[164] | 1 | /**
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| 2 | * @file
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| 3 | * Functions common to all TCP/IPv6 modules, such as the Internet checksum and the
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| 4 | * byte order functions.
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| 5 | *
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| 6 | */
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| 7 |
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| 8 | /*
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| 9 | * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
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| 10 | * All rights reserved.
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| 11 | *
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| 12 | * Redistribution and use in source and binary forms, with or without modification,
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| 13 | * are permitted provided that the following conditions are met:
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| 14 | *
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| 15 | * 1. Redistributions of source code must retain the above copyright notice,
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| 16 | * this list of conditions and the following disclaimer.
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| 17 | * 2. Redistributions in binary form must reproduce the above copyright notice,
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| 18 | * this list of conditions and the following disclaimer in the documentation
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| 19 | * and/or other materials provided with the distribution.
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| 20 | * 3. The name of the author may not be used to endorse or promote products
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| 21 | * derived from this software without specific prior written permission.
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| 22 | *
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| 23 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
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| 24 | * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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| 25 | * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
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| 26 | * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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| 27 | * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
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| 28 | * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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| 29 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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| 30 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
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| 31 | * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
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| 32 | * OF SUCH DAMAGE.
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| 33 | *
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| 34 | * This file is part of the lwIP TCP/IP stack.
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| 35 | *
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| 36 | * Author: Adam Dunkels <adam@sics.se>
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| 37 | *
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| 38 | */
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| 39 |
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| 40 | #include "lwip/opt.h"
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| 41 |
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| 42 | #include "lwip/def.h"
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| 43 | #include "lwip/inet.h"
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| 44 |
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| 45 | /* chksum:
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| 46 | *
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| 47 | * Sums up all 16 bit words in a memory portion. Also includes any odd byte.
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| 48 | * This function is used by the other checksum functions.
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| 49 | *
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| 50 | * For now, this is not optimized. Must be optimized for the particular processor
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| 51 | * arcitecture on which it is to run. Preferebly coded in assembler.
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| 52 | */
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| 53 |
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| 54 | static u32_t
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| 55 | chksum(void *dataptr, u16_t len)
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| 56 | {
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| 57 | u16_t *sdataptr = dataptr;
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| 58 | u32_t acc;
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| 59 |
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| 60 |
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| 61 | for(acc = 0; len > 1; len -= 2) {
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| 62 | acc += *sdataptr++;
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| 63 | }
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| 64 |
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| 65 | /* add up any odd byte */
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| 66 | if (len == 1) {
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| 67 | acc += htons((u16_t)(*(u8_t *)dataptr) << 8);
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| 68 | }
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| 69 |
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| 70 | return acc;
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| 71 |
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| 72 | }
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| 73 |
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| 74 | /* inet_chksum_pseudo:
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| 75 | *
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| 76 | * Calculates the pseudo Internet checksum used by TCP and UDP for a pbuf chain.
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| 77 | */
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| 78 |
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| 79 | u16_t
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| 80 | inet_chksum_pseudo(struct pbuf *p,
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| 81 | struct ip_addr *src, struct ip_addr *dest,
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| 82 | u8_t proto, u32_t proto_len)
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| 83 | {
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| 84 | u32_t acc;
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| 85 | struct pbuf *q;
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| 86 | u8_t swapped, i;
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| 87 |
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| 88 | acc = 0;
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| 89 | swapped = 0;
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| 90 | for(q = p; q != NULL; q = q->next) {
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| 91 | acc += chksum(q->payload, q->len);
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| 92 | while (acc >> 16) {
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| 93 | acc = (acc & 0xffff) + (acc >> 16);
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| 94 | }
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| 95 | if (q->len % 2 != 0) {
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| 96 | swapped = 1 - swapped;
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| 97 | acc = ((acc & 0xff) << 8) | ((acc & 0xff00) >> 8);
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| 98 | }
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| 99 | }
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| 100 |
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| 101 | if (swapped) {
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| 102 | acc = ((acc & 0xff) << 8) | ((acc & 0xff00) >> 8);
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| 103 | }
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| 104 |
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| 105 | for(i = 0; i < 8; i++) {
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| 106 | acc += ((u16_t *)src->addr)[i] & 0xffff;
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| 107 | acc += ((u16_t *)dest->addr)[i] & 0xffff;
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| 108 | while (acc >> 16) {
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| 109 | acc = (acc & 0xffff) + (acc >> 16);
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| 110 | }
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| 111 | }
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| 112 | acc += (u16_t)htons((u16_t)proto);
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| 113 | acc += ((u16_t *)&proto_len)[0] & 0xffff;
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| 114 | acc += ((u16_t *)&proto_len)[1] & 0xffff;
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| 115 |
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| 116 | while (acc >> 16) {
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| 117 | acc = (acc & 0xffff) + (acc >> 16);
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| 118 | }
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| 119 | return ~(acc & 0xffff);
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| 120 | }
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| 121 |
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| 122 | /* inet_chksum:
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| 123 | *
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| 124 | * Calculates the Internet checksum over a portion of memory. Used primarely for IP
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| 125 | * and ICMP.
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| 126 | */
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| 127 |
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| 128 | u16_t
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| 129 | inet_chksum(void *dataptr, u16_t len)
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| 130 | {
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| 131 | u32_t acc, sum;
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| 132 |
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| 133 | acc = chksum(dataptr, len);
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| 134 | sum = (acc & 0xffff) + (acc >> 16);
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| 135 | sum += (sum >> 16);
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| 136 | return ~(sum & 0xffff);
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| 137 | }
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| 138 |
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| 139 | u16_t
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| 140 | inet_chksum_pbuf(struct pbuf *p)
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| 141 | {
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| 142 | u32_t acc;
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| 143 | struct pbuf *q;
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| 144 | u8_t swapped;
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| 145 |
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| 146 | acc = 0;
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| 147 | swapped = 0;
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| 148 | for(q = p; q != NULL; q = q->next) {
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| 149 | acc += chksum(q->payload, q->len);
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| 150 | while (acc >> 16) {
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| 151 | acc = (acc & 0xffff) + (acc >> 16);
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| 152 | }
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| 153 | if (q->len % 2 != 0) {
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| 154 | swapped = 1 - swapped;
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| 155 | acc = (acc & 0xff << 8) | (acc & 0xff00 >> 8);
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| 156 | }
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| 157 | }
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| 158 |
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| 159 | if (swapped) {
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| 160 | acc = ((acc & 0xff) << 8) | ((acc & 0xff00) >> 8);
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| 161 | }
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| 162 | return ~(acc & 0xffff);
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| 163 | }
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