--- /dev/null
+/**
+ * @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 <adam@sics.se>
+ *
+ */
+
+#include "lwip/opt.h"
+
+#include "lwip/inet_chksum.h"
+#include "lwip/inet.h"
+
+#include <string.h>
+
+/* 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 <your_checksum_routine>
+ *
+ * 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);
+}
