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 29static 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 44static __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 61static 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 69static inline __wsum csum_sub(__wsum csum, __wsum addend) 70{ 71 return csum_add(csum, ~addend); 72} 73 74static 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 82static inline __sum16 csum16_sub(__sum16 csum, __be16 addend) 83{ 84 return csum16_add(csum, ~addend); 85} 86 87static inline __wsum 88csum_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 96static inline __wsum 97csum_block_add_ext(__wsum csum, __wsum csum2, int offset, int len) 98{ 99 return csum_block_add(csum, csum2, offset); 100} 101 102static inline __wsum 103csum_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 111static inline __wsum csum_unfold(__sum16 n) 112{ 113 return (__force __wsum)n; 114} 115 116static 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 123static inline void csum_replace4(__sum16 *sum, __be32 from, __be32 to) 124{ 125 *sum = csum_fold(csum_add(csum_sub(~csum_unfold(*sum), from), to)); 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 */ 134static inline void csum_replace2(__sum16 *sum, __be16 old, __be16 new) 135{ 136 *sum = ~csum16_add(csum16_sub(~(*sum), old), new); 137} 138 139struct sk_buff; 140void inet_proto_csum_replace4(__sum16 *sum, struct sk_buff *skb, 141 __be32 from, __be32 to, int pseudohdr); 142void inet_proto_csum_replace16(__sum16 *sum, struct sk_buff *skb, 143 const __be32 *from, const __be32 *to, 144 int pseudohdr); 145 146static 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 154static inline __wsum remcsum_adjust(void *ptr, __wsum csum, 155 int start, int offset) 156{ 157 __sum16 *psum = (__sum16 *)(ptr + offset); 158 __wsum delta; 159 160 /* Subtract out checksum up to start */ 161 csum = csum_sub(csum, csum_partial(ptr, start, 0)); 162 163 /* Set derived checksum in packet */ 164 delta = csum_sub(csum_fold(csum), *psum); 165 *psum = csum_fold(csum); 166 167 return delta; 168} 169 170static inline void remcsum_unadjust(__sum16 *psum, __wsum delta) 171{ 172 *psum = csum_fold(csum_sub(delta, *psum)); 173} 174 175#endif 176