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
  29 static inline
  30 unsigned 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
  44 static __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
  60 static inline unsigned int csum_add(unsigned int csum, unsigned int addend)
  61 {
  62         csum += addend;
  63         return csum + (csum < addend);
  64 }
  65
  66 static inline unsigned int csum_sub(unsigned int csum, unsigned int addend)
  67 {
  68         return csum_add(csum, ~addend);
  69 }
  70
  71 static inline unsigned int
  72 csum_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
  79 static inline unsigned int
  80 csum_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