www.pudn.com > lwip-1.3.0.rar > inet_chksum.c
/**
* @file
* Incluse internet checksum 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
*
*/
#include "lwip/opt.h"
#include "lwip/inet_chksum.h"
#include "lwip/inet.h"
#include
/* These are some reference implementations of the checksum algorithm, with the
* aim of being simple, correct and fully portable. Checksumming is the
* first thing you would want to optimize for your platform. If you create
* your own version, link it in and in your cc.h put:
*
* #define LWIP_CHKSUM
*
* Or you can select from the implementations below by defining
* LWIP_CHKSUM_ALGORITHM to 1, 2 or 3.
*/
#ifndef LWIP_CHKSUM
# define LWIP_CHKSUM lwip_standard_chksum
# ifndef LWIP_CHKSUM_ALGORITHM
# define LWIP_CHKSUM_ALGORITHM 1
# endif
#endif
/* If none set: */
#ifndef LWIP_CHKSUM_ALGORITHM
# define LWIP_CHKSUM_ALGORITHM 0
#endif
#if (LWIP_CHKSUM_ALGORITHM == 1) /* Version #1 */
/**
* lwip checksum
*
* @param dataptr points to start of data to be summed at any boundary
* @param len length of data to be summed
* @return host order (!) lwip checksum (non-inverted Internet sum)
*
* @note accumulator size limits summable length to 64k
* @note host endianess is irrelevant (p3 RFC1071)
*/
static u16_t
lwip_standard_chksum(void *dataptr, u16_t len)
{
u32_t acc;
u16_t src;
u8_t *octetptr;
acc = 0;
/* dataptr may be at odd or even addresses */
octetptr = (u8_t*)dataptr;
while (len > 1)
{
/* declare first octet as most significant
thus assume network order, ignoring host order */
src = (*octetptr) << 8;
octetptr++;
/* declare second octet as least significant */
src |= (*octetptr);
octetptr++;
acc += src;
len -= 2;
}
if (len > 0)
{
/* accumulate remaining octet */
src = (*octetptr) << 8;
acc += src;
}
/* add deferred carry bits */
acc = (acc >> 16) + (acc & 0x0000ffffUL);
if ((acc & 0xffff0000) != 0) {
acc = (acc >> 16) + (acc & 0x0000ffffUL);
}
/* This maybe a little confusing: reorder sum using htons()
instead of ntohs() since it has a little less call overhead.
The caller must invert bits for Internet sum ! */
return htons((u16_t)acc);
}
#endif
#if (LWIP_CHKSUM_ALGORITHM == 2) /* Alternative version #2 */
/*
* Curt McDowell
* Broadcom Corp.
* csm@broadcom.com
*
* IP checksum two bytes at a time with support for
* unaligned buffer.
* Works for len up to and including 0x20000.
* by Curt McDowell, Broadcom Corp. 12/08/2005
*
* @param dataptr points to start of data to be summed at any boundary
* @param len length of data to be summed
* @return host order (!) lwip checksum (non-inverted Internet sum)
*/
static u16_t
lwip_standard_chksum(void *dataptr, int len)
{
u8_t *pb = dataptr;
u16_t *ps, t = 0;
u32_t sum = 0;
int odd = ((u32_t)pb & 1);
/* Get aligned to u16_t */
if (odd && len > 0) {
((u8_t *)&t)[1] = *pb++;
len--;
}
/* Add the bulk of the data */
ps = (u16_t *)pb;
while (len > 1) {
sum += *ps++;
len -= 2;
}
/* Consume left-over byte, if any */
if (len > 0)
((u8_t *)&t)[0] = *(u8_t *)ps;;
/* Add end bytes */
sum += t;
/* Fold 32-bit sum to 16 bits */
while ((sum >> 16) != 0)
sum = (sum & 0xffff) + (sum >> 16);
/* Swap if alignment was odd */
if (odd)
sum = ((sum & 0xff) << 8) | ((sum & 0xff00) >> 8);
return sum;
}
#endif
#if (LWIP_CHKSUM_ALGORITHM == 3) /* Alternative version #3 */
/**
* An optimized checksum routine. Basically, it uses loop-unrolling on
* the checksum loop, treating the head and tail bytes specially, whereas
* the inner loop acts on 8 bytes at a time.
*
* @arg start of buffer to be checksummed. May be an odd byte address.
* @len number of bytes in the buffer to be checksummed.
* @return host order (!) lwip checksum (non-inverted Internet sum)
*
* by Curt McDowell, Broadcom Corp. December 8th, 2005
*/
static u16_t
lwip_standard_chksum(void *dataptr, int len)
{
u8_t *pb = dataptr;
u16_t *ps, t = 0;
u32_t *pl;
u32_t sum = 0, tmp;
/* starts at odd byte address? */
int odd = ((u32_t)pb & 1);
if (odd && len > 0) {
((u8_t *)&t)[1] = *pb++;
len--;
}
ps = (u16_t *)pb;
if (((u32_t)ps & 3) && len > 1) {
sum += *ps++;
len -= 2;
}
pl = (u32_t *)ps;
while (len > 7) {
tmp = sum + *pl++; /* ping */
if (tmp < sum)
tmp++; /* add back carry */
sum = tmp + *pl++; /* pong */
if (sum < tmp)
sum++; /* add back carry */
len -= 8;
}
/* make room in upper bits */
sum = (sum >> 16) + (sum & 0xffff);
ps = (u16_t *)pl;
/* 16-bit aligned word remaining? */
while (len > 1) {
sum += *ps++;
len -= 2;
}
/* dangling tail byte remaining? */
if (len > 0) /* include odd byte */
((u8_t *)&t)[0] = *(u8_t *)ps;
sum += t; /* add end bytes */
while ((sum >> 16) != 0) /* combine halves */
sum = (sum >> 16) + (sum & 0xffff);
if (odd)
sum = ((sum & 0xff) << 8) | ((sum & 0xff00) >> 8);
return sum;
}
#endif
/* inet_chksum_pseudo:
*
* Calculates the pseudo Internet checksum used by TCP and UDP for a pbuf chain.
* IP addresses are expected to be in network byte order.
*
* @param p chain of pbufs over that a checksum should be calculated (ip data part)
* @param src source ip address (used for checksum of pseudo header)
* @param dst destination ip address (used for checksum of pseudo header)
* @param proto ip protocol (used for checksum of pseudo header)
* @param proto_len length of the ip data part (used for checksum of pseudo header)
* @return checksum (as u16_t) to be saved directly in the protocol header
*/
u16_t
inet_chksum_pseudo(struct pbuf *p,
struct ip_addr *src, struct ip_addr *dest,
u8_t proto, u16_t proto_len)
{
u32_t acc;
struct pbuf *q;
u8_t swapped;
acc = 0;
swapped = 0;
/* iterate through all pbuf in chain */
for(q = p; q != NULL; q = q->next) {
LWIP_DEBUGF(INET_DEBUG, ("inet_chksum_pseudo(): checksumming pbuf %p (has next %p) \n",
(void *)q, (void *)q->next));
acc += LWIP_CHKSUM(q->payload, q->len);
/*LWIP_DEBUGF(INET_DEBUG, ("inet_chksum_pseudo(): unwrapped lwip_chksum()=%"X32_F" \n", acc));*/
while ((acc >> 16) != 0) {
acc = (acc & 0xffffUL) + (acc >> 16);
}
if (q->len % 2 != 0) {
swapped = 1 - swapped;
acc = ((acc & 0xff) << 8) | ((acc & 0xff00UL) >> 8);
}
/*LWIP_DEBUGF(INET_DEBUG, ("inet_chksum_pseudo(): wrapped lwip_chksum()=%"X32_F" \n", acc));*/
}
if (swapped) {
acc = ((acc & 0xff) << 8) | ((acc & 0xff00UL) >> 8);
}
acc += (src->addr & 0xffffUL);
acc += ((src->addr >> 16) & 0xffffUL);
acc += (dest->addr & 0xffffUL);
acc += ((dest->addr >> 16) & 0xffffUL);
acc += (u32_t)htons((u16_t)proto);
acc += (u32_t)htons(proto_len);
while ((acc >> 16) != 0) {
acc = (acc & 0xffffUL) + (acc >> 16);
}
LWIP_DEBUGF(INET_DEBUG, ("inet_chksum_pseudo(): pbuf chain lwip_chksum()=%"X32_F"\n", acc));
return (u16_t)~(acc & 0xffffUL);
}
/* inet_chksum_pseudo:
*
* Calculates the pseudo Internet checksum used by TCP and UDP for a pbuf chain.
* IP addresses are expected to be in network byte order.
*
* @param p chain of pbufs over that a checksum should be calculated (ip data part)
* @param src source ip address (used for checksum of pseudo header)
* @param dst destination ip address (used for checksum of pseudo header)
* @param proto ip protocol (used for checksum of pseudo header)
* @param proto_len length of the ip data part (used for checksum of pseudo header)
* @return checksum (as u16_t) to be saved directly in the protocol header
*/
u16_t
inet_chksum_pseudo_partial(struct pbuf *p,
struct ip_addr *src, struct ip_addr *dest,
u8_t proto, u16_t proto_len, u16_t chksum_len)
{
u32_t acc;
struct pbuf *q;
u8_t swapped;
u16_t chklen;
acc = 0;
swapped = 0;
/* iterate through all pbuf in chain */
for(q = p; (q != NULL) && (chksum_len > 0); q = q->next) {
LWIP_DEBUGF(INET_DEBUG, ("inet_chksum_pseudo(): checksumming pbuf %p (has next %p) \n",
(void *)q, (void *)q->next));
chklen = q->len;
if (chklen > chksum_len) {
chklen = chksum_len;
}
acc += LWIP_CHKSUM(q->payload, chklen);
chksum_len -= chklen;
LWIP_ASSERT("delete me", chksum_len < 0x7fff);
/*LWIP_DEBUGF(INET_DEBUG, ("inet_chksum_pseudo(): unwrapped lwip_chksum()=%"X32_F" \n", acc));*/
while ((acc >> 16) != 0) {
acc = (acc & 0xffffUL) + (acc >> 16);
}
if (q->len % 2 != 0) {
swapped = 1 - swapped;
acc = ((acc & 0xff) << 8) | ((acc & 0xff00UL) >> 8);
}
/*LWIP_DEBUGF(INET_DEBUG, ("inet_chksum_pseudo(): wrapped lwip_chksum()=%"X32_F" \n", acc));*/
}
if (swapped) {
acc = ((acc & 0xff) << 8) | ((acc & 0xff00UL) >> 8);
}
acc += (src->addr & 0xffffUL);
acc += ((src->addr >> 16) & 0xffffUL);
acc += (dest->addr & 0xffffUL);
acc += ((dest->addr >> 16) & 0xffffUL);
acc += (u32_t)htons((u16_t)proto);
acc += (u32_t)htons(proto_len);
while ((acc >> 16) != 0) {
acc = (acc & 0xffffUL) + (acc >> 16);
}
LWIP_DEBUGF(INET_DEBUG, ("inet_chksum_pseudo(): pbuf chain lwip_chksum()=%"X32_F"\n", acc));
return (u16_t)~(acc & 0xffffUL);
}
/* inet_chksum:
*
* Calculates the Internet checksum over a portion of memory. Used primarily for IP
* and ICMP.
*
* @param dataptr start of the buffer to calculate the checksum (no alignment needed)
* @param len length of the buffer to calculate the checksum
* @return checksum (as u16_t) to be saved directly in the protocol header
*/
u16_t
inet_chksum(void *dataptr, u16_t len)
{
u32_t acc;
acc = LWIP_CHKSUM(dataptr, len);
while ((acc >> 16) != 0) {
acc = (acc & 0xffff) + (acc >> 16);
}
return (u16_t)~(acc & 0xffff);
}
/**
* Calculate a checksum over a chain of pbufs (without pseudo-header, much like
* inet_chksum only pbufs are used).
*
* @param p pbuf chain over that the checksum should be calculated
* @return checksum (as u16_t) to be saved directly in the protocol header
*/
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 += LWIP_CHKSUM(q->payload, q->len);
while ((acc >> 16) != 0) {
acc = (acc & 0xffffUL) + (acc >> 16);
}
if (q->len % 2 != 0) {
swapped = 1 - swapped;
acc = (acc & 0x00ffUL << 8) | (acc & 0xff00UL >> 8);
}
}
if (swapped) {
acc = ((acc & 0x00ffUL) << 8) | ((acc & 0xff00UL) >> 8);
}
return (u16_t)~(acc & 0xffffUL);
}