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 /*
20 * Fixes:
21 *
22 * Ralf Baechle : generic ipv6 checksum
23 * <ralf@waldorf-gmbh.de>
24 */
25
26 #ifndef _CHECKSUM_H
27 #define _CHECKSUM_H
28
29 #include <asm/types.h>
30 #include <asm/byteorder.h>
31 #include <net/ip.h>
32 #include <asm/uaccess.h>
33 #include <asm/checksum.h>
34
35 #ifndef _HAVE_ARCH_IPV6_CSUM
36
37 static __inline__ unsigned short int csum_ipv6_magic(struct in6_addr *saddr,
38 struct in6_addr *daddr,
39 __u16 len,
40 unsigned short proto,
41 unsigned int csum)
42 {
43
44 int carry;
45 __u32 ulen;
46 __u32 uproto;
47
48 csum += saddr->s6_addr32[0];
49 carry = (csum < saddr->s6_addr32[0]);
50 csum += carry;
51
52 csum += saddr->s6_addr32[1];
53 carry = (csum < saddr->s6_addr32[1]);
54 csum += carry;
55
56 csum += saddr->s6_addr32[2];
57 carry = (csum < saddr->s6_addr32[2]);
58 csum += carry;
59
60 csum += saddr->s6_addr32[3];
61 carry = (csum < saddr->s6_addr32[3]);
62 csum += carry;
63
64 csum += daddr->s6_addr32[0];
65 carry = (csum < daddr->s6_addr32[0]);
66 csum += carry;
67
68 csum += daddr->s6_addr32[1];
69 carry = (csum < daddr->s6_addr32[1]);
70 csum += carry;
71
72 csum += daddr->s6_addr32[2];
73 carry = (csum < daddr->s6_addr32[2]);
74 csum += carry;
75
76 csum += daddr->s6_addr32[3];
77 carry = (csum < daddr->s6_addr32[3]);
78 csum += carry;
79
80 ulen = htonl((__u32) len);
81 csum += ulen;
82 carry = (csum < ulen);
83 csum += carry;
84
85 uproto = htonl(proto);
86 csum += uproto;
87 carry = (csum < uproto);
88 csum += carry;
89
90 return csum_fold(csum);
91 }
92
93 #endif
94
95 #ifndef _HAVE_ARCH_COPY_AND_CSUM_FROM_USER
96 static inline
97 unsigned int csum_and_copy_from_user (const char *src, char *dst,
98 int len, int sum, int *err_ptr)
99 {
100 if (verify_area(VERIFY_READ, src, len) == 0)
101 return csum_partial_copy_from_user(src, dst, len, sum, err_ptr);
102
103 if (len)
104 *err_ptr = -EFAULT;
105
106 return sum;
107 }
108 #endif
109
110 #ifndef HAVE_CSUM_COPY_USER
111 static __inline__ unsigned int csum_and_copy_to_user
112 (const char *src, char *dst, int len, unsigned int sum, int *err_ptr)
113 {
114 sum = csum_partial(src, len, sum);
115
116 if (access_ok(VERIFY_WRITE, dst, len)) {
117 if (copy_to_user(dst, src, len) == 0)
118 return sum;
119 }
120 if (len)
121 *err_ptr = -EFAULT;
122
123 return -1; /* invalid checksum */
124 }
125 #endif
126
127 static inline unsigned int csum_add(unsigned int csum, unsigned int addend)
128 {
129 csum += addend;
130 return csum + (csum < addend);
131 }
132
133 static inline unsigned int csum_sub(unsigned int csum, unsigned int addend)
134 {
135 return csum_add(csum, ~addend);
136 }
137
138 static inline unsigned int
139 csum_block_add(unsigned int csum, unsigned int csum2, int offset)
140 {
141 if (offset&1)
142 csum2 = ((csum2&0xFF00FF)<<8)+((csum2>>8)&0xFF00FF);
143 return csum_add(csum, csum2);
144 }
145
146 static inline unsigned int
147 csum_block_sub(unsigned int csum, unsigned int csum2, int offset)
148 {
149 if (offset&1)
150 csum2 = ((csum2&0xFF00FF)<<8)+((csum2>>8)&0xFF00FF);
151 return csum_sub(csum, csum2);
152 }
153
154 #endif
155
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