126 lines
2.7 KiB
C
126 lines
2.7 KiB
C
/*
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* Copyright 2004-2009 Analog Devices Inc.
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*
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* Licensed under the GPL-2 or later.
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*
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* An implementation of the TCP/IP protocol suite for the LINUX operating
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* system. INET is implemented using the BSD Socket interface as the
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* means of communication with the user level.
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*
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*/
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#include <linux/module.h>
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#include <net/checksum.h>
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#include <asm/checksum.h>
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#ifdef CONFIG_IP_CHECKSUM_L1
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static unsigned short do_csum(const unsigned char *buff, int len)__attribute__((l1_text));
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#endif
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static unsigned short do_csum(const unsigned char *buff, int len)
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{
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register unsigned long sum = 0;
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int swappem = 0;
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if (1 & (unsigned long)buff) {
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sum = *buff << 8;
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buff++;
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len--;
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++swappem;
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}
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while (len > 1) {
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sum += *(unsigned short *)buff;
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buff += 2;
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len -= 2;
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}
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if (len > 0)
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sum += *buff;
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/* Fold 32-bit sum to 16 bits */
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while (sum >> 16)
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sum = (sum & 0xffff) + (sum >> 16);
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if (swappem)
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sum = ((sum & 0xff00) >> 8) + ((sum & 0x00ff) << 8);
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return sum;
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}
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/*
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* This is a version of ip_compute_csum() optimized for IP headers,
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* which always checksum on 4 octet boundaries.
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*/
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__sum16 ip_fast_csum(unsigned char *iph, unsigned int ihl)
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{
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return (__force __sum16)~do_csum(iph, ihl * 4);
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}
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EXPORT_SYMBOL(ip_fast_csum);
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/*
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* computes the checksum of a memory block at buff, length len,
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* and adds in "sum" (32-bit)
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*
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* returns a 32-bit number suitable for feeding into itself
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* or csum_tcpudp_magic
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*
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* this function must be called with even lengths, except
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* for the last fragment, which may be odd
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*
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* it's best to have buff aligned on a 32-bit boundary
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*/
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__wsum csum_partial(const void *buff, int len, __wsum sum)
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{
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/*
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* Just in case we get nasty checksum data...
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* Like 0xffff6ec3 in the case of our IPv6 multicast header.
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* We fold to begin with, as well as at the end.
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*/
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sum = (sum & 0xffff) + (sum >> 16);
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sum += do_csum(buff, len);
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sum = (sum & 0xffff) + (sum >> 16);
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return sum;
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}
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EXPORT_SYMBOL(csum_partial);
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/*
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* this routine is used for miscellaneous IP-like checksums, mainly
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* in icmp.c
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*/
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__sum16 ip_compute_csum(const void *buff, int len)
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{
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return (__force __sum16)~do_csum(buff, len);
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}
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EXPORT_SYMBOL(ip_compute_csum);
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/*
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* copy from fs while checksumming, otherwise like csum_partial
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*/
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__wsum
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csum_partial_copy_from_user(const void __user *src, void *dst,
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int len, __wsum sum, int *csum_err)
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{
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if (csum_err)
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*csum_err = 0;
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memcpy(dst, (__force void *)src, len);
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return csum_partial(dst, len, sum);
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}
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EXPORT_SYMBOL(csum_partial_copy_from_user);
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/*
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* copy from ds while checksumming, otherwise like csum_partial
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*/
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__wsum csum_partial_copy(const void *src, void *dst, int len, __wsum sum)
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{
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memcpy(dst, src, len);
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return csum_partial(dst, len, sum);
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}
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EXPORT_SYMBOL(csum_partial_copy);
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