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
60static 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
67static inline __wsum csum_sub(__wsum csum, __wsum addend)
68{
69	return csum_add(csum, ~addend);
70}
71
72static inline __wsum
73csum_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
81static inline __wsum
82csum_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
90static inline __wsum csum_unfold(__sum16 n)
91{
92	return (__force __wsum)n;
93}
94
95#define CSUM_MANGLED_0 ((__force __sum16)0xffff)
96#ifdef CONFIG_INET_GRO
97static 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
104static inline void csum_replace2(__sum16 *sum, __be16 from, __be16 to)
105{
106	csum_replace4(sum, (__force __be32)from, (__force __be32)to);
107}
108
109struct sk_buff;
110extern void inet_proto_csum_replace4(__sum16 *sum, struct sk_buff *skb,
111				     __be32 from, __be32 to, int pseudohdr);
112
113static 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#endif /* CONFIG_INET_GRO */
121#endif
122