LXR linux/include/net/checksum.h

   1/*
   2 * INET         An implementation of the TCP/IP protocol suite for the LINUX
   3 *              operating system.  INET is implemented using the  BSD Socket
   4 *              interface as the means of communication with the user level.
   5 *
   6 *              Checksumming functions for IP, TCP, UDP and so on
   7 *
   8 * Authors:     Jorge Cwik, <jorge@laser.satlink.net>
   9 *              Arnt Gulbrandsen, <agulbra@nvg.unit.no>
  10 *              Borrows very liberally from tcp.c and ip.c, see those
  11 *              files for more names.
  12 *
  13 *              This program is free software; you can redistribute it and/or
  14 *              modify it under the terms of the GNU General Public License
  15 *              as published by the Free Software Foundation; either version
  16 *              2 of the License, or (at your option) any later version.
  17 */
  18
  19#ifndef _CHECKSUM_H
  20#define _CHECKSUM_H
  21
  22#include <linux/errno.h>
  23#include <asm/types.h>
  24#include <asm/byteorder.h>
  25#include <asm/uaccess.h>
  26#include <asm/checksum.h>
  27
  28#ifndef _HAVE_ARCH_COPY_AND_CSUM_FROM_USER
  29static inline
  30unsigned int csum_and_copy_from_user (const unsigned char __user *src, unsigned char *dst,
  31                                      int len, int sum, int *err_ptr)
  32{
  33        if (access_ok(VERIFY_READ, src, len))
  34                return csum_partial_copy_from_user(src, dst, len, sum, err_ptr);
  35
  36        if (len)
  37                *err_ptr = -EFAULT;
  38
  39        return sum;
  40}
  41#endif
  42
  43#ifndef HAVE_CSUM_COPY_USER
  44static __inline__ unsigned int csum_and_copy_to_user
  45(const unsigned char *src, unsigned char __user *dst, int len, unsigned int sum, int *err_ptr)
  46{
  47        sum = csum_partial(src, len, sum);
  48
  49        if (access_ok(VERIFY_WRITE, dst, len)) {
  50                if (copy_to_user(dst, src, len) == 0)
  51                        return sum;
  52        }
  53        if (len)
  54                *err_ptr = -EFAULT;
  55
  56        return -1; /* invalid checksum */
  57}
  58#endif
  59
  60static inline unsigned int csum_add(unsigned int csum, unsigned int addend)
  61{
  62        csum += addend;
  63        return csum + (csum < addend);
  64}
  65
  66static inline unsigned int csum_sub(unsigned int csum, unsigned int addend)
  67{
  68        return csum_add(csum, ~addend);
  69}
  70
  71static inline unsigned int
  72csum_block_add(unsigned int csum, unsigned int csum2, int offset)
  73{
  74        if (offset&1)
  75                csum2 = ((csum2&0xFF00FF)<<8)+((csum2>>8)&0xFF00FF);
  76        return csum_add(csum, csum2);
  77}
  78
  79static inline unsigned int
  80csum_block_sub(unsigned int csum, unsigned int csum2, int offset)
  81{
  82        if (offset&1)
  83                csum2 = ((csum2&0xFF00FF)<<8)+((csum2>>8)&0xFF00FF);
  84        return csum_sub(csum, csum2);
  85}
  86
  87#endif
  88