checksum.h 2.4 KB

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  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. #ifndef _CHECKSUM_H
  19. #define _CHECKSUM_H
  20. #include <linux/errno.h>
  21. #include <asm/types.h>
  22. #include <asm/byteorder.h>
  23. #include <asm/uaccess.h>
  24. #include <asm/checksum.h>
  25. #ifndef _HAVE_ARCH_COPY_AND_CSUM_FROM_USER
  26. static inline
  27. __wsum csum_and_copy_from_user (const void __user *src, void *dst,
  28. int len, __wsum sum, int *err_ptr)
  29. {
  30. if (access_ok(VERIFY_READ, src, len))
  31. return csum_partial_copy_from_user(src, dst, len, sum, err_ptr);
  32. if (len)
  33. *err_ptr = -EFAULT;
  34. return sum;
  35. }
  36. #endif
  37. #ifndef HAVE_CSUM_COPY_USER
  38. static __inline__ __wsum csum_and_copy_to_user
  39. (const void *src, void __user *dst, int len, __wsum sum, int *err_ptr)
  40. {
  41. sum = csum_partial(src, len, sum);
  42. if (access_ok(VERIFY_WRITE, dst, len)) {
  43. if (copy_to_user(dst, src, len) == 0)
  44. return sum;
  45. }
  46. if (len)
  47. *err_ptr = -EFAULT;
  48. return (__force __wsum)-1; /* invalid checksum */
  49. }
  50. #endif
  51. static inline __wsum csum_add(__wsum csum, __wsum addend)
  52. {
  53. u32 res = (__force u32)csum;
  54. res += (__force u32)addend;
  55. return (__force __wsum)(res + (res < (__force u32)addend));
  56. }
  57. static inline __wsum csum_sub(__wsum csum, __wsum addend)
  58. {
  59. return csum_add(csum, ~addend);
  60. }
  61. static inline __wsum
  62. csum_block_add(__wsum csum, __wsum csum2, int offset)
  63. {
  64. u32 sum = (__force u32)csum2;
  65. if (offset&1)
  66. sum = ((sum&0xFF00FF)<<8)+((sum>>8)&0xFF00FF);
  67. return csum_add(csum, (__force __wsum)sum);
  68. }
  69. static inline __wsum
  70. csum_block_sub(__wsum csum, __wsum csum2, int offset)
  71. {
  72. u32 sum = (__force u32)csum2;
  73. if (offset&1)
  74. sum = ((sum&0xFF00FF)<<8)+((sum>>8)&0xFF00FF);
  75. return csum_sub(csum, (__force __wsum)sum);
  76. }
  77. static inline __wsum csum_unfold(__sum16 n)
  78. {
  79. return (__force __wsum)n;
  80. }
  81. #define CSUM_MANGLED_0 ((__force __sum16)0xffff)
  82. #endif