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 /*
  20  *      Fixes:
  21  *
  22  *      Ralf Baechle                    :       generic ipv6 checksum
  23  *      <ralf@waldorf-gmbh.de>
  24  */
  25
  26 #ifndef _CHECKSUM_H
  27 #define _CHECKSUM_H
  28
  29 #include <asm/types.h>
  30 #include <asm/byteorder.h>
  31 #include <net/ip.h>
  32 #include <asm/uaccess.h>
  33 #include <asm/checksum.h>
  34
  35 #ifndef _HAVE_ARCH_IPV6_CSUM
  36
  37 static __inline__ unsigned short int csum_ipv6_magic(struct in6_addr *saddr,
  38                                                      struct in6_addr *daddr,
  39                                                      __u16 len,
  40                                                      unsigned short proto,
  41                                                      unsigned int csum)
  42 {
  43
  44         int carry;
  45         __u32 ulen;
  46         __u32 uproto;
  47
  48         csum += saddr->s6_addr32[0];
  49         carry = (csum < saddr->s6_addr32[0]);
  50         csum += carry;
  51
  52         csum += saddr->s6_addr32[1];
  53         carry = (csum < saddr->s6_addr32[1]);
  54         csum += carry;
  55
  56         csum += saddr->s6_addr32[2];
  57         carry = (csum < saddr->s6_addr32[2]);
  58         csum += carry;
  59
  60         csum += saddr->s6_addr32[3];
  61         carry = (csum < saddr->s6_addr32[3]);
  62         csum += carry;
  63
  64         csum += daddr->s6_addr32[0];
  65         carry = (csum < daddr->s6_addr32[0]);
  66         csum += carry;
  67
  68         csum += daddr->s6_addr32[1];
  69         carry = (csum < daddr->s6_addr32[1]);
  70         csum += carry;
  71
  72         csum += daddr->s6_addr32[2];
  73         carry = (csum < daddr->s6_addr32[2]);
  74         csum += carry;
  75
  76         csum += daddr->s6_addr32[3];
  77         carry = (csum < daddr->s6_addr32[3]);
  78         csum += carry;
  79
  80         ulen = htonl((__u32) len);
  81         csum += ulen;
  82         carry = (csum < ulen);
  83         csum += carry;
  84
  85         uproto = htonl(proto);
  86         csum += uproto;
  87         carry = (csum < uproto);
  88         csum += carry;
  89
  90         return csum_fold(csum);
  91 }
  92
  93 #endif
  94
  95 #ifndef _HAVE_ARCH_COPY_AND_CSUM_FROM_USER
  96 static inline
  97 unsigned int csum_and_copy_from_user (const char *src, char *dst,
  98                                       int len, int sum, int *err_ptr)
  99 {
 100         if (verify_area(VERIFY_READ, src, len) == 0)
 101                 return csum_partial_copy_from_user(src, dst, len, sum, err_ptr);
 102
 103         if (len)
 104                 *err_ptr = -EFAULT;
 105
 106         return sum;
 107 }
 108 #endif
 109
 110 #ifndef HAVE_CSUM_COPY_USER
 111 static __inline__ unsigned int csum_and_copy_to_user
 112 (const char *src, char *dst, int len, unsigned int sum, int *err_ptr)
 113 {
 114         sum = csum_partial(src, len, sum);
 115
 116         if (access_ok(VERIFY_WRITE, dst, len)) {
 117                 if (copy_to_user(dst, src, len) == 0)
 118                         return sum;
 119         }
 120         if (len)
 121                 *err_ptr = -EFAULT;
 122
 123         return -1; /* invalid checksum */
 124 }
 125 #endif
 126
 127 static inline unsigned int csum_add(unsigned int csum, unsigned int addend)
 128 {
 129         csum += addend;
 130         return csum + (csum < addend);
 131 }
 132
 133 static inline unsigned int csum_sub(unsigned int csum, unsigned int addend)
 134 {
 135         return csum_add(csum, ~addend);
 136 }
 137
 138 static inline unsigned int
 139 csum_block_add(unsigned int csum, unsigned int csum2, int offset)
 140 {
 141         if (offset&1)
 142                 csum2 = ((csum2&0xFF00FF)<<8)+((csum2>>8)&0xFF00FF);
 143         return csum_add(csum, csum2);
 144 }
 145
 146 static inline unsigned int
 147 csum_block_sub(unsigned int csum, unsigned int csum2, int offset)
 148 {
 149         if (offset&1)
 150                 csum2 = ((csum2&0xFF00FF)<<8)+((csum2>>8)&0xFF00FF);
 151         return csum_sub(csum, csum2);
 152 }
 153
 154 #endif