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 157