net: Add a separate file for IP checksumming
Move the checksum code out into its own file so it can be used elsewhere. Also use a new version which supports a length which is not a multiple of 2 and add a new function to add two checksums. Signed-off-by: Simon Glass <sjg@chromium.org>
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@ -482,6 +482,36 @@ extern void net_set_ip_header(uchar *pkt, IPaddr_t dest, IPaddr_t source);
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extern void net_set_udp_header(uchar *pkt, IPaddr_t dest, int dport,
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int sport, int len);
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/**
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* compute_ip_checksum() - Compute IP checksum
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*
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* @addr: Address to check (must be 16-bit aligned)
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* @nbytes: Number of bytes to check (normally a multiple of 2)
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* @return 16-bit IP checksum
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*/
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unsigned compute_ip_checksum(const void *addr, unsigned nbytes);
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/**
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* add_ip_checksums() - add two IP checksums
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*
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* @offset: Offset of first sum (if odd we do a byte-swap)
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* @sum: First checksum
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* @new_sum: New checksum to add
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* @return updated 16-bit IP checksum
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*/
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unsigned add_ip_checksums(unsigned offset, unsigned sum, unsigned new_sum);
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/**
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* ip_checksum_ok() - check if a checksum is correct
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*
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* This works by making sure the checksum sums to 0
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*
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* @addr: Address to check (must be 16-bit aligned)
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* @nbytes: Number of bytes to check (normally a multiple of 2)
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* @return true if the checksum matches, false if not
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*/
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int ip_checksum_ok(const void *addr, unsigned nbytes);
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/* Checksum */
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extern int NetCksumOk(uchar *, int); /* Return true if cksum OK */
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extern uint NetCksum(uchar *, int); /* Calculate the checksum */
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@ -7,6 +7,7 @@
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#ccflags-y += -DDEBUG
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obj-y += checksum.o
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obj-$(CONFIG_CMD_NET) += arp.o
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obj-$(CONFIG_CMD_NET) += bootp.o
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obj-$(CONFIG_CMD_CDP) += cdp.o
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60
net/checksum.c
Normal file
60
net/checksum.c
Normal file
@ -0,0 +1,60 @@
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/*
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* This file was originally taken from the FreeBSD project.
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*
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* Copyright (c) 2001 Charles Mott <cm@linktel.net>
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* Copyright (c) 2008 coresystems GmbH
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* All rights reserved.
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <common.h>
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#include <net.h>
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unsigned compute_ip_checksum(const void *vptr, unsigned nbytes)
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{
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int sum, oddbyte;
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const unsigned short *ptr = vptr;
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sum = 0;
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while (nbytes > 1) {
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sum += *ptr++;
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nbytes -= 2;
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}
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if (nbytes == 1) {
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oddbyte = 0;
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((u8 *)&oddbyte)[0] = *(u8 *)ptr;
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((u8 *)&oddbyte)[1] = 0;
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sum += oddbyte;
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}
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sum = (sum >> 16) + (sum & 0xffff);
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sum += (sum >> 16);
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sum = ~sum & 0xffff;
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return sum;
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}
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unsigned add_ip_checksums(unsigned offset, unsigned sum, unsigned new)
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{
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unsigned long checksum;
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sum = ~sum & 0xffff;
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new = ~new & 0xffff;
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if (offset & 1) {
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/*
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* byte-swap the sum if it came from an odd offset; since the
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* computation is endian independant this works.
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*/
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new = ((new >> 8) & 0xff) | ((new << 8) & 0xff00);
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}
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checksum = sum + new;
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if (checksum > 0xffff)
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checksum -= 0xffff;
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return (~checksum) & 0xffff;
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}
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int ip_checksum_ok(const void *addr, unsigned nbytes)
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{
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return !(compute_ip_checksum(addr, nbytes) & 0xfffe);
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}
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