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 __wsum csum_and_copy_from_user (const void __user *src, void *dst,
  31                                       int len, __wsum 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__ __wsum csum_and_copy_to_user
  45 (const void *src, void __user *dst, int len, __wsum 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 (__force __wsum)-1; /* invalid checksum */
  57 }
  58 #endif
  59
  60 #ifndef HAVE_ARCH_CSUM_ADD
  61 static inline __wsum csum_add(__wsum csum, __wsum addend)
  62 {
  63         u32 res = (__force u32)csum;
  64         res += (__force u32)addend;
  65         return (__force __wsum)(res + (res < (__force u32)addend));
  66 }
  67 #endif
  68
  69 static inline __wsum csum_sub(__wsum csum, __wsum addend)
  70 {
  71         return csum_add(csum, ~addend);
  72 }
  73
  74 static inline __sum16 csum16_add(__sum16 csum, __be16 addend)
  75 {
  76         u16 res = (__force u16)csum;
  77
  78         res += (__force u16)addend;
  79         return (__force __sum16)(res + (res < (__force u16)addend));
  80 }
  81
  82 static inline __sum16 csum16_sub(__sum16 csum, __be16 addend)
  83 {
  84         return csum16_add(csum, ~addend);
  85 }
  86
  87 static inline __wsum
  88 csum_block_add(__wsum csum, __wsum csum2, int offset)
  89 {
  90         u32 sum = (__force u32)csum2;
  91         if (offset&1)
  92                 sum = ((sum&0xFF00FF)<<8)+((sum>>8)&0xFF00FF);
  93         return csum_add(csum, (__force __wsum)sum);
  94 }
  95
  96 static inline __wsum
  97 csum_block_add_ext(__wsum csum, __wsum csum2, int offset, int len)
  98 {
  99         return csum_block_add(csum, csum2, offset);
 100 }
 101
 102 static inline __wsum
 103 csum_block_sub(__wsum csum, __wsum csum2, int offset)
 104 {
 105         u32 sum = (__force u32)csum2;
 106         if (offset&1)
 107                 sum = ((sum&0xFF00FF)<<8)+((sum>>8)&0xFF00FF);
 108         return csum_sub(csum, (__force __wsum)sum);
 109 }
 110
 111 static inline __wsum csum_unfold(__sum16 n)
 112 {
 113         return (__force __wsum)n;
 114 }
 115
 116 static inline __wsum csum_partial_ext(const void *buff, int len, __wsum sum)
 117 {
 118         return csum_partial(buff, len, sum);
 119 }
 120
 121 #define CSUM_MANGLED_0 ((__force __sum16)0xffff)
 122
 123 static inline void csum_replace4(__sum16 *sum, __be32 from, __be32 to)
 124 {
 125         __be32 diff[] = { ~from, to };
 126
 127         *sum = csum_fold(csum_partial(diff, sizeof(diff), ~csum_unfold(*sum)));
 128 }
 129
 130 /* Implements RFC 1624 (Incremental Internet Checksum)
 131  * 3. Discussion states :
 132  *     HC' = ~(~HC + ~m + m')
 133  *  m : old value of a 16bit field
 134  *  m' : new value of a 16bit field
 135  */
 136 static inline void csum_replace2(__sum16 *sum, __be16 old, __be16 new)
 137 {
 138         *sum = ~csum16_add(csum16_sub(~(*sum), old), new);
 139 }
 140
 141 struct sk_buff;
 142 void inet_proto_csum_replace4(__sum16 *sum, struct sk_buff *skb,
 143                               __be32 from, __be32 to, int pseudohdr);
 144 void inet_proto_csum_replace16(__sum16 *sum, struct sk_buff *skb,
 145                                const __be32 *from, const __be32 *to,
 146                                int pseudohdr);
 147
 148 static inline void inet_proto_csum_replace2(__sum16 *sum, struct sk_buff *skb,
 149                                             __be16 from, __be16 to,
 150                                             int pseudohdr)
 151 {
 152         inet_proto_csum_replace4(sum, skb, (__force __be32)from,
 153                                  (__force __be32)to, pseudohdr);
 154 }
 155
 156 #endif