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Linux/net/6lowpan/iphc.c

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  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_network_header(skb);
774         skb_copy_to_linear_data(skb, &hdr, sizeof(hdr));
775 
776         raw_dump_table(__func__, "raw header dump", (u8 *)&hdr, sizeof(hdr));
777 
778         return 0;
779 }
780 EXPORT_SYMBOL_GPL(lowpan_header_decompress);
781 
782 static const u8 lowpan_iphc_dam_to_sam_value[] = {
783         [LOWPAN_IPHC_DAM_00] = LOWPAN_IPHC_SAM_00,
784         [LOWPAN_IPHC_DAM_01] = LOWPAN_IPHC_SAM_01,
785         [LOWPAN_IPHC_DAM_10] = LOWPAN_IPHC_SAM_10,
786         [LOWPAN_IPHC_DAM_11] = LOWPAN_IPHC_SAM_11,
787 };
788 
789 static inline bool
790 lowpan_iphc_compress_ctx_802154_lladdr(const struct in6_addr *ipaddr,
791                                        const struct lowpan_iphc_ctx *ctx,
792                                        const void *lladdr)
793 {
794         const struct ieee802154_addr *addr = lladdr;
795         unsigned char extended_addr[EUI64_ADDR_LEN];
796         bool lladdr_compress = false;
797         struct in6_addr tmp = {};
798 
799         switch (addr->mode) {
800         case IEEE802154_ADDR_LONG:
801                 ieee802154_le64_to_be64(&extended_addr, &addr->extended_addr);
802                 /* check for SAM/DAM = 11 */
803                 memcpy(&tmp.s6_addr[8], &extended_addr, EUI64_ADDR_LEN);
804                 /* second bit-flip (Universe/Local) is done according RFC2464 */
805                 tmp.s6_addr[8] ^= 0x02;
806                 /* context information are always used */
807                 ipv6_addr_prefix_copy(&tmp, &ctx->pfx, ctx->plen);
808                 if (ipv6_addr_equal(&tmp, ipaddr))
809                         lladdr_compress = true;
810                 break;
811         case IEEE802154_ADDR_SHORT:
812                 tmp.s6_addr[11] = 0xFF;
813                 tmp.s6_addr[12] = 0xFE;
814                 ieee802154_le16_to_be16(&tmp.s6_addr16[7],
815                                         &addr->short_addr);
816                 /* context information are always used */
817                 ipv6_addr_prefix_copy(&tmp, &ctx->pfx, ctx->plen);
818                 if (ipv6_addr_equal(&tmp, ipaddr))
819                         lladdr_compress = true;
820                 break;
821         default:
822                 /* should never handled and filtered by 802154 6lowpan */
823                 WARN_ON_ONCE(1);
824                 break;
825         }
826 
827         return lladdr_compress;
828 }
829 
830 static bool lowpan_iphc_addr_equal(const struct net_device *dev,
831                                    const struct lowpan_iphc_ctx *ctx,
832                                    const struct in6_addr *ipaddr,
833                                    const void *lladdr)
834 {
835         struct in6_addr tmp = {};
836 
837         lowpan_iphc_uncompress_lladdr(dev, &tmp, lladdr);
838 
839         if (ctx)
840                 ipv6_addr_prefix_copy(&tmp, &ctx->pfx, ctx->plen);
841 
842         return ipv6_addr_equal(&tmp, ipaddr);
843 }
844 
845 static u8 lowpan_compress_ctx_addr(u8 **hc_ptr, const struct net_device *dev,
846                                    const struct in6_addr *ipaddr,
847                                    const struct lowpan_iphc_ctx *ctx,
848                                    const unsigned char *lladdr, bool sam)
849 {
850         struct in6_addr tmp = {};
851         u8 dam;
852 
853         switch (lowpan_dev(dev)->lltype) {
854         case LOWPAN_LLTYPE_IEEE802154:
855                 if (lowpan_iphc_compress_ctx_802154_lladdr(ipaddr, ctx,
856                                                            lladdr)) {
857                         dam = LOWPAN_IPHC_DAM_11;
858                         goto out;
859                 }
860                 break;
861         default:
862                 if (lowpan_iphc_addr_equal(dev, ctx, ipaddr, lladdr)) {
863                         dam = LOWPAN_IPHC_DAM_11;
864                         goto out;
865                 }
866                 break;
867         }
868 
869         memset(&tmp, 0, sizeof(tmp));
870         /* check for SAM/DAM = 10 */
871         tmp.s6_addr[11] = 0xFF;
872         tmp.s6_addr[12] = 0xFE;
873         memcpy(&tmp.s6_addr[14], &ipaddr->s6_addr[14], 2);
874         /* context information are always used */
875         ipv6_addr_prefix_copy(&tmp, &ctx->pfx, ctx->plen);
876         if (ipv6_addr_equal(&tmp, ipaddr)) {
877                 lowpan_push_hc_data(hc_ptr, &ipaddr->s6_addr[14], 2);
878                 dam = LOWPAN_IPHC_DAM_10;
879                 goto out;
880         }
881 
882         memset(&tmp, 0, sizeof(tmp));
883         /* check for SAM/DAM = 01, should always match */
884         memcpy(&tmp.s6_addr[8], &ipaddr->s6_addr[8], 8);
885         /* context information are always used */
886         ipv6_addr_prefix_copy(&tmp, &ctx->pfx, ctx->plen);
887         if (ipv6_addr_equal(&tmp, ipaddr)) {
888                 lowpan_push_hc_data(hc_ptr, &ipaddr->s6_addr[8], 8);
889                 dam = LOWPAN_IPHC_DAM_01;
890                 goto out;
891         }
892 
893         WARN_ONCE(1, "context found but no address mode matched\n");
894         return LOWPAN_IPHC_DAM_00;
895 out:
896 
897         if (sam)
898                 return lowpan_iphc_dam_to_sam_value[dam];
899         else
900                 return dam;
901 }
902 
903 static inline bool
904 lowpan_iphc_compress_802154_lladdr(const struct in6_addr *ipaddr,
905                                    const void *lladdr)
906 {
907         const struct ieee802154_addr *addr = lladdr;
908         unsigned char extended_addr[EUI64_ADDR_LEN];
909         bool lladdr_compress = false;
910         struct in6_addr tmp = {};
911 
912         switch (addr->mode) {
913         case IEEE802154_ADDR_LONG:
914                 ieee802154_le64_to_be64(&extended_addr, &addr->extended_addr);
915                 if (is_addr_mac_addr_based(ipaddr, extended_addr))
916                         lladdr_compress = true;
917                 break;
918         case IEEE802154_ADDR_SHORT:
919                 /* fe:80::ff:fe00:XXXX
920                  *                \__/
921                  *             short_addr
922                  *
923                  * Universe/Local bit is zero.
924                  */
925                 tmp.s6_addr[0] = 0xFE;
926                 tmp.s6_addr[1] = 0x80;
927                 tmp.s6_addr[11] = 0xFF;
928                 tmp.s6_addr[12] = 0xFE;
929                 ieee802154_le16_to_be16(&tmp.s6_addr16[7],
930                                         &addr->short_addr);
931                 if (ipv6_addr_equal(&tmp, ipaddr))
932                         lladdr_compress = true;
933                 break;
934         default:
935                 /* should never handled and filtered by 802154 6lowpan */
936                 WARN_ON_ONCE(1);
937                 break;
938         }
939 
940         return lladdr_compress;
941 }
942 
943 static u8 lowpan_compress_addr_64(u8 **hc_ptr, const struct net_device *dev,
944                                   const struct in6_addr *ipaddr,
945                                   const unsigned char *lladdr, bool sam)
946 {
947         u8 dam = LOWPAN_IPHC_DAM_01;
948 
949         switch (lowpan_dev(dev)->lltype) {
950         case LOWPAN_LLTYPE_IEEE802154:
951                 if (lowpan_iphc_compress_802154_lladdr(ipaddr, lladdr)) {
952                         dam = LOWPAN_IPHC_DAM_11; /* 0-bits */
953                         pr_debug("address compression 0 bits\n");
954                         goto out;
955                 }
956                 break;
957         default:
958                 if (lowpan_iphc_addr_equal(dev, NULL, ipaddr, lladdr)) {
959                         dam = LOWPAN_IPHC_DAM_11;
960                         pr_debug("address compression 0 bits\n");
961                         goto out;
962                 }
963 
964                 break;
965         }
966 
967         if (lowpan_is_iid_16_bit_compressable(ipaddr)) {
968                 /* compress IID to 16 bits xxxx::XXXX */
969                 lowpan_push_hc_data(hc_ptr, &ipaddr->s6_addr16[7], 2);
970                 dam = LOWPAN_IPHC_DAM_10; /* 16-bits */
971                 raw_dump_inline(NULL, "Compressed ipv6 addr is (16 bits)",
972                                 *hc_ptr - 2, 2);
973                 goto out;
974         }
975 
976         /* do not compress IID => xxxx::IID */
977         lowpan_push_hc_data(hc_ptr, &ipaddr->s6_addr16[4], 8);
978         raw_dump_inline(NULL, "Compressed ipv6 addr is (64 bits)",
979                         *hc_ptr - 8, 8);
980 
981 out:
982 
983         if (sam)
984                 return lowpan_iphc_dam_to_sam_value[dam];
985         else
986                 return dam;
987 }
988 
989 /* lowpan_iphc_get_tc - get the ECN + DCSP fields in hc format */
990 static inline u8 lowpan_iphc_get_tc(const struct ipv6hdr *hdr)
991 {
992         u8 dscp, ecn;
993 
994         /* hdr->priority contains the higher bits of dscp, lower are part of
995          * flow_lbl[0]. Note ECN, DCSP is swapped in ipv6 hdr.
996          */
997         dscp = (hdr->priority << 2) | ((hdr->flow_lbl[0] & 0xc0) >> 6);
998         /* ECN is at the two lower bits from first nibble of flow_lbl[0] */
999         ecn = (hdr->flow_lbl[0] & 0x30);
1000         /* for pretty debug output, also shift ecn to get the ecn value */
1001         pr_debug("ecn 0x%02x dscp 0x%02x\n", ecn >> 4, dscp);
1002         /* ECN is at 0x30 now, shift it to have ECN + DCSP */
1003         return (ecn << 2) | dscp;
1004 }
1005 
1006 /* lowpan_iphc_is_flow_lbl_zero - check if flow label is zero */
1007 static inline bool lowpan_iphc_is_flow_lbl_zero(const struct ipv6hdr *hdr)
1008 {
1009         return ((!(hdr->flow_lbl[0] & 0x0f)) &&
1010                 !hdr->flow_lbl[1] && !hdr->flow_lbl[2]);
1011 }
1012 
1013 /* lowpan_iphc_tf_compress - compress the traffic class which is set by
1014  *      ipv6hdr. Return the corresponding format identifier which is used.
1015  */
1016 static u8 lowpan_iphc_tf_compress(u8 **hc_ptr, const struct ipv6hdr *hdr)
1017 {
1018         /* get ecn dscp data in a byteformat as: ECN(hi) + DSCP(lo) */
1019         u8 tc = lowpan_iphc_get_tc(hdr), tf[4], val;
1020 
1021         /* printout the traffic class in hc format */
1022         pr_debug("tc 0x%02x\n", tc);
1023 
1024         if (lowpan_iphc_is_flow_lbl_zero(hdr)) {
1025                 if (!tc) {
1026                         /* 11:  Traffic Class and Flow Label are elided. */
1027                         val = LOWPAN_IPHC_TF_11;
1028                 } else {
1029                         /* 10:  ECN + DSCP (1 byte), Flow Label is elided.
1030                          *
1031                          *  0 1 2 3 4 5 6 7
1032                          * +-+-+-+-+-+-+-+-+
1033                          * |ECN|   DSCP    |
1034                          * +-+-+-+-+-+-+-+-+
1035                          */
1036                         lowpan_push_hc_data(hc_ptr, &tc, sizeof(tc));
1037                         val = LOWPAN_IPHC_TF_10;
1038                 }
1039         } else {
1040                 /* check if dscp is zero, it's after the first two bit */
1041                 if (!(tc & 0x3f)) {
1042                         /* 01:  ECN + 2-bit Pad + Flow Label (3 bytes), DSCP is elided
1043                          *
1044                          *                     1                   2
1045                          * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3
1046                          * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1047                          * |ECN|rsv|             Flow Label                |
1048                          * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1049                          */
1050                         memcpy(&tf[0], &hdr->flow_lbl[0], 3);
1051                         /* zero the highest 4-bits, contains DCSP + ECN */
1052                         tf[0] &= ~0xf0;
1053                         /* set ECN */
1054                         tf[0] |= (tc & 0xc0);
1055 
1056                         lowpan_push_hc_data(hc_ptr, tf, 3);
1057                         val = LOWPAN_IPHC_TF_01;
1058                 } else {
1059                         /* 00:  ECN + DSCP + 4-bit Pad + Flow Label (4 bytes)
1060                          *
1061                          *                      1                   2                   3
1062                          *  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
1063                          * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1064                          * |ECN|   DSCP    |  rsv  |             Flow Label                |
1065                          * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1066                          */
1067                         memcpy(&tf[0], &tc, sizeof(tc));
1068                         /* highest nibble of flow_lbl[0] is part of DSCP + ECN
1069                          * which will be the 4-bit pad and will be filled with
1070                          * zeros afterwards.
1071                          */
1072                         memcpy(&tf[1], &hdr->flow_lbl[0], 3);
1073                         /* zero the 4-bit pad, which is reserved */
1074                         tf[1] &= ~0xf0;
1075 
1076                         lowpan_push_hc_data(hc_ptr, tf, 4);
1077                         val = LOWPAN_IPHC_TF_00;
1078                 }
1079         }
1080 
1081         return val;
1082 }
1083 
1084 static u8 lowpan_iphc_mcast_ctx_addr_compress(u8 **hc_ptr,
1085                                               const struct lowpan_iphc_ctx *ctx,
1086                                               const struct in6_addr *ipaddr)
1087 {
1088         u8 data[6];
1089 
1090         /* flags/scope, reserved (RIID) */
1091         memcpy(data, &ipaddr->s6_addr[1], 2);
1092         /* group ID */
1093         memcpy(&data[1], &ipaddr->s6_addr[11], 4);
1094         lowpan_push_hc_data(hc_ptr, data, 6);
1095 
1096         return LOWPAN_IPHC_DAM_00;
1097 }
1098 
1099 static u8 lowpan_iphc_mcast_addr_compress(u8 **hc_ptr,
1100                                           const struct in6_addr *ipaddr)
1101 {
1102         u8 val;
1103 
1104         if (lowpan_is_mcast_addr_compressable8(ipaddr)) {
1105                 pr_debug("compressed to 1 octet\n");
1106                 /* use last byte */
1107                 lowpan_push_hc_data(hc_ptr, &ipaddr->s6_addr[15], 1);
1108                 val = LOWPAN_IPHC_DAM_11;
1109         } else if (lowpan_is_mcast_addr_compressable32(ipaddr)) {
1110                 pr_debug("compressed to 4 octets\n");
1111                 /* second byte + the last three */
1112                 lowpan_push_hc_data(hc_ptr, &ipaddr->s6_addr[1], 1);
1113                 lowpan_push_hc_data(hc_ptr, &ipaddr->s6_addr[13], 3);
1114                 val = LOWPAN_IPHC_DAM_10;
1115         } else if (lowpan_is_mcast_addr_compressable48(ipaddr)) {
1116                 pr_debug("compressed to 6 octets\n");
1117                 /* second byte + the last five */
1118                 lowpan_push_hc_data(hc_ptr, &ipaddr->s6_addr[1], 1);
1119                 lowpan_push_hc_data(hc_ptr, &ipaddr->s6_addr[11], 5);
1120                 val = LOWPAN_IPHC_DAM_01;
1121         } else {
1122                 pr_debug("using full address\n");
1123                 lowpan_push_hc_data(hc_ptr, ipaddr->s6_addr, 16);
1124                 val = LOWPAN_IPHC_DAM_00;
1125         }
1126 
1127         return val;
1128 }
1129 
1130 int lowpan_header_compress(struct sk_buff *skb, const struct net_device *dev,
1131                            const void *daddr, const void *saddr)
1132 {
1133         u8 iphc0, iphc1, *hc_ptr, cid = 0;
1134         struct ipv6hdr *hdr;
1135         u8 head[LOWPAN_IPHC_MAX_HC_BUF_LEN] = {};
1136         struct lowpan_iphc_ctx *dci, *sci, dci_entry, sci_entry;
1137         int ret, ipv6_daddr_type, ipv6_saddr_type;
1138 
1139         if (skb->protocol != htons(ETH_P_IPV6))
1140                 return -EINVAL;
1141 
1142         hdr = ipv6_hdr(skb);
1143         hc_ptr = head + 2;
1144 
1145         pr_debug("IPv6 header dump:\n\tversion = %d\n\tlength  = %d\n"
1146                  "\tnexthdr = 0x%02x\n\thop_lim = %d\n\tdest    = %pI6c\n",
1147                  hdr->version, ntohs(hdr->payload_len), hdr->nexthdr,
1148                  hdr->hop_limit, &hdr->daddr);
1149 
1150         raw_dump_table(__func__, "raw skb network header dump",
1151                        skb_network_header(skb), sizeof(struct ipv6hdr));
1152 
1153         /* As we copy some bit-length fields, in the IPHC encoding bytes,
1154          * we sometimes use |=
1155          * If the field is 0, and the current bit value in memory is 1,
1156          * this does not work. We therefore reset the IPHC encoding here
1157          */
1158         iphc0 = LOWPAN_DISPATCH_IPHC;
1159         iphc1 = 0;
1160 
1161         raw_dump_table(__func__, "sending raw skb network uncompressed packet",
1162                        skb->data, skb->len);
1163 
1164         ipv6_daddr_type = ipv6_addr_type(&hdr->daddr);
1165         spin_lock_bh(&lowpan_dev(dev)->ctx.lock);
1166         if (ipv6_daddr_type & IPV6_ADDR_MULTICAST)
1167                 dci = lowpan_iphc_ctx_get_by_mcast_addr(dev, &hdr->daddr);
1168         else
1169                 dci = lowpan_iphc_ctx_get_by_addr(dev, &hdr->daddr);
1170         if (dci) {
1171                 memcpy(&dci_entry, dci, sizeof(*dci));
1172                 cid |= dci->id;
1173         }
1174         spin_unlock_bh(&lowpan_dev(dev)->ctx.lock);
1175 
1176         spin_lock_bh(&lowpan_dev(dev)->ctx.lock);
1177         sci = lowpan_iphc_ctx_get_by_addr(dev, &hdr->saddr);
1178         if (sci) {
1179                 memcpy(&sci_entry, sci, sizeof(*sci));
1180                 cid |= (sci->id << 4);
1181         }
1182         spin_unlock_bh(&lowpan_dev(dev)->ctx.lock);
1183 
1184         /* if cid is zero it will be compressed */
1185         if (cid) {
1186                 iphc1 |= LOWPAN_IPHC_CID;
1187                 lowpan_push_hc_data(&hc_ptr, &cid, sizeof(cid));
1188         }
1189 
1190         /* Traffic Class, Flow Label compression */
1191         iphc0 |= lowpan_iphc_tf_compress(&hc_ptr, hdr);
1192 
1193         /* NOTE: payload length is always compressed */
1194 
1195         /* Check if we provide the nhc format for nexthdr and compression
1196          * functionality. If not nexthdr is handled inline and not compressed.
1197          */
1198         ret = lowpan_nhc_check_compression(skb, hdr, &hc_ptr);
1199         if (ret == -ENOENT)
1200                 lowpan_push_hc_data(&hc_ptr, &hdr->nexthdr,
1201                                     sizeof(hdr->nexthdr));
1202         else
1203                 iphc0 |= LOWPAN_IPHC_NH;
1204 
1205         /* Hop limit
1206          * if 1:   compress, encoding is 01
1207          * if 64:  compress, encoding is 10
1208          * if 255: compress, encoding is 11
1209          * else do not compress
1210          */
1211         switch (hdr->hop_limit) {
1212         case 1:
1213                 iphc0 |= LOWPAN_IPHC_HLIM_01;
1214                 break;
1215         case 64:
1216                 iphc0 |= LOWPAN_IPHC_HLIM_10;
1217                 break;
1218         case 255:
1219                 iphc0 |= LOWPAN_IPHC_HLIM_11;
1220                 break;
1221         default:
1222                 lowpan_push_hc_data(&hc_ptr, &hdr->hop_limit,
1223                                     sizeof(hdr->hop_limit));
1224         }
1225 
1226         ipv6_saddr_type = ipv6_addr_type(&hdr->saddr);
1227         /* source address compression */
1228         if (ipv6_saddr_type == IPV6_ADDR_ANY) {
1229                 pr_debug("source address is unspecified, setting SAC\n");
1230                 iphc1 |= LOWPAN_IPHC_SAC;
1231         } else {
1232                 if (sci) {
1233                         iphc1 |= lowpan_compress_ctx_addr(&hc_ptr, dev,
1234                                                           &hdr->saddr,
1235                                                           &sci_entry, saddr,
1236                                                           true);
1237                         iphc1 |= LOWPAN_IPHC_SAC;
1238                 } else {
1239                         if (ipv6_saddr_type & IPV6_ADDR_LINKLOCAL &&
1240                             lowpan_is_linklocal_zero_padded(hdr->saddr)) {
1241                                 iphc1 |= lowpan_compress_addr_64(&hc_ptr, dev,
1242                                                                  &hdr->saddr,
1243                                                                  saddr, true);
1244                                 pr_debug("source address unicast link-local %pI6c iphc1 0x%02x\n",
1245                                          &hdr->saddr, iphc1);
1246                         } else {
1247                                 pr_debug("send the full source address\n");
1248                                 lowpan_push_hc_data(&hc_ptr,
1249                                                     hdr->saddr.s6_addr, 16);
1250                         }
1251                 }
1252         }
1253 
1254         /* destination address compression */
1255         if (ipv6_daddr_type & IPV6_ADDR_MULTICAST) {
1256                 pr_debug("destination address is multicast: ");
1257                 iphc1 |= LOWPAN_IPHC_M;
1258                 if (dci) {
1259                         iphc1 |= lowpan_iphc_mcast_ctx_addr_compress(&hc_ptr,
1260                                                                      &dci_entry,
1261                                                                      &hdr->daddr);
1262                         iphc1 |= LOWPAN_IPHC_DAC;
1263                 } else {
1264                         iphc1 |= lowpan_iphc_mcast_addr_compress(&hc_ptr,
1265                                                                  &hdr->daddr);
1266                 }
1267         } else {
1268                 if (dci) {
1269                         iphc1 |= lowpan_compress_ctx_addr(&hc_ptr, dev,
1270                                                           &hdr->daddr,
1271                                                           &dci_entry, daddr,
1272                                                           false);
1273                         iphc1 |= LOWPAN_IPHC_DAC;
1274                 } else {
1275                         if (ipv6_daddr_type & IPV6_ADDR_LINKLOCAL &&
1276                             lowpan_is_linklocal_zero_padded(hdr->daddr)) {
1277                                 iphc1 |= lowpan_compress_addr_64(&hc_ptr, dev,
1278                                                                  &hdr->daddr,
1279                                                                  daddr, false);
1280                                 pr_debug("dest address unicast link-local %pI6c iphc1 0x%02x\n",
1281                                          &hdr->daddr, iphc1);
1282                         } else {
1283                                 pr_debug("dest address unicast %pI6c\n",
1284                                          &hdr->daddr);
1285                                 lowpan_push_hc_data(&hc_ptr,
1286                                                     hdr->daddr.s6_addr, 16);
1287                         }
1288                 }
1289         }
1290 
1291         /* next header compression */
1292         if (iphc0 & LOWPAN_IPHC_NH) {
1293                 ret = lowpan_nhc_do_compression(skb, hdr, &hc_ptr);
1294                 if (ret < 0)
1295                         return ret;
1296         }
1297 
1298         head[0] = iphc0;
1299         head[1] = iphc1;
1300 
1301         skb_pull(skb, sizeof(struct ipv6hdr));
1302         skb_reset_transport_header(skb);
1303         memcpy(skb_push(skb, hc_ptr - head), head, hc_ptr - head);
1304         skb_reset_network_header(skb);
1305 
1306         pr_debug("header len %d skb %u\n", (int)(hc_ptr - head), skb->len);
1307 
1308         raw_dump_table(__func__, "raw skb data dump compressed",
1309                        skb->data, skb->len);
1310         return 0;
1311 }
1312 EXPORT_SYMBOL_GPL(lowpan_header_compress);
1313 

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