unspecified, setting SAC\n");
1231                 iphc1 |= LOWPAN_IPHC_SAC;
1232         } else {
1233                 if (sci) {
1234                         iphc1 |= lowpan_compress_ctx_addr(&hc_ptr, dev,
1235                                                           &hdr->saddr,
1236                                                           &sci_entry, saddr,
1237                                                           true);
1238                         iphc1 |= LOWPAN_IPHC_SAC;
1239                 } else {
1240                         if (ipv6_saddr_type & IPV6_ADDR_LINKLOCAL &&
1241                             lowpan_is_linklocal_zero_padded(hdr->saddr)) {
1242                                 iphc1 |= lowpan_compress_addr_64(&hc_ptr, dev,
1243                                                                  &hdr->saddr,
1244                                                                  saddr, true);
1245                                 pr_debug("source address unicast link-local %pI6c iphc1 0x%02x\n",
1246                                          &hdr->saddr, iphc1);
1247                         } else {
1248                                 pr_debug("send the full source address\n");
1249                                 lowpan_push_hc_data(&hc_ptr,
1250                                                     hdr->saddr.s6_addr, 16);
1251                         }
1252                 }
1253         }
1254 
1255         /* destination address compression */
1256         if (ipv6_daddr_type & IPV6_ADDR_MULTICAST) {
1257                 pr_debug("destination address is multicast: ");
1258                 iphc1 |= LOWPAN_IPHC_M;
1259                 if (dci) {
1260                         iphc1 |= lowpan_iphc_mcast_ctx_addr_compress(&hc_ptr,
1261                                                                      &dci_entry,
1262                                                                      &hdr->daddr);
1263                         iphc1 |= LOWPAN_IPHC_DAC;
1264                 } else {
1265                         iphc1 |= lowpan_iphc_mcast_addr_compress(&hc_ptr,
1266                                                                  &hdr->daddr);
1267                 }
1268         } else {
1269                 if (dci) {
1270                         iphc1 |= lowpan_compress_ctx_addr(&hc_ptr, dev,
1271                                                           &hdr->daddr,
1272                                                           &dci_entry, daddr,
1273                                                           false);
1274                         iphc1 |= LOWPAN_IPHC_DAC;
1275                 } else {
1276                         if (ipv6_daddr_type & IPV6_ADDR_LINKLOCAL &&
1277                             lowpan_is_linklocal_zero_padded(hdr->daddr)) {
1278                                 iphc1 |= lowpan_compress_addr_64(&hc_ptr, dev,
1279                                                                  &hdr->daddr,
1280                                                                  daddr, false);
1281                                 pr_debug("dest address unicast link-local %pI6c iphc1 0x%02x\n",
1282                                          &hdr->daddr, iphc1);
1283                         } else {
1284                                 pr_debug("dest address unicast %pI6c\n",
1285                                          &hdr->daddr);
1286                                 lowpan_push_hc_data(&hc_ptr,
1287                                                     hdr->daddr.s6_addr, 16);
1288                         }
1289                 }
1290         }
1291 
1292         /* next header compression */
1293         if (iphc0 & LOWPAN_IPHC_NH) {
1294                 ret = lowpan_nhc_do_compression(skb, hdr, &hc_ptr);
1295                 if (ret < 0)
1296                         return ret;
1297         }
1298 
1299         head[0] = iphc0;
1300         head[1] = iphc1;
1301 
1302         skb_pull(skb, sizeof(struct ipv6hdr));
1303         skb_reset_transport_header(skb);
1304         memcpy(skb_push(skb, hc_ptr - head), head, hc_ptr - head);
1305         skb_reset_network_header(skb);
1306 
1307         pr_debug("header len %d skb %u\n", (int)(hc_ptr - head), skb->len);
1308 
1309         raw_dump_table(__func__, "raw skb data dump compressed",
1310                        skb->data, skb->len);
1311         return 0;
1312 }
1313 EXPORT_SYMBOL_GPL(lowpan_header_compress);
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root/net/6lowpan/iphc.c

DEFINITIONS
