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 "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 */
80static u16_t
81lwip_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@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
134static u16_t
135lwip_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
190static u16_t
191lwip_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 */
271u16_t
272inet_chksum_pseudo(struct packet *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 packet *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 */
331u16_t
332inet_chksum_pseudo_partial(struct packet *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 packet *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
395u16_t
396inet_chksum(void *dataptr, u16_t len)
397{
398  return ~LWIP_CHKSUM(dataptr, len);
399}
400
401#if 0
402/**
403 * Calculate a checksum over a chain of pbufs (without pseudo-header, much like
404 * inet_chksum only pbufs are used).
405 *
406 * @param p pbuf chain over that the checksum should be calculated
407 * @return checksum (as u16_t) to be saved directly in the protocol header
408 */
409u16_t
410inet_chksum_pbuf(struct pbuf *p)
411{
412  u32_t acc;
413  struct pbuf *q;
414  u8_t swapped;
415
416  acc = 0;
417  swapped = 0;
418  for(q = p; q != NULL; q = q->next) {
419    acc += LWIP_CHKSUM(q->payload, q->len);
420    acc = FOLD_U32T(acc);
421    if (q->len % 2 != 0) {
422      swapped = 1 - swapped;
423      acc = SWAP_BYTES_IN_WORD(acc);
424    }
425  }
426
427  if (swapped) {
428    acc = SWAP_BYTES_IN_WORD(acc);
429  }
430  return (u16_t)~(acc & 0xffffUL);
431}
432#endif
433
434/* These are some implementations for LWIP_CHKSUM_COPY, which copies data
435 * like MEMCPY but generates a checksum at the same time. Since this is a
436 * performance-sensitive function, you might want to create your own version
437 * in assembly targeted at your hardware by defining it in lwipopts.h:
438 *   #define LWIP_CHKSUM_COPY(dst, src, len) your_chksum_copy(dst, src, len)
439 */
440
441#if (LWIP_CHKSUM_COPY_ALGORITHM == 1) /* Version #1 */
442/** Safe but slow: first call MEMCPY, then call LWIP_CHKSUM.
443 * For architectures with big caches, data might still be in cache when
444 * generating the checksum after copying.
445 */
446u16_t
447lwip_chksum_copy(void *dst, const void *src, u16_t len)
448{
449  MEMCPY(dst, src, len);
450  return LWIP_CHKSUM(dst, len);
451}
452#endif /* (LWIP_CHKSUM_COPY_ALGORITHM == 1) */
453