/* * Copyright (c) 2001-2004 Swedish Institute of Computer Science. * All rights reserved.  *  * Redistribution and use in source and binary forms, with or without modification,  * are permitted provided that the following conditions are met: * * 1. Redistributions of source code must retain the above copyright notice, *    this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright notice, *    this list of conditions and the following disclaimer in the documentation *    and/or other materials provided with the distribution. * 3. The name of the author may not be used to endorse or promote products *    derived from this software without specific prior written permission.  * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT  * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT  * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY  * OF SUCH DAMAGE. * * This file is part of the lwIP TCP/IP stack. *  * Author: Adam Dunkels <adam@sics.se> * *//* inet6.c * * Functions common to all TCP/IP modules, such as the Internet checksum and the * byte order functions. * */#include "lwip/opt.h"#include "lwip/def.h"#include "lwip/inet.h"/* chksum: * * Sums up all 16 bit words in a memory portion. Also includes any odd byte. * This function is used by the other checksum functions. * * For now, this is not optimized. Must be optimized for the particular processor * arcitecture on which it is to run. Preferebly coded in assembler. */static u32_tchksum(void *dataptr, u16_t len){  u16_t *sdataptr = dataptr;  u32_t acc;      for(acc = 0; len > 1; len -= 2) {    acc += *sdataptr++;  }  /* add up any odd byte */  if (len == 1) {    acc += htons((u16_t)(*(u8_t *)dataptr) << 8);  }  return acc;}/* inet_chksum_pseudo: * * Calculates the pseudo Internet checksum used by TCP and UDP for a pbuf chain. */u16_tinet_chksum_pseudo(struct pbuf *p,       struct ip_addr *src, struct ip_addr *dest,       u8_t proto, u32_t proto_len){  u32_t acc;  struct pbuf *q;  u8_t swapped, i;  acc = 0;  swapped = 0;  for(q = p; q != NULL; q = q->next) {        acc += chksum(q->payload, q->len);    while (acc >> 16) {      acc = (acc & 0xffff) + (acc >> 16);    }    if (q->len % 2 != 0) {      swapped = 1 - swapped;      acc = ((acc & 0xff) << 8) | ((acc & 0xff00) >> 8);    }  }  if (swapped) {    acc = ((acc & 0xff) << 8) | ((acc & 0xff00) >> 8);  }    for(i = 0; i < 8; i++) {    acc += ((u16_t *)src->addr)[i] & 0xffff;    acc += ((u16_t *)dest->addr)[i] & 0xffff;    while (acc >> 16) {      acc = (acc & 0xffff) + (acc >> 16);    }  }  acc += (u16_t)htons((u16_t)proto);  acc += ((u16_t *)&proto_len)[0] & 0xffff;  acc += ((u16_t *)&proto_len)[1] & 0xffff;  while (acc >> 16) {    acc = (acc & 0xffff) + (acc >> 16);  }  return ~(acc & 0xffff);}/* inet_chksum: * * Calculates the Internet checksum over a portion of memory. Used primarely for IP * and ICMP. */u16_tinet_chksum(void *dataptr, u16_t len){  u32_t acc, sum;  acc = chksum(dataptr, len);  sum = (acc & 0xffff) + (acc >> 16);  sum += (sum >> 16);  return ~(sum & 0xffff);}u16_tinet_chksum_pbuf(struct pbuf *p){  u32_t acc;  struct pbuf *q;  u8_t swapped;    acc = 0;  swapped = 0;  for(q = p; q != NULL; q = q->next) {    acc += chksum(q->payload, q->len);    while (acc >> 16) {      acc = (acc & 0xffff) + (acc >> 16);    }        if (q->len % 2 != 0) {      swapped = 1 - swapped;      acc = (acc & 0xff << 8) | (acc & 0xff00 >> 8);    }  }   if (swapped) {    acc = ((acc & 0xff) << 8) | ((acc & 0xff00) >> 8);  }  return ~(acc & 0xffff);}