3 * Incluse internet checksum functions.
8 * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
11 * Redistribution and use in source and binary forms, with or without modification,
12 * are permitted provided that the following conditions are met:
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
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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,
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29 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
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33 * This file is part of the lwIP TCP/IP stack.
35 * Author: Adam Dunkels <adam@sics.se>
41 #include "lwip/inet_chksum.h"
42 #include "lwip/inet.h"
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:
51 * #define LWIP_CHKSUM <your_checksum_routine>
53 * Or you can select from the implementations below by defining
54 * LWIP_CHKSUM_ALGORITHM to 1, 2 or 3.
58 # define LWIP_CHKSUM lwip_standard_chksum
59 # ifndef LWIP_CHKSUM_ALGORITHM
60 # define LWIP_CHKSUM_ALGORITHM 1
64 #ifndef LWIP_CHKSUM_ALGORITHM
65 # define LWIP_CHKSUM_ALGORITHM 0
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)
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)
77 /** Split an u32_t in two u16_ts and add them up */
78 #define FOLD_U32T(u) ((u >> 16) + (u & 0x0000ffffUL))
80 #if (LWIP_CHKSUM_ALGORITHM == 1) /* Version #1 */
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)
88 * @note accumulator size limits summable length to 64k
89 * @note host endianess is irrelevant (p3 RFC1071)
92 lwip_standard_chksum(void *dataptr, u16_t len)
99 /* dataptr may be at odd or even addresses */
100 octetptr = (u8_t*)dataptr;
102 /* declare first octet as most significant
103 thus assume network order, ignoring host order */
104 src = (*octetptr) << 8;
106 /* declare second octet as least significant */
113 /* accumulate remaining octet */
114 src = (*octetptr) << 8;
117 /* add deferred carry bits */
118 acc = (acc >> 16) + (acc & 0x0000ffffUL);
119 if ((acc & 0xffff0000UL) != 0) {
120 acc = (acc >> 16) + (acc & 0x0000ffffUL);
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);
129 #if (LWIP_CHKSUM_ALGORITHM == 2) /* Alternative version #2 */
135 * IP checksum two bytes at a time with support for
137 * Works for len up to and including 0x20000.
138 * by Curt McDowell, Broadcom Corp. 12/08/2005
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)
146 lwip_standard_chksum(void *dataptr, int len)
151 int odd = ((u32_t)pb & 1);
153 /* Get aligned to u16_t */
154 if (odd && len > 0) {
155 ((u8_t *)&t)[1] = *pb++;
159 /* Add the bulk of the data */
166 /* Consume left-over byte, if any */
168 ((u8_t *)&t)[0] = *(u8_t *)ps;;
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);
179 /* Swap if alignment was odd */
181 sum = SWAP_BYTES_IN_WORD(sum);
188 #if (LWIP_CHKSUM_ALGORITHM == 3) /* Alternative version #3 */
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.
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)
198 * by Curt McDowell, Broadcom Corp. December 8th, 2005
202 lwip_standard_chksum(void *dataptr, int len)
208 /* starts at odd byte address? */
209 int odd = ((u32_t)pb & 1);
211 if (odd && len > 0) {
212 ((u8_t *)&t)[1] = *pb++;
218 if (((u32_t)ps & 3) && len > 1) {
226 tmp = sum + *pl++; /* ping */
228 tmp++; /* add back carry */
231 sum = tmp + *pl++; /* pong */
233 sum++; /* add back carry */
239 /* make room in upper bits */
240 sum = FOLD_U32T(sum);
244 /* 16-bit aligned word remaining? */
250 /* dangling tail byte remaining? */
251 if (len > 0) { /* include odd byte */
252 ((u8_t *)&t)[0] = *(u8_t *)ps;
255 sum += t; /* add end bytes */
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);
263 sum = SWAP_BYTES_IN_WORD(sum);
270 /* inet_chksum_pseudo:
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.
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
283 inet_chksum_pseudo(struct pbuf *p,
284 struct ip_addr *src, struct ip_addr *dest,
285 u8_t proto, u16_t proto_len)
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);
306 /*LWIP_DEBUGF(INET_DEBUG, ("inet_chksum_pseudo(): wrapped lwip_chksum()=%"X32_F" \n", acc));*/
310 acc = SWAP_BYTES_IN_WORD(acc);
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);
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);
327 /* inet_chksum_pseudo:
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.
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
339 /* Currently only used by UDPLITE, although this could change in the future. */
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)
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));
358 if (chklen > chksum_len) {
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);
371 /*LWIP_DEBUGF(INET_DEBUG, ("inet_chksum_pseudo(): wrapped lwip_chksum()=%"X32_F" \n", acc));*/
375 acc = SWAP_BYTES_IN_WORD(acc);
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);
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);
391 #endif /* LWIP_UDPLITE */
395 * Calculates the Internet checksum over a portion of memory. Used primarily for IP
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
404 inet_chksum(void *dataptr, u16_t len)
406 return ~LWIP_CHKSUM(dataptr, len);
410 * Calculate a checksum over a chain of pbufs (without pseudo-header, much like
411 * inet_chksum only pbufs are used).
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
417 inet_chksum_pbuf(struct pbuf *p)
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);
435 acc = SWAP_BYTES_IN_WORD(acc);
437 return (u16_t)~(acc & 0xffffUL);