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
csum_and_copy_from_user(const void __user * src,void * dst,int len,__wsum sum,int * err_ptr)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
csum_and_copy_to_user(const void * src,void __user * dst,int len,__wsum sum,int * err_ptr)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
csum_add(__wsum csum,__wsum addend)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
csum_sub(__wsum csum,__wsum addend)67 static inline __wsum csum_sub(__wsum csum, __wsum addend)
68 {
69 return csum_add(csum, ~addend);
70 }
71
72 static inline __wsum
csum_block_add(__wsum csum,__wsum csum2,int offset)73 csum_block_add(__wsum csum, __wsum csum2, int offset)
74 {
75 u32 sum = (__force u32)csum2;
76 if (offset&1)
77 sum = ((sum&0xFF00FF)<<8)+((sum>>8)&0xFF00FF);
78 return csum_add(csum, (__force __wsum)sum);
79 }
80
81 static inline __wsum
csum_block_sub(__wsum csum,__wsum csum2,int offset)82 csum_block_sub(__wsum csum, __wsum csum2, int offset)
83 {
84 u32 sum = (__force u32)csum2;
85 if (offset&1)
86 sum = ((sum&0xFF00FF)<<8)+((sum>>8)&0xFF00FF);
87 return csum_sub(csum, (__force __wsum)sum);
88 }
89
csum_unfold(__sum16 n)90 static inline __wsum csum_unfold(__sum16 n)
91 {
92 return (__force __wsum)n;
93 }
94
95 #define CSUM_MANGLED_0 ((__force __sum16)0xffff)
96
csum_replace4(__sum16 * sum,__be32 from,__be32 to)97 static inline void csum_replace4(__sum16 *sum, __be32 from, __be32 to)
98 {
99 __be32 diff[] = { ~from, to };
100
101 *sum = csum_fold(csum_partial(diff, sizeof(diff), ~csum_unfold(*sum)));
102 }
103
csum_replace2(__sum16 * sum,__be16 from,__be16 to)104 static inline void csum_replace2(__sum16 *sum, __be16 from, __be16 to)
105 {
106 csum_replace4(sum, (__force __be32)from, (__force __be32)to);
107 }
108
109 struct sk_buff;
110 extern void inet_proto_csum_replace4(__sum16 *sum, struct sk_buff *skb,
111 __be32 from, __be32 to, int pseudohdr);
112
inet_proto_csum_replace2(__sum16 * sum,struct sk_buff * skb,__be16 from,__be16 to,int pseudohdr)113 static inline void inet_proto_csum_replace2(__sum16 *sum, struct sk_buff *skb,
114 __be16 from, __be16 to,
115 int pseudohdr)
116 {
117 inet_proto_csum_replace4(sum, skb, (__force __be32)from,
118 (__force __be32)to, pseudohdr);
119 }
120
121 #endif
122