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 (at) sics.se> 36 * 37 */ 38 39 #include "lwip/opt.h" 40 41 #include "lwip/inet_chksum.h" 42 #include "lwip/def.h" 43 44 #include <stddef.h> 45 #include <string.h> 46 47 /* These are some reference implementations of the checksum algorithm, with the 48 * aim of being simple, correct and fully portable. Checksumming is the 49 * first thing you would want to optimize for your platform. If you create 50 * your own version, link it in and in your cc.h put: 51 * 52 * #define LWIP_CHKSUM <your_checksum_routine> 53 * 54 * Or you can select from the implementations below by defining 55 * LWIP_CHKSUM_ALGORITHM to 1, 2 or 3. 56 */ 57 58 #ifndef LWIP_CHKSUM 59 # define LWIP_CHKSUM lwip_standard_chksum 60 # ifndef LWIP_CHKSUM_ALGORITHM 61 # define LWIP_CHKSUM_ALGORITHM 2 62 # endif 63 #endif 64 /* If none set: */ 65 #ifndef LWIP_CHKSUM_ALGORITHM 66 # define LWIP_CHKSUM_ALGORITHM 0 67 #endif 68 69 #if (LWIP_CHKSUM_ALGORITHM == 1) /* Version #1 */ 70 /** 71 * lwip checksum 72 * 73 * @param dataptr points to start of data to be summed at any boundary 74 * @param len length of data to be summed 75 * @return host order (!) lwip checksum (non-inverted Internet sum) 76 * 77 * @note accumulator size limits summable length to 64k 78 * @note host endianess is irrelevant (p3 RFC1071) 79 */ 80 static u16_t 81 lwip_standard_chksum(void *dataptr, u16_t len) 82 { 83 u32_t acc; 84 u16_t src; 85 u8_t *octetptr; 86 87 acc = 0; 88 /* dataptr may be at odd or even addresses */ 89 octetptr = (u8_t*)dataptr; 90 while (len > 1) { 91 /* declare first octet as most significant 92 thus assume network order, ignoring host order */ 93 src = (*octetptr) << 8; 94 octetptr++; 95 /* declare second octet as least significant */ 96 src |= (*octetptr); 97 octetptr++; 98 acc += src; 99 len -= 2; 100 } 101 if (len > 0) { 102 /* accumulate remaining octet */ 103 src = (*octetptr) << 8; 104 acc += src; 105 } 106 /* add deferred carry bits */ 107 acc = (acc >> 16) + (acc & 0x0000ffffUL); 108 if ((acc & 0xffff0000UL) != 0) { 109 acc = (acc >> 16) + (acc & 0x0000ffffUL); 110 } 111 /* This maybe a little confusing: reorder sum using htons() 112 instead of ntohs() since it has a little less call overhead. 113 The caller must invert bits for Internet sum ! */ 114 return htons((u16_t)acc); 115 } 116 #endif 117 118 #if (LWIP_CHKSUM_ALGORITHM == 2) /* Alternative version #2 */ 119 /* 120 * Curt McDowell 121 * Broadcom Corp. 122 * csm (at) broadcom.com 123 * 124 * IP checksum two bytes at a time with support for 125 * unaligned buffer. 126 * Works for len up to and including 0x20000. 127 * by Curt McDowell, Broadcom Corp. 12/08/2005 128 * 129 * @param dataptr points to start of data to be summed at any boundary 130 * @param len length of data to be summed 131 * @return host order (!) lwip checksum (non-inverted Internet sum) 132 */ 133 134 static u16_t 135 lwip_standard_chksum(void *dataptr, int len) 136 { 137 u8_t *pb = (u8_t *)dataptr; 138 u16_t *ps, t = 0; 139 u32_t sum = 0; 140 int odd = ((mem_ptr_t)pb & 1); 141 142 /* Get aligned to u16_t */ 143 if (odd && len > 0) { 144 ((u8_t *)&t)[1] = *pb++; 145 len--; 146 } 147 148 /* Add the bulk of the data */ 149 ps = (u16_t *)(void *)pb; 150 while (len > 1) { 151 sum += *ps++; 152 len -= 2; 153 } 154 155 /* Consume left-over byte, if any */ 156 if (len > 0) { 157 ((u8_t *)&t)[0] = *(u8_t *)ps; 158 } 159 160 /* Add end bytes */ 161 sum += t; 162 163 /* Fold 32-bit sum to 16 bits 164 calling this twice is propably faster than if statements... */ 165 sum = FOLD_U32T(sum); 166 sum = FOLD_U32T(sum); 167 168 /* Swap if alignment was odd */ 169 if (odd) { 170 sum = SWAP_BYTES_IN_WORD(sum); 171 } 172 173 return (u16_t)sum; 174 } 175 #endif 176 177 #if (LWIP_CHKSUM_ALGORITHM == 3) /* Alternative version #3 */ 178 /** 179 * An optimized checksum routine. Basically, it uses loop-unrolling on 180 * the checksum loop, treating the head and tail bytes specially, whereas 181 * the inner loop acts on 8 bytes at a time. 182 * 183 * @arg start of buffer to be checksummed. May be an odd byte address. 184 * @len number of bytes in the buffer to be checksummed. 185 * @return host order (!) lwip checksum (non-inverted Internet sum) 186 * 187 * by Curt McDowell, Broadcom Corp. December 8th, 2005 188 */ 189 190 static u16_t 191 lwip_standard_chksum(void *dataptr, int len) 192 { 193 u8_t *pb = (u8_t *)dataptr; 194 u16_t *ps, t = 0; 195 u32_t *pl; 196 u32_t sum = 0, tmp; 197 /* starts at odd byte address? */ 198 int odd = ((mem_ptr_t)pb & 1); 199 200 if (odd && len > 0) { 201 ((u8_t *)&t)[1] = *pb++; 202 len--; 203 } 204 205 ps = (u16_t *)pb; 206 207 if (((mem_ptr_t)ps & 3) && len > 1) { 208 sum += *ps++; 209 len -= 2; 210 } 211 212 pl = (u32_t *)ps; 213 214 while (len > 7) { 215 tmp = sum + *pl++; /* ping */ 216 if (tmp < sum) { 217 tmp++; /* add back carry */ 218 } 219 220 sum = tmp + *pl++; /* pong */ 221 if (sum < tmp) { 222 sum++; /* add back carry */ 223 } 224 225 len -= 8; 226 } 227 228 /* make room in upper bits */ 229 sum = FOLD_U32T(sum); 230 231 ps = (u16_t *)pl; 232 233 /* 16-bit aligned word remaining? */ 234 while (len > 1) { 235 sum += *ps++; 236 len -= 2; 237 } 238 239 /* dangling tail byte remaining? */ 240 if (len > 0) { /* include odd byte */ 241 ((u8_t *)&t)[0] = *(u8_t *)ps; 242 } 243 244 sum += t; /* add end bytes */ 245 246 /* Fold 32-bit sum to 16 bits 247 calling this twice is propably faster than if statements... */ 248 sum = FOLD_U32T(sum); 249 sum = FOLD_U32T(sum); 250 251 if (odd) { 252 sum = SWAP_BYTES_IN_WORD(sum); 253 } 254 255 return (u16_t)sum; 256 } 257 #endif 258 259 /* inet_chksum_pseudo: 260 * 261 * Calculates the pseudo Internet checksum used by TCP and UDP for a pbuf chain. 262 * IP addresses are expected to be in network byte order. 263 * 264 * @param p chain of pbufs over that a checksum should be calculated (ip data part) 265 * @param src source ip address (used for checksum of pseudo header) 266 * @param dst destination ip address (used for checksum of pseudo header) 267 * @param proto ip protocol (used for checksum of pseudo header) 268 * @param proto_len length of the ip data part (used for checksum of pseudo header) 269 * @return checksum (as u16_t) to be saved directly in the protocol header 270 */ 271 u16_t 272 inet_chksum_pseudo(struct pbuf *p, 273 ip_addr_t *src, ip_addr_t *dest, 274 u8_t proto, u16_t proto_len) 275 { 276 u32_t acc; 277 u32_t addr; 278 struct pbuf *q; 279 u8_t swapped; 280 281 acc = 0; 282 swapped = 0; 283 /* iterate through all pbuf in chain */ 284 for(q = p; q != NULL; q = q->next) { 285 LWIP_DEBUGF(INET_DEBUG, ("inet_chksum_pseudo(): checksumming pbuf %p (has next %p) \n", 286 (void *)q, (void *)q->next)); 287 acc += LWIP_CHKSUM(q->payload, q->len); 288 /*LWIP_DEBUGF(INET_DEBUG, ("inet_chksum_pseudo(): unwrapped lwip_chksum()=%"X32_F" \n", acc));*/ 289 /* just executing this next line is probably faster that the if statement needed 290 to check whether we really need to execute it, and does no harm */ 291 acc = FOLD_U32T(acc); 292 if (q->len % 2 != 0) { 293 swapped = 1 - swapped; 294 acc = SWAP_BYTES_IN_WORD(acc); 295 } 296 /*LWIP_DEBUGF(INET_DEBUG, ("inet_chksum_pseudo(): wrapped lwip_chksum()=%"X32_F" \n", acc));*/ 297 } 298 299 if (swapped) { 300 acc = SWAP_BYTES_IN_WORD(acc); 301 } 302 addr = ip4_addr_get_u32(src); 303 acc += (addr & 0xffffUL); 304 acc += ((addr >> 16) & 0xffffUL); 305 addr = ip4_addr_get_u32(dest); 306 acc += (addr & 0xffffUL); 307 acc += ((addr >> 16) & 0xffffUL); 308 acc += (u32_t)htons((u16_t)proto); 309 acc += (u32_t)htons(proto_len); 310 311 /* Fold 32-bit sum to 16 bits 312 calling this twice is propably faster than if statements... */ 313 acc = FOLD_U32T(acc); 314 acc = FOLD_U32T(acc); 315 LWIP_DEBUGF(INET_DEBUG, ("inet_chksum_pseudo(): pbuf chain lwip_chksum()=%"X32_F"\n", acc)); 316 return (u16_t)~(acc & 0xffffUL); 317 } 318 319 /* inet_chksum_pseudo: 320 * 321 * Calculates the pseudo Internet checksum used by TCP and UDP for a pbuf chain. 322 * IP addresses are expected to be in network byte order. 323 * 324 * @param p chain of pbufs over that a checksum should be calculated (ip data part) 325 * @param src source ip address (used for checksum of pseudo header) 326 * @param dst destination ip address (used for checksum of pseudo header) 327 * @param proto ip protocol (used for checksum of pseudo header) 328 * @param proto_len length of the ip data part (used for checksum of pseudo header) 329 * @return checksum (as u16_t) to be saved directly in the protocol header 330 */ 331 u16_t 332 inet_chksum_pseudo_partial(struct pbuf *p, 333 ip_addr_t *src, ip_addr_t *dest, 334 u8_t proto, u16_t proto_len, u16_t chksum_len) 335 { 336 u32_t acc; 337 u32_t addr; 338 struct pbuf *q; 339 u8_t swapped; 340 u16_t chklen; 341 342 acc = 0; 343 swapped = 0; 344 /* iterate through all pbuf in chain */ 345 for(q = p; (q != NULL) && (chksum_len > 0); q = q->next) { 346 LWIP_DEBUGF(INET_DEBUG, ("inet_chksum_pseudo(): checksumming pbuf %p (has next %p) \n", 347 (void *)q, (void *)q->next)); 348 chklen = q->len; 349 if (chklen > chksum_len) { 350 chklen = chksum_len; 351 } 352 acc += LWIP_CHKSUM(q->payload, chklen); 353 chksum_len -= chklen; 354 LWIP_ASSERT("delete me", chksum_len < 0x7fff); 355 /*LWIP_DEBUGF(INET_DEBUG, ("inet_chksum_pseudo(): unwrapped lwip_chksum()=%"X32_F" \n", acc));*/ 356 /* fold the upper bit down */ 357 acc = FOLD_U32T(acc); 358 if (q->len % 2 != 0) { 359 swapped = 1 - swapped; 360 acc = SWAP_BYTES_IN_WORD(acc); 361 } 362 /*LWIP_DEBUGF(INET_DEBUG, ("inet_chksum_pseudo(): wrapped lwip_chksum()=%"X32_F" \n", acc));*/ 363 } 364 365 if (swapped) { 366 acc = SWAP_BYTES_IN_WORD(acc); 367 } 368 addr = ip4_addr_get_u32(src); 369 acc += (addr & 0xffffUL); 370 acc += ((addr >> 16) & 0xffffUL); 371 addr = ip4_addr_get_u32(dest); 372 acc += (addr & 0xffffUL); 373 acc += ((addr >> 16) & 0xffffUL); 374 acc += (u32_t)htons((u16_t)proto); 375 acc += (u32_t)htons(proto_len); 376 377 /* Fold 32-bit sum to 16 bits 378 calling this twice is propably faster than if statements... */ 379 acc = FOLD_U32T(acc); 380 acc = FOLD_U32T(acc); 381 LWIP_DEBUGF(INET_DEBUG, ("inet_chksum_pseudo(): pbuf chain lwip_chksum()=%"X32_F"\n", acc)); 382 return (u16_t)~(acc & 0xffffUL); 383 } 384 385 /* inet_chksum: 386 * 387 * Calculates the Internet checksum over a portion of memory. Used primarily for IP 388 * and ICMP. 389 * 390 * @param dataptr start of the buffer to calculate the checksum (no alignment needed) 391 * @param len length of the buffer to calculate the checksum 392 * @return checksum (as u16_t) to be saved directly in the protocol header 393 */ 394 395 u16_t 396 inet_chksum(void *dataptr, u16_t len) 397 { 398 return ~LWIP_CHKSUM(dataptr, len); 399 } 400 401 /** 402 * Calculate a checksum over a chain of pbufs (without pseudo-header, much like 403 * inet_chksum only pbufs are used). 404 * 405 * @param p pbuf chain over that the checksum should be calculated 406 * @return checksum (as u16_t) to be saved directly in the protocol header 407 */ 408 u16_t 409 inet_chksum_pbuf(struct pbuf *p) 410 { 411 u32_t acc; 412 struct pbuf *q; 413 u8_t swapped; 414 415 acc = 0; 416 swapped = 0; 417 for(q = p; q != NULL; q = q->next) { 418 acc += LWIP_CHKSUM(q->payload, q->len); 419 acc = FOLD_U32T(acc); 420 if (q->len % 2 != 0) { 421 swapped = 1 - swapped; 422 acc = SWAP_BYTES_IN_WORD(acc); 423 } 424 } 425 426 if (swapped) { 427 acc = SWAP_BYTES_IN_WORD(acc); 428 } 429 return (u16_t)~(acc & 0xffffUL); 430 } 431 432 /* These are some implementations for LWIP_CHKSUM_COPY, which copies data 433 * like MEMCPY but generates a checksum at the same time. Since this is a 434 * performance-sensitive function, you might want to create your own version 435 * in assembly targeted at your hardware by defining it in lwipopts.h: 436 * #define LWIP_CHKSUM_COPY(dst, src, len) your_chksum_copy(dst, src, len) 437 */ 438 439 #if (LWIP_CHKSUM_COPY_ALGORITHM == 1) /* Version #1 */ 440 /** Safe but slow: first call MEMCPY, then call LWIP_CHKSUM. 441 * For architectures with big caches, data might still be in cache when 442 * generating the checksum after copying. 443 */ 444 u16_t 445 lwip_chksum_copy(void *dst, const void *src, u16_t len) 446 { 447 MEMCPY(dst, src, len); 448 return LWIP_CHKSUM(dst, len); 449 } 450 #endif /* (LWIP_CHKSUM_COPY_ALGORITHM == 1) */ 451
