lwip/core/inet.c

   1 /*
   2  * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without modification,
   6  * are permitted provided that the following conditions are met:
   7  *
   8  * 1. Redistributions of source code must retain the above copyright notice,
   9  *    this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright notice,
  11  *    this list of conditions and the following disclaimer in the documentation
  12  *    and/or other materials provided with the distribution.
  13  * 3. The name of the author may not be used to endorse or promote products
  14  *    derived from this software without specific prior written permission.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
  17  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
  18  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
  19  * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  20  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
  21  * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  22  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  23  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
  24  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
  25  * OF SUCH DAMAGE.
  26  *
  27  * This file is part of the lwIP TCP/IP stack.
  28  *
  29  * Author: Adam Dunkels <adam@sics.se>
  30  *
  31  */
  32
  33
  34 /* inet.c
  35  *
  36  * Functions common to all TCP/IP modules, such as the Internet checksum and the
  37  * byte order functions.
  38  *
  39  */
  40
  41
  42 #include "lwip/opt.h"
  43
  44 #include "lwip/arch.h"
  45
  46 #include "lwip/def.h"
  47 #include "lwip/inet.h"
  48
  49 #include "lwip/sys.h"
  50
  51 /* This is a reference implementation of the checksum algorithm, with the
  52  * aim of being simple, correct and fully portable. Checksumming is the
  53  * first thing you would want to optimize for your platform. You will
  54  * need to port it to your architecture and in your sys_arch.h:
  55  *
  56  * #define LWIP_CHKSUM <your_checksum_routine>
  57 */
  58 #ifndef LWIP_CHKSUM
  59 #define LWIP_CHKSUM lwip_standard_chksum
  60
  61 /**
  62  * lwip checksum
  63  *
  64  * @param dataptr points to start of data to be summed at any boundary
  65  * @param len length of data to be summed
  66  * @return host order (!) lwip checksum (non-inverted Internet sum)
  67  *
  68  * @note accumulator size limits summable lenght to 64k
  69  * @note host endianess is irrelevant (p3 RFC1071)
  70  */
  71 static u16_t
  72 lwip_standard_chksum(void *dataptr, u16_t len)
  73 {
  74   u32_t acc;
  75   u16_t src;
  76   u8_t *octetptr;
  77
  78   acc = 0;
  79   /* dataptr may be at odd or even addresses */
  80   octetptr = (u8_t*)dataptr;
  81   while (len > 1)
  82   {
  83     /* declare first octet as most significant
  84        thus assume network order, ignoring host order */
  85     src = (*octetptr) << 8;
  86     octetptr++;
  87     /* declare second octet as least significant */
  88     src |= (*octetptr);
  89     octetptr++;
  90     acc += src;
  91     len -= 2;
  92   }
  93   if (len > 0)
  94   {
  95     /* accumulate remaining octet */
  96     src = (*octetptr) << 8;
  97     acc += src;
  98   }
  99   /* add deferred carry bits */
 100   acc = (acc >> 16) + (acc & 0x0000ffffUL);
 101   if ((acc & 0xffff0000) != 0) {
 102     acc = (acc >> 16) + (acc & 0x0000ffffUL);
 103   }
 104   /* This maybe a little confusing: reorder sum using htons()
 105      instead of ntohs() since it has a little less call overhead.
 106      The caller must invert bits for Internet sum ! */
 107   return htons((u16_t)acc);
 108 }
 109
 110 #endif
 111
 112 #if 0
 113 /*
 114  * Curt McDowell
 115  * Broadcom Corp.
 116  * csm@broadcom.com
 117  *
 118  * IP checksum two bytes at a time with support for
 119  * unaligned buffer.
 120  * Works for len up to and including 0x20000.
 121  * by Curt McDowell, Broadcom Corp. 12/08/2005
 122  */
 123
 124 static u16_t
 125 lwip_standard_chksum2(void *dataptr, int len)
 126 {
 127   u8_t *pb = dataptr;
 128   u16_t *ps, t = 0;
 129   u32_t sum = 0;
 130   int odd = ((u32_t)pb & 1);
 131
 132   /* Get aligned to u16_t */
 133   if (odd && len > 0) {
 134     ((u8_t *)&t)[1] = *pb++;
 135     len--;
 136   }
 137
 138   /* Add the bulk of the data */
 139   ps = (u16_t *)pb;
 140   while (len > 1) {
 141     sum += *ps++;
 142     len -= 2;
 143   }
 144
 145   /* Consume left-over byte, if any */
 146   if (len > 0)
 147     ((u8_t *)&t)[0] = *(u8_t *)ps;;
 148
 149   /* Add end bytes */
 150   sum += t;
 151
 152   /*  Fold 32-bit sum to 16 bits */
 153   while (sum >> 16)
 154     sum = (sum & 0xffff) + (sum >> 16);
 155
 156   /* Swap if alignment was odd */
 157   if (odd)
 158     sum = ((sum & 0xff) << 8) | ((sum & 0xff00) >> 8);
 159
 160   return sum;
 161 }
 162
 163 /**
 164  * An optimized checksum routine. Basically, it uses loop-unrolling on
 165  * the checksum loop, treating the head and tail bytes specially, whereas
 166  * the inner loop acts on 8 bytes at a time.
 167  *
 168  * @arg start of buffer to be checksummed. May be an odd byte address.
 169  * @len number of bytes in the buffer to be checksummed.
 170  *
 171  * @todo First argument type conflicts with generic checksum routine.
 172  *
 173  * by Curt McDowell, Broadcom Corp. December 8th, 2005
 174  */
 175
 176 static u16_t
 177 lwip_standard_chksum4(u8_t *pb, int len)
 178 {
 179   u16_t *ps, t = 0;
 180   u32_t *pl;
 181   u32_t sum = 0, tmp;
 182   /* starts at odd byte address? */
 183   int odd = ((u32_t)pb & 1);
 184
 185   if (odd && len > 0) {
 186     ((u8_t *)&t)[1] = *pb++;
 187     len--;
 188   }
 189
 190   ps = (u16_t *)pb;
 191
 192   if (((u32_t)ps & 3) && len > 1) {
 193     sum += *ps++;
 194     len -= 2;
 195   }
 196
 197   pl = (u32_t *)ps;
 198
 199   while (len > 7)  {
 200     tmp = sum + *pl++;          /* ping */
 201     if (tmp < sum)
 202       tmp++;                    /* add back carry */
 203
 204     sum = tmp + *pl++;          /* pong */
 205     if (sum < tmp)
 206       sum++;                    /* add back carry */
 207
 208     len -= 8;
 209   }
 210
 211   /* make room in upper bits */
 212   sum = (sum >> 16) + (sum & 0xffff);
 213
 214   ps = (u16_t *)pl;
 215
 216   /* 16-bit aligned word remaining? */
 217   while (len > 1) {
 218     sum += *ps++;
 219     len -= 2;
 220   }
 221
 222   /* dangling tail byte remaining? */
 223   if (len > 0)                  /* include odd byte */
 224     ((u8_t *)&t)[0] = *(u8_t *)ps;
 225
 226   sum += t;                     /* add end bytes */
 227
 228   while (sum >> 16)             /* combine halves */
 229     sum = (sum >> 16) + (sum & 0xffff);
 230
 231   if (odd)
 232     sum = ((sum & 0xff) << 8) | ((sum & 0xff00) >> 8);
 233
 234   return sum;
 235 }
 236 #endif
 237
 238 /* inet_chksum_pseudo:
 239  *
 240  * Calculates the pseudo Internet checksum used by TCP and UDP for a pbuf chain.
 241  */
 242
 243 u16_t
 244 inet_chksum_pseudo(struct pbuf *p,
 245        struct ip_addr *src, struct ip_addr *dest,
 246        u8_t proto, u16_t proto_len)
 247 {
 248   u32_t acc;
 249   struct pbuf *q;
 250   u8_t swapped;
 251
 252   acc = 0;
 253   swapped = 0;
 254   /* iterate through all pbuf in chain */
 255   for(q = p; q != NULL; q = q->next) {
 256     LWIP_DEBUGF(INET_DEBUG, ("inet_chksum_pseudo(): checksumming pbuf %p (has next %p) \n",
 257       (void *)q, (void *)q->next));
 258     acc += LWIP_CHKSUM(q->payload, q->len);
 259     /*LWIP_DEBUGF(INET_DEBUG, ("inet_chksum_pseudo(): unwrapped lwip_chksum()=%"X32_F" \n", acc));*/
 260     while (acc >> 16) {
 261       acc = (acc & 0xffffUL) + (acc >> 16);
 262     }
 263     if (q->len % 2 != 0) {
 264       swapped = 1 - swapped;
 265       acc = ((acc & 0xff) << 8) | ((acc & 0xff00UL) >> 8);
 266     }
 267     /*LWIP_DEBUGF(INET_DEBUG, ("inet_chksum_pseudo(): wrapped lwip_chksum()=%"X32_F" \n", acc));*/
 268   }
 269
 270   if (swapped) {
 271     acc = ((acc & 0xff) << 8) | ((acc & 0xff00UL) >> 8);
 272   }
 273   acc += (src->addr & 0xffffUL);
 274   acc += ((src->addr >> 16) & 0xffffUL);
 275   acc += (dest->addr & 0xffffUL);
 276   acc += ((dest->addr >> 16) & 0xffffUL);
 277   acc += (u32_t)htons((u16_t)proto);
 278   acc += (u32_t)htons(proto_len);
 279
 280   while (acc >> 16) {
 281     acc = (acc & 0xffffUL) + (acc >> 16);
 282   }
 283   LWIP_DEBUGF(INET_DEBUG, ("inet_chksum_pseudo(): pbuf chain lwip_chksum()=%"X32_F"\n", acc));
 284   return (u16_t)~(acc & 0xffffUL);
 285 }
 286
 287 /* inet_chksum:
 288  *
 289  * Calculates the Internet checksum over a portion of memory. Used primarely for IP
 290  * and ICMP.
 291  */
 292
 293 u16_t
 294 inet_chksum(void *dataptr, u16_t len)
 295 {
 296   u32_t acc;
 297
 298   acc = LWIP_CHKSUM(dataptr, len);
 299   while (acc >> 16) {
 300     acc = (acc & 0xffff) + (acc >> 16);
 301   }
 302   return (u16_t)~(acc & 0xffff);
 303 }
 304
 305 u16_t
 306 inet_chksum_pbuf(struct pbuf *p)
 307 {
 308   u32_t acc;
 309   struct pbuf *q;
 310   u8_t swapped;
 311
 312   acc = 0;
 313   swapped = 0;
 314   for(q = p; q != NULL; q = q->next) {
 315     acc += LWIP_CHKSUM(q->payload, q->len);
 316     while (acc >> 16) {
 317       acc = (acc & 0xffffUL) + (acc >> 16);
 318     }
 319     if (q->len % 2 != 0) {
 320       swapped = 1 - swapped;
 321       acc = (acc & 0x00ffUL << 8) | (acc & 0xff00UL >> 8);
 322     }
 323   }
 324
 325   if (swapped) {
 326     acc = ((acc & 0x00ffUL) << 8) | ((acc & 0xff00UL) >> 8);
 327   }
 328   return (u16_t)~(acc & 0xffffUL);
 329 }
 330