lib/drivers/lwip/src/core/ipv4/inet_chksum.c

   1 /**
   2  * @file
   3  * Incluse internet checksum functions.
   4  *
   5  */
   6
   7 /*
   8  * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
   9  * All rights reserved.
  10  *
  11  * Redistribution and use in source and binary forms, with or without modification,
  12  * are permitted provided that the following conditions are met:
  13  *
  14  * 1. Redistributions of source code must retain the above copyright notice,
  15  *    this list of conditions and the following disclaimer.
  16  * 2. Redistributions in binary form must reproduce the above copyright notice,
  17  *    this list of conditions and the following disclaimer in the documentation
  18  *    and/or other materials provided with the distribution.
  19  * 3. The name of the author may not be used to endorse or promote products
  20  *    derived from this software without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
  23  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
  24  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
  25  * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  26  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
  27  * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  28  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  29  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
  30  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
  31  * OF SUCH DAMAGE.
  32  *
  33  * This file is part of the lwIP TCP/IP stack.
  34  *
  35  * Author: Adam Dunkels <adam@sics.se>
  36  *
  37  */
  38
  39 #include "lwip/opt.h"
  40
  41 #include "lwip/inet_chksum.h"
  42 #include "lwip/inet.h"
  43
  44 #include <stddef.h>
  45
  46 /* These are some reference implementations of the checksum algorithm, with the
  47  * aim of being simple, correct and fully portable. Checksumming is the
  48  * first thing you would want to optimize for your platform. If you create
  49  * your own version, link it in and in your cc.h put:
  50  *
  51  * #define LWIP_CHKSUM <your_checksum_routine>
  52  *
  53  * Or you can select from the implementations below by defining
  54  * LWIP_CHKSUM_ALGORITHM to 1, 2 or 3.
  55  */
  56
  57 #ifndef LWIP_CHKSUM
  58 # define LWIP_CHKSUM lwip_standard_chksum
  59 # ifndef LWIP_CHKSUM_ALGORITHM
  60 #  define LWIP_CHKSUM_ALGORITHM 1
  61 # endif
  62 #endif
  63 /* If none set: */
  64 #ifndef LWIP_CHKSUM_ALGORITHM
  65 # define LWIP_CHKSUM_ALGORITHM 0
  66 #endif
  67
  68 /** Like the name says... */
  69 #if LWIP_PLATFORM_BYTESWAP && (BYTE_ORDER == LITTLE_ENDIAN)
  70 /* little endian and PLATFORM_BYTESWAP defined */
  71 #define SWAP_BYTES_IN_WORD(w) LWIP_PLATFORM_HTONS(w)
  72 #else
  73 /* can't use htons on big endian (or PLATFORM_BYTESWAP not defined)... */
  74 #define SWAP_BYTES_IN_WORD(w) ((w & 0xff) << 8) | ((w & 0xff00) >> 8)
  75 #endif
  76
  77 /** Split an u32_t in two u16_ts and add them up */
  78 #define FOLD_U32T(u)          ((u >> 16) + (u & 0x0000ffffUL))
  79
  80 #if (LWIP_CHKSUM_ALGORITHM == 1) /* Version #1 */
  81 /**
  82  * lwip checksum
  83  *
  84  * @param dataptr points to start of data to be summed at any boundary
  85  * @param len length of data to be summed
  86  * @return host order (!) lwip checksum (non-inverted Internet sum)
  87  *
  88  * @note accumulator size limits summable length to 64k
  89  * @note host endianess is irrelevant (p3 RFC1071)
  90  */
  91 static u16_t
  92 lwip_standard_chksum(void *dataptr, u16_t len)
  93 {
  94   u32_t acc;
  95   u16_t src;
  96   u8_t *octetptr;
  97
  98   acc = 0;
  99   /* dataptr may be at odd or even addresses */
 100   octetptr = (u8_t*)dataptr;
 101   while (len > 1) {
 102     /* declare first octet as most significant
 103        thus assume network order, ignoring host order */
 104     src = (*octetptr) << 8;
 105     octetptr++;
 106     /* declare second octet as least significant */
 107     src |= (*octetptr);
 108     octetptr++;
 109     acc += src;
 110     len -= 2;
 111   }
 112   if (len > 0) {
 113     /* accumulate remaining octet */
 114     src = (*octetptr) << 8;
 115     acc += src;
 116   }
 117   /* add deferred carry bits */
 118   acc = (acc >> 16) + (acc & 0x0000ffffUL);
 119   if ((acc & 0xffff0000UL) != 0) {
 120     acc = (acc >> 16) + (acc & 0x0000ffffUL);
 121   }
 122   /* This maybe a little confusing: reorder sum using htons()
 123      instead of ntohs() since it has a little less call overhead.
 124      The caller must invert bits for Internet sum ! */
 125   return htons((u16_t)acc);
 126 }
 127 #endif
 128
 129 #if (LWIP_CHKSUM_ALGORITHM == 2) /* Alternative version #2 */
 130 /*
 131  * Curt McDowell
 132  * Broadcom Corp.
 133  * csm@broadcom.com
 134  *
 135  * IP checksum two bytes at a time with support for
 136  * unaligned buffer.
 137  * Works for len up to and including 0x20000.
 138  * by Curt McDowell, Broadcom Corp. 12/08/2005
 139  *
 140  * @param dataptr points to start of data to be summed at any boundary
 141  * @param len length of data to be summed
 142  * @return host order (!) lwip checksum (non-inverted Internet sum)
 143  */
 144
 145 static u16_t
 146 lwip_standard_chksum(void *dataptr, int len)
 147 {
 148   u8_t *pb = dataptr;
 149   u16_t *ps, t = 0;
 150   u32_t sum = 0;
 151   int odd = ((u32_t)pb & 1);
 152
 153   /* Get aligned to u16_t */
 154   if (odd && len > 0) {
 155     ((u8_t *)&t)[1] = *pb++;
 156     len--;
 157   }
 158
 159   /* Add the bulk of the data */
 160   ps = (u16_t *)pb;
 161   while (len > 1) {
 162     sum += *ps++;
 163     len -= 2;
 164   }
 165
 166   /* Consume left-over byte, if any */
 167   if (len > 0) {
 168     ((u8_t *)&t)[0] = *(u8_t *)ps;;
 169   }
 170
 171   /* Add end bytes */
 172   sum += t;
 173
 174   /* Fold 32-bit sum to 16 bits
 175      calling this twice is propably faster than if statements... */
 176   sum = FOLD_U32T(sum);
 177   sum = FOLD_U32T(sum);
 178
 179   /* Swap if alignment was odd */
 180   if (odd) {
 181     sum = SWAP_BYTES_IN_WORD(sum);
 182   }
 183
 184   return sum;
 185 }
 186 #endif
 187
 188 #if (LWIP_CHKSUM_ALGORITHM == 3) /* Alternative version #3 */
 189 /**
 190  * An optimized checksum routine. Basically, it uses loop-unrolling on
 191  * the checksum loop, treating the head and tail bytes specially, whereas
 192  * the inner loop acts on 8 bytes at a time.
 193  *
 194  * @arg start of buffer to be checksummed. May be an odd byte address.
 195  * @len number of bytes in the buffer to be checksummed.
 196  * @return host order (!) lwip checksum (non-inverted Internet sum)
 197  *
 198  * by Curt McDowell, Broadcom Corp. December 8th, 2005
 199  */
 200
 201 static u16_t
 202 lwip_standard_chksum(void *dataptr, int len)
 203 {
 204   u8_t *pb = dataptr;
 205   u16_t *ps, t = 0;
 206   u32_t *pl;
 207   u32_t sum = 0, tmp;
 208   /* starts at odd byte address? */
 209   int odd = ((u32_t)pb & 1);
 210
 211   if (odd && len > 0) {
 212     ((u8_t *)&t)[1] = *pb++;
 213     len--;
 214   }
 215
 216   ps = (u16_t *)pb;
 217
 218   if (((u32_t)ps & 3) && len > 1) {
 219     sum += *ps++;
 220     len -= 2;
 221   }
 222
 223   pl = (u32_t *)ps;
 224
 225   while (len > 7)  {
 226     tmp = sum + *pl++;          /* ping */
 227     if (tmp < sum) {
 228       tmp++;                    /* add back carry */
 229     }
 230
 231     sum = tmp + *pl++;          /* pong */
 232     if (sum < tmp) {
 233       sum++;                    /* add back carry */
 234     }
 235
 236     len -= 8;
 237   }
 238
 239   /* make room in upper bits */
 240   sum = FOLD_U32T(sum);
 241
 242   ps = (u16_t *)pl;
 243
 244   /* 16-bit aligned word remaining? */
 245   while (len > 1) {
 246     sum += *ps++;
 247     len -= 2;
 248   }
 249
 250   /* dangling tail byte remaining? */
 251   if (len > 0) {                /* include odd byte */
 252     ((u8_t *)&t)[0] = *(u8_t *)ps;
 253   }
 254
 255   sum += t;                     /* add end bytes */
 256
 257   /* Fold 32-bit sum to 16 bits
 258      calling this twice is propably faster than if statements... */
 259   sum = FOLD_U32T(sum);
 260   sum = FOLD_U32T(sum);
 261
 262   if (odd) {
 263     sum = SWAP_BYTES_IN_WORD(sum);
 264   }
 265
 266   return sum;
 267 }
 268 #endif
 269
 270 /* inet_chksum_pseudo:
 271  *
 272  * Calculates the pseudo Internet checksum used by TCP and UDP for a pbuf chain.
 273  * IP addresses are expected to be in network byte order.
 274  *
 275  * @param p chain of pbufs over that a checksum should be calculated (ip data part)
 276  * @param src source ip address (used for checksum of pseudo header)
 277  * @param dst destination ip address (used for checksum of pseudo header)
 278  * @param proto ip protocol (used for checksum of pseudo header)
 279  * @param proto_len length of the ip data part (used for checksum of pseudo header)
 280  * @return checksum (as u16_t) to be saved directly in the protocol header
 281  */
 282 u16_t
 283 inet_chksum_pseudo(struct pbuf *p,
 284        struct ip_addr *src, struct ip_addr *dest,
 285        u8_t proto, u16_t proto_len)
 286 {
 287   u32_t acc;
 288   struct pbuf *q;
 289   u8_t swapped;
 290
 291   acc = 0;
 292   swapped = 0;
 293   /* iterate through all pbuf in chain */
 294   for(q = p; q != NULL; q = q->next) {
 295     LWIP_DEBUGF(INET_DEBUG, ("inet_chksum_pseudo(): checksumming pbuf %p (has next %p) \n",
 296       (void *)q, (void *)q->next));
 297     acc += LWIP_CHKSUM(q->payload, q->len);
 298     /*LWIP_DEBUGF(INET_DEBUG, ("inet_chksum_pseudo(): unwrapped lwip_chksum()=%"X32_F" \n", acc));*/
 299     /* just executing this next line is probably faster that the if statement needed
 300        to check whether we really need to execute it, and does no harm */
 301     acc = FOLD_U32T(acc);
 302     if (q->len % 2 != 0) {
 303       swapped = 1 - swapped;
 304       acc = SWAP_BYTES_IN_WORD(acc);
 305     }
 306     /*LWIP_DEBUGF(INET_DEBUG, ("inet_chksum_pseudo(): wrapped lwip_chksum()=%"X32_F" \n", acc));*/
 307   }
 308
 309   if (swapped) {
 310     acc = SWAP_BYTES_IN_WORD(acc);
 311   }
 312   acc += (src->addr & 0xffffUL);
 313   acc += ((src->addr >> 16) & 0xffffUL);
 314   acc += (dest->addr & 0xffffUL);
 315   acc += ((dest->addr >> 16) & 0xffffUL);
 316   acc += (u32_t)htons((u16_t)proto);
 317   acc += (u32_t)htons(proto_len);
 318
 319   /* Fold 32-bit sum to 16 bits
 320      calling this twice is propably faster than if statements... */
 321   acc = FOLD_U32T(acc);
 322   acc = FOLD_U32T(acc);
 323   LWIP_DEBUGF(INET_DEBUG, ("inet_chksum_pseudo(): pbuf chain lwip_chksum()=%"X32_F"\n", acc));
 324   return (u16_t)~(acc & 0xffffUL);
 325 }
 326
 327 /* inet_chksum_pseudo:
 328  *
 329  * Calculates the pseudo Internet checksum used by TCP and UDP for a pbuf chain.
 330  * IP addresses are expected to be in network byte order.
 331  *
 332  * @param p chain of pbufs over that a checksum should be calculated (ip data part)
 333  * @param src source ip address (used for checksum of pseudo header)
 334  * @param dst destination ip address (used for checksum of pseudo header)
 335  * @param proto ip protocol (used for checksum of pseudo header)
 336  * @param proto_len length of the ip data part (used for checksum of pseudo header)
 337  * @return checksum (as u16_t) to be saved directly in the protocol header
 338  */
 339 /* Currently only used by UDPLITE, although this could change in the future. */
 340 #if LWIP_UDPLITE
 341 u16_t
 342 inet_chksum_pseudo_partial(struct pbuf *p,
 343        struct ip_addr *src, struct ip_addr *dest,
 344        u8_t proto, u16_t proto_len, u16_t chksum_len)
 345 {
 346   u32_t acc;
 347   struct pbuf *q;
 348   u8_t swapped;
 349   u16_t chklen;
 350
 351   acc = 0;
 352   swapped = 0;
 353   /* iterate through all pbuf in chain */
 354   for(q = p; (q != NULL) && (chksum_len > 0); q = q->next) {
 355     LWIP_DEBUGF(INET_DEBUG, ("inet_chksum_pseudo(): checksumming pbuf %p (has next %p) \n",
 356       (void *)q, (void *)q->next));
 357     chklen = q->len;
 358     if (chklen > chksum_len) {
 359       chklen = chksum_len;
 360     }
 361     acc += LWIP_CHKSUM(q->payload, chklen);
 362     chksum_len -= chklen;
 363     LWIP_ASSERT("delete me", chksum_len < 0x7fff);
 364     /*LWIP_DEBUGF(INET_DEBUG, ("inet_chksum_pseudo(): unwrapped lwip_chksum()=%"X32_F" \n", acc));*/
 365     /* fold the upper bit down */
 366     acc = FOLD_U32T(acc);
 367     if (q->len % 2 != 0) {
 368       swapped = 1 - swapped;
 369       acc = SWAP_BYTES_IN_WORD(acc);
 370     }
 371     /*LWIP_DEBUGF(INET_DEBUG, ("inet_chksum_pseudo(): wrapped lwip_chksum()=%"X32_F" \n", acc));*/
 372   }
 373
 374   if (swapped) {
 375     acc = SWAP_BYTES_IN_WORD(acc);
 376   }
 377   acc += (src->addr & 0xffffUL);
 378   acc += ((src->addr >> 16) & 0xffffUL);
 379   acc += (dest->addr & 0xffffUL);
 380   acc += ((dest->addr >> 16) & 0xffffUL);
 381   acc += (u32_t)htons((u16_t)proto);
 382   acc += (u32_t)htons(proto_len);
 383
 384   /* Fold 32-bit sum to 16 bits
 385      calling this twice is propably faster than if statements... */
 386   acc = FOLD_U32T(acc);
 387   acc = FOLD_U32T(acc);
 388   LWIP_DEBUGF(INET_DEBUG, ("inet_chksum_pseudo(): pbuf chain lwip_chksum()=%"X32_F"\n", acc));
 389   return (u16_t)~(acc & 0xffffUL);
 390 }
 391 #endif /* LWIP_UDPLITE */
 392
 393 /* inet_chksum:
 394  *
 395  * Calculates the Internet checksum over a portion of memory. Used primarily for IP
 396  * and ICMP.
 397  *
 398  * @param dataptr start of the buffer to calculate the checksum (no alignment needed)
 399  * @param len length of the buffer to calculate the checksum
 400  * @return checksum (as u16_t) to be saved directly in the protocol header
 401  */
 402
 403 u16_t
 404 inet_chksum(void *dataptr, u16_t len)
 405 {
 406   return ~LWIP_CHKSUM(dataptr, len);
 407 }
 408
 409 /**
 410  * Calculate a checksum over a chain of pbufs (without pseudo-header, much like
 411  * inet_chksum only pbufs are used).
 412  *
 413  * @param p pbuf chain over that the checksum should be calculated
 414  * @return checksum (as u16_t) to be saved directly in the protocol header
 415  */
 416 u16_t
 417 inet_chksum_pbuf(struct pbuf *p)
 418 {
 419   u32_t acc;
 420   struct pbuf *q;
 421   u8_t swapped;
 422
 423   acc = 0;
 424   swapped = 0;
 425   for(q = p; q != NULL; q = q->next) {
 426     acc += LWIP_CHKSUM(q->payload, q->len);
 427     acc = FOLD_U32T(acc);
 428     if (q->len % 2 != 0) {
 429       swapped = 1 - swapped;
 430       acc = SWAP_BYTES_IN_WORD(acc);
 431     }
 432   }
 433
 434   if (swapped) {
 435     acc = SWAP_BYTES_IN_WORD(acc);
 436   }
 437   return (u16_t)~(acc & 0xffffUL);
 438 }