| /** |
| * @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); |
| } |