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