inet6.c
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/**
* @file
* Functions common to all TCP/IPv6 modules, such as the Internet checksum and the
* byte order functions.
*
*/
/*
* 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>
*
*/
#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_t
chksum(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_t
inet_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_t
inet_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_t
inet_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);
}