148 lines
3.5 KiB
C
148 lines
3.5 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* This file contains network checksum routines that are better done
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* in an architecture-specific manner due to speed..
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* Comments in other versions indicate that the algorithms are from RFC1071
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*/
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#include <linux/module.h>
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#include <linux/string.h>
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#include <asm/byteorder.h>
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#include <asm/checksum.h>
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/*
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* computes the checksum of the TCP/UDP pseudo-header
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* returns a 16-bit checksum, already complemented.
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*/
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__sum16 csum_tcpudp_magic(__be32 saddr, __be32 daddr,
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__u32 len, __u8 proto, __wsum sum)
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{
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return (__force __sum16)~from64to16(
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(__force u64)saddr + (__force u64)daddr +
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(__force u64)sum + ((len + proto) << 8));
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}
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EXPORT_SYMBOL(csum_tcpudp_magic);
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__wsum csum_tcpudp_nofold(__be32 saddr, __be32 daddr,
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__u32 len, __u8 proto, __wsum sum)
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{
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unsigned long result;
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result = (__force u64)saddr + (__force u64)daddr +
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(__force u64)sum + ((len + proto) << 8);
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/*
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* Fold down to 32-bits so we don't lose in the typedef-less
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* network stack.
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*
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* 64 to 33
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*/
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result = (result & 0xffffffff) + (result >> 32);
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/* 33 to 32 */
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result = (result & 0xffffffff) + (result >> 32);
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return (__force __wsum)result;
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}
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EXPORT_SYMBOL(csum_tcpudp_nofold);
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/*
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* Do a 64-bit checksum on an arbitrary memory area..
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*/
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static inline unsigned long do_csum(const unsigned char *buff, int len)
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{
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const unsigned long *dst = (unsigned long *)buff;
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unsigned long doff = 7 & (unsigned long) dst;
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unsigned long checksum = 0;
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unsigned long word, patch;
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unsigned long partial_dest, second_dest;
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len -= 8;
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if (!doff) {
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while (len > 0) {
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word = *dst;
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checksum += word;
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checksum += (checksum < word);
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dst++;
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len -= 8;
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}
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len += 8;
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word = *dst;
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if (len != 8)
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maskll(word, len, word);
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checksum += word;
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checksum += (checksum < word);
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} else {
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dst = (unsigned long *)((unsigned long)dst & (~7UL));
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word = *dst;
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inshl(word, 8 - doff, partial_dest);
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dst++;
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while (len >= 0) {
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word = *dst;
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insll(word, 8 - doff, second_dest);
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patch = partial_dest | second_dest;
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checksum += patch;
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checksum += (checksum < patch);
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inshl(word, 8 - doff, partial_dest);
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dst++;
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len -= 8;
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}
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len += 8;
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word = *dst;
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insll(word, 8 - doff, second_dest);
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patch = partial_dest | second_dest;
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maskll(patch, len, patch);
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checksum += patch;
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checksum += (checksum < patch);
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}
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return from64to16(checksum);
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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(const void *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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unsigned long result = do_csum(buff, len);
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/* add in old sum, and carry.. */
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result += (__force u32)sum;
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/* 32+c bits -> 32 bits */
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result = (result & 0xffffffff) + (result >> 32);
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return (__force __wsum)result;
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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)~from64to16(do_csum(buff, len));
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}
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EXPORT_SYMBOL(ip_compute_csum);
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