mirror of https://gitee.com/openkylin/linux.git
156 lines
3.7 KiB
C
156 lines
3.7 KiB
C
/*
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* INET An implementation of the TCP/IP protocol suite for the LINUX
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* operating system. INET is implemented using the BSD Socket
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* interface as the means of communication with the user level.
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*
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* MIPS specific IP/TCP/UDP checksumming routines
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*
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* Authors: Ralf Baechle, <ralf@waldorf-gmbh.de>
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* Lots of code moved from tcp.c and ip.c; see those files
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* for more names.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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* $Id: checksum.c,v 1.1 2002/09/28 14:58:40 gerg Exp $
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*/
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#include <net/checksum.h>
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#include <linux/module.h>
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#include <linux/types.h>
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#include <asm/byteorder.h>
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#include <asm/string.h>
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#include <asm/uaccess.h>
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static inline unsigned short from32to16 (unsigned long sum)
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{
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unsigned int result;
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/*
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%0 %1
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hsw %1, %0 H L L H
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add %1, %0 H L H+L+C H+L
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*/
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asm ("hsw %1, %0; add %1, %0" : "=&r" (result) : "r" (sum));
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return result >> 16;
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}
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static inline unsigned int do_csum(const unsigned char * buff, int len)
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{
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int odd, count;
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unsigned int result = 0;
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if (len <= 0)
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goto out;
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odd = 1 & (unsigned long) buff;
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if (odd) {
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result = be16_to_cpu(*buff);
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len--;
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buff++;
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}
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count = len >> 1; /* nr of 16-bit words.. */
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if (count) {
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if (2 & (unsigned long) buff) {
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result += *(unsigned short *) buff;
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count--;
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len -= 2;
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buff += 2;
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}
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count >>= 1; /* nr of 32-bit words.. */
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if (count) {
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unsigned int carry = 0;
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do {
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unsigned int w = *(unsigned int *) buff;
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count--;
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buff += 4;
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result += carry;
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result += w;
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carry = (w > result);
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} while (count);
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result += carry;
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result = (result & 0xffff) + (result >> 16);
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}
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if (len & 2) {
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result += *(unsigned short *) buff;
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buff += 2;
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}
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}
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if (len & 1)
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result += le16_to_cpu(*buff);
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result = from32to16(result);
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if (odd)
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result = ((result >> 8) & 0xff) | ((result & 0xff) << 8);
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out:
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return result;
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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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unsigned short ip_fast_csum(unsigned char * iph, unsigned int ihl)
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{
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return ~do_csum(iph,ihl*4);
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}
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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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unsigned short ip_compute_csum(const unsigned char * buff, int len)
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{
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return ~do_csum(buff,len);
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}
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/*
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* computes a partial checksum, e.g. for TCP/UDP fragments
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*/
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unsigned int csum_partial(const unsigned char *buff, int len, unsigned int sum)
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{
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unsigned int result = do_csum(buff, len);
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/* add in old sum, and carry.. */
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result += sum;
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if(sum > result)
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result += 1;
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return result;
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}
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EXPORT_SYMBOL(csum_partial);
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/*
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* copy while checksumming, otherwise like csum_partial
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*/
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unsigned int csum_partial_copy(const unsigned char *src, unsigned char *dst,
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int len, unsigned int sum)
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{
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/*
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* It's 2:30 am and I don't feel like doing it real ...
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* This is lots slower than the real thing (tm)
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*/
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sum = csum_partial(src, len, sum);
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memcpy(dst, src, len);
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return sum;
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}
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/*
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* Copy from userspace and compute checksum. If we catch an exception
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* then zero the rest of the buffer.
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*/
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unsigned int csum_partial_copy_from_user (const unsigned char *src,
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unsigned char *dst,
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int len, unsigned int sum,
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int *err_ptr)
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{
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int missing;
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missing = copy_from_user(dst, src, len);
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if (missing) {
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memset(dst + len - missing, 0, missing);
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*err_ptr = -EFAULT;
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}
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return csum_partial(dst, len, sum);
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}
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